~T~ Mosby An Affiliate ofElsevier
ISBN-13: 978-1-56053-490-7 ISBN-10: 1-56053-490-7
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Library of Congress Control Number: 2002113077 SLEEP MEDICINE PEARLS, 2nd edition
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CONTRIBUTORS These individuals were coauthors on selected patient cases andfundamentals:
Mary H. Wagner, MD Assistant Professor of Pediatrics, Department of Pediatric Pulmonary Medicine, University of Florida, Gainesville, Florida • Patients 63, 64, 65, 77 Stephan Eisenschenk, MD Assistant Professor of Neurology, University of Florida, Gainesville, Florida • Fundamentals of Sleep Medicine 20, Patients 98, 100 Robin L. Gilmore, MD Professor of Neurology, University of Florida, Gainesville, Florida • Fundamentals of Sleep Medicine 20, Patients 98, 100 Susan M. Harding, MD Associate Professor of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama, Birmingham, Alabama • Patients 97, 99
vii
CREDIT REFERENCES Fundamentals of Sleep Medicine 10 Figure 4 from Farre R, Rigau J, Montserrat JM, et al: Relevance of linearizing nasal prongs for assessing hypopneas and flow limitation during sleep. Am J Respir Crit Care Med 200 I; 163:494-497; with permission. alld Figure 6 from Jasani R, Sanders MH, Strollo PJ Jr: Diagnostic studies for sleep apnea/hypopnea. In Johnson JT, Gluckman JL, Sanders MH (eds): Management of Obstructive Sleep Apnea. London, Martin Dunitz, 2002, p 68; with permission.
Patient 29 Figure 3 from Norman RG, Ahmed MM, Walsleben JA, Rapoport OM: Detection of respiratory events during NPSG: Nasal cannula/pressure sensor versus thermistor. Sleep 1997; 20: 1175-1184; with permiSSIOn.
Fundamentals of Sleep Medicine 12 Figure from Ayappa I, Norman RG, Krieger AC, et al: Noninvasive detection of respiratory effortrelated arousals (RERAs) by a nasal cannula/pressure transducer system. Sleep 2000;23:763-771, with permission. Patient 34 Second figure from Weigand L, Zwillich CW, Wiegand 0, White DP: Changes in upper airway muscle activation and ventilation during phasic REM sleep in normal men. J Appl Physiol 1991; 71:488-497; with permission. Fundamentals of Sleep Medicine 14 Figure I from Condos R, Norman RG, Krishnasamy I, et al: Flow limitation as a noninvasive assessment of residual upper-airway resistance during continuous positive airway pressure therapy of obstructive sleep apnea. Am J Respir Crit Care Med 1994; 150:475-480; with permission. Patient 41 Figure, images A and B, from Berry RB: Medical therapy. In Johnson JT, Gluckman JL, Sanders MH (eds): Management of Obstructive Sleep Apnea. London, Martin Dunitz, 2002, p 95; with permission. Patient 42 Figure from Martins de Araujo MT, Vieira SB, Vasquez EC, Fleury B: Heated humification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy. Chest 2000; 117: 142-147; with permission. Patient 45 Figure 2 from Sanders MH, Kern N: Obstructive sleep apnea treated by independently adjusted inspiratory and expiratory positive airway pressures via nasal mask. Chest 1990; 98:317-324; with permission. Patient 48 Figure from Troell RJ, Strom CG: Surgical therapy for snoring. Fed Pract 1997; 14:29-52; with permission. Patient 50 Figure I from Li KK: Surgical management of OSA. In Lee-Chiong TL, Sateia MJ, Carskadon MA (eds): Sleep Medicine. Philadelphia, Hanley & Belfus, 2002, pp 435-446; with permission. alld Figures 2 & 3 from Troell RJ, Powel NB, Riley RW: Hypopharyngeal airway surgery for obstructive sleep apnea syndrome. Semin Respir Crit Care Med 1998; 19:175-183; with permission.
Patient 85 Figure from Aldrich MS, Chervin RD, Malow BA: Value of the multiple sleep latency test for the diagnosis of narcolepsy. Sleep 1997; 20:620-629; with permission. viii
PREFACE TO THE FIRST EDITION
Sleep Medicine Pearls. an exploration of the diagnostic tools and physiologic principles of sleep medicine, offers 101 cases covering a wide spectrum of disorders that affect sleep. The patient presentations and the questions and discussions challenge readers at all levels with varying degrees of complexity. This book differs from others in The Pearl Seriesv in that 13 sections of basic didactic material, called Fundamentals of Sleep Medicine, are included for the many physicians who have received little or no formal training in sleep medicine. The cases following each Fundamental illustrate the concepts outlined in the tutorial section. There also is a convenient Glossary of sleep medicine terms at the back of the book. Some of the discussions center on problems in diagnosis or sleep monitoring; others, evaluate complex treatment choices. The goal was to present information relevant to the everyday interpretation of sleep studies and to the treatment of a wide variety of sleep problems. I hope that Sleep Medicine Pearls is useful not only to physicians who are new to sleep medicine, but also to more experienced doctors caring for patients with sleep disorders.
PREFACE TO THE SECOND EDITION
In the 4 years since the publication of the first edition of Sleep Medicine Pearls much has changed in the field of sleep disorders medicine. I have thoroughly updated all of the first edition cases that are included here and have added many new patients and relevant Fundamentals of Sleep Medicine. This second edition contains additional material about nasal pressure monitoring, the controversy over definitions of hypopnea, autoCPAP, the new Medicare guidelines for CPAP reimbursement, pediatric sleep medicine, nocturnal seizures, digital polysomnography, narcolepsy, modafinil, and the restless legs syndrome. Where possible I have added more figures and tables to make discussions clearer. The cases in Sleep Medicine Pearls. 2nd edition. illustrate problems that all physicians caring for patients with sleep disorders face every day. The reader response to the first edition was very gratifying and made all the hard work worthwhile. I hope the new edition will prove as useful, both to physicians being introduced to sleep medicine and to those who are more experienced but dealing with difficult diagnostic and management issues. RICHARD B. BERRY, MD
ix
Dedication I dedicate the second edition of Sleep Medicine Pearls to my wife, Catherine Ann Berry, and my son, David Louie Berry. They are my greatest joy.
ACKNOWLEDGMENTS I wish to acknowledge the help of the sleep laboratory staff at the Malcom Randall VAMC in Gainesville, Florida, including Tom Williford, Jolene Burley, Gilbert Hill, Gary Koch, Carol Crampton, and Michelle Baker, for their assistance in acquiring many of the new sleep tracings added to this second edition. The staff at the University of Florida Sleep Disorders Center at Shands at AGH also helped in identifying good cases to present, including several pediatric cases. The team there includes John Crawford (clinical coordinator), Vicki Moore, Sharon Blasiole, Timothy Stone, Claudette Jouett, and Mike Robinette. Greg Westyle of the medical media section at the Malcom Randall VAMC took many of the photographs added to the second edition. Finally, the patience and attention to detail of Hanley & Belfus Editor Jacqueline Mahon was essential to completion of the book.
xi
FUNDAMENTALS OF SLEEP MEDICINE 1
Sleep Stages and Electroencephalographic Patterns
Sleep is divided into nonrapid eye movement (NREM) and rapid eye movement (REM) sleep. NREM sleep is further subdivided into stages 1--4. Stages 1 and 2 are light sleep; stages 3 and 4 are deep sleep, also called slow wave or delta sleep. Time is divided into epochs (commonly 30 seconds each). The sleep stage assigned to each epoch is the stage occupying the majority of time within that epoch. Sleep staging criteria depend on electroencephalographic (EEG), eye movement or electro-oculographic (EOG), and chin (submental) electromyographic (EMG) recordings (see Appendix II). Recognition of certain characteristic EEG patterns is essential for sleep staging (see figure next page). By EEG convention, negative polarity results in an upward deflection. This is often confusing for physicians being introduced to EEG. Sleep Stages Wake-stage W NREM sleep Stage 1 Stage 2 Stage 3 Stage 4 REM sleep-stage REM
Recorded For Staging EEG-central, occipital EOG-eye movement EMG-chin/submental
EEG terminology defines waves by their frequency in cycles per second, or hertz (Hz). The classically described frequency ranges are: delta « 4 Hz), theta (4-7 Hz), alpha (8-13 Hz), beta (> 13 Hz). Alpha waves are commonly noted when the patient is in an awake but relaxed state with the eyes closed. They are best recorded over the occiput and are attenuated when the eyes are open. Bursts of alpha waves also are seen during brief awakenings from sleep called arousals. Stage 1 is scored when alpha activity occupies less than 50% of an epoch. The EEG of stage 1 shows a low-voltage, mixed-frequency pattern with theta wave activity. Near the transition from stage 1 to stage 2 sleep, vertex sharp waves-high amplitude negative waves (upward deflection on EEG tracings) with a short duration -occur. They are more prominent in central than occipital EEG tracings. Stage 2 is defined by the presence of either sleep spindles or K complexes. Sleep spindles are oscillations of 12-14 Hz with a duration of 0.5-1.5 seconds. They may persist into stages 3 and 4, but usually do not occur in stage REM. The K complex is a high-amplitude, biphasic wave of at least 0.5-second duration. As classically defined, a K complex consists of an initial sharp, negative voltage (by convention an upward deflection) followed by a positive deflection (down) slow wave. Spindles frequently are superimposed on K complexes. Sharp waves differ from K complexes in that they are narrower, not biphasic, and usually of lower amplitude. As sleep deepens, slow (delta) waves appear. These are high-amplitude, broad waves. In human sleep scoring, by convention, slow waves are defined as EEG activity slower than 2 Hz (longer than 0.5-second duration) that have an amplitude (peak to peak) of > 75 microvolts as measured in central EEG tracings. Stage 3 is scored when 20-50% of an epoch has slow wave activity meeting this criteria. Stage 4 is scored when more than 50% of an epoch contains slow wave activity. As a K complex resembles slow wave activity, differentiating the two is sometimes difficult. However, by definition a K complex should stand out (be distinct) from the lower-amplitude, background EEG
1
5 sec (
~ sharp wave
spindle
~
i ~ftf\
~r\ slow waves
saw tooth waves activity. Therefore, a continuous series of high-voltage slow waves would not be considered a series of K complexes. Stage REM is not defined by a characteristic EEG wave pattern, although saw-tooth waves may be present. Saw-tooth waves are in the theta frequency range and may be notched. The EEG of stage REM looks much like that of stage I sleep-a low-voltage, mixed-frequency pattern. Stage REM is defined by eye movement and chin EMG criteria (see Appendix II and Patient 10). Movement time (MT) is not really a sleep stage but is used as the designation for epochs in which the EEG is obscured by movement artifact. That is, the epoch is not really scorable. Movement time is scored when more than 50% of the epoch is obscured by artifact. It should not be used when the patient is clearly awake. If an epoch meeting criteria for movement time is between two epochs of wake, the epoch is also scored as wake. Movement time should not be confused with the term movement arousal (see Patient 12).
REFERENCES 1. Rechtschaffen A. Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of
Human Sleep. Los Angeles. Brain Information Service/Brain Research Institute. UCLA. 1968. 2. Williams RL. Karacan I. Hursch CJ: Electroencephalography of Human Sleep: Clinical Applications. New York. John Wiley & Sons. 1974. 3. West P. Kryger MH: Sleep and respiration: Terminology and methodology. Clin Chest Med (Symposium on Sleep Disorders) 1985; 6:691-718. 4. Caraskadon MA. Rechschaffen A: Monitoring and staging human sleep. In Kryger MH. Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
2
PATIENT 1 A 30-year-old man taking a hypnotic nightly A 30-year-old man was studied for complaints of frequent awakenings during the night. He had been using triazolam, a benzodiazepine hypnotic, for 5 years to maintain sleep. Several physicians had encouraged him to discontinue this medication but he had been unable to do so. The patient gave a history of snoring, and a sleep study was ordered to eliminate the possibility that the frequent awakenings were secondary to obstructive sleep apnea. He was asked to reduce the dose of triazolam from .25 mg to .125 mg for I week and then discontinue the medication for at least 2 weeks before the upcoming sleep study. Figure: A sample tracing of the central electroencephalogram (EEG) taken during the sleep study is shown below.
Question:
Do you think the patient complied with the request to discontinue triazolam?
-
1 sec
3
Diagnosis:
Frequent sleep spindles suggest continued benzodiazepine use.
Discussion: Benzodiazepine use often is associated with a large increase in spindle activity. The frequent spindles are often called pseudo-spindles or drug spindles. They sometimes can be differentiated from typical spindles (12-14 Hz) by a slightly higher frequency of 15 Hz. Drug spindles may appear in REM sleep and immediately at sleep onset. Some recommend using non-spindle criteria for staging sleep. However, this is often difficult, and benzodiazepine intake usually results in an increase in the scored stage 2 sleep. This medication also slightly curtails sleep stages 3 and 4 and reduces REM sleep Sleep spindles are secondary to thalamocortical oscillations and are characteristic of stage 2 sleep, although they may occur in stages 3 and 4 sleep. They mayor may not have the shape of yarn wound on spindles, which gives them their name (see figure below). When the healthcare provider first is learning sleep staging, he or she may encounter some difficulty distinguishing sleep spindles from alpha activity. Alpha activity (8-13 Hz) is somewhat slower. Additionally, spindles usually occur
•
Spindle shape
1 sec
4
in short bursts, unlike the almost continuous spindle activity noted in the present study. The EEG tracing on the next page shows a sleep spindle during stage 2 sleep (A) followed by lengthy alpha activity (B). With digital monitoring systems, you can change the time base from the usual 30-second window (paper speed equivalent of 10 mm/sec) to a 10second window (paper speed 30 mm/sec eqivalent) and make measurements of EEG activity. In the program shown on page 5, the two cursors are placed on adjacent peaks of activity of a burst of spindle activity. The first number in the difference is seconds and the second is the frequency in seconds or (12.5 Hz = 1/.08 sec). An alternative is to count the peaks in 1 second. In the present case, the tremendous amount of spindle activity (refer to figure on page 3) suggests that the patient had continued to take triazolam. A urine drug screen at the time of the sleep study revealed the presence of a benzodiazepine. When confronted with this evidence, the patient admitted that he was dependent on the medication.
Clinical Pearls I. Ubiquitous sleep spindle (or pseudo-spindle) activity suggests that the patient is on a benzodiazepine. 2. Urine drug screens are useful in patients possibly dependent on medication who are undergoing a sleep study "off" medication. 3. Knowledge of medications the patient is taking (or is refraining from taking) at the time of the sleep study often is important in interpreting the results.
REFERENCES 1. Johnson LC, Hanson K, Bickford RG: Effect of flurazepam on sleep spindles and K complexes. Electroencephalogr Clin Neu-
rophysiol 1976; 40:67-77. 2. Johnson LC, Spinweber CL, Seidel WF, et al: Sleep spindle and delta changes during chronic use of a short acting and a long acting benzodiazepine hypnotic. Electroencephalogr Clin Neurophysiol 1983; 55:662-667. 3. Obermeyer WH, Beneca RM: Effects of drugs on sleep. Neurol Clin (Sleep Disorders II) 1996; 14:827-840. 4. Butkov N: Atlas of Clinical Polysomnography. Ashland, OR, Synapse Media, 1996, pp 291-292.
5
PATIENT 2 A 30-year-old man with insomnia A 30-year-old man with insomnia of S-year duration underwent a sleep study. The IS-second sleep tracing shown below (central and occipital EEG) illustrates a transition from wakefulness to sleep. The tracing was preceded by an epoch with prominent alpha activity for the entire 30 seconds (stage Wake). Alpha activity stopped during the IS-second tracing and was absent for the remainder of the epoch (stage I).
Question:
A
Where does alpha activity stop-at point A or B?
Central
Occipital
6
B
5 sec
Answer:
Prominent alpha activity ends at point B.
Discussion: While recording occipital EEG leads is optional, failure to do so may underestimate the degree of wakefulness. Occipital leads allow more precise monitoring of the timing of sleep onset. The transition from drowsy stage Wake to stage 1 sleep is characterized by a reduction in alpha wave activity to less than 50% of the epoch. Unfortunately, this reduction does not always mean sleep is present. Alpha activity also is suppressed when the eyes are open. Such a state usually is accompanied by rapid eye movements (see Fundamentals 4) or blinks. The EEG of eyes-open wakefulness typically has considerable high-frequency activity. In contrast, the EEG of stage 1 has low-voltage, slower activity in the theta range. During biocalibrations at the start of the sleep study, patients are asked to close and then open their eyes. This allows the sleep scorer to note the EEG and eye lead patterns of eyes-open and eyes-closed wakefulness for the patient.
In the tracing below, alpha activity is prominent in the central leads until the command "eyes open" (EO) is given. Note the eye blinks (E8) in the right (ROC-AI) and left (LOC-A 2 ) eye leads. In this tracing, alpha activity is more prominent in the central leads than in the occipital leads and also is quite prominent in the eye leads. The presence of rapid eye movements or blinks in the second part of the tracing is typical of eyes-open wakefulness. In the present patient, alpha activity is not prominent from point A to point B in the central EEG lead (refer to previous figure). However, clear-cut, highamplitude alpha activity persists in the occipital lead until point B, demonstrating the utility of occipital leads in detecting alpha activity and sleep onset. After point B, waves in the theta range (lower frequency) become more prominent. The transition from alpha activity to theta activity at point B is consistent with transition from stage Wake to stage 1 sleep.
alpha activity
chin EMG
~."... t_r_-+..."'l.jW.'.
ilIoIlo.....__...........
~t.
.
to
II"
Clinical Pearls 1. Alpha activity is usually more prominent in occipital than central EEG tracings. 2. Prominent alpha activity in the EEG is common during drowsy (eyes-closed) wakefulness. 3. Alpha activity is suppressed during wakefulness when the eyes are open.
REFERENCES 1. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute, UCLA, 1968. 2. West P, Kryger MH: Sleep and respiration: Terminology and methodology. Clin Chest Med (Symposium on Sleep Disorders) 1985; 6:691-718.
7
-
FUNDAMENTALS OF SLEEP MEDICINE 2
Electroencephalographic Lead Placement
Standard monitoring to detect the presence and stage of sleep requires only a few of the traditional EEG leads. The international 10-20 nomenclature for EEG electrode placement is used. The 10-20 terminology refers to the fact that the electrodes are positioned at either 10% or 20% of the distance between landmarks (see figure). Standard landmarks include the nasion (bridge of the nose) and inion (prominence at the base of the occiput). The distance between the two preauricular points also is an important standard. In the 10-20 system, even-numbered subscripts refer to the right side of the head and odd-numbered subscripts to the left. For example, C 3 and C 4 are the left and right central leads, respectively. These are placed along a line running between the two preauricular points and down 20% of this distance from the vertex.
Vertex 20%
t
20 %
20%
~
.+-C4
•••.{J'. 0. %. ,-.' _100,{,
~ ,/
!20%
. . . . • •••
< ~ea::lar Point
Central leads are the minimum required for staging sleep. Sleep spindles, K complexes, and slow waves can all be seen in these leads. The other important sleep EEG leads are the right and left occipital leads (02 and 01)' These are placed slightly off midline and above the level of the inion and preauricular points (as shown in the figure). The occipital leads are important for detecting alpha waves. Sometimes alpha waves will be detected in the occipital leads and not the central leads. Recognition of alpha activity is important for detecting transitions between wake and sleep. Standard EEG monitoring for sleep studies records the voltage difference between an exploring electrode and a reference electrode (bipolar). The electrode pair (exploring electrode-reference electrode) is called a derivation. The standard reference electrodes are the left and right mastoid leads (AI and A2) · The mastoid electrode on the opposite side of the head from the exploring electrode usually is chosen as
8
the reference (C,-A 2 or C 4-A\, 02-A\ or 0\-A 2) to produce the greatest voltage difference. Typically, the C" C 4, 02' 01' A 2, and AI leads all are placed. However, only one set of central and occipital leads is recorded at one time (for example, C,-A 2 and 0,-A 2). The other leads are available if one of the monitored leads becomes defective during the night, allowing continued recording without awakening the patient to place new leads. EEG Monitoring RIGHT
LEFT
Central
C4
C,
Occipital
°2
°1
Mastoid
A2
AI
ELECTRODES
In digital recording systems with a large number of channels, it is often possible to record two central and two occipital channels simultaneously. In some digital systems, the central, occipital, and mastoid electrodes are recorded against a single reference electrode (ref) typically placed on the midline of the scalp (referential recording). Traditional bipolar tracings can be viewed by digital subtraction (C4-ref) (Aj-ref ) = C 4-A I. An advantage is that you can choose any electrode pair to display. The disadvantage is that failure of the reference electrode ruins the recording from all electrodes (see Patient 21). The visual appearance of the EEG tracings depends not only on lead placement but also on the paper speed, amplifier gain, and filter settings. The standard paper speed for sleep studies is 10 millimeters per second. At this speed, 30 seconds (the usual epoch length) is 30 centimeters or one page of standard paper. Other time scales are better for respiratory events. The paper speed for clinical EEG studies usually is 15-30 mm/sec. This faster speed is useful for recognition of seizure activity. Another advantage of digital systems is that different page lengths (virtual paper speeds) can be viewed during recording or review. A 3D-second window (10 mm/sec) is used for scoring sleep, 60- to 240-second windows for scoring respiratory events and changes in arterial oxygen saturation, and IO-second windows (30 mm/sec) for seizure detection or determining the frequency of EEG activity. The standard EEG amplifier gain adjustment for sleep studies is 50 microvolts equals I centimeter of pen deflection. Calibration of the EEG amplitude is important for detecting stages 3 and 4 sleep because they have an EEG voltage criteria. In digital systems, calibration signals can also be recorded to verify that the gain is accurate. Amplitude gridlines can be placed on central EEG channels to facilitate scoring of sleep by amplitude criteria.
REFERENCES I. Rechtschaffen A. Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles. Brain Information Service/Brain Research Institute. UCLA, 1968. 2. Williams RL. Karacan I. Hursch CJ: Electroencephalography of Human Sleep: Clinical Applications. New York. John Wiley & Sons. 1974. 3. Caraskadon MA, Rechschaffen A: Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
9
PATIENT 3 A 50-year-old man with insomnia A 30-second epoch of the central EEG (C 3-A,) was recorded during the sleep study of this patient and is shown below as two 15-second segments. The dotted lines show 75 microvolts (p,v) of deflection. The dark bars above the segments mark slow wave activity meeting voltage criteria (~ 75 fLV peak to peak). The numbers above the bars are the approximate durations in seconds.
Question:
What stage is this epoch?
5.0
3.0
~5UV 1 sec
10
7.0
2.0
Answer:
This epoch is in stage 4.
Discussion: Identification of sleep stages 3 and 4 depends on determining the amount of slow wave activity meeting voltage criteria. Slow wave activity for the purpose of sleep staging is slower than 2 Hz (longer than 0.5-second duration) and the amplitude is > 75 fLV peak to peak. In paper recording, the standard calibration is 50 fLV equals I cm pen deflection. Thus, 75 fLV is equivalent to a pen deflection of 1.5 ern, Digital recording allows you to place amplitude gridlines on the central EEG tracing during review to assist with scoring. In the tracing below, grid lines are set at - 37.5 and + 37.5 microvolts (difference of 75 uv), Stage 3 is scored when 20-50% of the epoch has slow wave activity meeting voltage criteria (6-15 seconds of a 30-second epoch). Stage 4 is scored when more than 50% of an epoch contains such slow wave activity. Stage 2 has less than 20% (6 seconds in a 30-second epoch) of slow wave activity. Of course, to be scored as stage 2 the epoch also must meet other criteria for stage 2 (sleep spindles or K complexes). As humans age, the amplitude of the EEG during sleep diminishes. Therefore, slow wave activity may be present in older patients but may not meet voltage criteria. In young subjects, stage 3 is relatively brief, and most slow wave sleep is stage 4. In
older subjects, most of slow wave sleep is stage 3. Some authorities are against using a voltage criteria for scoring sleep, but this is the standard practice. Note that the amplitude of the slow wave activity recorded can be diminished if the low-frequency filter is set too high (y, amp equals I or higher, meaning that a signal of I Hz is reduced to 50% of its original amplitude by the filter). Thus, it is important to know the filter settings and to be informed if they are changed (e.g., to diminish artifact) during the night. In the present case, approximately 17 seconds of the 30-second epoch contained slow wave activity meeting voltage criteria. Therefore, the epoch is scored as stage 4. Note that most of the high-voltage, slow wave activity was present in the first portion of the epoch. In actual practice, detailed measurement of the duration of slow wave activity is unnecessary. An "eyeball estimate" usually suffices. Epochs that are on the borderline between stages 2 and 3 or stages 3 and 4 may necessitate more careful examination, but for most clinical studies such precision is not warranted. Even authorities on sleep staging can disagree on whether a given segment of the record meets criteria. Faster EEG activity often is superimposed on underlying slow activity, making visual interpretation somewhat arbitrary. Many sleep laboratories report the sum of stages 3 and 4.
+37.5 uv -37.5
UV +-----i---+--+---t-"-+----+-r-+-...:.r----+
I
75 uv
~
1 sec Clinical Pearls I. Scoring of stages 3 and 4 depends on identification of the percentage of the epoch occupied by slow wave activity meeting voltage (amplitude) criteria (> 75 fLV peak to peak). 2. The appearance of a record and the amount of slow wave sleep scored depends on the voltage calibration of the EEG tracings and the filter settings (especially the low-frequency filter). 3. Most digital systems allow placement of amplitude gridlines during review that can assist in determining if amplitude criteria are met.
REFERENCES I. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles. Brain Information Service/Brain Research Institute, UCLA, 1968. 2. Tyner FS. Knot JR, Mayer WB: Fundamentals of EEG technology. New York, Raven Press, 1983. 3. Caraskadon MA, Rechschaffen A : Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
11
FUNDAMENTALS OF SLEEP MEDICINE 3
Eye Movement Monitoring
Electro-oculographic (eye movement) leads typically are placed at the outer corners of the eyes-at the right outer canthus (ROC) and the left outer canthus (LaC). In a common approach, two eye channels are recorded and the eye electrodes are referenced to the opposite mastoid (ROC-AI and LOC-A 2) . However, some sleep centers use the same mastoid electrode as a reference (ROC-AI and LaC-AI)' To detect vertical as well as horizontal eye movements, one electrode is placed slightly above and one slightly below the eyes (see figure). Recording of eye movements is possible because a potential difference exists across the eyeball: front positive ( +), back negative (- ). Eye movements are detected by electro-oculographic recording of voltage changes. When the eyes move toward an electrode, a positive voltage is recorded (see ROC figure below). By standard convention, polygraphs are calibrated so that a negative LOC voltage causes an upward pen deflection (negative polarity up). Thus, eye movement toward an electrode results in a downward deflection. Note that movement of both of the eyes is always toward one electrode and away from the other because eye movements are conjugate. If the eye channels are calibrated with the same polarity settings, eye movements produce out-or-phase deflections in the two eye tracings (e.g., one up, one down). The schematic below shows the recorded results of eye movements to the right and left, assuming both amplifier channels have negative polarity up. Remember, this means an upward deflection occurs when the eyes move away from an electrode. The same approach can be used to understand the tracings resulting from vertical eye movements. Because ROC is positioned above the eyes (and LaC below), upward eye movements are toward ROC and away from Lac. Thus, upward eye movement results in a downward deflection in the ROC tracing and an upward deflection in the LaC tracing.
ROC
0 0 00
LOC
Look Right
-oo-
Look Left
-GG+
ROC ----""""Vr-----
Key Points I. Conjugate eye movements produce out-of-phase deflections when the usual twochannel method properly calibrated for monitoring eye movements is applied. 2. Eye movements can be recorded because a voltage difference exists between the front (+ ) and the back (- ) of each eye.
REFERENCES 1. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute, UCLA, 1968. 2. West P, Kryger MH: Sleep and respiration: Terminology and methodology. Clin Chest Med (Symposium on Sleep Disorders) 1985; 6:691-718. 3. Kenan SA: Polysomnographic techniques: An overview. In Chokroverty S (ed): Sleep Disorders Medicine. Boston, ButterworthHeinemann, 1999, pp 151-169.
13
FUNDAMENTALS OF SLEEP MEDICINE 4
Eye Movement Patterns
The tracings below show two important patterns of eye movements recorded during sleep. ROC and LOC are right and left outer canthus electrodes; Al and A 2 are the left and right mastoid electrodes, respectively. Slow rolling eye movements are characterized by a smooth undulation of the tracings (A). This pattern frequently is seen during drowsy wakefulness and stage I sleep. Slow rolling eye movements also may be seen following arousals (brief awakenings) or after a shift to a lighter stage of sleep. Rapid eye movements (REMs) are sharper, and the baseline between the movements usually is flat (8). Even sharper movements are seen with eye blinks. A
ROC-A
1
1 sec I--i
B
ROC-A
1
~~j~ IJ
LOC - A 2
f"-L--"'--~-'-'/\~IV
During wakefulness with eyes open, eye blinks or rapid eye movements are common. In an eyesclosed drowsy state, slow rolling eye movements and EEG alpha activity are noted. Slow rolling eye movements continue to be present after the transition from stage Wake to stage I sleep (alpha activity in less than 50% of the epoch). As sleep progresses to stage 2, these movements disappear. During slow wave sleep, eye movements are not seen. However, slow wave activity usually is noted in the eye movement channels. With the onset of stage REM, REMs appear episodically. REMs are characteristic of stage REM sleep, and they are critical to the detection of this stage. The REM density (number of REMs per minute of REM sleep) increases during the night. Early episodes of REM sleep sometimes are difficult to recognize because REMs are relatively infrequent. At times it also may be difficult to differentiate between a brief episode of slow rolling eye movements and REMs. A useful approach is to find a period of unequivocal REM sleep (usually in the last part of the recording) and note the appearance of the patient's stage REM sleep. Remember that REMs can be seen during wakefulness (eyes open). However, in contrast to stage REM, during wakefulness the chin EMG amplitude is not reduced, and the EEG may have more prominent, high-frequency activity.
14
Key Points 1. Slow rolling eye movements may be seen during drowsy wakefulness and stage sleep. 2. The presence of REMs is a defining characteristic of REM sleep. 3. REMs in early episodes of REM sleep are infrequent (lower REM density) and identification of REM sleep may be more difficult. 4. Identification of early periods of REM sleep may be aided by observing the patterns during unequivocal stage REM sleep later in the night.
REFERENCES 1. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute, UCLA. 1968. 2. West P, Kryger MH: Sleep and respiration: Terminology and methodology. Clin Chest Med (Symposium on Sleep Disorders) 1985; 6:691-718. 3. Caraskadon MA, Rechschaffen A : Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
15
PATIENT 4 A 20-year-old man with excessive daytime sleepiness A 20-year-old patient was evaluated in the sleep laboratory for excessive daytime sleepiness. Sleep was recorded in 30-second epochs. Figure: Below is the last half of an epoch (15 seconds). The electrode C4 (right central) and O 2 (right occipital) are referenced to the left mastoid (AI)' The right outer canthus (ROC) and left outer canthus (LaC) electrodes are referenced to the opposite mastoid electrodes (AI and A2 , respectively). The chin electromyogram (EMG) also is shown.
Question:
C4-A 1
O2 - A1
Are rapid eye movements present at point A, point B, or both?
\~~~~JVw~wJJ~~ ~JM~~\r~v~I.lI\"'I1"VIV\r\fV'lI.tJ'Y'~~~
ROC - A 1 LaC - A 2 Chin EMG
16
A
Answer:
Rapid eye movements are present at point B.
Discussion: High-voltage EEG activity also may be picked up by electro-oculography (EOG). In the standard two-channel scheme for monitoring eye movements, with both channels having the same polarity, large-amplitude EEG activity (K complexes, slow waves) produces deflections that are in-phase (both up or down) in the two eye channels. In contrast, conjugate eye movements produce out-of-phase deflections (one up, one down) in the two eye channels. During stages 3 and 4, it also is common to detect considerable amounts of slow wave activity in the eye lead tracings. Sleep is staged by epochs (usually 30 seconds). When there is a transition of sleep stages within an epoch, the convention is to score the epoch according to which stage occupied the majority of the epoch. However, epochs are not scored in isolation. For example, eye movements are not present in every epoch of REM sleep: epochs with eye move-
ments sometimes are referred to as phasic REM and epochs without eye movements as tonic REM. Tonic REM epochs must otherwise meet criteria for stage REM (same EEG and EMG) and are contiguous with epochs of phasic REM. Rules for identifying epochs of tonic REM are discussed in Fundamentals 6. In the present patient, the tracing shows a K complex at point A and two rapid eye movements at point B. At point A the deflections in both eye channels are in-phase, but at point B they are out-ofphase. In the first part of the tracing, the K complex without slow waves is consistent with stage 2 sleep. In the second part, the appearance of REMs with a low-amplitude chin EMG is consistent with REM sleep. However, as point B occurs near the end of the epoch, the epoch was scored as stage 2 sleep, and the subsequent epoch was scored as stage REM.
Clinical Pearls I. In the standard two-channel EOG method, high-amplitude EEG activity picked up by the eye leads produces deflections that are in-phase (assuming both channels have the same polarity setting). 2. When a sleep stage transition occurs within an epoch, the epoch is scored according to which stage occupies the majority of the epoch.
REFERENCES I. Rechtschaffen A. Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles. Brain Information Service/Brain Research Institute, UCLA, 1968. 2. Williams RL. Karacan I, Hursch CJ: Electroencephalography (EEG) of Human Sleep: Clinical Applications. New York. John Wiley & Sons. 1974. 3. West P, Kryger MH: Sleep and respiration: Terminology and methodology. Clin Chest Med (Symposium on Sleep Disorders) 1985; 6:691-718. 4. Caraskadon MA. Rechschaffen A : Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
17
FUNDAMENTALS OF SLEEP MEDICINE 5
Chin (Submental) Electromyography
Staging sleep depends on electroencephalographic (EEG), eye movement, and chin electromyographic (EMG) criteria. Usually, three EMG leads are placed in the mental and submental areas (see figure at right). The voltage between two of these three is monitored (for example, EMG I-EMG3). If either of these leads fail, the third lead can be substituted. The chin EMG is an essential element only for identifying stage REM sleep. In stage REM, the chin EMG is relatively reduced: the amplitude is equal to or lower than the lowest EMG amplitude in NREM sleep. If the EMG gain is adjusted high enough to show some activity in NREM sleep, a drop in activity often is seen on transition to REM sleep. Depending on the gain, a reduction in the EMG amplitude from wakefulness to sleep and often a further reduction on transition from stage I to stage 4 may be seen. The reduction in the chin EMG amplitude during REM sleep is a reflection EMG3 of the generalized skeletal-muscle hypotonia present in this sleep stage. In the tracings below, there is a fall in chin EMG amplitude just before the REMs (arrows) occur. The combination of REMs, a relatively reduced chin EMG, and a low-voltage mixed-frequency EEG is consistent with stage REM. Note that a reduction in airflow follows the onset of REMs. Even in normal persons, a reduction in airflow often occurs during phasic REM (stage REM with eye movements present).
chin EMG
~~ ~"lIIi-.~
~.f~
1 sec Airflow 18
While the chin EMG amplitude may progressively decrease with the transition from wakefulness to stage 4 NREM sleep, this change is not a requirement for the staging of sleep. In the IS-second tracings below, the chin EMG actually was higher in stage 3 than in stage 2 sleep.
Stage 2
chin EMG Stage 3
chin EMG Key Points 1. Recording of EMG activity in the chin area helps identify stage REM. 2. The amplitude of chin EMG activity is relatively reduced in stage REM compared to NREM sleep. That is, the amplitude of the chin EMG in REM sleep is equal to or lower than the lowest level recorded in NREM sleep.
REFERENCES I. Rechtschaffen A. Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles. Brain Information Service/Brain Research Institute. UCLA. 1968. 2. Williams RL. Karacan r. Hursch CJ: Electroencephalography (EEG) of Human Sleep: Clinical Applications. New York. John Wiley & Sons. 1974. 3. Caraskadon MA. Rechschaffen A : Monitoring and staging human sleep. In Kryger MH. Roth T. Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co .• 2000, pp 1197-1215.
19
PATIENT 5 A 40-year-old man experiencing difficulty falling asleep A 40-year-old man was evaluated for difficulty falling asleep. The tracing below was recorded soon after lights out. C 4-A I and OrAl are the central and occipital EEG channels; ROC-AI and LOC-A 2 are the right and left eye movement (EOG) channels. The chin EMG also is presented. Question:
chin EMG
20
What sleep stage is shown?
Answer:
The sleep stage shown is Wake (eyes open).
Discussion: The appearance of stage W (wakefulness) depends on whether the eyes are open or closed and if the subject being monitored is alert or drowsy. When the patient is alert, the EEG shows a low-voltage, high-frequency pattern. When the patient is tense, muscle artifact consisting of a mixed high-frequency pattern can be seen in the tracingsthe EEG electrodes are recording the EMG activity of the underlying scalp muscles. Note the change in the EEG below when the patient is asked to grit his teeth. With relaxation, lower frequency activity appears in the waking EEG. However, alpha activity (8-13 Hz) usually is not prominent until the eyes are closed (having the eyes open attenuates the alpha activity). REMs or eye blinks are commonly seen during eyes-open wakefulness. The level of the chin EMG amplitude tends to be relatively high unless the amplifier gain is very low.
With eye closure and the onset of a drowsy, relaxed state, prominent alpha activity usually appears, the background EEG frequency slows, and slow rolling eye movements are present. The chin EMG amplitude may fluctuate as the patient drifts in and out of a drowsy state In the present case, REMs are seen in the eye leads (sharp, out-of-phase deflections), and the EEG tracings show a low-voltage, fast-frequency pattern (refer to previous figure). The chin EMG amplitude is relatively high. Toward the end of the tracing, more prominent alpha activity is seen as REMs vanish (probable eye closure). This pattern is different from stage REM, which also contains REMs. In that stage, the EEG exhibits a lower frequency and the chin EMG amplitude is relatively reduced. Stage REM for this patient was associated with a flat-line EMG tracing.
grit teeth
Clinical Pearls 1. Stage Wake (eyes open) may feature REMs but differs from stage REM in the amplitude of the chin EMG and the pattern of the EEG. 2. Muscle artifact may be present in the EEG and EOG channels if the subject being monitored is tense. The artifact usually diminishes as the patient becomes drowsy and falls asleep.
REFERENCES I. Rechtschaffen A. Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles. Brain Information Service/ Brain Research Institute, UCLA. 1968. 2. Caraskadon MA. Rechschaffen A ; Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
21
PATIENT 6 A 30-year-old woman having trouble falling asleep A 30-year-old woman who complained of difficulty falling asleep was monitored in the sleep laboratory. Sixty-six epochs (each 30 seconds long) of stage Wake were recorded before the first epoch of sleep (stage I in this case). Figure: A IS-second tracing was obtained soon after lights out. The central and occipital EEG tracings are C4-A 1 and 02-Al' respectively. ROC-A) and LOC-A 2 are the eye movement (EOG) tracings.
Question:
What is the sleep stage and sleep latency?
ROC-A 1
chin EMG 5 sec
22
Answer:
The sleep stage is Wake. The sleep latency is 33 minutes.
Discussion: Sleep latency is defined as the time from lights out until the first epoch of any stage of sleep. In most age groups this occurs within 30 minutes. Several factors must be considered when evaluating sleep latency. The bedtime in the laboratory should mimic the patient's normal bedtime. Time before lights out (and after electrode placement) should be allowed for adaptation to the surroundings. Many normal people experience some difficulty falling asleep in a new environment. Changes in sleep latency and sleep architecture that result from sleeping in a novel environment are termed the first-night effect. Most research studies of the effects of medication or interventions on sleep architecture include an adaptation night to attempt to control for this effect. In contrast, some patients with psychophysiologic insomnia may fall asleep more easily in a new environment. Determining sleep onset is an important part of sleep staging. The usual progression at sleep onset is from stage Wake (eyes open) to drowsy wakefulness (eyes closed) and finally to stage 1 sleep. In general, the EEG in stage Wake with the eyes open is composed of low-amplitude, high-frequency activity. REMs and eye blinks may be present. The amplitude of the chin EMG is relatively high. As the person becomes drowsy, the eyes close and slow rolling eye movements and alpha activity (8-13 Hz) are prominent. Stage 1 is scored when alpha activity is present in less than 50% of the epoch. Slow rolling eye movements commonly persist into stage 1 sleep. The EMG amplitude mayor may not decrease (depends on amplifier gain).
In patients who do not produce prominent alpha activity, this progression to sleep is more difficult to detect, and the exact timing of transition from wakefulness to stage I sleep may be indeterminate. The typical characteristics of the transition - attenuation of higher frequencies and increased theta activity (4-7 Hz)-can be subtle in these patients. However, the onset of stage 2 sleep is more easily determined, and for this reason many sleep centers also compute a latency to stage 2 sleep or a latency to sustained sleep (defined as three consecutive epochs of sleep). Recognition of alpha activity can be enhanced by monitoring occipital leads and by carefully observing the EEG during biocalibrations to note the patterns of eyes-open and eyes-closed periods. (For a detailed discussion of biocalibrations, see Fundamentals 8.) Briefly, the patient is recorded opening and closing the eyes and looking right, left, up, and down. The resultant displays provide the EEG patterns for eyes-open and eyes-closed wakefulness and for deflections in the eye movement channels during REMs. Comparisons can assist in recognition of stage Wand stage I in difficult cases. In the present case, the sleep tracing shows almost continuous alpha activity (8-13 Hz), which is consistent with stage Wake (drowsy, eyes closed). The eye leads show some slow rolling eye movements. The EMG activity is relatively high. We are told that 66 epochs (33 minutes) of stage W were recorded after lights out and before the first epoch of sleep. Thus, the sleep latency is 33 minutes. This is a long sleep latency and is consistent with the patient's complaints of difficulty initiating sleep.
Clinical Pearls I. The sleep latency is prolonged past 30 minutes in patients with sleep-onset insomnia. 2. The timing of sleep onset can be difficult to determine in patients who do not produce significant alpha activity. Monitoring occipital leads can help detect alpha activity. 3. The timing of lights out in the laboratory should mimic the patient's normal bedtime. 4. The first-night effect can increase the sleep latency.
REFERENCES I. Agnew HW, Webb WB. Williams RL: The first-night effect: An EEG study of sleep. Psychophysiology 1966; 2:263-266. 2. Caraskadon MA, Rechschaffen A : Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000. pp 1197-1215.
23
PATIENT 7 A 30-year-old man having difficulty staying awake during the day A 30-year-old man was monitored for complaints of excessive daytime sleepiness. In the IS-second tracing below, C 4-A I and 02-A, are the central and occipital EEG tracings and ROC-AI and LOC-A 2 are the right and left eye movement (EOG) tracings. The chin EMG tracing also is shown.
Question:
What is this sleep stage?
5 sec
24
T
Answer:
The tracings indicate stage I sleep.
Discussion: The stage I EEG is characterized by low-voltage, mixed-frequency activity (4-7 Hz). Stage I is scored when less than 50% of an epoch contains alpha waves and criteria for deeper stages of sleep are not met. Slow rolling eye movements often are present in the eye movement tracings, and the level of muscle tone (EMG) is equal or diminished compared to that in the awake state. Some patients do not exhibit much alpha activity, making detection of sleep onset difficult. The ability of a patient to produce alpha waves can be determined from biocalibrations at the start of the study. The patient is asked to lie quietly with eyes open and then with the eyes closed. Alpha activity usually appears with eye closure. When patients do not produce significant alpha activity or when differentiating eyes-open wakefulness (attenuates alpha) from stage I sleep, several points are helpful.
First, with the eyes open, eye movements usually are much sharper than slow rolling eye movements (blinks or REMs). Second, the EEG of wakefulness (when no alpha is present) tends to have more highfrequency components. Note the slower (wider) EEG activity at point T in the figure. This activity is in the theta range. Third, often the easiest method to determine sleep onset in difficult cases is to find the first epoch of unequivocal sleep (usually stage 2) and work backward. The examiner can be confident of the point of sleep onset within one or two epochs. In the present case, alpha activity for less than 50% of the epoch; the presence of low-amplitude, mixed-frequency EEG activity and slow rolling eye movements; and the absence of spindles or K complexes (stage 2) classify this tracing as stage I sleep.
Clinical Pearls I. The stage I EEG is characterized by low-amplitude and mixed-frequency activity with alpha activity present less than 50% of the time. 2. In cases where determination of sleep onset is difficult, find the first epoch of unequivocal stage 2 sleep and work backward toward the beginning of the night.
REFERENCES I. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute. UCLA, 1968. 2. Caraskadon MA, Rechschaffen A : Monitoring and staging human sleep. In Kryger MH. Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
25
PATIENT 8 A 35-year-old woman with insomnia A 35-year-old woman was monitored for complaints of insomnia. The IS-second tracing below was recorded soon after sleep onset.
Questions:
What stage of sleep is illustrated? What is the large-amplitude EEG deflection?
50uvL
O 2 -A 1 ROC-A
1
chin EMG
26
~A~ ~~~"'fI'Il
Answer:
The patient is in stage 2 sleep. The large-amplitude deflection is a K complex.
Discussion: Stage 2 sleep is characterized by the presence of one or more sleep spindles (bursts of 12-14 Hz activity) or K complexes (largeamplitude, biphasic EEG deflections). To qualify as stage 2, an epoch also must contain less than 20% of slow (delta) wave EEG activity. Slow wave activity is defined as waves with a frequency < 2 Hz and a minimum peak-to-peak amplitude> 75 microvolts peak to peak. Stage 2 occupies the greatest
proportion of the total sleep time and accounts for roughly 40-50% of sleep. In the present case, the tracing shows the presence of a K complex and no slow wave activity. Therefore, the sleep is stage 2. Note that the K complex is transmitted to the eye leads, resulting in deflections in the EEG and eye leads that are in-phase. This occurs when all channels are calibrated with the same polarity (by convention, negative polarity up).
Clinical Pearls I. Stage 2 is scored when one or more sleep spindles or K complexes are noted but the epoch does not have enough slow wave activity to meet criteria for stage 3 sleep. 2. Stage 2 sleep accounts for the largest proportion of the total sleep time. 3. When the EEG and eye channels are properly calibrated, a K complex produces inphase (same direction) deflections in the two eye lead channels.
REFERENCES 1. Rechtschaffen A. Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of
Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute, UCLA, 1968. 2. Caraskadon MA, Rechschaffen A : Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
27
PATIENT 9 A 25-year-old man with a history of sleep-walking A 25-year-old man was monitored for complaints of sleep-walking. These episodes had been present since childhood. The IS-second tracing below occurred just before body movements were noted during sleep.
In which half of the night is this event likely to have occurred?
Question:
C 4 -A 1 O2-A1
ROC-A
1
chin EMG
. 5 sec
28
...
Answer:
This event occurred during stage 4 NREM sleep in the first half of the night.
Discussion: Stages 3 and 4 NREM sleep are called slow wave, delta, or deep sleep. Stage 3 is scored when slow wave activity (frequency < 2 Hz and amplitude > 75 microvolts) is present for 20-50% of the epoch. Stage 4 is scored when more than 50% of the epoch is occupied by slow wave activity meeting the above criteria. Spindles may be present in the EEG. Frequently, the high-voltage EEG activity is transmitted to the eye leads. The EMG often is lower than during stages I and 2 sleep, but this is variable. Stage 3 sleep in younger patients often is brief and represents a transition from stage 2 to stage 4 sleep. In older patients, the EEG amplitude is lower, and the total amount of slow wave sleep is reduced. In these patients, the amount of stage 3 sleep may exceed the amount of stage 4 sleep. During the night there are three to five cycles of NREM sleep with episodes of REM sleep between the cycles. The amplitude of the slow waves (and amount of slow wave sleep) is highest in the first sleep cycles. Typically, stages 3 and 4 occur mostly in the early portions of the night. The episodes of REM sleep occur about every 90-120 minutes, and
they are of longer duration as the night progresses. An overview of the cyclic nature of sleep can be shown using a hypnogram (see figure below). Note the periods of slow wave sleep (A, B, and C) in the early part of the night and longer REM episodes (dark bars) during the second half of the night. Several parasomnias (disorders associated with sleep) occur in stages 3 and 4 sleep and therefore can be predicted to occur in the early part of the night. These include somnambulism (sleep-walking) and night terrors. In contrast, parasomnias occurring in REM sleep (for example, nightmares) are more common in the early morning hours. In the present case, the epoch of sleep displayed (refer to previous figure) occurred about I hour after sleep monitoring had begun. High-amplitude, slow wave activity occupies essentially all of the tracing. Note that slow wave activity also is present in the eye leads. The chin EMG activity is relatively low. After this epoch the patient was noted to sit up and "pick at the bed sheets." The presence of body movements occurring out of slow wave sleep is consistent with a mild form of somnambulism.
-
REM
Wake Q)
O'l
..... en CO
c.. Q) Q)
en
Rem
51 52 53 54
c A
23
B
24
2
3
4
5
6
7
8
Time
Clinical Pearls I. Sleep occurs in cycles of NREM sleep separated by periods of REM sleep. 2. Stages 3 and 4 sleep occur mostly in the first few cycles of NREM sleep. 3. Parasomnias originating in slow wave sleep tend to occur in the early part of the night.
REFERENCES I. Williams RL, Karacan I, Hursch CJ: Electroencephalography (EEG) of Human Sleep: Clinical Applications. New York. John Wiley & Sons. 1974.
2. Caraskadon MA, Rechschaffen A : Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
29
PATIENT 10 A 20-year-old man with daytime sleepiness A 20-year-old man was monitored for complaints of increased daytime sleepiness. The recording below was obtained about 100 minutes after lights out.
Question:
What stage of sleep is shown?
A
B
chin EMG
5 sec
30
Answer:
The tracing displays stage REM sleep.
Discussion: Stage REM sleep is characterized by a low-voltage, mixed-frequency EEG, the presence of episodic REMs, and a relatively lowamplitude chin EMG. Saw-tooth waves (refer to previous figure, point A) also may occur in the EEG. There usually are three to five episodes of REM sleep during the night, which tend to increase in length as the night progresses. The number of eye movements per unit time (REM density) also increases during the night. Not all epochs of REM sleep contain REMs. Epochs of sleep otherwise meeting criteria for stage REM and contiguous with epochs of unequivocal stage REM (REMs present) are scored as stage REM. (See Fundamentals 6 for a detailed discussion of this concept.) Stage REM is associated with many unique physiologic changes, such as widespread skeletal muscle hypotonia. Skeletal muscle hypotonia is a protective mechanism to prevent the acting out of dreams. In a pathologic state known as the REM behavior disorder, muscle tone is present, and body movements and even violent behavior can occur during REM sleep. Important respiratory changes occur during REM sleep. The pattern of breathing becomes more irregular. REM sleep is not homogeneous, and periods of phasic activity (eye movements present) are associated with the most significant changes. Even in normal subjects, a reduction in tidal vol-
ume may be seen during bursts of eye movement. As more eye movements occur in the early-morning REM episodes, this is the time of the most profound changes in ventilation. The diaphragm becomes the only active inspiratory muscle during REM sleep, and the ventilatory responses to hypoxia and hypercapnia are reduced. Hence, patients with lung disease typically experience the most severe arterial oxygen desaturation episodes during earlymorning REM. Upper-airway muscle activity also is reduced during periods of phasic REM, possibly explaining why some patients have obstructive apnea only during REM sleep. During bursts of eye movements a decrease in diaphragmatic activity may also be noted. In the figure below, a three-breath decrease in flow and esophageal pressure deflections is seen during REM in an normal person. Many nonrespiratory physiologic changes, such as nocturnal penile tumescence, occur during REM sleep as well. Dreaming is more common and more complex in stage REM. Nightmares also occur during this sleep stage. In the present case, REMs (refer to previous figure, point B); a low-voltage, mixed-frequency EEG; and a low-amplitude EMG are consistent with REM sleep. The saw-tooth waves (at point A) are not an essential part of the definition of stage REM, but are a clue that REM sleep is present.
C4-A,
°2-A,
ROC-A1 LaC-A, EMG
Airflow (nasal press)
Esoph
press
31
Clinical Pearls I. Saw-tooth waves are a clue that REM sleep is present. 2. Alterations in ventilation are common during phasic REM sleep (eye movements present). Episodes of reduction in tidal volume. upper airway muscle activity, and diaphragmatic activity usually are associated with bursts of eye movements. 3. As eye movements are more common (higher REM density) during early-morning episodes of REM sleep. this is the time of the greatest changes in ventilation. 4. Patients with lung disease typically have the most severe arterial oxygen desaturations during the early-morning periods of REM sleep.
REFERENCES I. Gould GA. Gugger M. Molloy J. et al: Breathing pattern and eye movement density during REM sleep in humans. Am Rev Respir Dis 1988; 138:874-877. 2. Wiegand L, Zwillich CWoWiegand D, et al: Changes in upper airway muscle activation and ventilation during phasic REM sleep in normal men. J Appl Physiol 1991; 71:488-497. 3. Gould GA, Gugger M. Molloy J, et al: Breathing pattern and eye movement density during REM sleep in humans. Am Rev Respir Dis. 1988; 138 :874-847.
32
PATIENT 11 A 40-year-old man with a history of snoring and daytime sleepiness A 40-year-old man was monitored in the sleep laboratory because of a history of snoring and daytime sleepiness. The following tracings (A and B) show different chin EMG patterns.
Question:
Rapid eye movements are present in both A and B. Which tracing is stage REM?
A C 4 -A 1 O2-A 1 ROC-A 1
LOC - A 2
,.. ++ . ,
"llt~~
chin EMG
~,.,. k~" 5 sec
B C4-A 1
O 2 -A 1 ROC-A 1 LOC -A 2
chin EMG
5 sec
33
Answer:
Tracing B is stage REM; tracing A is stage Wake.
Discussion: Staging sleep depends on EEG, eye movement, and chin (submental) EMG criteria. However, the chin EMG is an essential element only for identifying stage REM sleep. The chin EMG must be relatively reduced in stage REM: the amplitude must be equal to or lower than the lowest EMG amplitude in NREM sleep. If the EMG gain is adjusted high enough to show some activity in NREM sleep, a drop in activity on transition to REM sleep may be evident. Depending on the gain, there usually is a reduction in the EMG amplitude from wakefulness to sleep and often a further reduction on transition from stage I to stage 4. It is essential that the EMG gain is high enough to see some activity during wakefulness. Obviously, if the EMG trace shows a flat line during wakefulness, no further decreases in EMG activity will be detected. In the present case, the tracings demonstrate the utility of the chin EMG in identifying REM sleep. In both A and B the EEG is low voltage, and REMs are present. However, in B the EMG is reduced compared to A. This reduced level of EMG activity
was seen throughout the night in REM sleep. A more subtle finding is that more high-frequency activity is present in the central EEG of A compared to B. The lack of more prominent alpha activity in A (stage Wake) is due to the fact that the eyes were probably open (REMs). The eye movements in eyes-closed wakefulness are usually of the slow rolling type. The EMG of REM sleep can show phasic bursts of activity; however, the tonic activity is reduced. These tracings illustrate the difficulty in distinguishing REM sleep from wakefulness with REMs. The appearance of REM sleep varies between patients. There are patients in whom REM sleep may look like tracing A! Thus, it is essential to find a period of unequivocal REM in each patient and note that patient's characteristic pattern of eye movements and chin EMG amplitude. Note that because the REM density (number of REMs per minute of REM sleep) is higher in REM periods later in the night, it is usually easier to find periods of unequivocal REM late in the monitoring period.
Clinical Pearls I. The chin EMG is reduced in stage REM compared to wakefulness. This fact is useful in differentiating eyes-open wakefulness (with REMs) from stage REM sleep. 2. The chin EMG amplitude in a given stage depends on the amplifier gain. The gain should be high enough so that a reduction in amplitude is evident as sleep progresses from wakefulness to slow wave sleep/REM. 3. Identification of early periods of REM sleep can be aided by observing the pattern of unequivocal periods of REM later in the recording period.
REFERENCES 1. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of
Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute. UCLA. 1968. 2. Williams RL, Karacan I, Hursch CJ: Electroencephalography (EEG) of Human Sleep: Clinical Applications. New York, John Wiley & Sons, 1974.
34
PATIENT 12 A 34-year-old man with sleep disturbance A 34-year-old man complained of excessive daytime sleepiness despite sleeping at least 9 hours per night. On awakening, he never felt refreshed. He had no bed partners and lived by himself. Physical Examination: Normal. Sleep Study: A total sleep time (minutes of stages 1-4 and REM sleep) of 420 minutes was noted. Figure: Three hundred events such as the one illustrated below were recorded.
Question: How can these events explain why the patient is sleepy despite the normal to increased total sleep time?
ROC-A
1
LOC - A 2 5 seconds
chin EMG
f · .. • .•
35
Answer:
Frequent arousals result in sleep fragmentation and daytime sleepiness.
Discussion: Arousal from sleep denotes a transition from a state of sleep to wakefulness. Frequent arousals can cause daytime sleepiness by shortening the total amount of sleep. The EEG will show brief changes (1-5 seconds) consistent with wakefulness and then a rapid return to a pattern consistent with sleep. A given epoch (30-second period) may be classified as sleep despite the brief "microawakening." Considerable experimental evidence suggests that frequent, brief arousals prevent sleep from being restorative even if the total amount of sleep is normal. Thus, the restorative function of sleep depends on continuity as well as duration. Many disorders that are associated with excessive daytime sleepiness also are associated with frequent, brief arousals. For example, patients with obstructive sleep apnea frequently have arousals coincident with apnea/hypopnea termination. Periodic limb movements in sleep may trigger brief arousals and cause daytime sleepiness. Therefore, determination of the frequency of arousals has become a standard part of the analysis of sleep architecture during sleep testing. Movement arousals were defined in the R&K scoring manual (the classic sleep staging manual of Rechtschaffen and Kales) as an increase in EMG that is accompanied by a change in pattern on any dditional channel. For EEG channels, qualifying changes included a decrease in amplitude, paroxysmal high voltage activity, or an increase in alpha activity. Subsequently, arousals were the object of considerable research, but the criteria used to define them were somewhat variable. A preliminary report from the Atlas Task Force of the American Sleep Disorders Association (ASDA) has become the standard definition. According to the ASDA Task Force, an arousal should be scored in nonrapid eye movement (NREM) sleep when there is "an abrupt shift in EEG frequency, which may include theta, alpha, and/or frequencies> 16 Hz, but not spindles," of 3second or longer duration. The 3-second duration was chosen for methodological reasons; shorter arousals may also have physiologic importance. To be scored as an arousal, the shift in EEG frequency
36
must follow at least 10 continuous seconds of any stage of sleep. Arousals in NREM sleep may occur without a concurrent increase in the submental EMG amplitude. In REM sleep, however, the required EEG changes must be accompanied by a concurrent increase in EMG amplitude for an arousal to be scored. This extra requirement was added because spontaneous bursts of alpha rhythm are a fairly common occurrence in REM (but not NREM) sleep. Finally, according to these recommendations, increases in the chin EMG in the absence of EEG changes are not considered evidence of arousal in either NREM or REM sleep. Similarly, sudden bursts of delta (slow wave) activity in the absence of other changes do not qualify as evidence of arousal. Because cortical EEG changes must be present to meet the above definition, such events also are termed electrocortical arousals. Note that the preliminary ASDA guidelines represent a consensus on events likely to be of physiologic significance. The committee recognized that other EEG phenomena, such as delta bursts, also can represent evidence of arousal in certain contexts. The frequency of arousals usually is computed as the arousal index (number of arousals per hour of sleep). Relatively little data is available to define a normal range for the arousal index. Normal young adults studied after adaptation nights frequently have an arousal index of five per hour or less. In one study, however, normal subjects of variable ages had a mean arousal index of 20 per hour, and the arousal index was found to increase with age. However, a respiratory arousal index (arousals associated with respiratory events) as low as lO/hr has been associated with daytime sleepiness in some individuals with the upper airway resistance syndrome (see Fundamentals 12). In the present patient, a delta wave followed by speeding of the EEG for more than 3 seconds and an increase in the chin EMG amplitude are present (see figure). The arousal index (number of arousals/hour of sleep) for this case is [300/(420/60)]
= 42.8/hr.
Clinical Pearls I. Frequent, brief electrocortical arousals can result in excessive daytime sleepiness even if the total sleep time is normal. 2. The scoring of arousals is based on changes in the EEG in NREM sleep or the EEG and chin EMG in REM sleep. 3. The arousal index (arousals per hour of sleep) is an important index of sleep fragmentation and the restorative quality of sleep. 4. The upper limit of normal for the arousal index is not clearly defined. Normal individuals may have 20-25 arousals/hour. In one study, some individuals with a respiratory arousal index of 10-20 /hr had excessive sleepiness that responded to treatment.
REFERENCES 1. Bonnet MH: Performance and sleepiness as a function of frequency and placement of sleep disruption. Psychophysiology 1986; 23:263-71. 2. American Sleep Disorders Association - The Atlas Task Force: EEG arousals: Scoring rules and examples. Sleep 1992; 15:174-184. 3. Roehrs T, Merlotti L, Petrucelli N, et al: Experimental sleep fragmentation. Sleep 1994; 17:438-443. 4. Mathur R, Douglas NJ: Frequency of EEG arousals from nocturnal sleep in normal subjects. Sleep 1995; 18:330-333. 5. Guillemenault C, Stoohs R. Clerk A, Cetel M, et al: A cause of excessive daytime sleepiness: The upper airway resistance syndrome. Chest 1993:104:781-787.
37
PATIENT 13 A 22-year-old woman with frequent awakenings during sleep secondary to chronic pain
Question 1: The figure below shows an epoch of REM sleep with a burst of alpha and faster activity for over 3 seconds. Should this event be scored as an arousal?
4 seconds C4-Al C3-A2 Ol-A2 ROC-Al LOC-A2
EKG Chin EMG Question 2:
C4-Al
C3-A2 02-Al Ol-A2 ROC-Al LOC-A2
38
,
I
T I
,
1
I
"
If
,
I
•
Y
, +
i
The figure below shows stage 4 sleep. What else is present?
."
Answers:
In Figure I, there is no arousal as the chin EMG does not increase. In Figure 2, alpha sleep
is present.
Discussion: According to the ASDA rules for scoring an arousal during REM sleep, an increase in the chin EMG must be present in order to score an arousal. The rationale for this rule is that bursts of alpha are common during REM sleep and do not necessarily reflect a change in sleep state. Of note, the frequency of alpha in REM sleep often is 1-2 Hz slower. In Figure I, notice that there is no change in heart rate (EKG). There is a change in airflow, but this is not uncommon during bursts of eye movements in REM sleep. In Figure 2, alpha waves are superimposed upon slow waves. This is an example of alpha sleep. As the alpha waves are present during delta sleep (slow wave sleep) this is also called alpha-delta sleep. Alpha sleep is defined as the diffuse presence of alpha activity during a stage of sleep in which it is normally not present. Alpha intrusion refers to a brief superimposition of alpha activity on sleep (although some use the term synonmously with alpha sleep). In this example, the alpha activity is very prominent. When alpha activity is less distinct, you
can change the time base (if you are using digital monitoring) to show a lO-second page (30 mm/sec equivalent paper speed). Below is a section of the tracing in which you can see the alpha activity present on top of the slow wave activity. Alpha intrusion makes the scoring of sleep more difficult. You might assume that the presence of alpha activity in more than 50% of the epoch would make an epoch stage Wake. However, K complexes or slow waves are not present during wake. Hence you can stage sleep as stage 2, 3, or 4 dependent on the usual criteria using these waveforms. Scoring stage I is more difficult as it is usually defined by less than 50% alpha activity, rather than the presence of other EEG activity. If prominent theta activity is present or you can see definite vertex sharp waves, then you might be confident in scoring stage I. Alpha intrusion can be associated with any cause of discomfort during sleep. It has been associated with depression, fibromyalgia, chronic pain syndromes, and even discomfort from monitoring equipment.
9 cps C4-Al C3-A2 02-Al Ol-A2 ROC-Al LOC-A2 chin EMG
Clinical Pearls l. Scoring an arousal during REM sleep requires an increase in the chin EMG. 2. Alpha intrusion can be present during any stage of sleep (alpha sleep) and can make sleep staging difficult. 3. Using a different time base (faster paper speed) can allow visualization of background alpha EEG activity.
REFERENCE Butkov N: Atlas of Clinical Polysomnography. Ashland, OR, Synapse Media, 1996, pp 110-112.
39
PATIENT 14 A 40-year-old man being treated for depression A 40-year-old man being treated for depression underwent a sleep study to evaluate complaints of excessive daytime sleepiness. Sleep Study: The tracing below shows prominent slow eye movements and rapid eye movements (R) in conjunction with K complexes and slow wave activity.
Question:
C4-Al 02-Al ROC-Al LOC-A2
EKG
40
What sleep stage is shown in the tracing?
Diagnosis: This is stage 2 sleep. The prominent eye movements are secondary to medication (serotonin reuptake inhibitor). Discussion: Slow eye movements (slow rolling eye movements) are characteristic of drowsy wakefulness and stage I sleep. They usually are absent during stages 2, 3. and 4 NREM sleep. They may folIowan arousal and typically are characteristic of transition to a lighter stage of sleep. Rapid eye movements are seen during Wake (usually eyes open) and during REM sleep. Eye movements both slow and rapid may be prominent during stages 2, 3, and 4 NREM sleep in patients taking serotonin reuptake inhibitors (e.g., fluoxetine, paroxetine) and, less commonly, tricyclic antidepressants. The fact that REM sleep is not present can usually be ascertained by noting the relatively high chin EMG activity and the presence ofK complexes and slow wave activity.
Studies in depressed patients have shown that fluoxetine increased the REM density (number of REMs per minute of REM sleep) while increasing the REM latency and decreasing the amount of REM sleep. A medication history is essential when evaluating a sleep study. Most sleep laboratories have patients fill out both a pre-study and post-study questionnaire to carefully document drug and alcohol consumption. In the current case, the tracing shows both slow and rapid eye movements. However, K complexes are present and the EMG shows considerable activity. Therefore, the tracing is best classified as stage 2 sleep. The patient was taking paroxetine at the time the tracing was performed.
Clinical Pearls I. Prominent slow and rapid eye movement activity may be seen in stages 2, 3, and 4 NREM sleep in patients taking serotonin reuptake inhibitor antidepressants. 2. The presence of an EEG typical for NREM sleep and a level of EMG activity that is higher than the REM level identify the affected sleep as NREM instead of REM sleep. 3. A drug history is essential when evaluating a sleep study.
REFERENCES I. Schenck CH. Mahowlad MW. Kim SW. et al: Prominent eye movements during NREM sleep and REM sleep behavior disorder associated with ftuoxetine treatment of obsessive-compulsive disorder. Sleep 1992; 15:226-235. 2. Armitage R. Trivedi M. Rush AJ: Fluoxetine and oculomotor activity during sleep in depressed patients. Neuropsychopharrnacology 1995;12:159-165.
41
FUNDAMENTALS OF SLEEP MEDICINE 6
Additional Sleep Staging Rules
The EEG, EOG and chin EMG characteristics of the different stages of sleep are discussed in Patients 1-12 and summarized in Appendix 2. There are additional scoring rules to handle special situations. These rules are necessary because K complexes, sleep spindles, and REMs are episodic. The three-minute rule concerns stage 2 sleep. This rule, as outlined by the classic sleep staging manual of Rechtschaffen and Kales, states that if the period of time between spindles or K complexes is shorter than 3 minutes and if the intervening sleep would otherwise meet criteria for stage I (less than 50% alpha activity) with no evidence of intervening arousal, then this period of sleep is scored as stage 2. If the period of time is 3 minutes or longer, then the intervening sleep is scored as stage I. Figure 1 (below) shows five epochs (30 seconds each) of sleep, with K complexes (K) in epochs 69 and 73. The central and occipital EEG tracings in epochs 70-72 are assumed not to contain sleep spindles, K complexes, or evidence of arousal. The time between the K complexes is less than 3 minutes; therefore, this intervening sleep is scored as stage 2.
70
71
72
I I
K
K
~---....;....---;..------;----:--t-.....: I
'V
°2- A1 ~ I
ROC - A 1
t1'
=1-
I
LOC - A 2
:1~----.~~----r---..-----.--"~ I
chin EMG :UI.UH.... il!I.1I Itl... I Stage 2
Stage 2
I'- .•,.....
IllI,• .-MI"
Stage 2
I
d"'~
Stage 2
",••• ..: Stage 2
Staging of REM sleep also requires special rules (REM rules) to define the beginning and end, because REMs are episodic, and the three indicators of stage REM (EEG, EOG, EMG) may not change to (or from) the REM-like pattern simultaneously. Rechtschaffen and Kales recommend that any section of the record that is contiguous with stage REM and displays a relatively low-voltage, mixed-frequency EEG be scored as stage REM regardless of whether REMs are present, providing the EMG is at the stage REM level. To be REM-like, the EEG must not contain spindles, K complexes, or slow waves. Figure 2 (next page) shows four epochs, with a K complex in epoch 69 and REMs in epoch 72. After epoch 69 there are no K complexes or sleep spindles, and the EMG falls to the REM level during the last part of epoch 70. Hence, epoch 71 meets criteria for REM sleep except that there are no eye movements. Epoch 71 is scored as stage REM because it is contiguous with an epoch of unequivocal REM sleep (epoch 72). Epoch 70 also does not contain K complexes or sleep spindles, but is scored as stage 2 by the three-minute rule. 42
Epoch 69
® C4 - A 1 O2 - A 1
72
71
70
I 1 K complex 1-1 1 1---1\;
REM A
ROC-A1 I~ LOC-A 2
EMG
~
V
~1.Il. 11M , •• iblt"I.•••I' III •• • 1' Stage 2
Stage REM
Stage 2
Stage REM
These rules are more difficult to apply if arousals break the continuity of sleep. With respect to the three-minute rule, sleep following an arousal is scored according to its nature. In Figure 3 (below), a brief arousal occurs at the end of epoch 71 (alpha waves in EEG, increased EMG). The sleep before the arousal is scored by the three-minute rule as stage 2. Epoch 71 is scored as stage 2 because most of the epoch is stage 2. Epoch 72 is scored as stage I because there are no K complexes or spindles, and the slow rolling eye movements (SR) following the arousal are more characteristic of stage I than stage 2.
®
I I
Epoch 69
70
71
K
I
Ht
LOC - A 2
I
r-1t
~--,...1t---'T
'SR
I I
,1
\..(V"--..,........'Y,--..--.;
~11.UiL II1II• • : 111M Stage 2
A-
I
I
chin EMG
'V
'MIl:
I
ROC - A 1
t-----:'
aIP~:
I
73
K
I
C c A 1 :--{. °2- A1
72
I
I
Itl'lI.
~.t . . . .II~IIllU.I1"'I...".iIIl-~-*........... •• 1 tl~
Stage 2
Stage 2
Stage 1
Stage 2
In REM sleep, bursts of alpha waves are common and do not signify an arousal unless the chin EMG amplitude also increases. Deciding how to score an epoch of sleep with a REM-like EEG/EMG but no REMs that is separated from contiguous unequivocal REM sleep by an intervening arousal is sometimes difficult. The decision in this case is between stage REM and stage I sleep (with an EMG at the REM level). The EEGs of stage I and REM sleep are similar, but subtle differences are present:
REM Sleep EEG Saw-tooth waves may occur Alpha waves 1-2 Hz slower than wakefulness
Stage 1 EEG No saw-tooth waves Vertex sharp waves may occur
A very brief arousal and/or the presence of saw-tooth waves in the sleep following the arousal is evidence that the sleep after the arousal is still stage REM(until definite evidence for another sleep stage is noted). Conversely, a prolonged arousal (with persistent alpha waves) followed by slow rolling eye
43
movements is evidence that the arousal induced a change from stage REM to stage 1 sleep. Sharp waves or incipient spindles (shorter than O.S-second duration) on the EEG also are evidence for stage 1. If stage I is scored following the arousal, all subsequent epochs are scored as stage I until evidence of another sleep stage is noted (spindles or K complexes-stage 2). In Figure 4 (below), a brief arousal signified by EEG alpha waves and an EMG increase occurs at the end of epoch 70. Epoch 70 is scored as REM because the majority of the epoch is REM-like. and it is contiguous with an epoch of unequivocal REM sleep. Epoch 72 contains a K complex and is scored as stage 2.
@
Epoch 69
C 4 -A 1 02-
70
I
A1
ROC-A1 LOC-A 2 EMG
71
I 1 alpha l !#NI 1 I I I
1 1 1
72 K complex
~I
'YWv
1--.1\ I
REMs
..
IV I I Stage REM
1 I
iL -J\--...JV . . . . M• •
I I I
,"'lInll , t•• J
I
I Stage REM
Stage REM
Stage 2
Epoch 71 is scored as stage REM because the arousal was brief and the EEG and EMG are REM-like for most of the epoch.
®
Epoch 69
I
I
I C4 - A 1 I 02- A 1 I I ROC-A 1 I LOC-A 2 EMG
71
70
alpha I waves
f". -
72
K complex]
"V-
lL-
~
SR
:v I
~ I
Stage REM
Stage REM
--V
I ,.......ltll.'1 I
J. Stage 1
I I I I I I I JUII I
Stage 2
An epoch containing slow rolling eye movements and following a prolonged arousal is illustrated in Figure S. This epoch is labeled stage 1. The reader is referred to reference 1 for special rules governing the unusual case in which spindles occur during REM sleep
REFERENCES 1. Rechtschaffen A. Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of
Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute, UCLA. J 968. 2. Caraskadon MA. Rechschaffen A: Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, WB Saunders Co .• 2000, pp 1197-1215.
44
PATIENT 15 A 30-year-old man with severe snoring and occasional breathing lapses A 30-year-old man was evaluated for a history of loud snoring and possible sleep apnea. Below is a schematic representation of five epochs of the patient's sleep. Assume that epoch 69 is stage 2 sleep (a K complex is shown). No K complexes, sleep spindles, or arousals are noted in epochs 70-75. The EEG in these epochs otherwise meets criteria for stage 2.
Question:
What sleep stage is scored in epochs 70-75?
Epoch 69
,
, I I
C4 - A 1 A1
75
76 K complex I
1r-:
~ ,'-it , I
I
I I I
ROC-A 1 I~
,
LOC-A 2
I I
I
EMG
74
73
72
71
K complexI I
I
02-
70
,'-Jv
h ,
v:
, ,
I
I
,
,
,..••Url:+... lIMIII ..... l'i. I"",'''' t.1Il1''ff~''''. I
I
Stage 2 Stage?
~
I
I
,
I
Stage?
I
1*" .11 t·1It
,
,
Stage? Stage? Stage? Stage? Stage 2
45
Answer:
Epochs 70-75 are scored as stage 1 because the interval between K complexes is longer than
3 minutes.
Discussion: Stage 2 is characterized by the presence of either sleep spindles, which are bursts of 12-14 Hz activity, or K complexes, which are large-amplitude, biphasic EEG deflections. To qualify as stage 2, an epoch also must contain less than 20% of slow (delta) wave EEG activity. Slow waves are large-amplitude (> 75 microvolt) deflections with a frequency of < 2 Hz. K complexes and sleep spindles are episodic and may not occur in each epoch. According to the three-minute rule, if the period of time between spindles or K complexes is < 3 minutes and if the intervening sleep would other-
wise meet criteria for stage I (less than 50% alpha activity) with no evidence of intervening arousal, then this period of sleep is scored as stage 2. If the period of time is z 3 minutes, then the intervening sleep is scored as stage I. In the current patient, the time between intervening K complexes in epochs 69 and 76 is longer than 3 minutes; therefore, the intervening sleep is scored as stage I. The 3-minute time frame is somewhat arbitrary. It was selected based on the spindle-tospindle and K complex-to-K complex intervals typically observed.
Clinical Pearl Use the three-minute rule to stage sleep occurring between K complexes or spindles which would otherwise meet criteria for stage 2 sleep except that K complexes or sleep spindles are absent.
REFERENCES I. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles. Brain Information Service/Brain Research Institute, UCLA. 1968. 2. Caraskadon MA, Rechschaffen A: Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
46
PATIENT 16 A 35-year-old woman experiencing uncontrollable episodes of sleep A 35-year-old woman was evaluated for possible narcolepsy. A schematic representation of eight epochs of the patient's sleep is shown. A K complex occurs in epoch 69 (stage 2 sleep). The chin EMG amplitude decreases at the start of epoch 70 and briefly increases at the end of epoch 75. A REM occurs in epoch 76.
Question:
What sleep stage is scored in epochs 70-75?
j
Epoch 69
70
71
72
73
74
I I Kcomplex I I I C4 - A1 I I I I O2 - A1 I-'\J I I I I ROC-A1 I LOC-A2 I-----Av I I I
alpha!
I
•
:-A;
IREMs
'h I
II'-{ I I I I I
MI
l'llit u 1*' tid III
I
76
.
H
EMG
75
I
Stage 2
Stage?
Stage?
Stage?
Stage?
Stage?
Stage?
Stage REM
47
Answer:
Epochs 70-75 are scored as stage REM.
Discussion: Stage REM is characterized by a low-amplitude, mixed-frequency EEG and an absence of sleep spindles and K complexes. The eye movement channels show REMs, and the chin EMG is relatively reduced (equal to or lower than the lowest level of NREM sleep). These EEG, EOG, and EMG characteristics may not all start or end at the same time. REMs are episodic and may not occur in all epochs of REM sleep. Therefore, the REM rule is useful for scoring epochs that do not contain REMs: Any section of record contiguous with stage REM in which the EEG is relatively low-voltage and mixed-frequency (no spindles, no K complexes) is scored stage REM regardless of whether or not REMs are present, providing the EMG is at the stage REM level. The rule holds for both the beginning and end of a segment of REM sleep. During sleep scoring, once unequivocal REM sleep is noted, the examiner should work backward to determine if preceding epochs meet the above criteria for REM sleep (see Fundamentals 6). At the transition from NREM to REM sleep, the above REM rule takes precedence over the threeminute rule. However, when an arousal separates the end of unequivocal stages 2--4 NREM sleep and the beginning of unequivocal REM sleep, the scoring of the intervening sleep prior to the arousal is more problematic. The arousal mayor may not signify a change in sleep stage. The EEGs of stage I and REM sleep can look similar. If the EMG of the
I
C4 - A1 O2 - A1 ROC-A 1 LOC-A2
71
HI I I
alpha'
:-t I
l---"\t
:---At ~i '
75 I I I I
fIIJ
.-
I I I I I
76
I
I
I I I
I I I REMs I
I
I
I
I
I
I
I~I I~
I
I I I
..,
Ill.'.'III'I I
Stage 2
74
73
72
I I I I Kcomplex I
I
48
70
I I I
I
EMG
Epoch 69
period in question is at the REM level, the decision is between stage I, stage 2 (based all the threeminute rule), or stage REM. The scoring manual recommends scoring sleep between the last spindle or K complex and an arousal as stage 2 if the time duration is < 3 minutes. If the segment is > 3 minutes, the sleep is scored as stage REM (rather than stage I-an exception to the three-minute rule). In the example below, note the arousal at the end of epoch 72. Sleep after the arousal is scored on the basis of the REM rule. Sleep before the arousal is scored according to a combination of the threeminute rule and the REM rule. On the other hand, if an arousal is prolonged or followed by an obvious change to stage I sleep (slow rolling eye movements), then the sleep following the arousal is scored as stage 1 until unequivocal evidence for another sleep stage is present. The presence of saw-tooth waves favors stage REM. In the present case, epoch 76 is unequivocal REM sleep (referto previous figure). Epochs 70-75 have a REM-like EEG and EMG except for a brief arousal at the end of epoch 75. The choices for epochs 70-75 include stages 1,2, or REM sleep. As the interval after the last K complex (epoch 69) exceeds 3 minutes, it is not stage 2 sleep. Thus, the choices are stage I or REM sleep. Epochs 70-75 look like REM sleep, except for the absence of REMs, and are contiguous with unequivocal REM sleep. Therefore, they are scored as stage REM.
Stage 2
Stage 2
Stage 2
I
I
Stage REM Stage REM Stage REM Stage REM
Clinical Pearls I. Sleep that is contiguous with an epoch of unequivocal REM sleep and meets criteria for stage REM. except that no REMs are present, is scored as stage REM (REM rule). 2. To identify the start of an episode of REM sleep, first identify an epoch of unequivocal REM (REM-like EEG, REMs present, EMG at REM level) and then work backward using the REM rule. To determine the end of an episode of REM. work forward from an epoch of unequivocal REM sleep. 3. When a brief arousal separates unequivocal stages 2-4 NREM sleep and the start of REM sleep, epochs with a REM-like EEG and EMG prior to the arousal are scored as stage 2 if the arousal occurred less than 3 minutes after the last sleep spindle or K complex. Otherwise, the segment is considered stage REM sleep (combination of three-minute rule and REM rule).
REFERENCES I. Rechtschaffen A, Kales A (eds): A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles, Brain Information Service/Brain Research Institute, UCLA, 1968. 2. Caraskadon MA, Rechschaffen A: Monitoring and staging human sleep. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
49
FUNDAMENTALS OF SLEEP MEDICINE 7
Sleep Architecture Definitions
A number of variables have been defined to help characterize the quantity, composition, and quality of sleep.
Standard Sleep Variables Time in bed (TIB) Movement time Total sleep time (TST) Wake after sleep onset (WASO) Sleep period time (SPT) Sleep efficiency (0/0) Sleep latency (min) REM latency (min)
Monitoring period-lights out to lights on Epochs in which stage is indeterminant due to artifact Total minutes of sleep (stages 1-4 and REM) Minutes of wake after initial sleep onset and before the final awakening TST + WASO (TST * 100) I TIB Time from lights out to the first epoch of sleep Time from sleep onset to the first epoch of REM sleep
Any condition that results in frequent or prolonged awakenings (such as sleep-maintenance insomnia or sleep apnea) results in an increased WASO. Even if the WASO is small, it is possible to have a low sleep efficiency if the final awakening occurs early in the monitoring period (early-morning awakening). That is, TST/TIB is reduced, even though TST/SPT is normal. The sleep latency reflects how rapidly the patient fell asleep. Patients with sleep-onset insomnia (difficulty in initiating sleep) typically have a long sleep latency (more than 30 minutes). Some sleep laboratories also compute the latency to stage 2 sleep. The REM latency is the time from the first sleep (not lights out) to the first epoch of REM sleep. The REM latency, normally 70-120 minutes, can be reduced in narcolepsy, sleep apnea. and depression, and after withdrawal of REM-suppressing medications. REM latency is discussed in Patient 18 and Fundamentals 9. The division of total sleep time among the sleep stages often is called the sleep architecture. A common approach is to express the minutes spent in each stage of sleep as a percentage of either TST or SPT. There are few widely accepted normative values for sleep architecture. In this book, the normal ranges are the mean ::+::: one standard deviation, as presented by Williams et al., and the values are age- and sexdependent. In some laboratories movement time (MT) is considered part of the TST (TST = stage I + stage 2 + stage 3 + stage 4 + stage REM + MT). Recall that any epoch that would be scored as MT that is surrounded by wake is scored as Wake. For simplicity, in this book MT is assumed to be zero. The fraction of slow wave sleep (stages 3 and 4) decreases considerably with age, while the amount of sleep stages I and 2 and WASO increase. The reduction in stages 3-4 sleep is mainly because of a decrease in the amplitude of slow waves that occurs with increasing age. The fraction of REM sleep changes little after young adulthood. The following table shows typical values for normal sleep at two different ages and in a patient with severe obstructive sleep apnea. Note that here and throughout this book, in the tables showing sleep stages as a percentage of sleep period time, Wake = WASO (does not include epochs of wake recorded before sleep onset or after final awakening).
50
Obstructive Sleep
Normal Sleep (o/c SPT) AGE
Wake Stage I Stage 2 Stages 3 and 4 Stage REM
20
I 5 45 21
28
AGE
60
8 10
57
APNEA
(%SPT) 10
25 55
2
o
23
10
Key Point The normal ranges for many parameters of sleep architecture. particularly the amount of slow wave sleep. are age-dependent.
REFERENCES
I. Williams RL. Karacan r. Hursch CJ: Electroencephalography (EEG) of Human Sleep: Clinical Applications. New York. John Wiley & Sons. 1974. pages 49-60. 2. Bonnet MH: Sleep deprivation. In Kryger MH. Roth T. Dement W (eds): Principles and Practice of Sleep Medicine. Philadelphia. WB Saunders. 1994. pp 50-67. 3. Caraskadon MA. Rechschaffen A: Monitoring and staging human sleep. In Kryger MH. Roth T. Dement WC (eds): Principles and Practice of Sleep Medicine. Philadelphia. WB Saunders Co .• 2000. pp 1197-1215.
51
PATIENT 17 A 23-year-old man with difficulty sleeping A 23-year-old man was monitored because he complained of poor sleep. He admitted to the sleep technician that he had taken his usual benzodiazepine sleeping pill before arriving in the sleep laboratory because he feared that otherwise he would be unable to sleep. Physical Examination: Normal.
Sleep Study Time in bed (monitoring time) Total sleep time (TST) Sleep period time (SPT) WASO Sleep efficiency (%) Sleep latency REM latency
450 min (430-454) 428.5 min (405-434) 432.5 min (410-439) 4min 95 (91-99) 5 min (3-26) 120 min (78-99)
( ) = normal values for age; sleep efficiency
=(TST * 100) I TIB
Question:
52
What is abnormal about the sleep architecture?
Sleep Stages
%SPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
1 (0-1) 6 (3-6) 71 (40-51) 7.8 (16-26) 15.2 (22-34)
Answer: The percentages of stages 3, 4, and REM sleep are reduced, and the amount of stage 2 sleep is increased. The REM latency also is mildly increased. Discussion: Sleep architecture can be altered by several factors, including sleep disorders, coexistent medical disorders, prior sleep for the last week (sleep deprivation), medications (or withdrawal), beverages, and exposure to a novel sleep environment (the first-night effect). It is essential to know the patient's normal sleep patterns and recent sleep history (sleep diary). An earlier-than-normal bedtime during the sleep study can increase the sleep latency. A later-than-normal bedtime can decrease the REM latency. Prior sleep deprivation can cause a rebound in the amount of slow wave and REM sleep. While it is important to know the patient's medication intake, it is equally important to know if usual medications and/or beverages (caffeine or ethanolcontaining) were not taken (see table below). Abrupt withdrawal of certain medications can profoundly affect sleep architecture. Withdrawal of stimulants
or tricyclic antidepressants (REM suppressors) can cause a rebound in the amount of REM sleep and/or shorten the REM latency. Abrupt withdrawal of medications decreasing a given sleep stage can cause a rebound in the amount of that sleep stage. Virtually all antidepressants-except for nefazodone, bupropion, and possibly trazodone and mirtazapine-decrease REM sleep. The former two may actually increase REM sleep in depressed patients. The older MAO inhibitors are said to be the most potent suppressors of REM sleep. In the current case, the total amount of sleep and sleep efficiency were normal. However, the amounts of stages 3, 4, and REM sleep were reduced. This change is not unusual with benzodiazepines, which tend to decrease slow wave sleep and, to a lesser degree, REM sleep. The amounts of stage 2 sleep and sleep spindle activity were increased tremendously.
Common Medications Affecting Sleep Architecture • DECREASE REM SLEEP Ethanol Tricyclic antidepressants Selective serotonin reuptake inhibitors MAO inhibitors Lithium Amphetamines Methy Iphenidate Clonidine Benzodiazepines (mild) SWS = slow wave sleep
*=
• INCREASE REM SLEEP Nefazodone Reserpine Bupropion (depressed patients) Withdrawal of REM-suppressing medications
• No CHANGE IN REM SLEEP Mirtazapine* Trazodone* • DECREASE SWS Benzodiazepines
Some studies show decreased REM sleep.
Clinical Pearls I. Analysis of sleep architecture can provide important insight into the causes of sleep disturbance. 2. A medication history (including over-the-counter medications) and a history of the pattern of sleep for several days prior to the sleep study are essential when analyzing sleep architecture. 3. The lights-out time should always mimic the patient's usual bedtime, if possible.
53
REFERENCES I. Bonnet MH: Sleep deprivation. In Kryger MH. Roth T. Dement W (eds): Principles and Practice of Sleep Medicine. Philadelphia. WB Saunders. 1994. pp 50-67. 2. Obermeyer WHo Benca RM: Effects of drugs on sleep. Neurol Clin (Sleep Disorders II) 1996; 14:l;27-840. 3. Walter TJ. Golish JA: Psychotropic and Neurologic Medications. In Lee-Chiong TL. Sateia MJ. Caraskadon MA (eds): Sleep Medicine. Philadelphia. Hanley and Belfus. 2002. pp 587-599. 4. Nofzinger EA. Reynolds CF. Thase ME. et al: REM sleep enhancement by bupropion in depressed men. Am J Psychiatry
1995;152:274-276. 5. Schweitzer PK: Drugs that disturb sleep and wakefulness. In Kryger MH. Roth T. Dement WC (eds): Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia. WB Saunders. 2000. pp 441-461.
S4
PATIENT 18 A 25-year-old man with daytime sleepiness and fatigue A 25-year-old man has experienced daytime sleepiness and fatigue during the last year. Prior to these symptoms, he broke up with his girlfriend and has been quite depressed. He has trouble waking up and getting out of bed in the morning. Recently, his primary care physician began him on 20 mg of f1uoxetine every morning. There is no history of cataplexy (muscle weakness triggered by emotion) or sleep paralysis. The patient has never been told that he snores. Physical Examination: Normal. Sleep Study Time in bed (monitoring time) Total sleep time (TST) Sleep period time (SPT) WASO Sleep efficiency (0/0) Sleep latency REM latency
( ) = normal
457.5 min (430-454) 406.5 min (405-434) 432.5 min (410-439) 26 min 89 (91-99) 15 min (3-26) 140 min (78-99)
values for age: sleep efficiency
Questions:
Slee Sta es
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
6 (0-1) 8 (3-6) 49 (40-51) 25 (16-26) 12(22-34)
= (TST * 100) / TIB
What is abnormal about the sleep architecture? What is the most likely cause?
55
Diagnosis:
Prolonged REM latency and decreased REM sleep probably secondary to medication.
Discussion: The REM latency is the time from the first epoch of sleep until the first epoch of stage REM - usually about 70-120 minutes, depending on the age of the patient. Alterations in REM latency can be due to the presence of disease processes, but many other factors increase or decrease this time period as well (see table below). Narcolepsy, a disorder causing excessive daytime sleepiness, often is associated with a very short REM latency (10-15 minutes or less) referred to as sleep-onset REM. However, this finding is neither specific for nor always present in narcolepsy. Obstructive sleep apnea or any other cause of REM deprivation also may be associated with a short REM latency. Depression typically causes only modest shortening (40-50 minutes); however, depression can have an effect as extreme as narcolepsy. The propensity for REM sleep is associated with the daily (circadian) change in body temperature. By delaying bedtime, the time of sleep onset may move closer to the time of initial REM sleep. Usually this is not a problem, unless the lights-out time is much later than the patient's normal bedtime. Abrupt withdrawal of REM-suppressing medications also can reduce REM latency. A medication history is essential for proper interpretation of the sleep study results. If a diagnosis of narcolepsy is suspected, patients usually are asked to stop medications altering REM latency for at least 2 weeks prior to the sleep study, because
changes in REM latency are an essential part of diagnostic criteria. This is problematic for depressed patients with possible narcolepsy, as most antidepressants increase the REM latency. The exceptions are mirtazapine, nefazodone, and bupropion. The first two do not change the REM latency. Bupropion may actually decrease the REM latency in depressed patients. One case report found that bupropion decreased the propensity of a patient with narcolepsy to have early REM periods. The effect of bupropion on the multiple sleep latency test in narcolepsy has not been studied in a large group. A common mistake is to abruptly withhold REMsuppressing medications just before the sleep study. This may cause a rebound in the amount of REM sleep and possibly shorten the REM latency. In the present case, the sleep architecture is fairly normal except for the prolonged REM latency, decreased amount of REM sleep, and slightly decreased sleep efficiency (increased stage W as percentage of SPT). The changes in REM sleep are most likely secondary to the use of ftuoxetine (Prozac), a selective serotonin reuptake inhibitor (SSRI) antidepressant. Sleep efficiency often is decreased in patients with depression. In some of these patients, treatment with SSRIs improves sleep quality. In others, the medications themselves disturb sleep. However, when this patient was seen for discussion of the sleep study results, he claimed to be feeling better and denied any symptoms of daytime sleepiness.
Common Factors Altering REM Latency SHORT REM LATENCY
LONG REM LATENCY
No CHANGE IN REM LATENCY
Narcolepsy Prior REM deprivation Sleep apnea Depression, schizophrenia Withdrawal of REM suppressants Later than normal bedtime Bupropion*
First-night effect Nefazodone Medical disease (COPD, chronic Mirtazapine pain syndromes) Ethanol REM suppressant medications: Tricyclic antidepressants SSRIs (e.g., fluoxetine, sertaline, paroxetine, citalopram) Trazodone MAO inhibitors (most) Venlafaxine Stimulant medications (e.g., amphetamine, methlyphenidate) Clonidine
* in depressed patients COPD
56
= chronic obstructive pulmonary disease, SSRls = selective serotonin reuptake inhibitors
Clinical Pearls I. The REM latency is the time from the first epoch of sleep until the first epoch of stage REM. 2. A short REM latency is associated with withdrawal of REM-suppressant medications as well as several sleep disorders, including narcolepsy, sleep apnea, and depression.
REFERENCES I. Standards of Practice Committee, American Sleep Disorders Association: The clinical use of the multiple sleep latency test. Sleep 1992; 15:268-276. 2. Obermeyer WHo Benca RM: Effects of drugs on sleep. Neurol Clin (Sleep Disorders II) 1996; 14:827-840. 3. Rye DB. Dihenia B. Bliwise DL: Reversal of atypical depression. sleepiness. and REM-sleep propensity in narcolepsy with bupropion. Depress Anxiety 1998;7:92-95. 4. Walter TJ, Golish JA: Psychotropic and Neurologic Medications. In Lee-Chiong TL. Sateia MJ. Caraskadon MA (eds): Sleep Medicine. Philadelphia. Hanley and Belfus, 2002, pp 587-599. 5. Schweitzer PK: Drugs that disturb sleep and wakefulness. In Kryger MH. Roth T. Dement WC (eds): Principles and Practice of Sleep Medicine. Philadelphia, WB Saunders, 2000, pp 441--461.
57
FUNDAMENTALS OF SLEEP MEDICINE 8
Polysomnography
"Polysornnography" is the term used to denote the continuous and simultaneous recording of multiple variables during sleep.
Routinely Monitored Variables VARIABLES
METHODS
PURPOSE
EEG (central, occipital), right and left EOG, chin EMG EKG Airflow (nasal and oral)
Detect the presence and stage of sleep
Scalp/face surface electrodes
Measures cardiac rate and rhythm Detects apnea and hypopnea
Respiratory effort
Detects respiratory effort
Anterior tibialis EMG
Detects periodic leg movements
Arterial oxygen saturation
Measures Sa0 2 , detects desaturation Detects snoring
Chest electrodes Thermistors, thermocouples Pneumotachograph in mask, nasal pressure Respiratory movement-chest and abdominal bands (piezoelectric, impedance) Intercostal EMG Esophageal pressure Separate channel for each leg or one common channel Alternate: leg movement Transducers Pulse oximetry
Upper airway sound/vibration
Microphone, vibration transducer
EEG = electroencephalogram, EOG= electro-oculogram, EMG = electromyogram, EKG = electrocardiogram
A typical twelve-channel recording montage (the set of variables being recorded): Channel I 2 3 4 5
6
Variable Central EEG Occipital EEG Right EOG Left EOG Chin EMG EKG
Channel 7 8 9 10 II 12
Variable Right leg EMG Left leg EMG Airflow Chest movement Abdominal movement Sa0 2
Additional channels are commonly used to record pulse rate (from the oximeter), snoring, body position (from position sensor), and end-tidal CO? (pediatric cases). In special circumstances, esophageal pressure and transcutaneous CO 2 are also recorded. During positive-pressure titration, the flow signal from the CPAP machine is usually substituted for airflow. Many laboratories also record a nasal-oral thermister signal and a nasal pressure signal on separate channels. The variables shown here are recorded on a polygraph, using a standard paper speed of 10 mmfsec, and/or digitally acquired on a computer system.
58
Sleep monitoring also requires continuous visual and auditory monitoring of the patient. This is especially important to detect changes in the sleeping posture (supine-lateral decubitus) and allows the patient to signal the technician if assistance is needed. Visual monitoring generally is accomplished via a low-light camera system with video monitors in the recording room. Video recording is needed for evaluation of parasomnias and is now used in most laboratories. Systems are available to allow synchronization of the polysomnographic recording and the video record. Today may systems offer digital video recording, and this makes synchronization of video and polysomnographic recordings very convenient. Where evaluation for possible nocturnal seizures is a consideration, a full EEG montage also should be recorded. If sufficient EEG channels are not available, a limited montage may be helpful (see Fundamentals 20). The signal from each variable recorded enters the system via an amplifier that must be correctly adjusted (sensitivity, low filter, high filter, polarity). EEG, EOG, and EMG channel AC amplifiers are calibrated with a standard voltage signal (usually 50 micovolts) that is available by pushing a button on the polygraph. The sensitivity is adjusted so that the desired output signal (pen deflection) for a given voltage input is obtained (see table below). Low- and high-frequency filters attenuate signals with frequencies outside (below and above, respectively) the desired range of recorded frequency. While filters reduce artifact from unwanted signals, they also can impair recording of desired variables. For example, the low filter must be set low enough so that slow waves and eye-movement signals are not attenuated. In many digital systems, signals are recorded without filtering. Digital filters are than added to change the display of the signals. This is helpful if you prefer to look at the tracings using an alternative filter setting.
Polysomnograph Settings SENSITIVITY
EEG (central, occipital) EOG EMG (chin, legs) EKG Airflow (therrn) Chest/abdomen Snoring Oximetry Nasal pressure
5-10 uv/mrn 50 uv/mm variable variable variable I volt = 100% variable
CPAP flow
variable
5 uv/mm
5 uv/rnm
Low FILTER (Hz) 0.3 0.3 10.0 0.3 0.1 0.1 30.0 DC DC or .01 0.01-0.03
HIGH FILTER (Hz)
30 30 90 30 15 15 90-100 15 15 (100 if snoring to be seen) 15
Filter settings are given as 1/2 amplitude frequency (the amplitude of a signal at this frequency is attenuated by 50%). DC = direct current (no low filter)
In addition to high and low filter setsens LF tings, most recording systems have 50-60 ~ ~(J.l.v/mm) Hz "notch" filters to remove 60-cycle interEEG ~ 5 - 0.3 ference. These filters do not add that much when a high filter setting of 30 Hz is used as EEG 5- 0.3this already reduces 60-Hz activity considerably. However, for EMG channels in which the high filter is set at 90-100, the EOG 55 -_ 0.3 notch filter may be used. Sixty-Hz filters should never be used as an alternative to adEOG 0.3equate electrode application, which is eschin EMG sential to reducing 60-cycle artifact (see Pa10 - 10 tient 20). Deflections from a calibration signal of 50 microvolts are shown in the sample tracing above. The smaller signal in the chin EMG channel is ondary to the higher low-frequency (LF) setting.
V ~
=i-C ,1
---+--t-
HF 30 30 30 30 30 sec-
59
Biocalibration A biocalibration procedure is performed while signals are acquired with the patient connected to the monitoring equipment. This procedure permits checking of amplifier settings, integrity of monitoring leads/transducers, and recording abilities of airflow and respiratory effort transducers as well as leg EMG. It also provides a record of the patient's EEG and eye movements during wakefulness with eyes closed and open. Biocalibration Eyes closed Eyes open Look right, look left; look up, look down; blink eyes Grit teeth
Breathe in, breathe out
Hold breath Wiggle right toe, left toe
What To Check (Technician and Scorer) Alpha EEG activity, slow rolling eye movements Attenuation of alpha EEG activity, pattern of eyesopen wakefulness Integrity, amplitude, polarity of eye channels, pattern ofREMs Chin EMG Adjust chin EMG gain so that some activity is present during relaxed wakefulness Airflow channel working Airflow, chest, abdomen tracings should have same polarity and be of reasonable amplitude Direction of inspiration (upward deflection) Apnea occurrence Leg movements
The next figure is a sample tracing during eye movement biocalibration. The patient has been asked to hold the head still and look in different directions (Left, Right, Down, Up) and then blink (B) the eyes.
chin EMG Next, respiratory channels (recording airflow and chest/abdominal movement) are adjusted so that tidal breathing induces a reasonable deflection in all three channels (see figure, right) with the same polarity (inspiration up, arrows). Amplifier gain (sensitivity) and chest/abdominal band positions may need adjustment. The patient is asked to breathe in and hold the breath to simulate apnea, then resume normal breathing.
60
In Airflow
Chest Abdomen
The patient is then asked to wiggle the right and left toes to check the ability of the anterior tibialis EMG to detect leg movements (see tracing below).
chin EMG EKG R Leg EMG L Leg EMG
REFERENCES I. Harris CD: Recording montage. In Shepard JW (ed): Atlas of Sleep Medicine. Mount Kisco. NY, Futura Publishing Co., 1991, pp 1-5. 2. Introduction to the Polysomnograph (video/manual). Available from: Synapse Media, 4702 Cloudcrest Drive, Medford, Oregon; Tel. 800/949-8195. 3. Butkov N: Polysomnography. In Lee-Chiong TL, Sateia MJ, Carskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002, pp 605-637.
61
PATIENT 19 A 30-year-old man having difficulty staying awake during the day A 30-year-old man was studied to evaluate complaints of excessive daytime sleepiness. An artifact was noted in his recording. The EEG leads C 4-A) and 02-A" both eye leads (ROC-A) and LOC-A 2), a chin EMG, and an EKG lead were monitored. After the initial artifact was noted, the EEG leads were "double referenced" (C 4-A I2 and 02-Al)' meaning the combined leads AI and A 2 were used as the reference for the central and occipital EEG derivations (see figure).
Question:
C4-A , 2 O2 - A
What is the artifact?
.ifV~
'2
ROC -At
LOC - A 2 \J Chin
EMG
EKG
62
'"
T T T T T ,
t
T ,
t T , , T T T T T t , 1
t
t
,
,
Answer:
It is an EKG artifact, minimized by double referencing.
Discussion: The EKG artifact is one of the most common and easily recognizable recording artifacts. It can be identified by sharp deflections in the signals of affected channels corresponding exactly in time to the QRS of the EKG. Fortunately, this artifact does not interfere a great deal with visual sleep staging, as the artifact does not mimic usual EEG patterns. The artifact can be minimized by placing the mastoid electrodes sufficiently high (behind the ear) so that they are over bone instead of neck tissue (fat). Double referencing to both mastoid electrodes also can minimize EKG artifact.
This works because if the EKG voltage vector is toward one mastoid, it is away from the other. Hence, the EKG component of the two signals (C 4-A 1 and C 4-A2) tend to cancel each other out. If the recording system does not allow double referencing, then you can link the mastoid electrodes A 1 and A2 with a jumper cable at the electrode box. In the present case, EKG artifact is prominent in the eye leads and chin EMG. It is less prominent in the EEG leads (refer to figure, arrows) because of double referencing. The artifact is larger than desirable, but the record still can be scored.
Clinical Pearls 1. EKG artifact can be easily recognized as sharp deflections in the affected leads corresponding to the QRS complex in the EKG lead. 2. Proper application of the mastoid electrodes and double referencing can prevent or minimize this artifact.
REFERENCES I. Harris CD, Dexter 0: Recording artifacts. In Shepard JW (ed): Atlas of Sleep Medicine. Mount Kisco, New York, Futura Publishing, 1991. pp 50-51. 2. Butkov N: Clinical Polysomnography. Ashland, OR, Synapse Media, 1996. pp 344-346.
63
PATIENT 20 A 25-year-old man complaining of excessive daytime sleepiness A 25-year-old man was being monitored for complaints of excessive daytime sleepiness. After several minutes of recording, the patient was noted to scratch his chin, and a humming noise was heard from the polygraph pens. A portion of the tracing is shown below.
Question:
What artifact is responsible for the humming?
C4-A1
O 2 -A 1 ROC-A 1 LOC - A 2
chin EMG
A
64
Answer:
There is a sixty-cycle artifact in the chin EMG channel.
Discussion: Sixty-cycle artifact is a common problem in sleep-study recording. It is caused by 60-Hz electrical activity from power lines and can be minimized by correct application of electrodes and proper design of the sleep laboratory. When prominent, the artifact causes a characteristic humming of the pens as they oscillate at 60 cycles per second. The artifact usually is easy to spot in the EEG and EGG leads, but may be more subtle in the EMG leads. Most EEG amplifiers have a 60-cycle notch amplifier to minimize the recording of this signal. If a 60-cycle filter is out (disengaged), the amplitude of the artifact increases tremendously (see figure below). If the paper speed is increased to 60 millimeters per second, then there will be 10 cycles in I centimeter (Yr: sec at that paper speed) or a frequency of 60 Hz. In a digital system, changing the time base to a 5or IO-second page is equivalent to increasing the paper speed and will also reveal the problem. The problem can also be recognized on either type of system on the usual 3D-second page by a very dense, uniform, "squared off" tracing that does not vary. EEG amplifiers are alternating current (AC)-eoupled, which allows them to record low-voltage EEG activity (50 microvolts) while rejecting high-voltage
direct current (DC) activity. Differential amplifiers can record low-voltage physiologic signals by amplifying the difference in voltage between two electrodes while rejecting the common-mode signal consisting of higher-voltage, 60-Hz, background activity. When recording the voltage difference between two electrodes, the background AC activity is rejected only if the electrode impedances are low and fairly equal. If one electrode is faulty (disconnected or high impedance), then the 60-Hz AC activity will be more prominent. Although most AC amplifiers have notch filters to minimize AC activity, these filters may not prevent 60-Hz activity from being prominent when electrode impedances are very different. The ideal impedance of electrodes is below 5000 ohms. Electrode impedance should be checked by the sleep technician after electrode application. In the present case, when the patient scratched his chin he moved one of the EMG electrodes, altering its impedance (refer to previous figure, point A). The problem was fixed (note portion of tracing after A) by switching to a spare chin EMG electrode that had been placed in the submental area. Note the considerable EKG artifact in the left eye channel in this tracing.
Paper speed 10 mm/sec 60 mm/sec
(
60 cycle filter on
~\~~~\\\\~ I I 1/6 sec
65
Clinical Pearls I. Sixty-cycle artifact causes a humming in the recording pens. 2. Causes of sixty-cycle artifact include high and unequal electrode impedances (faulty attachment), lead failure, and interference from nearby power lines. 3. Sixty-cycle filters can minimize 60-cycle interference, but the problem often requires switching to a different electrode. 4. The ideal electrode impedance is 5000 ohms or less, but 5000-10,000 is adequate. The impedance of all electrodes should be checked before lights out. Low and equal impedances will minimize 60-cycle electrical interference.
REFERENCES I. Harris CD. Dexter DO: Recording artifacts. In Shepard JW (ed): Atlas of Sleep Medicine. Mount Kisco. NY. Futura Publishing Co, 1991,pp 19-23. 2. Butkov N: Atlas of Clinical Polysomnography. Volume II. Ashland, OR, Synapse Media. 1996, pp 331-333.
66
PATIENT 21 A 30-year-old man with loud snoring A 30-year-old man seeking assistance for loud snoring was studied using a digital monitoring system. The EEG, EOG, EMG, and chin leads were acquired in a referential manner (each electrode recorded against a common reference), while the EKG, airflow, chest movement, and abdominal movement were acquired as bipolar tracings. The arterial oxygen saturation (Sa0 2 ) was acquired as a DC signal. Only some of the signals showed 60-cycle artifact, which confused the technicians.
Questions:
What is the problem? How would you fix the bad tracings?
LOC-A2 ROC-Al C3-A2 C4-Al 01-A2 02-Al
.......
.,.. --~_._.~ ... ,,--_ .........~ _ " ' 1 " ' 1 & " , . , . ""I'~~I1I... tl
_ "'\Il!'~" ,......
•
.~
,'ttI .. 'y..
...
\lJWu, .. ..,. lU"."f,'~"
~'~'~~~~~I~~
......"... 'M ••uIH"'hll
__
.I~
~~-,~~ ~_»_lM~~U.~¥~~ljll"UIUI.
chin 1-chin3 EKG R,L Legs
airflow chest abdomen
~----~---~------
5a02
67
Answer:
The common referential ground electrode(s) is bad and should be replaced immediately.
Discussion: Most digital sleep systems now permit acquisition of a mixture of referential, bipolar, and DC signals. Usually C 4 , C 3 , 02' 01' AI' A 2, chin I, chin2, chin3, ROC, and LOC are each recorded against a common reference electrode (or several linked electrodes; see chart below). Of note, some labs also record the EKG or leg EMGs referentially as well. Referential recording has many advantages. If all referential electrode signals are displayed, this display view can quickly identify if any of the individual electrodes are bad. However, the usual bipolar display views are still possible, as during review the computer than performs subtractions to show typical views. For example (C4-reference)-(AI- reference) = C4-Al. The referential method of acquiring signals allows re-referencing after the data has already been acquired. The original data is not changed, but many display views are possible. You can see any signal against any other signal recorded referentially. If one of the mastoid electrodes should fail during the night, you can also change the display view (for example C 4-A2 to C 4 A I)' You could look at any combination of chin electrodes (e.g., chin l-chin2, chin l-chin3, chin2-chin3).
However, a potential disadvantage to referential monitoring is that if the reference electrode (s) should fail, all the referential electrode signals acquired will be bad (usually showing popping or 60cycle artifact). As discussed in the previous case, the ability of a differential amplifier channel to reject 60-cycle interference depends on the integrity of both signals. If the reference electrode is bad, each of the channels (X-reference) will be bad where X is the electrode acquired referentially (for example, C 4 or AI)' True bipolar recording is typically used for airflow, chest and abdominal movement, snoring, EKG, and often leg EMGs. Each sensor has two outputs, and the voltage between them is recorded. None of these signals is affected by the common reference electrode. In the present case, all of the referential electrode tracings showed artifact (refer to previous figure). No bipolar or DC channels showed the problem. This meant that the common reference electrode(s) (or one of the linked electrodes used for the common reference) was bad. When the common ground was fixed, the tracing on the next page was noted.
Referential recording
Bipolar recording
C4 C3
C4 - A1 C3 -A2 02 - A1 01- A2
02--
reference
01 A1 A2 Display bipolar views C4-A1
=
(C4 - ref) - (A1-ref)
C4-A2 = (C4 - ref) - (A2-ref)
68
LOC-A2 ROC-Al C3-A2 C4-Al 01 -A2 w-.~~~~"""""""loo\r'4Jio""V\MN."""""~~~~rw.N 02-Al chin l-chin3 EKG R,L Legs _
airflow chest
abdomen Sa02
Clinical Pearls I. Many digital systems allow referential recording of EEG, EGG, and EMG leads. This allows re-referencing and multiple display views during study review. However, failure of the common reference in this system will impair all leads acquired referentially. 2. If all referential leads show artifact, then the problem is the common reference (or one of the linked electrodes used as the common reference) 3. Bipolar and DC channels that do not depend on the common reference will not be affected by failure of the common reference electrode(s).
REFERENCES I. Geyer JD, Payne TA, Carny PR, Aldrich MS: Atlas of Digital Polysomnography. Philadelphia, Lippincott Williams and Wilkins, 2000. 2. Butkov N: Polysomnography. In Lee-Chiong TL, Sateia MJ, Carskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002, pp 605-637.
69
PATIENT 22 A 40-year-old man with complaints of snoring An obese 40-year-old man was monitored in the sleep laboratory. The EEG, EGG, and EMG tracings showed a definite artifact. Below is a sample 15-second tracing.
Questions:
What is this type of artifact? How can it be minimized?
LOC-A 2
Chin EMG
.
5 SEC
70
Answers:
This is sweat or slow frequency artifact. It can be minimized by cooling the patient.
Discussion: Sweat artifact (or slow frequency artifact) is characterized by a slowly undulating movement of the baseline of affected channels. The movement mayor may not be synchronous with the patient's respiration. When in-phase with the patient's respiration, the artifact also is called respiratory artifact. Sweat artifact is believed to be secondary to the effects of perspiration. Sweat alters the electrode potential, thereby producing an artifact that mimics delta waves and results in overscoring of stages 3 and 4 NREM sleep. When the artifact is not present in all channels, it may be secondary to pressure on an electrode (or pulling on the electrode). In any case, the artifact is usually coming from one or more electrodes on the side the patient is lying on. For example, if the patient is sleeping with the left side down and C 4-A 1, 02-A" and ROC-AI are af-
fected, but LOC-A 2 shows no artifact, then lead AI requires attention. Switching to CrA z or C4-A z may be tried, but if switching electrodes does not solve the problem, then other actions are necessary. Options include reducing the room temperature, uncovering the patient, and/or using a fan. As a lastditch alternative, the setting of the low-frequency filter may be increased (e.g., from 0.3 to I). Unfortunately, this maneuver decreases the amount of delta activity recorded, but still may be preferable to a totally unscorable record. Sweat artifact can be prevented by maintaining a low room temperature, especially when very obese or heavily perspiring patients are studied. In the present case, the sweat artifact is present in leads referenced to both AI and A z. The room temperature was lowered, and the patient was uncovered. Over the next 15 minutes, the artifact resolved.
Clinical Pearls I. Sweat or respiratory artifact is characterized by a slowly undulating baseline. 2. Maintaining a sufficiently cool room temperature is essential when studying obese
patients. 3. Changing the electrodes to those opposite the side the patient is lying on can eliminate the artifact in some cases. 4. If all electrodes are involved, use a fan or lower the room temperature.
REFERENCES 1. Harris CD, Dexter 0: Recording artifacts. In Shepard JW (ed): Atlas of Sleep Medicine. Mount Kisco. New York. Futura Pub-
lishing, 1991, pp 50-51. 2. Butkov N: Atlas of Clinical Polysomnography, Vol II. Ashland, OR, Synapse Media, 1996, pp 348-349.
71
PATIENT 23 Two patients with recording artifacts Patient A: A 40-year-old man with frequent awakenings at night was monitored in the sleep laboratory. The EEG, EGG, and EMG tracings showed a definite artifact. Below is a sample IS-second tracing.
Questions:
What is the artifact? Which lead is responsible for the problem?
LOC· Al Chin EMG
.
,. ,
..... 4
••• ,.,
Or
FI
I.
I'
.. i.
1 • . ,. . . . '
Patient B: A 50-year-old man was undergoing sleep monitoring as an evaluation for excessive daytime sleepiness. The tracing (below) looked much like REM sleep except for an unusual pattern in the eye leads showing deflections only in the right eye (points A).
Questions:
What sleep stage is shown? How do you know the eye channels are working?
ROC· A1 A
chin
EMG
72
A
A
A A
Answers: Patient A - This artifact is due to electrode popping in lead A I. Patient B - Stage REM in a patient with an artificial left eye. Check the biocalibrations. Discussion: Electrode popping is a common and severe artifact that makes the staging of sleep very difficult. It is characterized by sudden, highamplitude deflection (channel blocking) secondary to an electrode pulling away from the skin (sudden loss of signal). The popping tends to be regular and corresponds to body movement during breathing. Electrode popping often is caused by the patient lying on one mastoid electrode or pulling on an electrode during respiration. Popping also can occur if the electrode gel dries out during the night. This artifact frequently can be handled by switching to an alternate lead. For example, if 0, is the problem, the exploring occipital electrode is switched to 0 I' This is one reason that redundant electrodes are routinely placed. Alternatively, the offending electrode is repaired by adding electrode gel, or replaced. In Patient A, the regular high-voltage deflections are noted in all EEG and EOG channels except 0,A2 . The common electrode to all the affected channels is A I; therefore, the problem is most likely in electrode A r- The patient was sleeping on his left
side. After changing the reference electrode to A, (C 3-A2, ROC-A 2, LOC-A 2) the problem was eliminated. The change could have been to C 4-A 2, but using an exploring electrode opposite the reference is preferable (if possible) as this produces a larger voltage signal. Biocalibrations are an important initial part of all sleep studies (see Fundamentals 8). Patients are asked to look left, right, up, and down to test the effectiveness of both the eye electrodes and the amplifier settings at detecting eye movements. In Patient B, no movement was seen in LOC-A, during biocalibration. The technician questioned-the patient, who reported that he had an artificial (glass) left eye. At the usual amplifier settings, movements of the right eye (relatively far away) did not result in deflections in LOC-A,. The absence of any deflection in the EEG lead-s coincident with the deflections in ROC-AI indicated that these deflections were due to eye movements and not to transmitted EEG activity. The eye movements, low-voltage EEG, and low-amplitude EMG are consistent with stage REM sleep.
Clinical Pearls Patient A: I. Electrode popping artifact is a sudden, high-voltage deflection occurring at regular intervals usually coincident with respiration. 2. Electrode popping artifact is due to an electrode pulling away from the skin. 3. The offending electrode sometimes can be identified by noting if the affected channels have a common electrode. 4. Recording from alternative electrodes may eliminate the problem of electrode popping. Patient B: I. Always check biocalibrations prior to sleep study interpretation. 2. Pay special attention to the deflections resulting from voluntary eye movements. In the usual two-channel setup for detecting eye movements, proper calibration should result in reasonably sized, out-of-phase deflections.
REFERENCES I. Harris CD, Dexter D: Recording artifacts. In Shepard JW (ed): Atlas of Sleep Medicine. Mount Kisco, New York, Futura Publishing, 1991, pp 30-31. 2. Butkov N: Polysomnography. In Lee-Chiong TL. Sateia MJ, Carskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002, pp 605-637. 3. Caraskadon MA, Rechschaffen A : Monitoring and staging human sleep. In Kryger MH. Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders Co., 2000, pp 1197-1215.
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PATIENT 24 A 29-year-old man struggling with daytime sleepiness A 29-year-old, generally healthy man was studied to evaluate complaints of daytime sleepiness. He was taking no medications, and his wife reported only occasional snoring. During the initial part of the test, the technician noted considerable sweat artifact (the air-conditioner thermostat was malfunctioning). The low-frequency filter (j-j amp) setting on the EEG channels was increased from 0.3 to I to control the artifact after only 30 minutes of recording. Physical Examination: Unremarkable. Sleep Study Time in bed (monitoring time) Total sleep time (TST) Sleep period time (SPT) WASO Sleep efficiency Sleep latency
435 min (430-454) 406.5 min (405-434) 432.5 min (410-439) 26 min 93% ( 91-99) 2.5 min (3-26)
( ) = normal values for age, sleep efficiency = (TST
Question:
74
Sleep Stages
% SPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
1 (0-1) 6 (3-6) 60 (40-51) 8 (16-26) 25 (22-34)
* 100) / TIB
Can you explain the abnormality in sleep architecture?
Answer:
Reduced recording of slow wave activity secondary to the low-frequency filter setting.
Discussion: The high- and low-frequency filter settings can significantly alter the EEG amplifier response to a signal. The low filter settings can dramatically reduce the amplitude of slow wave activity if set too high. A ~ amp low-filter setting of 0.3 Hz means that a sine wave input of 0.3 Hz is attenuated by 50%. On some amplifiers, a low filter setting of 0.3 means that a signal of 0.3 Hz is attenuated by 70.7 or 80% of the original signal. Regardless of the exact meaning for a given amplifier, a low filter setting of 0.3 does not significantly attenuate the majority of slow wave activity « 2 Hz). However, a low filter setting of I Hz does produce considerable attenuation of slow wave activity. Thus, less activity meets the minimum voltage criterion of 75 microvolts. At the bottom of the page is a tracing showing the effect of changing the low filter from a ~ amp setting of 0.3 Hz (usual setting) to I Hz. Note the abrupt reduction in the slow wave activity. Setting the low-frequency filter of the eye movement channels too high also markedly reduces eye movement amplitude. The low filter setting usually recommended for EEG and EOG leads is 0.3 Hz. For EMG and EKG channels, a low filter setting (~ amp) of 10 is used, as the relevant activity is of a much higher frequency. Filter settings are sometimes given as time constants. Most altematingcurrent amplifiers employ resistance-capacitance (RC) circuits as input filters. In a simple, low filter RC circuit, the frequency (fc) at which the output voltage across the resistor is attenuated to 70.7% of the input voltage is related to the time constant (Tc) by the formula
Fe
=
1/(21T Tc).
The Tc = RC where R is the resistance and C the capacitance. Since amplifiers are routinely calibrated by step (square wave) voltage changes rather than sine wave signals, the time constant can be noted from the time it takes for the deflection to return to baseline. In RC circuits, an increase in step voltage produces an abrupt increase in voltage across the resistor, then an exponential fall in voltage to lie (0.37) of the maximum voltage in one time constant. When the ~ amp frequency is higher, the time constant is smaller (more rapid fall).
1/2 amp Lo
.3 Hz
1Hz
37~Lt---4
I
tc
1 sec
I
In the present case, the change in low filter settings was the most likely cause for the small amount of slow wave sleep recorded. When the study was scored without using voltage criteria, a higher but still subnormal amount of slow wave sleep was scored. The low filter setting should be increased only as a last resort (see treatment of sweat artifact, Patient 22).
1/2 amp LO .3 hz
1 hz
5 sec chin EMG
75
Clinical Pearls I. The filter settings should be recorded during calibration and any changes during sleep monitoring noted. The sleep scorer should be informed of any changes. 2. A higher-than-recommended low filter setting in the EEG leads (especially the central EEG) decreases the amplitude of slow wave activity and hence the amount of slow wave sleep that is scored.
REFERENCES I. Tyner FA, Knott 1R, Mayer WB, 1r: Fundamentals of EEG technology. New York, Raven Press, 1983, pp 89-119. 2. Fisch B1: Spehlman's EEG Primer. New York, Elsevier, 1991, pp 51-60.
76
FUNDAMENTALS OF SLEEP MEDICINE 9
Multiple Sleep Latency Test and Maintenance of Wakefulness Test
The multiple sleep latency test (MSLT) consists of sleep monitoring during five naps spread over the day, usually at two-hour intervals (10 AM, 12 noon, 2 PM, 4 PM, 6 PM). Generally, the test is preceded by nocturnal polysomnography. In the morning, the patient changes into comfortable street clothes, and nap monitoring begins 1.5 to 3 hours after nocturnal recording has ceased. Monitoring includes central EEG, occipital EEG (optional but recommended), chin EMG, EKG, and airflow (if sleep apnea is a possibility). The patient is instructed to fall asleep at lights out and is given 20 minutes to do so. Once sleep is attained, the patient is given another 15 minutes to reach stage REM sleep. The nap test is stopped if the patient fails to fall asleep within 20 minutes, or fails to reach REM sleep within 15 minutes of sleep onset. After nap termination, the patient is instructed to get out of bed and remain awake until the next nap opportunity. The sleep latency (time from lights out until the beginning of the first epoch of any stage of sleep) and the REM latency (time from the first sleep until the beginning of the first epoch of REM sleep) are determined for each nap. Results of the MSLT in normal subjects show a mean sleep latency longer than 15 minutes and zero to one REM periods in five naps (Table I). However, some otherwise normal subjects have a mean sleep latency in the 10- to 15-minute range. This range represents mild sleepiness, and a mean sleep latency < 10 minutes is considered abnormal. A mean sleep latency of 5-10 minutes represents moderate sleepiness; shorter than 5 minutes is severe (pathological) sleepiness. It is important not to confuse mean MSLT sleep latency with nocturnal sleep latency. A short sleep latency at the regular bedtime is not abnormal. However, a majority of patients with narcolepsy have a nap sleep latency shorter than 5 minutes, and patients with moderate-to-severe sleep apnea usually have a mean nap sleep latency shorter than 10 minutes.
Table 1. Multiple Sleep Latency Test Results MEAN SLEEP LATENCY
< 5 min 5-10 min 10-15 min
Severe sleepiness Moderate sleepiness Mild sleepiness
REM ONSETS
o or
I in 5 naps 2 or more in 5 naps
Normal Abnormal
The presence of two or more REM periods in five naps is characteristic of narcolepsy. However, only 70-80% of patients with narcolepsy and cataplexy will have this finding on a given day. Furthermore, two or more REM periods is not specific to narcolepsy and can occur with any cause of REM sleep deprivation or disturbance. Sleep apnea and, occasionally, psychiatric disorders can be associated with a short REM latency. Acute withdrawal of REM-suppressing medications (tricyclic antidepressants, lithium, serotonin reuptake inhibitors, stimulants) can be associated with REM sleep during naps. Ideally, any medication affecting either the sleep latency or the REM latency should be withdrawn for 2 weeks before the sleep study and MSLT. When this is not practical, the medications should not be abruptly discontinued just prior to testing. Most sleep centers have the patient keep a sleep log (diary) of the amount and pattern of sleep during the 2 weeks preceding the MSLT, because sleep loss or disturbance during this period can affect the sleep latency. Proper interpretation of the MSLT requires analysis of the nocturnal polysomnogram. Note if the
77
amount and quality of sleep were adequate and if sleep disorders were present that could affect the sleep latency. Specific conditions such as sleep apnea or periodic leg movements in sleep should be documented. Decreased amounts of REM sleep (or REM-sleep fragmentation) during the night from any cause can increase the number of REM periods recorded on the MSL T. For example, sleep apnea is a common cause of two or more REM periods on the MSLT. In general, if the nocturnal sleep is significantly disturbed it is best to cancel the MSL T and repeat the test after the identified sleep disorder is adequately treated. The standard MSL T criteria for narcolepsy are: mean sleep latency shorter than 5 minutes and two or more REM episodes in five naps (Table 2). Narcoleptic patients with a longer sleep latency (5-10 minutes) and two more REM onsets often show a shorter sleep latency on retesting. When sleep apnea is present, interpretation of the MSLT is problematic. The sleep apnea should be treated first. If narcolepsy is suspected, a repeat sleep study showing adequate sleep (adequate treatment of sleep apnea) should be performed, followed by an MSLT. When treatment is with nasal continuous positive airway pressure (CPAP), both the repeat sleep study and the MSLT are performed on the prescribed level of CP AP.
Table 2. MSLT Findings in Patients Evaluatedfor Daytime Sleepiness NARCOLEPSY WITH CATAPLEXY ;::: 2 sleep onset REM period Mean sleep latency < 5 minutes Both
SLEEP-RELATED BREATHING DISORDERS 7% 39% 4%
74% 87% 67%
From Aldrich MS, Chervin RD, Malow BA. Value of the multiple sleep latency test (MSLT) forthe diagnosis of narcolepsy. Sleep 1997; 20:620-629; with permission. The maintenance of wakefulness test (MWT) was designed to test the patient's ability to stay awake. The patient is seated upright in bed in a dimly lighted room and asked to remain awake for either 20 or 40 minutes. The usual EEG, EOG, and EMG monitoring is performed to detect sleep. The test is terminated if sleep is noted or after 20/40 minutes if the patient maintains wakefulness. The test is repeated four to five times across the day, and the mean sleep latency is determined (20 or 40 minutes if no sleep is recorded). When both the MSLT and MWT were administered to a group of patients with excessive daytime sleepiness, the correlation was significant but low. Several individuals did not fall asleep during the MWT, but had some degree of daytime sleepiness as assessed by the MSLT. The MWT is more likely than the MSLT to show improvement after treatment of daytime sleepiness. In one study, the MWT sleep latency increased from 18 to 31 minutes in a group of patients with obstructive sleep apnea (OSA) after adequate treatment. One normative study (Table 3) has suggested that a normal MWT latency should be > 19 minutes on a 40-minute test (sleep defined as three consecutive epochs of stage I or anyone epoch of another stage of sleep) or > II minutes on an abbreviated 20-minute MWT (sleep defined as any epoch of sleep). Currently, there is no consensus on what constitutes a normal MWT.
Table 3. Proposed "Normal" for the Maintenance of Wakefulness Test LENGTH OF MWT
MEAN SLEEP LATENCY
20-minute naps 40-minute naps
Normal> II min Normal> 19 min
The MWT latency required for a person to safely pursue an occupation critically dependent on alertness has not been standardized. Furthermore, the ability to stay awake is not the same as maintaining alertness. Studies using driving simulators have attempted to provide a performance-based test of alertness. Test results showed decreased alertness in patients with OSA and in patients with narcolepsy, as compared to a control group. However, these results did not correlate with MSLT results, and half of each group performed as well as controls. While these studies are important first steps, they have not been validated by performance tests of the real thing.
78
Key Points I. Proper interpretation of a multiple sleep latency test (MSLT) requires analysis of: the preceding nocturnal sleep study, a careful medication history, and sleep habits (diary) for at least I week preceding the MSL T. 2. The mean nap sleep latency is a measure of the tendency to fall asleep during normal waking hours. 3. The number of naps with REM sleep can provide evidence for narcolepsy. However, this finding is neither highly sensitive nor specific for the disorder. 4. Obstructive sleep apnea (OSA) is also a common cause of two or more REM periods on an MSLT. Therefore, if OSA is present it should be adequately treated before the MSLT can be used to support a diagnosis of narcolepsy. 5. The maintenance of wakefulness test may be more likely to show a significant improvement after treatment of daytime sleepiness.
REFERENCES Multiple Sleep Latency Test I. Richardson GS. Carskadon MA. Flagg W: Excessive daytime sleepiness in man: Multiple sleep latency measurements in narcoleptic and control subjects. Electroencephalogr Clin Neurophysiol 1978; 45:621-627. 2. Carskadon MA: Guidelines for the multiple sleep latency test. Sleep 1986; 9:519-524. 3. Standards of Practice Committee. American Sleep Disorders Association: The clinical use of the multiple sleep latency test. Sleep 1992; 15:268-276. 4. Chervin RD, Aldrich MS. Sleep onset REM periods during multiple sleep latency tests in patients evaluated for sleep apnea. Am J Respir Crit Care Med 2000; 161:426--431. 5. Aldrich MS. Chervin RD. Malow BA. Value of the multiple sleep latency test (MSLT) for the diagnosis of narcolepsy. Sleep 1997; 20:620-629. Maintenance of Wakefulness Test 1. Poceta, JS. Timms RM. Jeong D. et al: Maintenance of wakefulness test in obstructive sleep apnea syndrome. Chest 1992; 10I:893-902. 2. Sangal RB, Thomas L. Mitler MM: Maintenance of wakefulness test and multiple sleep latency test: Measurements of different abilities in patients with sleep disorders. Chest 1992; 101:898-902. 3. George CFP. Boudreau AC. Smiley A: Comparison of simulated driving performance in narcolepsy and sleep apnea patients. Sleep 1996; 19:711-717. 4. Doghramji K, Mitler MM, Sangal RB, et al: A normative study of the maintenance of wakefulness test (MWT). Electroencephalogr Clin Neurophysiol 1997; 103:554-562.
79
PATIENT 25 A 25-year-old man with daytime sleepiness A 25-year-old man complained that for 2 years he'd had problems with sleepiness during the day. A nocturnal sleep study failed to show any abnormality. A multiple sleep latency test (MSLT) was performed the next day. Figure: The results of the five naps are shown below in tabular format. The sleep stage of each 30second epoch is listed below the epoch number.
Questions:
What is the sleep latency and REM latency of each nap? What is the mean sleep latency
for the MSLT?
= REM.
LO
= lights
out, W
=stage Wake
Nap 1
R
epoch stage
70
71
72
73
74
75
76
77
LO
W
W
W
I
1
I
I
epoch stage
90
91
92
93
94
95
96
97
LO
W
W
I
I
I
I
epoch stage
101 2
102 3
103 3
104 3
105 4
106 4
epoch stage
112 2
113 3
114 3
115 3
116 4
78 2
79 2
R
I
98 2
99 2
100 2
107 4
108 4
109 4
110 4
4
117 4
118 4
119 4
120 4
121 4
122 4
80
Nap 2
III
Nap3 epoch stage epoch stage
130
131
132
133
134
135
136
137
138
139
140
LO
W
W
W
I
I
I
I
I
I
I
141 2
142 2
143 2
144 2
145 3
146 3
147 3
148 3
149
150
151
R
R
167 1
168
169
W
W
I
178
179
180
181
R
R
Nap4 epoch stage
160
161
162
163
164
165
166
LO
W
W
W
W
W
I
epoch stage
171 2
172 3
173 3
174 3
175 4
176 4
177 4
170
Nap 5 epoch stage epoch stage
190
191
192
193
194
195
196
197
198
199
200
LO
W
W
W
W
W
W
W
W
W
W
201
202
203
204
205
206
207
208
209
210
211
W
W
W
W
W
W
W
W
W
W
W
114
115
116
117
118
119
120
121
W
W
W
W
W
W
W
W
122 W
131
132
133
epoch stage
112
113
W
W
epoch stage
123
124
125
126
127
128
129
130
W
W
W
W
W
W
W
W
80
Answers: Nap I Nap 2 Nap 3 Nap4 Nap 5
Sleep Latency 1.5 min (3 epochs) 1.0 min (2 epochs) 1.5 min (3 epochs) 2.5 min (5 epochs) 20 min
Mean
5.3 min
Discussion: The patient is given 20 minutes after lights out to fall asleep for each MSL T nap. If sleep does not occur, then the sleep latency is set at 20 minutes by convention. Once sleep is attained, the patient is given another 15 minutes to attain REM sleep. The sleep latency is the time from lights out until the first epoch of any stage of sleep. The REM latency is the time from the first epoch of sleep until the first epoch of REM sleep. There is a normal variation in sleep latency over the day in most subjects, with the minimum usually occurring near noon or early afternoon (naps 3 or 4) and the maximum in the late afternoon. The propensity of REM also varies, with REM periods most likely to occur in the morning naps. In the present patient, the mean sleep latency was
REM Latency 3 min (6 epochs) None 7.5 min (15 epochs) 6 min (12 epochs) None
consistent with moderate-to-severe sleepiness. Note that in nap 5 no sleep was attained, and the sleep latency was set at 20 minutes. The patient had difficulty falling asleep in this nap because he was "nervous and ready to go home." If nap 5 were excluded, the mean sleep latency would be much lower. REM sleep was present in three of five naps. In nap 4, epochs of wakefulness were noted between sleep onset and the first epoch of REM. The intervening wakefulness was included in the computation of the REM latency. The findings of this study were interpreted in light of the nocturnal polysomnographic findings and clinical history, and a diagnosis of narcolepsy was supported. (See Patients 77 and 78 for detailed discussions of narcolepsy).
Clinical Pearls I. If no sleep is attained after 20 minutes of monitoring during an MSLT, then the nap is terminated, and the sleep latency is considered to be 20 minutes. 2. Sleep latency can vary considerably between naps in the MSLT. This is the reason for five naps spread out over the normal waking period. 3. The normal propensity for REM sleep is highest during the first naps. 4. The sleep latency tends to be shortest at noon and early afternoon naps.
REFERENCES 1. Richardson GS, Carskadon MA, Flagg W: Excessive daytime sleepiness in man: Multiple sleep latency measurements in narcoleptic and control subjects. Electroencephalogr Clin Neurophysiol 1978; 45:621-627. 2. Carskadon MA: Guidelines for the multiple sleep latency test. Sleep 1986; 9:519-524. 3. Standards of Practice Committee, American Sleep Disorders Association: The clinical use of the multiple sleep latency test. Sleep
1992; 15:268-276.
81
FUNDAMENTALS OF SLEEP MEDICINE 10
Monitoring Respiration During Sleep
Respiratory Definitions. The apnea + hyponea index (AHl), sometimes called the respiratory disturbance index (RDl), is the number of apneas + hyponeas per hours of sleep. Apnea is defined as an absence of airflow at the nose and mouth for IO seconds or longer. This time duration is arbitrary, but widely applied. The presence or absence of respiratory (inspiratory effort) determines the type of apnea. Central apnea is defined by an absence of inspiratory effort. Obstructive apnea occurs despite persistent respiratory effort. Mixed apnea has an initial central part (no inspiratory effort) and a terminal obstructive portion. In the figure below, respiratory effort (signaled by movement) is detected by bands around the chest and abdomen as well as esophageal pressure deflections. In central apnea, no movement of the chest and abdomen or esophageal pressure deflections are detected during the apnea. In obstructive apnea, respiratory effort persists during the apnea. Note that during obstructive apnea, the chest and abdomen often move in a paradoxical manner (one inward and the other outward, see arrows). Esophageal pressure deflections increase during the terminal portion of apnea. In mixed apnea, an initial central portion of the apnea (point C) is followed by an obstructi ve portion (Fig. I). APNEA TYPES OBSTRUCTIVE
CENTRAL
Airflow
NV"v------/\A
Chest
~
Abdomen
/\IV'v-----I\/\
Esoph pressure
~
1
MIXED
Paradoxical Movement
Airflow Chest Abdomen EsOph pressure
FiGURE I
Hypopnea definitions vary widely and are controversial. Basically, hypopnea is a reduction in airflow. However, how airflow is measured and whether an associated desaturation or arousal is required can significantly affect the number of hypopneas detected in a given patient. This prompted some to characterize hypopnea as" a floating metric." Techniques of airflow detection/measurement are discussed below. Desaturation means a drop in the arterial oxygen saturation from baseline. A consensus conference sponsored by the American Academy of Sleep Medicine (AASM) published one set of guidelines for hypopnea indentification
82
("Chicago criteria"), and subsequently the Clinical Practice Review Committee (CPRC) of the same organization advocated still another definition of hypopnea. Of note, the Centers for Medicare and Medicaid Services (CMS) has adopted the CPRC definition. In the table below, the first two definitions are samples of what has been used in some laboratories, and the second two summarize the "Chicago" and CMS criteria.
Four Definitions of Hypopnea AIRFLOW REDUCTION
Hypopnea I Hypopnea 2
A
AASM Consensus Conference "Chicago criteria" B
AASM-CPRC and CMS (Medicare)
DESATURATION OR AROUSAL
50% reduction in airflow for 10 seconds or longer Not required 2: 2% desaturation or arousal 30% reduction in flow for 10 seconds or longer Not required • 50% reduction in airflow from baseline for IO seconds or longer • Airflow measured using: pneumotachograph, nasal pressure, or RIP sum reduction in both channels of dual-channel RIP (RC, AB) 2: 3% desaturation or arousal • Discernable reduction in airflow signal from baseline for 2: IO seconds (but less than a 50% reduction) • Airflow measured using pneumotachograph, nasal pressure, or RIP sum with reduction in either channel of dual-channel RIP (RC,AB) 2: 4% drop in Sa0 2 (arousal Reduction in airflow by 30% from baseline for not considered) 2: 10 seconds
RIP = respiratory inductance plethysmography. RC saturation (SaO z)
= rib cage, AS = abdomen. 4% desaturation means a 4% drop in the oxygen
The CPRC provided several reasons for their choice of hypopnea definition. First, the scoring of desaturation has good intra- and inter-scoring reliability while the scoring of arousals does not. Second, the Sleep Heart Health Study using this definition of hypopnea was able to show that even mild elevations of the AHI (2: 5/hr) are associated with an increased risk of cardiovascular disease. However, this definition does not recognize the sleep-disturbing effects of hypopneas associated with arousal but less than a 4% desaturation. Another problem in any definition of hypopnea is that the "baseline" flow may be hard to define in patients with repetitive apnea/hypopnea. Hypopneas can be further classified as central, obstructive, or mixed. However, classification is presumptive unless upper airway resistance is measured (supraglottic pressure or esophageal pressure deflections). Central hypopneas are characterized by a reduction in flow that is proportional to the reduction in inspiratory effort (see decreased esophageal pressure deflections, Fig. 2, arrows). Obstructive hypopneas are produced by upper airway narrowing. There is an increase in esophageal pressure deflections
Central Hypopnea airflow (nasal pressure) Esophageal pressure
Obstructive Hypopnea airflow (nasal pressure) Esophageal pressure
FIGURE
2
83
which may have a crescendo pattern prior to event termination (Fig. 2, dots) compared to baseline deflections (b). Obstructive hypopneas are often associated with reduction in chest and abdominal movements, which tend to be paradoxical (Fig. 3, double arrow). If airflow is monitored with a pneumotachograph or nasal pressure, airflow has a flattened shape in obstructive hypopneas in contrast to the round shape during central hypopneas. The detection of snoring during a hypopnea also suggests an obstructive nature. A mixed hypopnea is characterized by both a decrease in respiratory effort and an increase in upper airway resistance. However, in routine clinical practice, hypopneas are rarely classified.
t
inspiration
RIPsum
RC
AB FIGURE
3. Obstructive hypopnea with respiratory impedance plethysmography.
The apnea index (AI), hypopnea index (HI), and the apnea + hypopnea index (AHI) are all defined as the total number of events divided by the total sleep time in hours. The AHI is commonly used to quantify the severity of OSA. An AHI < 5/hr is considered normal in adults. Guidelines for severity are: AHI 5 to < 15 /hr = mild OSA, AHI l5-30/hr = moderate OSA, and AHI > 30/hr = severe OSA. However, these are only rough guidelines. The validity of these cutoffs is questionable unless you use the same measurement techniques and hypopnea definitions that were used to establish these values. It is also often helpful to compute the AHI for NREM, REM, and the supine and non-supine sleeping positions separately. Doing so can identify REM-associated or positional OSA (AHI more than twice as high in a given situation). Techniques to Measure Airflow or Tidal Volume. Until recently, airflow was detected in the clinical setting using thermistors or thermocouples, which measure changes in temperature induced by airflow. They are generally adequate to detect an absence of airflow (apnea), but their signal does not vary proportionately to airflow. Hence, they are not accurate means of detecting hypopnea (changes in airflow). The gold standard for measuring airlow is a pneumotachograph. This device works by allowing measurement of the pressure drop across a linear resistance (wire screen): Pressure = Flow x Resistance. The resistance is fixed over a range of flows. The pneumotachograph is worn in a mask covering the nose and mouth. Recently, nasal cannula connected to pressure transducers have been used to measure nasal pressure (pressure change across the nasal inlet). Unlike the pneumotach, the resistance is not constant, and: Pressure = constant (flow)? or Flow = constant x vnasal pressure. However, in clincal practice nasal pressure rather than the square root is used as a flow signal. While this is much more accurate than using a thermistor, it tends to underestimate airflow at low flow rates and overestimate flow at high flows (Fig. 4). If the nasal pressure signal is "linearized by taking the square root," it very closely approximates the flow from a pneumotachograph. In both pneumotachographs and nasal pressure the signal vs time profile (shape) gives additional important information. The profile is flattened during airflow limitation (constant or decreased flow despite increased driving pressure). Airflow limitation is characteristically present during obstructive hyopopneas or snoring. In central hypopnea, the nasal pressure signal magnitude is reduced, but the profile is round. The most important limitation of the nasal pressure technique is that about 10% of patients are "mouth breathers," and the nasal pressure signal will be misleading. Another problem is that events that are actually hypopneas may be classified as apneas (nasal pressure underestimates flow at low flow rates). The former problem is handled by the simulataneous use of a nasal-oral or oral thermistor. The second issue is not really a problem in clinical practice unless it is essential that apnea and hypopnea
84
Pneumotachograph
Flow
Linearized Nasal Prongs
o
10
20
30 40
time (sec) FIGURE 4. Nasal pressure compared to pneumotachograph during an obstructive hypopnea.
be differentiated. Many sleep laboratories consider a drop in flow to below 10-25% of baseline as an apnea. Respiratory inductance plethysmography is another method that can be used to detect apnea and hypopnea (refer to Fig. 3). The ribcage and abdominal sensor signals can be summed in an uncalibrated manner (RIPsum = RC + AB) or as a calibrated signal (RIPsum = [a X RC] + [b X AB]) as an estimate of tidal volume (not flow). Here a and b are calibration factors determined during a calibration procedure. During an apnea the sum of rib cage and abdomen signals may be near zero. In the case of hypopnea there is a reduction in the RIPsum signal (low tidal volume) as well as both the RC and AB signals. In the case of obstructive hypopnea, there may also be paradox, with chest and abdomen moving in opposite directions (Fig. 3, double arrow). Exhaled CO 2 has also been used to detect airflow. A small nasal cannula connected to a COz monitor samples the exhaled air and gives a value as the PCO z (partial pressure of COz)' During normal tidal breathing the end tidal PCO z (peak value from each breath) is an estimate of arterial PCO z (see Patient 26). This type of monitoring is most frequently used in children, in whom 'periods of hypoventilation (increased end tidal PCO z) can be detected (see Patient 64). In adults, absence of fluctuation in the exhaled CO 2 signal can be used to detect apnea. However, the signal can also be absent if the patient switches to mouth breathing.
Hypopnea Detection HYPOPNEA Nasal pressure RIP Esophageal pressure
Reduced deflection Reduced deflection in RIPsum, RC, AB Depends on type
OBSTRUCTIVE HYPOPNEA Flattened shape Paradox in RC and AB Increased deflections
CENTRAL HYPOPNEA Round shape No paradox in RC and AB Decreased deflections
RIP = respiratory inductance plethysmography, RC = rib cage, AB = abdomen
Measuring Respiratory Effort. Inspiratory effort is usually detected with a piezo-electric sensor connected to a band around the chest and abdomen. These are inexpensive, but can be misleading if the belts are not applied properly. The signal from these devices depends on the degree of tension on the transducer. They are adequate in detecting effort in most patients, but do not really quantify the changes in chest or abdominal volume during breathing. Respiratory inductance plethysmography is a more accurate
85
method of detecting changes in chest and abdominal volume. The inductance of coils in bands around the chest (ribcage) or abdomen changes during movement (dependent on the cross-sectional area encircled by the band) and is converted to a voltage. The ribcage and abdomen signals can be added as explained above. If tightly calibrated, during obstructive apnea RIPsum :::: zero (see Patient 26). The most sensitive method of detecting respiratory effort is by measurement of esophageal pressure. Changes in esophageal pressure are estimates of changes in pleural pressure. Such monitoring is routinely performed in only a few centers. Esophageal pressure is measured using air-filled balloons, fluid-filled catheters, or catheters with pressure transducers on their tips. Measuring Arterial Oxygen Saturation. Arterial oxygen saturation (SaO z) is measured during sleep studies using pulse oximetry (finger or ear probes). A desaturation is defined as a decrease in SaO z of 4% or more from baseline. Note that the nadir in SaO? commonly follows apnea (hypopnea) termination by approximately 6-8 seconds (longer in severe desaturations; Fig. 5). This delay is secondary to circulation time and instrumental delay (the oximeter averages over several cycles before producing a reading). In Figure 5, the apneas and the corresponding nadirs in saturation are identified. Various measures have been applied to assess the severity of desaturation, including computing the number of desaturations, the average minimum SaO z of desturations, the time below 80%, 85%, and 90%, as well as the mean SaO z and the minimum saturation during NREM and REM sleep. Oximeters may vary considerably in the number of desaturations they detect and their ability to discard movement artifact. Using long averaging times can dramatically affect the detection of desaturations (Fig. 6). Here, the results of identical oximeters monitoring the same patient.are shown. The averaging time of one of the oximeters is increased, and there are obvious large differences in the results. The ability of oximeters to detect desturations is especially important in light of the recent CMS definition of hypopnea that depends critically on detection of desaturation.
Airflow
26 sec
48 sec
35 sec
82%
75%
FIGURE
averaging time 3 sec
)
~'f o
5
60
averaging time 21 sec
(
120 nme (s)
FIGURE
86
6
)
180
240
REFERENCES I. Block AJ. Boysen PG. Wynne JW, et al: Sleep apnea, hypopnea, and oxygen desaturation in normal subjects: A strong male predominance. N Engl J Med 1979: 330:513-517. 2. Redline S, Sander M: Hypopnea, a floating metric: Implications for prevalence, morbidity estimates. and case finding. Sleep 1997:20: 1209-1217. 3. American Academy of Sleep Medicine Task Force: Sleep-Related breathing disorders in adults: Recommendation for syndrome definition and measurement techniques in Clinical Research. Sleep 1999:22:667-689. 4. Redline S, Kapur VK, Sanders MH, et al: Effects of varying approaches for identifying respiratory disturbances on sleep apnea assesment. Am J Respir Crit Care Med 2000; 161:369-374. 5. Farre R. Rigau J. Montserrat JM. Balleste E. Navaja D: Relevance of linearizing nasal prongs for assessing hypopneas and flow limitation during sleep. Am J Respir Crit Care Med 2001: 163:494-497. 6. Meoli AL, Casey KR, Clark RW: Clinical Practice Review Committee-AASM. Hypopnea in sleep-disordered breathing in adults. Sleep 200 I ;24:469--470. 7. Berry RB: Nasal and esophageal pressure monitoring. In Lee-Chiiong TL, Sateia MJ. Caraskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002. pp 661-671.
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PATIENT 26 A 45-year-old man with possible sleep apnea A 45-year-old man underwent polysomnography for evaluation of suspected sleep apnea. Apnea detection was performed by monitoring airflow with a thermocouple and measuring exhaled COo. Figure: Although the thermocouple revealed apnea (no deflections), the CO 2 tracing revealed persistent deflections that differed from those observed during the pre-apnea period.
Questions:
Is apnea present? If so, why is the exhaled CO 2 tracing fluctuating?
r
increasing
Exhaled CO
2
Airflow (Thermocouple1
88
Answers: Apnea is present. The CO 2 tracing fluctuates due to persistent exhalation (small expiratory puffs) during obstructive (inspiratory) apnea. Discussion: Monitoring of airflow during sleep studies can be performed by several methods, the most common of which features temperaturesensitive devices placed near the nose and mouth. Airflow causes a change in the temperature of the devices, which results in a change in voltage (thermocouple) or resistance (thermistor) of the transducer. The alteration in the signal originating from these transducers when appropriately amplified causes a deflection in the airflow tracing. Although convenient, temperature-sensitive devices do not always accurately reflect the magnitude of change in airflow and sometimes can be misleading. During apnea, the tracing may continue to fluctuate secondary to changes in temperature from contact with the patient's body or room air. Pneumotachographs accurately measure flow and can provide information about the shape of the airflow profile. However, they require masks covering the nose and mouth and therefore are less comfortable. Measurement of the pressure difference across a known resistance (the pneumotachograph wire screen) when calibrated reflects the flow rate (flow = pressure / resistance). Pneumotachographs also can reveal detail not seen in thermocouple monitoring, such as vibration in the flow (snoring), a flat profile (airflow limitation), or expiratory puffs of air during inspiratory apnea. Another method for monitoring airflow is to measure exhaled CO 2, As expired air is rich in CO 2 while ambient air has essentially none, respiration is detected by fluctuations in measured CO 2, Air is sampled via a small nasal or nasal-oral cannula by continuous suction and is measured downstream at an analyzer. The increases in CO 2 values (reflecting exhalation) are time-delayed because there is a finite time for the sampled air to reach the analyzer. The plateau value of measured CO 2 (end tidal PC0 2) can provide an estimate of arterial PC0 2 and is increased during periods of hypoventilation. Apnea is detected by an absence of deflection in the CO 2 tracing. This method of monitoring airflow is widely used in pediatric sleep monitoring because children with "sleep apnea" frequently have long periods of hypoventilation (increased end tidal PC0 2) rather than discrete apneas or hypopneas. However, the method can be misleading. During apnea (absence of inspiratory airflow), small expiratory puffs may continue. These small exhalations are rich in CO 2 and can cause significant deflections in the CO 2 signal, giving a false impression about the nature of airflow (C0 2 not airflow, is measured). . Recently, measurement of nasal pressure has been used to detect airflow. Pressure just inside the
nasal inlet is measured by connecting nasal cannulas (oxygen- or CO 2-monitoring) directly to sensitive pressure transducers. The pressure deflections are reasonable, semiquantitative estimates of the magnitude and shape of airflow. This method works similarly to a pneumotachograph by measuring the pressure drop across the resistance of the nasal inlet. The major difficulty with this method is that oral airflow is not detected (see Fundamentals 10). Simultaneous use of an oral thermocouple can solve this problem. Of note, nasal cannula are available that allow simultaneous measurement of end tidal CO 2 and nasal pressure. One prong samples nasal pressure (connected to pressure transducer), and one prong samples exhaled CO 2, The RIPsum signal (also known as Vsum) of respiratory inductance plethysmography can provide a semiquantitative estimate of tidal volume (see figure below). In this method, changes in the inductance of coils in bands around the rib cage (RC) and abdomen (AB) during respiratory movement are translated into voltage signals. The sum of the two signals (RIPsum = [a X RC] + [b X AB]) can be calibrated by choosing appropriate constants: a and b. During obstructive apnea, the two signals cancel (a * RC = -b * AB), and RIPsum is close to zero. inspiration
RIPsum RC (rib cage) AS (abdomen)
Respiratory inductance plethysmography can also be used to detect hypopneas. Central hyponeas are characterized by a reduction in all three signals (RC, AB, RIPsum) without evidence of paradox. Obstructive hypopneas are characterized by a reduction in the RIPsum and usually one or both of the RC and AB signals. In addition, the RC and AB signals often show paradox (move in opposite directions) during the hypopnea. In the present case, simultaneous monitoring with a pneumotachograph (see following figure) showed that the fluctuations in CO 2 during apnea were secondary to small expiratory puffs (rich in CO 2) during inspiratory apnea. While you could argue that this is not absolute apnea (no airflow), most would agree that very low flow (or no inspiratory flow) and apnea are equivalent physiologically. In fact, many clinicians characterize flow reduced to less than 10-25% of baseline as an apnea.
89
i
Increasing
Exhaled PC0
2
Pneumotach
Thermocouple
Clinical Pearls I. Temperature or CO) measuring devices for monitoring air flow can be inaccurate because they do not reflect the magnitude of airflow. 2. Pneumotachography accurately measures flow and provides a detailed airflow profile that may include information not seen in thermistor/thermocouple monitoring. However, a mask over the nose and mouth must be used. 3. More practical options for monitoring airflow include nasal cannulas connected to pressure transducers (nasal pressure) and respiratory inductance plethysmography.
REFERENCES I. Chada TS. Watson H. Birch S. et al: Validation of respiratory inductance plethysmography using different calibration procedures. Am Rev Respir Dis 1982; 125:644-649. 2. Tobin M. Cohn MA. Sackner MA: Breathing abnormalities during sleep. Arch Intern Med 1983; 143: 1221-1228. 3. Monserrat JP, Farre R, Ballester E, et al: Evaluation of nasal prongs for estimating nasal flow. Am J Respir Crit Care Med 1997; 155:211-215. 4. Norman RG. Ahmed MM. Walsleben JA, et al: Detection of respiratory events during NPSG: Nasal cannula/pressure sensor versus thermistor. Sleep 1997; 20:1175-1184. 5. Kryger MH: Monitoring respiratory and cardiac function. In Kryger MH. Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia. WB Saunders, 2000, pp 1217-1230.
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PATIENT 27 A 50-year-old man with possible central apnea A 50-year-old, obese man was evaluated at another hospital for complaints of excessive daytime sleepiness. He underwent a sleep study in which many apneas were noted. Because of minimal movement in the chest and abdominal bands, the apnea was labeled as central by the technician scoring the study. A second sleep study was performed on presentation to this sleep laboratory because the patient's history suggested obstructive apnea. Figure: A sample tracing of one of the recorded events is shown below.
Question:
What type of apnea is present?
Airflow
Chest
1 sec J-I Abdomen
91
Diagnosis:
Obstructive apnea. There is minimal chest and abdominal movement due to obesity.
Discussion: The diagnosis of obstructive apnea depends on demonstration of apnea despite continued inspiratory effort. This usually is accomplished by detecting chest and abdominal movement. During obstructive apnea/hypopnea, the chest and abdominal tracings may show paradoxical motion (one in, the other out). Sometimes changes in phase between chest and abdomen are more subtle. In the following tracings from a patient with obstructive apnea, paradox is not present in the initial part (a) but is obvious in the last part of the tracing (b). Paradoxical movement tends to be most pronounced in REM sleep, when there is hypotonia of the chest wall muscles.
Some of the many different methods of detecting movement include piezo-electric transducers in bands, mercury strain gauges, and respiratory impedance plethysmography (RIP). RIP converts changes in the impedance of a coil in a band around the body secondary to changes in the enclosed area during chest/abdominal excursions into a voltage signal. The rib cage (RC) and abdominal (AB) signals are then added (RIPsum = [a X RC] + [b X AB)). If the coefficients a and b are selected by calibration, RIPsum is a reasonable estimate of tidal volume (see Patient 26). During obstructive apnea, the rib cage and abdominal contributions to RIPsum cancel (a X RC = - b X AB), and RIPsum is close to zero (apnea). In all of the above methods, a change in body position may alter the ability to detect chest/abdominal movement. This may require adjusting band placement or amplifier sensitivity. In addition, very obese patients may show little chest/abdominal wall movement despite considerable inspiratory effort. Thus, be cautious about making the diagnosis of central apnea solely on the basis of surface detection of inspiration effort.
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The most sensitive method of detecting respiratory effort is to measure the esophageal pressure. Changes in esophageal pressure are estimates of pleural pressure changes. In the past, this method required esophageal balloons, which were stiff and uncomfortable. Recently, esophageal pressure has been measured using small, soft, fluid-filled catheters (pediatric feeding tubes) connected to pressure transducers, such as the disposable transducers commonly used in intensive care units. This technique is usually well tolerated. New esophageal balloon catheters are also now available with a removable stylet. These are more flexible and comfortable for the patient than the older balloon catheters. In one study using both RIP and esophageal pressure monitoring, apneas were found to have been correctly classified by RIP alone in 91 % of patients. Thus, monitoring chest and abdominal movement is satisfactory for most patients. In a few patients, obstructive apneas may be incorrectly labeled as central if esophageal pressure monitoring is not performed. Of note, RIP monitoring of chest and abodomen is probably more sensitive than piezo-electric belts at detecting respiratory effort. With piezo-electric belts the signal is dependent on the tension on the transducer. This mayor may not be proportionate to changes in the area surrounded by the belt. In addition, if the belts are not sufficently tight or move during the night, the signal can be very low. In all types of surface monitoring, correct placement ofthe belts is essential to obtain a good signal. In the present case, definite chest and abdominal movements are evident, although of a small magnitude. The simultaneous esophageal pressure trace (see figure below) reveals that inspiratory effort clearly is present and increasing during the event. Therefore, the event is an obstructive apnea.
Airflow Chest Abdomen Esophageal Pressure
1 sec
....
Clinical Pearls I. Chest and abdominal movements during obstructive apnea may be small in magnitude and difficult to detect in some obese individuals. 2. The most sensitive method of detecting respiratory effort is to monitor the esophageal pressure. 3. During obstructive apnea and hypopnea, the chest and abdomen movements may be out-of-phase, demonstrating a subtle difference rather than an obvious paradox. 4. If apneas are classified solely by chest and abdominal bands, some events may be incorrectly classified as central.
REFERENCES 1. Chervin RD and Aldrich MS. Effects of esophageal pressure monitoring on sleep architecture. Am J Respir Crit Care Med
1997;56:881-885. 2. Staats BA. Bonekat HW. Harris CD. et al: Chest wall motion in sleep apnea. Am Rev Respir Dis 1984; 130:59-63. 3. Flemale A. Gillard C, Dierckx JP: Comparison of central venous. esophageal and mouth occlusion pressure with water-filled catheters for estimating pleural pressure changes in healthy adults. Eur Resp J 1988; 1:51-57. 4. Kryger MH: Monitoring respiratory and cardiac function. In Kryger MH. Roth T. Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders. 2000. pp 1217-1230. 5. Berry RB: Nasal and esophageal pressure monitoring. In Lee-Chiong TL. Sateia MJ, Caraskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002. pp 661-672.
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PATIENT 28 A 30-year-old man with heavy snoring A 30-year-old man was referred for evaluation of heavy snoring. He denied excessive daytime sleepiness. The patient's wife reported that he stopped breathing during the night. Physical Examination: Blood pressure 150/85, pulse 88/min. HEENT: edematous palate. Neck: 18-inch circumference. Chest: clear. Cardiac: normal. Extremities: no edema. Sleep Study: Total sleep time: 350 minutes (normal 400--443). Total apneas: 200 (5% central, 30% mixed, 65% obstructive). Total hypopneas: 50. Figure: A typical apnea is illustrated below. Chest and abdomen tracings show movements of these areas (respiratory effort).
Questions:
Which type of apnea is illustrated? What is the diagnosis?
Airflow
Chest
Abdomen Arterial Oxygen
Saturation
94
Answers: The illustrated event is a mixed apnea. The diagnosis is obstructive sleep apnea. Discussion: An obstructive apnea is one in which ventilatory effort is present. A mixed apnea is composed of an initial central apnea (no inspiratory effort) followed by an obstructive portion. Most patients with obstructive sleep apnea have predominantly mixed or obstructive apneas. However, the presence of a small fraction of central events is not unusual. Both mixed and obstructive apneas have the same clinical significance and usually the same etiology (upper airway obstruction). The initial, central portion of a mixed apnea is believed to be due to the hyperventilation following the preceding apnea. As the patient returns to sleep, the PCO z is below the apneic threshold (the level of COz that triggers ventilation). The result is an absence of inspiratory effort (central apnea). During the apnea, the PCO z rises until inspiratory effort returns. However, apnea persists despite the
return of inspiratory effort secondary to an obstructed upper airway. Adequate treatment of upper airway obstruction prevents apnea and postapnea hyperventilation. Thus, both the central and obstructive components of mixed apneas are eliminated by effective treatments such as tracheostomy or nasal continuous positive airway pressure (CPAP). Some central apneas may persist, but usually resolve with time. In the current case, the illustrated event is a mixed event with an initial central portion (A) followed by an obstructive portion. Paradoxical motion is seen in the chest and abdomen tracings during the obstructive portion (B). The patient was treated with nasal CPAP which virtually eliminated mixed and obstructive apnea (AHI < 5/hr). A few central apneas and hypopneas persisted in REM sleep.
Clinical Pearls I. Many patients with the obstructive sleep apnea syndrome have both mixed and obstructive apneas. The underlying pathogenesis of both is upper airway obstruction. 2. In most cases of obstructive sleep apnea, adequate treatment of upper airway obstruction eliminates both obstructive and mixed apnea.
REFERENCES l. Sanders MH: Nasal CPAP effect on patterns of sleep apnea. Chest 1984; 86:839-844. 2. Dempsey lA, Skatrud 18: A sleep-induced apneic threshold and its consequences. Am Rev Respir Dis 1986; 133:1163-1170. 3. Iber C, Davies SF, Champan RC, Mahowald MW: A possible mechanism for mixed apnea in obstructive sleep apnea. Chest 1986; 89:800-805.
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PATIENT 29 A 33-year-old man complaining of daytime sleepiness A 33-year-old man was evaluated for daytime sleepiness of 3-year duration. His wife reported that he snored heavily and stopped breathing when sleeping on his back. Physical Examination: Normal except for mild obesity (140% of ideal body weight) and a long, edematous palate and uvula. Sleep Study: No apneas were noted; however, 400 events such as the one illustrated below were recorded. Airflow was monitored with a nasal-oral thermister and nasal pressure sensor. Respiratory effort was detected by recording piezo-electric belts around the chest and abdomen.
Questions:
What is the diagnosis? What is the illustrated event?
30.6 sec II
nasal pressure airflow [therm) chest abdomen
$a02
---:-:---------------------97% 93%
96
Diagnosis:
Obstructive sleep apnea (hypopnea) syndrome. The event is an obstructive hypopnea.
Discussion: While the definition of apnea is well standardized, the definition of hypopnea varies among clinicians. All agree that hypopnea is a reduction in airflow (or tidal volume) from the preceding baseline for 10 seconds or longer. As discussed in Fundamentals of Sleep Medicine 10, some definitions require an associated arousal or desaturation (drop in the SaO? of 2-4%). The choice of definitions and the type of sensor used to monitor airflow can dramatically change the number of hypopneas that are detected. Nasal pressure monitors usually detect more hypopneas than devices measuring changes in temperature. Obstructive hypopneas occur because of upper airway narrowing and have the same consequences as obstructive apneas; they disturb sleep (arousals) and often result in variable drops in the SaO? The separation of severe hypopneas from apneas -is not precise. Whether an event appears as an apnea or hypopnea may depend on the amplifier gain and the method used to detect flow. Some sleep labs consider a reduction in flow to below 25% of baseline as an apnea. The use of nasal pressure to monitor flow tends to identify more events as apneas. This could be because oral flow (inspiratory and expiratory mouth breathing or oral expiratory puffs) may fail to cause a deflection in the nasal pressure signal, or be-
u s;
cause nasal pressure tends to underestimate flow when flow rates are low (see Fundamentals 10). The figure below shows an event that appears as an apnea in the nasal pressure signal, although deflections in the thermistor tracing are noted. airflow- ~JlnA!1n~ _~~~~nAn!1nJ\ thermistor ~ VVV V v ~ - - ~ ~ v VVVV V V'
chest
nasal
pressure
I~
iI
The nasal pressure signal should be amplified or recorded as either a DC signal or an AC signal with a long time constant or a very small low filter setting (~ 0.0 I). If this is not done, the characteristic airflow flattening will be less apparent. An AC amplifier with a short time constant sees no change in flow (flow plateau) as zero flow. The figure below shows the same signal recorded with a short time constant (1.6 sec), a long time constant (5.0 sec), and as a DC signal.
§
~
o
?: 0 ~ LL
-
U
~
~
~
~
o
LL
~
?: ~ 0
-0
U
?:
0
LL
0
5
10
15
20
25
30
Time (sec) Dotted line = zero flow
97
When using respiratory inductance plethysmography, hypopneas are characterized by a drop in RIPsum (an estimate of tidal volume) and usually a drop in either the chest or abdominal deflections (or both). Typically during obstructive hypopnea there may be chest-abdomen paradox (one moving in while the other moves out). However, with piezo-electric sensor bands, the changes in chest and abdominal movements are more variable. Paradox may not be detected. If a snore detector is employed, you may also see evidence of snoring during obstructive hypopneas.
In the present patient, the nasal pressure signal (see figure on previous page) shows a clear decrease in magnitude and a flattened shape during the event. After event termination, the shape of the nasal pressure becomes rounded again. In contrast, there is little change in airflow by thermistor or chest/abdominal deflections. There is chest and abdominal paradox, but this is present both during and after event resolution. The obstructive hypopnea is followed by a 4% desaturation.
Clinical Pearls I. The separation of events into apneas and hypopneas is imprecise and may depend on the sensitivity/calibration of the airflow recording system. Thus the apnea-hypopnea index is a more accurate (and inclusive) estimate of the severity of sleep-disordered breathing than the apnea index. 2. Paradoxical motion of the chest or abdomen during hypopnea suggests an obstructive hypopnea. However, this finding may be absent (especially if piezo-electric belts are used for monitoring chest/abdominal movement). 3. Nasal pressure monitoring detects more hypopneas than thermistors. The flattened shape of the nasal pressure signal also helps identify hypopneas as obstructive. It is important to record nasal pressure as a DC signal-or use the approprite filter settings if recorded as an AC signal. 4. Some events may appear as apneas in the nasal pressure signal and hypopneas in the thermistor signal. 5. Identification of hypopneas is important because these events may result in arterial oxygen desaturation and arousal from sleep.
REFERENCES I. Block Al, Boysen PG. Wynne Wl. et al: Sleep apnea. hypopnea. and oxygen desaturation in normal subjects: A strong male predominance. N Engl 1 Med 1979; 300:513-517. 2. Gould GA, KF Whyte. GB Rhind, et al: The sleep hypopnea syndrome. Am Rev Respir Dis 1988; 137:895-898. 3. Berg S, Haight lSl, Yap V. Hollstein V. Cole P: Comparison of direct and indirect measurements of respiratory airflow: Implications for hypopneas. Sleep 1997;20:60-64. 4. Norman RG. Ahmed MM. Walsleben lA. Rapoport OM: Detection of respiratory events during NPSG: Nasal cannula/pressure sensor versus thermistor. Sleep 1997;20: 1175-1184.
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FUNDAMENTALS OF SLEEP MEDICINE 11
Excessive Daytime Sleepiness
Excessive daytime sleepiness (EDS) is the most common complaint evaluated by sleep disorder specialists. Sleep apnea is the most common cause. However, do not automatically assume that every patient with EDS and snoring has sleep apnea. All of the causes of daytime sleepiness listed below must be carefully considered. Note that it is common for more than one of these disorders to be present in a given individual. Become acquainted with the patient's medical history, and explore a relevant review of symptoms. For example, congestive heart failure is commonly associated with a type of central sleep apnea (Patient 69), and patients with renal failure often have periodic limb movements in sleep (PLMS). Hypothyroidism and acromegaly are predisposing conditions for sleep apnea. In addition, some medications can cause daytime sleepiness or fatigue. Patients with some of the disorders listed below may present with complaints of insomnia (difficulty initiating and maintaining sleep) rather than EDS. In fact, patients with PLMS more commonly present with insomnia complaints than EDS. Problems with insomnia also may predominate in those with depression. Even patients with sleep apnea (for which EDS is a cardinal manifestation) may seek medical evaluation primarily because of frequent nocturnal awakenings rather than daytime sleepiness.
Evaluating Causes of Excessive Daytime Sleepiness DISORDERS
Ev ALUATION
Sleep apnea syndromes Upper airway resistance syndrome Narcolepsy Depression Periodic leg (limb) movements in sleep Idiopathic hypersomnia Withdrawal from stimulants Insufficient sleep syndrome Drug dependence/abuse Medication side effects Post-traumatic hypersomnia Brain tumors
All cases History Self-rating scales of sleepiness Sleep-wake diary Polysomnography Selected cases MSLT (narcolepsy) Drug screen
A good history is essential in evaluating patients with EDS. Differentiating complaints of fatigue and daytime sleepiness can be difficult. Quantifying the degree of daytime sleepiness is challenging because patients tend to underestimate. Questionnaires such as the Epworth Sleepiness Scale or Stanford Sleepiness Scale are attempts to standardize the evaluation of self-rated symptoms of sleepiness. The Stanford Scale measures subjective feelings of sleepiness ("fogginess, beginning to lose interest in staying awake"). In contrast, the Epworth Scale measures average sleep propensity (chance of dozing) over eight common situations that almost everyone encounters. The test was developed by Johns at the Epworth Hospital in Melbourne, Australia. It has gained popularity because it is simple and short. The propensity to fall asleep is rated as 0 (never), 1,2, or 3 (high chance of dozing; see table). The maximum score is 24, and normal is assumed to be 10 or less. The Epworth Sleepiness Scale correlates roughly with the severity of ob-
99
structive sleep apnea and improves after CPAP treatment. The Scale has a low but significant correlation with the MSLT (an objective measure of sleepiness). However, changes in the Epworth Scale after treatment may not always correlate with changes in the MSL T.
Epworth Sleepiness Scale SITUATION - "USUAL WAY OF LIFE IN RECENT TIMES"
Sitting and reading Watching TV Sitting, inactive in a public place (e.g., a theater or a meeting) As a passenger in a car for an hour without a break Lying down to rest in the afternoon when circumstances permit Sitting talking to someone Sitting quietly after a lunch without alcohol In a car, while stopped for a few minutes in traffic Total:
CHANCE OF DOZING (SCORED 0, I, 2, 3 )
0-3 0-3 0-3 0-3 0-3 0-3 0-3 0-3 0-24 (0-10 normal)
o = would NEVER doze. I = SLIGHT chance of dozing, 2 = MODERATE chance of dozing, 3 = HIGH chance of dozing Question the patient about which activities are compromised by decreased alertness (e.g., driving, work, social situations). Record the normal bedtime, waketime, and average hours of sleep. Surprisingly, the simple answer for some patients is that they are trying to exist on an inadequate amount of sleep. Many sleep disorders centers have patients fill out a sleep-wake diary for 2 weeks before being evaluated. This diary documents patterns of sleep and daytime sleepiness. Questioning bed partners is absolutely essential in evaluating patients with EDS. A history of loud snoring and observed gasping or apnea is suggestive of obstructive sleep apnea syndrome, whereas a history of leg jerks or kicking suggests periodic limb movements in sleep. The age at onset of symptoms provides a clue to the disorder. While sleep apnea can start at any age, it typically presents in middle-aged or older individuals. In contrast, narcolepsy usually starts in late adolescence or the 20s. The patient should be questioned about cataplexy (loss of muscle tone during moments of increased emotion such as laughter), which is characteristic of narcolepsy. Sleep paralysis (inability to move while still awake, at sleep onset, or after awakening) and hypnagogic hallucinations (vivid sensory imagery, usually visual, occurring at sleep onset while still awake) also are common in narcolepsy, but can occur in normal individuals as well. Symptoms of depression suggest that this common disorder is the cause of daytime sleepiness. Physical examination should pay special attention to the blood pressure, upper airway (nose, mouth, and throat), neck circumference, and signs of right or left heart failure or hypothyroidism.
History in Excessive Daytime Sleepiness Age of onset Duration of symptoms Daily activities impaired (e.g., driving, work, social situations) Medications, ethanol, sleeping pill use Sleep habits: bedtime, duration of sleep
Bed partner observations: snoring, gasping, apnea, leg kicks Symptoms of narcolepsy: cataplexy, sleep paralysis, hypnagogic hallucinations Symptoms of depression
In addition to the history and physical examination, a nocturnal sleep study (polysomnography) is required for most patients presenting with EDS. The severity of the disorder frequently is underestimated by the patient. Moreover, several disorders may be present in the same individual (e.g., narcolepsy, obstructive sleep apnea, and periodic limb movements in sleep). If a diagnosis of narcolepsy is suspected, an MSLT following the nocturnal sleep study can be useful. The MSLT provides objective evidence of the tendency to fall asleep during the day and can help make the diagnosis of narcolepsy (sleep-onset REM).
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REFERENCES I. Johns MW: Sleepiness in different situations measured by the Epworth Sleepiness Scale. Sleep 1994; 17:703-710. 2. Johns MW. Daytime sleepiness, snoring, and obstructive sleep apnea. The Epworth Sleepiness Scale. Chest 1993: 103:30-36. 3. American Sleep Disorders Association: International Classification of Sleep Disorders: Diagnostic and Coding Manual. Rochester, Minnesota, ASDA, 1997. 4. Mitler MA, Carskadon MA, Hirshkowitz M: Evaluating sleepiness. In Kryger MH, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders, 2000, pp 1251-1257.
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PATIENT 30 A 45-year-old man with a snoring problem A 45-year-old man sought treatment of his snoring, which had been present for many years. His wife slept in another bedroom because the snoring "shook the walls." The patient denied symptoms of excessive daytime sleepiness (Epworth Sleepiness Scale score 6/24 [normal]), morning headache, or problems at work (he was a successful accountant). He did admit to drinking more than five cups of coffee daily. There was no history of recent weight gain or alcohol use. Physical Examination: Height 5 feet 10 inches, weight 190 pounds, blood pressure 150/90. Neck: 18-inch circumference, no jugular venous distention. HEENT: edematous uvula, dependent palate (see figure). Chest: clear. Cardiac: normal. Extremities: no edema. Figure: Compare the typical adult with the individual presenting in this case.
Question: What missing bit of historical information is essential to determining whether or not a sleep study should be performed to rule out obstructive sleep apnea?
normal
patient Dependent palate Long edematous uvula High tongue base
102
Answer:
Question the spouse about observed apnea/gasping during sleep.
Discussion: Obstructive sleep apnea (OSA) is a common disorder occurring in about 4% of men and 2% of women. During sleep, closure of the upper airway results in cessation of airflow despite continued respiratory effort. The termination of apnea is associated with a brief awakening. The resulting sleep fragmentation reduces the amount of slow wave and REM sleep and causes varying degrees of daytime sleepiness. The presence and severity of OSA can be precisely defined by sleep monitoring. However, because attended in-lab monitoring is expensive and of limited availability, appropriate screening techniques are important. In a study examining the predictive value of a number of historical and physical findings-neck circumference, hypertension, habitual snoring, and bed partner reports of gasping/ choking - respirations were found to be the best predictors. Body weight, recent weight gain, and older age also were significant factors. Interestingly, the classic daytime symptoms said to be present in sleep apnea (daytime sleepiness, morning headaches, and cognitive impairment) were not predictive of the disorder. Unfortunately, many patients who deny symptoms of daytime sleepiness do have significant sleep apnea. Structured questionnaires such as the Berlin Questionnaire have also proved useful in identifying patients likely to have OSA. Once a patient has been selected, the physician decides on the appropriate diagnostic study (see table). Levell-attended, full polysomnographyis the gold standard and the only study recommended by the American Academy of Sleep Medicine under usual circumstances. Level 2 - full, unattended (ambulatory) polysomnography-is now available and has been used successfully. However, significant amounts of data are lost (i.e., leads fall off) in 10-15% of these ambulatory studies. Level 3 (cardiopulmonary studies) is recommended when there is a high pre-test probability of OSA, and traditional polysomnography is not available locally or the delay in obtaining a study in not acceptable.
Level 3 might also be useful in patients who cannot be moved to the sleep laboratory or for follow-up after treatment. Level 4 studies consist of monitoring of one or two bioparameters (usually oximetry with our without snoring or airflow), but these have an appreciable false negative rate. The other factor to consider is that if a positive-pressure titration is ultimately needed, the combination of a Level 3-4 study plus a traditional in-lab CPAP titration is no cheaper than a single partial-night sleep study (initial part is diagnostic, second part is positive-pressure titration). An additional issue is reimbursement. Currently, unattended studies are poorly reimbursed in the U.S. How the data from portable monitoring is analyzed is as important as which data is recorded. Full disclosure (a second-by-second view of the raw data rather than a simple overnight summary) is the optimal way to determine if the recording was technically adequate and to arrive at a correct diagnosis. False negative studies may occur for a number of reasons: inadequate sleep, no REM sleep recorded, no sleep in the supine position, respiratory events with minimal desaturation (oximetry screening), sleep disturbance for reasons other than apnea (periodic leg movements), or respiratory-related arousals with minimal apnea/hypopnea. Regardless of whether full polysomnography or an unattended screening study is performed, it is critical that a physician knowledgeable in sleep medicine evaluate the technical adequacy of the study and correlate the findings with the patient's symptoms. When the clinical suspicion of a sleep disorder is high (e.g., sleep apnea), a negative screening study should prompt more comprehensive sleep testing. In the present case, the patient's wife reported hearing her husband stop breathing and then abruptly "snort and gasp for air." This history along with the presence of hypertension, a large neck, and habitual snoring suggested that a sleep study should be performed. The patient had an AHI of 60/hour. After nasal CPAP therapy his energy level improved, and he was more productive at work.
Levels of Sleep Studies TYPE OF STUDY
Levell
Attended polysomnography
Level 2 Level 3
Unattended full polysomnography Cardiopulmonary study-four or more bioparameters (usually unattended) Single or dual bioparameter(s)
Level 4
BIOPARAMETERS MEASURED
EEG, EOG, chin EMG, airflow, effort, EKG, Sa0 2 , ± leg EMG, body position Same as Level I, but technologist not present Airflow, effort, Sa0 2 , EKG (or heart rate), ± body position Oximetry, oximetry + airflow or snoring
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Clinical Pearls 1. The presence or absence of excessive daytime sleepiness- the cardinal manifestation of OSA - is not a good predictor of OSA. 2. A large neck circumference, hypertension, habitual snoring, and witnessed choking! gasping during sleep are good predictors of the presence of sleep apnea. 3. Screening studies (depending on the data recorded) may have a high number of false negatives if mild-to-moderate cases of OSA are studied. 4. Obtain an attended, full polysomnography study when there is a high index of suspicion for OSA but a negative screening study. 5. Raw data and tracings of screening studies must be visualized-summary of data can be misleading. 6. Screening studies probably do not save money if a subsequent attended CPAP titration is required in most cases. Attended polysomnography of the partial-night type (initial diagnostic portion, then CPAP titration) is probably more cost-effective if moderate to severe OSA is likely.
REFERENCES 1. Young T, Palta M, Leder R, et al: The occurrence of sleep-disordered breathing among middle-aged adults. N Engl J Med 1993; 328: 1230-1235. 2. Flemons WW, Whitelaw WA, Brant R, et al: Likelihood ratios for a sleep apnea clinical prediction rule. Am J Respir Crit Care Med 1994; 150: 1279-1285. 3. Standards of Practice Committee, American Sleep Disorders Association: Portable recording in the assessment of obstructive sleep apnea. Sleep 1994; 17:378-392. 4. Netzer NC, Stoohs RA, Netzer CM, et al: Using the Berlin Questionnaire to identify patients at risk for the sleep apnea syndrome. Ann Intern Med 1999; 132:485--491.
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PATIENT 31 A 40-year-old woman with "mild" sleep apnea A 40-year-old woman was referred by her internist for evaluation of daytime sleepiness. About a year ago he had ordered a screening sleep oximetry study, which showed minimal desaturation. The patient was labeled as having mild disease and told to lose weight. However, her daytime sleepiness persisted despite 10 pounds of weight loss. Her husband reported that she snored softly and frequently had a "pause" in breathing. Her score on the Epworth Sleepiness Scale was 20/24 (severe sleepiness). Physical Examination: Mildly obese woman - weight 120 pounds, height 5 feet 2 inches. HEENT: edematous palate. Neck: 15 ~inch circumference. Chest: clear. Cardiac: normal. Extremities: no edema. Figure: The initial portion of the oximetry study is shown below.
Question:
Do you agree that this patient has mild sleep apnea?
105
Diagnosis:
Severe sleep apnea with minimal arterial oxygen desaturation.
Discussion: In determining the severity of obstructive sleep apnea (OSA), several factors must be considered. Some patients with minimal desaturation have frequent events, a high arousal index, and severe daytime sleepiness. Thus, if an oximetry study is used to screen patients for OS A, the tracing should be scrutinized for evidence of the sawtooth pattern of repeated changes in SaO,. It is not sufficient to simply observe summary information. In fact, some patients have respiratory arousals without any changes in SaO,. Alternatively, other patients with an AHI in the -moderate range (1530/hr) have impressive arterial oxygen desaturations and a low sleeping baseline SaO,. Studies of breath holding in normal subjects suggest that the rate of Sa0 2 fall is inversely proportional to the baseline Sa0 2 and to the lung volume (oxygen stores) at the start of breath hold. The rate of fall is disproportionately higher at low lung volumes secondary to increases in ventilation/perfusion mismatch. A study of OSA patients found that the severity of nocturnal arterial oxygen desaturation was related to several factors, including: the awake supine Pa0 2, the percentage of sleeptime spent in apnea, and the expiratory reserve vol-
Thus a low ERV means that the patient has low oxygen stores at the start of apnea (a low FRC) and significant ventilation/perfusion mismatch at low lung volumes (identified by a high RV). Clinically, the groups of OSA patients with severe desaturation include patients with a low PO J for any reason (severe obesity, daytime hypoventilation, and chronic obstructive pulmonary disease [COPD]). In fact, some patients can have significant desaturation after events as short as 10-15 seconds. The severity of desaturation also depends on sleep stage. In most OSA patients, the longest apneas and most severe desaturations occur in REM sleep. Some studies also have suggested that at equivalent apnea length, the severity of desaturation is worse in obstructive than central apnea. In evaluating oximetry, remember that patients with a high carboxyhemoglobin (heavy smoking) will have a falsely high SaO, because the devices do not differentiate carboxyhemoglobin and oxyhemoglobin. In addition, oximeters vary widely in their ability to record desaturations. This is especially true if the averaging time is long (see Fundamentals 10).
ume.
Factors Determining the Severity of Desaturation
Patients with a baseline Pa0 2 of 55-60 mmHg are on the steep part of the oxyhemoglobin saturation curve. A small fall in Pa0 2 results in significant desaturation. While apnea duration is an obvious factor in the severity of desaturation, the length of the ventilatory period between events also is important. Some patients do not completely resaturate between events as they quickly return to sleep, and the airway closes again. Long event duration and short periods between apneas mean the percentage of sleeptime spent in apnea is high. The clinical significance of a low expiratory reserve volume (ERV) may be less obvious. The ERV is the difference between the functional residual capacity (FRC; end expiratory lung volume) and the residual volume (RV; volume at maximal exhalation). The FRC is reduced in obesity secondary to low compliance of the chest wall/abdomen. The residual volume is increased if patients have any degree of obstructive airway disease (airtrapping).
Event duration Length of ventilatory period between events Baseline sleeping Sa0 2 (P0 2) Oxygen stores (FRC) Tendency for V/Q mismatch-presence of lung disease, ERV = FRC - RV
106
In the present case, the oximetry tracing revealed a subtle "sawtooth" pattern consistent with frequent small changes in Sa0 2. A complete sleep study revealed an AHI of 60/hr. The events were short (mean duration 15 seconds), and the baseline sleeping Sa0 2 was 95%. The patient was only mildly obese and had no evidence of COPD. Thus, it is not surprising that the arterial oxygen desaturation was mild. However, the arousal index was 55/hr-consistent with severe sleep fragmentation. The patient was treated with nasal CPAP, and she experienced a rapid improvement.
Clinical Pearls 1. Some patients with minimal arterial oxygen desaturation have severe OSA, indicated by a high AHI and severe sleep fragmentation. 2. The severity of arterial oxygen desaturation in patients with OSA depends on the baseline supine P0 2. the percentage of apnea time (apnea length), and the degrees of obesity (decreased FRC) and obstructive lung disease (increased RV). 3. Arterial oxygen desaturation usually is more severe in REM than NREM sleep and in obstructive rather than central apnea (equivalent length). 4. Screening for OSA with oximetry can result in false negatives in patients with mild arterial oxygen desaturation during apnea/hypopnea. 5. When evaluating oximetry results always examine the tracings as well as the summary data.
REFERENCES I. Findley U, Ries AL, Tisi OM: Hypoxemia during apnea in normal subjects: Mechanisms and impact of lung volume. J Appl
Physiol 1983; 55: 1777-1783. 2. Bradley TD, Martinez D, Rutherford R, et al: Physiological determinants of nocturnal arterial oxygenation in patients with obstructive sleep apnea. J Appl Physiol 1985; 59: 1364-1368. 3. Series F, Cormier Y, La Forge J: Influence of apnea type and sleep stage on nocturnal postapneic desaturation. Am Rev Respir Dis 1990; 141:1522-1526. 4. Netzer N, Eliasson AH, Netzer C, et al. Overnight pulse oximetry for sleep-disordered breathing in adults: A review. Chest 200 I; 120:625-633.
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FUNDAMENTALS OF SLEEP MEDICINE 12
Respiratory Arousals
Respiratory arousals are associated with respiratory events. They include arousals associated with the termination of apnea, hypopnea, and respiratory effort-related arousals (RERAs). RERAs are also called upper airway resistance syndrome events. RERAs are defined as arousals associated with episodes of high inspiratory effort that do not meet criteria for obstructive apnea or hypopnea. The gold standard measurement of inspiratory effort is esophageal (or supraglottic) pressure deflections. Usually arousal follows a crescendo pattern of progressive effort over several breaths, but arousal from a sustained increased effort also qualifies. The rationale for the definition of RERAs is based on studies of the mechanisms by which respiratory stimuli induce arousal from sleep. These studies suggest that the arousal stimulus during upper airway narrowing or closure is related to the level of inspiratory effort (airway suction pressure, esophageal pressure deflection), at least during NREM sleep. While either hypoxia or hypercapnia may drive inspiratory effort, it is the magnitude of the inspiratory effort and the threshold for arousal that determine if arousal occurs. During experimental mask occlusion in normal subjects, arousal usually occurs when suction pressure reaches 20-30 em H 20 . However, snorers and patients with OSA may not arouse until esophageal pressures reach 40-80 cm H 20 ; these results imply a decrease in arousability in these groups. During obstructive apnea/hypopnea, the arousal response and apnea termination are associated with a preferential increase in upper airway muscle activity and restoration of airway patency. Thus, while frequent arousals are believed to cause excessive daytime sleepiness in patients with OSA, the arousal response is believed essential for termination of the apnea. The fact that only 60-80% of event terminations are associated with clear-cut cortical EEG changes may represent a lack of sensitivity of routine monitoring methods (limited montage) or arousal on a subcortical level. It has been demonstrated that subcortical or "autonomic arousals" (increase in heart rate or blood pressure) also result in daytime sleepiness. Does counting and tabulating arousals add anything to the managment of patients with OSA? Some have argued that the respiratory arousal index (RAI), which is the number of respiratory arousals per hour of sleep, adds little to the AHI with respect to patient management. However, neither the AHI nor the RAJ correlate very well with objective or subjective measures of sleepiness. This probably is explained by variability in the sleep need of individuals. The RAJ might still be useful if a level could be identified that would allow the determination that a patient's sleepiness is the result of sleep-disordered breathing. The original description of the upper airway resistance syndrome identified a group with an AHJ < 5/hr who had daytime sleepiness that improved after treatment of upper airway obstruction. The group had an RAI > lO/hr as a criterion. However, there are no large studies of the RAJ in normal subjects. One small study found a median RAJ of 10/hr in a group of normals and 21/hr in a group with upper airway resistance syndrome (Epworth score> 10 and AHJ < l5/hr). Until better information is available, it is reasonable to assume that an RAJ> lO/hr can explain sypmptoms of daytime sleepiness as long as no other cause for sleepiness is available. Alternatively, there may be some individuals with an RAJ < 10 /hr on a given study who do have upper airway-associated daytime sleepiness. Monitoring of esophageal pressure is the gold standard for detecting increased respiratory effort. As such, measurement of esophageal pressure is considered essential to detect RERAs. However, esophageal pressure is rarely measured in most clinical sleep laboratories. It has been recognized that flattening of the nasal pressure signal identifies periods of high respiratory effort with reasonable accuracy. A flow limitation arousal (FLA) may be defined as an arousal preceded by significant flattening which temporarily resolves after the arousal. One study (see figure) suggested that FLAs and RERAs using esophageal pressure correlated fairly well. Of note, in this study there were patients with daytime sleepiness and an 108
RAI < lO/hr. In addition, some arousals were preceded by flow limitation but no increase in esophageal pressure, and others were preceded by an increase in esophageal pressure without flow limitation. Flow limitation events can be seen without an associated arousal. These appear to be common even in normal individuals. The significance of these events remains to be determined. In sleep laboratories not using nasal pressure, "snore arousals" (defined as those following heavy snoring) are included in the RAI. In patients with milder aSA, the definition of hypopnea really determines how many RERAs are present. If you accept any drop in the flow (nasal pressure) for lO or more seconds + an arousal as a hypopnea, there will be few RERAs as most events will be termed hypopneas. If you require a 4% desaturation and a 30% drop in flow, then there will be fewer hypopneas and more RERAs.
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Flow limitation events with arousal by nasal cannula (events/hr)
Key Points 1. Respiratory effort arousals (RERAs) are arousals following periods of high inspiratory effort that do not meet criteria for apnea or hypopnea. 2. Flow limitation arousals (nasal pressure) appear to provide a reasonable estimate of the RERA frequency in most patients. Esophageal monitoring is still the gold standard for detecting RERAs. 3. The respiratory arousal index is the number of arousals per hour of sleep that are associated with apnea, hypopnea, or RERAs. 4. An RAI > lO/hr + symptoms of daytimes sleepiness + no other reason to explain sleepiness can be used to define the upper airway resistance syndrome or mild aSA. 5. Although the RAI is an index of the amount of sleep fragmentation secondary to respiratory events, it does not correlate better with measures of sleepiness than the AHI in unselected patients (both have a significant but low correlation in most studies). 6. The relative number of hypopneas and RERAs will depend on the definition of hypopnea.
REFERENCES I. Guillemenault C, Stoohs R, Clerk A, et al: A cause of excessive daytime sleepiness: The upper airway resistance syndrome. Chest 1993; 104:781-787. 2. Berry RB, Gleeson K: Respiratory arousal from sleep: Mechanisms and significance. Sleep 1997; 20:654-675. 3. Martin SE, Wraith PK, Deary IJ and Douglas NJ: The effect of nonvisible sleep fragmentation on daytime function Am J Respir CritCareMed 1997; 155:1596-1601. 4. Douglas NJ: Upper airway resistance syndrome is not a distinct syndrome. Am J Resp Crit Care Med 2000;161: 1410-1415. 5. Ayappa I, Norman RG. Krieger AC, et al: Noninvasive detection of respiratory effort-related arousals (RERAs) by a nasal cannula/pressure transducer system. Sleep 2000;23:763-771. 6. Rees K, Kingshott RN, Wraith PK, Douglas NJ: Frequency and signficance of increased upper airway resistance during sleep. Am J Resp Crit Care Med 2000;162: 1210-1214.
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PATIENT 32 A 30-year-old woman with severe fatigue A 30-year-old woman of normal body weight complained of severe fatigue and daytime sleepiness of 3-year duration. Her husband reported that she snored, especially during periods of nasal congestion. There was no history of symptoms characteristic of narcolepsy (cataplexy, sleep paralysis, or hypnagogic hallucinations). The patient reported getting at least 8 hours of sleep each night and denied feeling depressed. There was no history of alcohol or sedative use. An extensive medical examination found no cause for the patient's fatigue. A polysomnogram and a multiple sleep latency test (MSL T) were performed at another hospital. The Epworth Sleepiness score was 18/24 (moderate to severe sleepiness). Physical Examination: General: normal body weight. HEENT: high arched hard palate, dependent soft palate, long uvula. Prior Sleep Study* Total sleep time Sleep period time (SPT) Sleep latency REM latency AHI AHI, NREM AHI, REM Desaturations **
406.55 min (394-457) 432.5 min (414-453) 2.5 min (0-19) 70 min (69-88) 3 events/hour « 5/hr)
Sleep Stages
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
6 (0-6) 8.8 (3-6) 56.1 (46-62) 13.8 (7-21) 15.3 (21-31)
Total arousal index Respiratory arousal index
25/hr 2/hr
Spontaneous arousal index PLM arousal index
o 12.3 o
23/hr O/hr
*Airflow detected by thermistor **Drops in SaO) of 4% or more Hypopnea = 30% reduction in airflow for'" 10 seconds + 2% drop in SaO) or an arousal ( ) = normal values for age. AHI = apnea + hypopnea index. PLM = periodic limb (leg) movement
MSLT: Mean sleep latency 2 minutes, no REM periods in five naps. Figure: The results above prompted another sleep study, with nasal pressure monitoring. Events similar to the one illustrated below were common. Questions: What is the cause of the patient's severe sleepiness? How can you explain the high number of spontaneous arousals?
C4-Al 02-Al ROC-A1 LOC-A2 chin
EKG
~~. ~ ~ ~ H --\ ~ I j.
to M I
snore airflow (therm) nasal pressure chest
abdomen
5a02 110
94%
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Diagnosis:
Upper airway resistance syndrome or mild OSA.
Discussion: When symptoms or findings of daytime sleepiness are more severe than expected from the AHI on a sleep study, several possibilities must be considered. The sleep study may have underestimated the severity of illness (no supine monitoring, low amount of REM sleep). Additionally, a variety of disorders can cause daytime sleepiness, including insufficient sleep, narcolepsy, depression, periodic leg movements in sleep, idiopathic hypersomnolence, drug abuse, and the upper airway resistance syndrome (UARS). UARS is manifested by little or no discrete apnea or hypopnea but repeated arousal during periods of high upper airway resistance (increased inspiratory effort). Fatigue rather than daytime sleepiness can be the major complaint. While snoring is common in UARS, not all patients with this syndrome snore. This diagnosis may be missed with routine sleep monitoring unless the large number of unexplained arousals is noticed. On close examination, subtle changes in airflow or inspiratory effort precede the arousals. Monitoring of esophageal pressure in these patients reveals high esophageal pressure deflections preceding arousal (see figure, next page). A progressive increase in respiratory effort-the crescendo pattern-may be seen prior to arousal. Other patients have a stable but high level of inspiratory effort associated with arousal. The arousals characterizing UARS are called respiratory effort-related arousals (RERAs). An RERA is defined as an arousal following a period of high or crescendo respiratory effort (esophageal pressure deflections) that does not meet criteria for obstructive apnea or hypopnea. A given event might be classified as either an RERA or a hypopnea depending on the definition for hypopnea. For example, a reduction of airflow for more than 10 seconds associated with increased inspiratory effort and followed by an arousal but not a 4% desaturation would be classified as an RERA if one requires a 4% desturation for an event to be classified as a hypopnea. The same event would be called an obstructive hypopnea using definitions not requiring a desaturation. While esophageal pressure is not available in many sleep labs, nasal pressure monitoring is gaining popularity. As discussed in Fundamentals 10, nasal pressure monitoring is noninvasive and requires only a sensitive pressure transducer and a monitoring system with either DC capability or AC amplifier with a very low frequency filter capability. Nasal pressure monitoring in UARS reveals repetitive episodes of airflow limitation (flattening) followed by an arousal and temporary reversal of the flattening (return to a rounded pattern). One
study has suggested that nasal pressure will detect the majority of the RERAs detected by esophageal pressure monitoring (see Fundamentals 12). However, esophageal pressure monitoring remains the gold standard. It is believed that the symptoms of UARS are secondary to arousals and sleep fragmentation. However, other factors could also be important. Interestingly, a group of sleepy women with high esophageal pressure deflections during sleep but minimal arousals improved after treatment of presumed UARS. An expert panel of sleep physicians recently suggested that UARS is not a separate syndrome, but simply part of the spectrum between simple snoring and obstructive apnea. It was also suggested that RERAs be separately tabulated as part of polysomnography. An alternative is to simply include RERAs as a component of the events comprising respiratory arousals (i.e., in addition to arousals following apneas and hyopneas). In patients with a high RERA index (RERAs per hour of sleep), the AHI may not accurately classify the severity. Some have suggested adding the RERA index and AHI to identifity a true "respiratory disturbance index." In the current case, the previous polysomnogram showed a low overall AHI, but the arousal index was elevated. Airflow was monitored with a thermistor, and the definition of hypopnea was at least a 30% reduction in flow for 2: 10 seconds associated with a 2: 2% desaturation or an arousal. The AHI was < 5/hr, and the MSLT confirmed daytime sleepiness without evidence of REM onsets. The patient was given the diagnosis of idiopathic hypersomnia. However, repeat testing using the same hypopnea definition but nasal pressure to monitor flow revealed an AHI of 8/hr. If a 4% desaturation was required for an event to be classified as a hypopnea, the AHI was < 5/hr. The patient might then be labeled as having UARS. However, with the hypopnea definition used in the study the patient was considered to have mild OSA. In the tracing on page 110, note the flattening in the nasal pressure signal but minimal changes in the airflow (thermistor) signal. There was no desaturation. The event was scored as an RERA, as the flow was not reduced by 30% for 2: 10 seconds but the flattened nasal pressure signal suggested increased inspiratory effort. (Using more liberal definitions of hypopnea, you might consider the event an obstructive hypopnea.) The patient did not wish to try CPAP or an oral appliance. She underwent a uvulopalatopharyngoplasty and attempted to lose weight. She experienced a gradual resolution of her symptoms over the next 3 months.
111
While one may argue about definitions of RERAs and hypopneas, respiratory arousals were causing this patient's symptoms. The spontaneous arousals on the first study were correctly identified as respiratory arousals with the use of nasal pressure. The
normal range forthe respiratory arousal index (RAl) has not been well defined. However, many consider an RAJ > lO/hr in a symptomatic patient without other explanations for sleepiness to be an indication for treatment.
ROC-A 1 LOC - A 2 chin EMG nasal pressure (airflow) Esoph Pressure
50 uv
I
--=---5 sec Clinical Pearls
I. The UARS (or RERAs) always should be considered in patients with unexplained, excessive daytime sleepiness. 2. Using standard monitoring, the only clue that UARS may be present is repetitive episodes of subtle changes in respiration followed by arousals (or transient EEG changes). 3. Monitoring of esophageal pressure can help diagnose UARS by documenting high levels of inspiratory effort (upper airway resistance) preceding arousal. 4. Nasal pressure monitoring may allow recognition of RERAs in most cases. However, esophageal pressure remains the gold standard. 5. Whether an event is labeled an RERA or an obstructive hypopnea depends on the definition of hypopnea.
REFERENCES I. Guilleminault C. Stoohs R. Clerk A. et al: A cause of excessive daytime sleepiness: The upper airway resistance syndrome. Chest 1993; 104:781-787. 2. Guilleminault C. Stoohs R. Clerk A, et al: Excessive daytime somnolence in women with abnormal respiratory effort during sleep, Sleep 1993; 16:S137-138, 3, Guilleminault C. Stoohs R. Kim U. et al: Upper airway-sleep-disordered breathing in women. Ann Intern Med 1995; 122:493-501. 4. American Academy of Sleep Medicine Task Force: Sleep-related breathing disorders in adults: Recommendation for syndrome definition and measurement techniques in clinical research. Sleep 1999;22:667-689. 5. Loube DI. Gay PC. Strohl KP. et al: Indications for positive airway pressure treatment of adult obstructive sleep apnea patients. A consensus statement. Chest 1999; 115:863-866. 6. Ayappa I. Norman RG. Krieger AC, et al: Noninvasive detection of respiratory effort-related arousals (RERAs) by a nasal cannula/pressure transducer system. Sleep 2000;23:763-771.
112
PATIENT 33 A 30-year-old man with heavy snoring and daytime sleepiness A 30-year-old man was evaluated for complaints of heavy snoring, moderate daytime sleepiness (Epworth Sleepiness Scale score 18/24), and apnea (witnessed by his wife) of at least 5-year duration. The patient had gained about 30 pounds over this period. He admitted to drinking several cocktails nightly. There was no history of cataplexy or sleep paralysis. Physical Examination: Blood pressure 160/88, pulse 88. General: obese - weight 210 pounds, height 5 feet 10 inches. HEENT: dependent, edematous uvula. Neck: 18-inch circumference. Chest: clear. Cardiac: normal. Extremities: no edema.
Sleep Study AHI AHI, NREM sleep AHI, REM sleep PLM index Arousal index Minimum Sa0 2 Body position AHI = apnea
+ hypopnea index, PLM
Question:
12/hr 10/hr (80% of total sleep time) 20/hr (20% of total sleep time) 5/hr 20/hr 85% 25% lateral decubitus, 75% supine
= periodic limb movement
In view of the severe symptoms, why does the sleep study document only mild apnea?
113
Answer:
The patient was abstinent from alcohol at the time of the study.
Discussion: The clinician often is faced with the problem of interpreting a sleep study that at first glance appears to show milder obstructive sleep apnea (GSA) than suspected on the basis of the history (significant daytime sleepiness). Rough guidelines for interpreting the apnea + hypopnea index (AHI) are: AHI < 15 mild, 15-30 moderate, > 30 severe. However, the AHI is only one means of assessing the severity of GSA. In fact, the correlation between AHI and symptomatic or MSLT measures of daytime sleepiness is low (but statistically significant). Two patients with the same AHI may have quite different amounts of daytime sleepiness. The arousal index also must be considered. Some patients with an AHI indicating mild apnea have considerably more respiratory arousals secondary to high respiratory effort (respiratory effort-related
arousals). Another explanation for a sleep study showing milder than expected GSA is the normal night-tonight variation in the AHI, which is due to different body positions, variations in nasal resistance, variable amounts of REM sleep, and the effects of medications and beverages. Some patients have apnea only while supine or in stage REM sleep. Therefore, in these patients the AHI depends on the amount of time spent sleeping supine or in REM sleep. Nasal congestion is a factor because increases in nasal resistance increase the amount of apnea. Always consider the patient's use of ethanol when evaluating GSA. This drug has a powerful, preferential, inhibitory effect on upper airway muscle activity and increases snoring and apnea. In addition
to increasing the AHI, ethanol impairs the arousal response to airway occlusion; thus, apneas tend to be longer and associated with more severe desaturations. Ethanol suppresses REM sleep. This usually results in an increase in the REM latency and a shift of REM toward the morning (as the ethanol level drops). Therefore, the regular use of ethanol worsens sleep apnea considerably. Conversely, abstinence from ethanol could reduce the AHI and apnea duration/degree of arterial oxygen desaturation recorded on a sleep study. Some have hypothesized that ethanol might reduce the effectiveness of an optimal level of nasal CPAP. However, at least two studies have shown that this is not the case. The use of alcohol still should be discouraged in patients undergoing this treatment, because they may fall asleep without putting the nasal CPAP on, or they may remove the CPAP during the night. Many sleep labs find pre- and post-study questionnaires very helpful in documenting the typical and actual prestudy intake of alcohol or hypnotics. Patients should be asked about drugs they took prior to the sleep study as well as about any usual medications or ethanol they did not take. This will help the physicians reading the study. In the present patient, the arousal index was only slightly higher than the AHI, and both REM sleep and the supine position were evaluated. However, the patient did not ingest his favorite alcoholic beverages before this sleep study. Repeat testing after the patient's usual intake of ethanol showed an AHI of 40 and an increase in mean apnea duration by 5 seconds.
Clinical Pearls I. When a sleep study reveals milder apnea than suspected on the basis of clinical symptoms, consider the effects of body position, the amount of REM sleep, and the possible presence of the upper airway resistance syndrome (arousal index much higher than the AHI). 2. In milder GSA there may be more night to night variability in the AHI 3. The effects of ethanol use (or abstinence) on the severity of sleep apnea always should be considered. 4. Ethanol use increases the amount of apnea and the duration of obstructive events, as well as the severity of desaturation. 5. Ethanol increases the REM latency and decreases the amount of REM sleep.
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REFERENCES I. Taasan V, Wynne JW, Cassisi N, Block AJ: The effect of nasal packing on sleep-disordered breathing and nocturnal oxygen desaturation. Laryngoscope 1981; 91 (7): 1163-1172. 2. Issa FG, Sullivan CE: Alcohol, snoring, and sleep apnea. J Neurol Neurosurg Psychiatry 1982; 45:353-359. 3. Remmers JE: Obstructive sleep apnea- A common disorder exacerbated by alcohol. (Editorial) Am Rev Respir Dis 1984; 130:153-155. 4. Berry RB, Desa MM, Light RW: Effect of ethanol on the efficacy of nasal continuous positive airway pressure as a treatment for obstructive sleep apnea. Chest 1991; 99:339-343. 5. Berry RB, Bonnet MH. Light RW: The effect of ethanol on the arousal response to airway occlusion during sleep in normal subjects. Am Rev Respir Dis 1992; 145:445-452.
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PATIENT 34 A 45-year-old man with a distinct pattern of desaturation A 45-year-old man was evaluated for complaints of heavy snoring for many years and daytime sleepiness of about 4-year duration. There was no history of cataplexy or sleep paralysis. The patient did not drink alcohol. Physical Examination: Height 5 feet 10 inches, weight 180 pounds. HEENT: edematous uvula. Neck: 15-inch circumference. Otherwise normal exam. Figure: A tracing of oximetry for this patient is show below.
Sleep Study Time in bed Total sleep time Sleep period time (SPT) Sleep latency REM latency Arousal index (/hr) AHI AHI, NREM sleep AHI, REM sleep
( ) = normal
480 min (390-468) 350 min (343-436) 425 min (378-452) 10 min (2-18) 90 min (55-78) 20/hr 12/hr «5/hr) 5/hr 50/hr
values for age, PLM
Questions:
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
18 (1-12) 13(5-11) 49 (44-66) 5 (2-15) 15 (19-27)
PLM index
O/hr
= periodic leg movement.
Does the overall AHI of 12/hr mean this patient has mild OSA? Should he be treated?
2 hrs Body Position 8a0
4hrs
Back
100 2 80
t REM periods
116
Sleep Stages
6 hrs Side
8 hrs Back
Answer:
REM-related obstructive sleep apnea with severe arterial oxygen desaturations.
Discussion: Some patients have episodes of obstructive sleep apnea (OSA) primarily during REM sleep. Thus, the overall AHI may be low even if the AHI during REM sleep is fairly high. Other OSA patients have a much higher AHI or more severe arterial oxygen desaturation during REM sleep. In the absence of other disorders to explain the excessive daytime sleepiness, many clinicians have empirically treated patients who have REMspecific sleep apnea with usual treatments such as nasal continuous positive airway pressure (CPAP). Some patients with REM-specific sleep apnea have heavy snoring during NREM or exhibit repetitive respiratory effort-related arousals secondary to high inspiratory effort during NREM sleep without overt apnea or hypopnea. If nasal pressure is used to detect airtlow, these events may be more obvious. One study of a group of patients with a low overall AHI « IO/hr), but varying amounts of apnea-hypopnea during REM sleep, found that 80% with a REM-specific AHI > 15/hr had a short sleep latency during daytime naps (evidence of excessive sleepiness). Thus, frequent apneahypopnea during REM sleep alone may justify treatment. Although the finding of a higher AHI during REM sleep is common, the reason is still not clear. It has been assumed that since REM sleep is associated with muscle hypotonia, it results in a more collapsible upper airway. However, studies of the critical closing pressure have not confirmed that the airway is more collapsible during REM sleep. It is
possible that this study method does not accurately represent the physiology of REM sleep. REM sleep is not homogeneous, and upper airway muscle tone is often lowest during bursts of phasic eye movements. This can be seen with intramuscular electrodes in the genioglossus but not on the chin surface EMG (see figure below). In addition, ventilatory drive (esophageal pressure deflections) may also decrease during bursts of phasic eye movements. In the tracing below in a normal individual, note the three smaller breaths and lower genioglossus muscle activity (tongue muscle) illustrating the non-homogenous nature of REM sleep. In addition, the frequency of eye movements increases in the later REM periods of the night. Periods of decreased ventilation also tend to be more common later in the night even in normal individuals (see Patient 10). During REM sleep, end expiratory lung volume also falls, and this may also have an effect on upper airway patency as upper airway volume decreases with decreases in lung volume. The desaturations also tend to be more severe and apneic events longer during REM than NREM sleep. In the present case, the patient had a very high AHI in REM sleep and almost no apnea-hypopnea during NREM sleep (AHI = 5/hr). The REM-associated apneas were quite long, and the desaturation impressive (see first figure). The patient underwent a nasal CPAP trial and was treated with 10 cm H 20 , with resolution of his symptoms. During the trial, he had a large rebound in the amount of REM sleep (30% of SPT).
EOG«===~= EEG<
= 'r:
~'--~
airflow
integrated genioglossus eMG
f"L'7
J 117
Clinical Pearls I. Some patients have obstructive sleep apneas and hypopneas primarily during REM sleep, resulting in a low overall AHI despite frequent events and associated arousals and desaturations during REM sleep. 2. In patients with excessive daytime sleepiness and significant, REM-specific sleep apnea, treatment is indicated. Other possible causes of daytime sleepiness should be excluded. 3. The reasons for the higher AHI during REM sleep are complex. REM sleep is not homogenous, and episodes of decreased upper airway muscle activity or ventilatory drive may be the cause of hypopneas or apneas during REM sleep.
REFERENCES I. Gould GA. Gugger M. Molloy J. et al: Breathing pattern and eye movement density during REM sleep in humans. Am Rev Respir Dis 1988; 138:874-877. 2. Wiegand L, Zwillich CWo Wiegand D, White DP: Changes in upper airway muscle activation and ventilation during phasic REM sleep in normal men. J Appl PhysioI1991;71:488-497. 3. Kass JE, Akers SM, Bartter TC, et al: REM-specific sleep-disordered breathing: A possible cause of excessive daytime sleepiness. Am J Respir Crit Care Med 1996; 154: 167-169. 4. Boudewyns A, Punjabi N, Van de Heyning PH, et al: Abbreviated method for assessing upper airway function in obstructive sleep apnea. Chest 2000; 118:1031-1041. 5. Penzel T, Moeller M, Becker HF: Effects of sleep position and sleep stage on collapsibility of the upper airways in sleep apnea. Sleep 2001;24:90-95.
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FUNDAMENTALS OF SLEEP MEDICINE 13
Treatment of Obstructive Sleep Apnea
The first, essential determination in selecting appropriate treatment for obstructive sleep apnea (OSA) is the severity of illness. The AHI provides an overall index of the frequency of respiratory disturbance. Arbitrary but useful guidelines are: mild 5-14, moderate 15-30, severe> 30 events/hr.
Factors in Assessing GSA Severity Apnea + hypopnea index Amount of supine sleep and REM sleep in the diagnostic study Respiratory arousal index (sleep fragmentation) Severity of daytime sleepiness/requirement for alertness Severity of arterial oxygen desaturation Comorbid illness (e.g., congestive heart failure, ischemic heart disease) Sleep-associated arrhythmias Objective measurements of daytime sleepiness It also is essential to consider factors that may have prevented a night of sleep recording from accurately estimating the usual severity of illness (e.g., minimal supine sleep, lack of REM sleep). This is especially important for partial-night studies. The amount of sleep fragmentation (frequency of arousals) may correlate better with symptoms of daytime sleepiness than the AHI in individual patients with minimal desaturation. The severity of arterial oxygen desaturation can have important consequences for the development of pulmonary hypertension and right heart failure. Some patients have minimal desaturation, but are very sleepy. Other patients have mild symptoms of daytime sleepiness, but severe signs of cor pulmonale. When assessing the severity of daytime sleepiness, question family members about their estimates of the patient's sleepiness. Additionally, consider the requirements for alertness; for example, a professional truck driver has a more critical need for alertness than a retired 80-year-old patient. A consenus conference recently recommended that all patients with an RDI of > 30/hr be treated whether or not symptoms were present. In addition, symptomatic patients with an RDI > 5/hr were also felt to require treatment. Here RDI was defined as AHI + RERA index. The clinical practice parameters of the American Academy of Sleep Medicine suggest that treatment is also indicated in sleepy patients with a respiratory arousal index of 10/hr or more. Generally, each category of severity in OSA is best managed by specific treatments (see table). However, a given treatment might work in other categories of disease as well. For example, a patient with severe OSA can have dramatic improvement with an oral appliance, or a patient with upper airway resistance syndrome may tolerate treatment with nasal continuous positive airway pressure. All of these treatments are discussed in the following cases.
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General Treatment Guidelines UARS/MILD OSA
MODER ATE OSA
SEVERE OSA
Weight loss Position therapy Treat nasal congestion Oral appliances UPPP for OSA, UARS LAUP for snoring (UARS?) Positive airway pressure
Positive airway pressure Oral appliances UPPP,GAHM Weight loss-adjunctive Position therapy-adjunctive
Positive airway pressure Tracheostomy GAHM,MMO Oral appliances Weight loss-adjunctive
UARS = upper airway resistance syndrome, UPPP = uvulopalatopharyngoplasty, LAUP = laser-assisted uvulopalatoplasty, GAHM = genioglossus advancement hyoid myotomy, MMO = mandibulo-maxillary osteotomy, positive airway pressure = CPAP or bilevel pressure
REFERENCES I. Thorpy M, et al: ASDA Standards of Practice Committee. Practice parameters for the treatment of snoring and obstructive sleep apnea with oral appliances. Sleep 1995; 18:511-513. 2. Thorpy M, et al: Practice parameters for the treatment of obstructive sleep apnea in adults: The efficacy of surgical modifications of the upper airway. Report of the American Sleep Disorders Association. Sleep 1996; 19: 152-155. 3. Chesson AL, et al: ASDA Standards of Practice Committee. Practice parameters for the indications for polysomnography and related procedures. Sleep 1997;20:406-422. 4. Loube Dr, Gay PC, Strohl KP,et al: Indications for positive airway pressure treatment of adult obstructive sleep apnea patients. A consensus statement. Chest 1999; 115:863-866.
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PATIENT 35 A 30-year-old man with weight loss and sleep apnea A 30-year-old man-height 5 feet 10 inches, weight 230 pounds-was diagnosed as having severe obstructive sleep apnea (AHI 60/hr). He underwent a nasal CPAP titration, and CPAP at a level of 12 cm H20 was found to reduce his AHI to < 5/hr. The patient underwent treatment and noted a rapid resolution in his daytime sleepiness. However, he found CPAP to interfere with his social life. After 1 year of treatment he began a high-fiber, low-fat diet to reduce elevated cholesterol. Over the next 5 months he lost 30 pounds, and his cholesterol improved. He stopped using CPAP and did not feel that his daytime sleepiness returned. Another sleep study was performed. Based on the results of the study, the patient declined to resume CPAP. Surgical and oral appliance options were discussed. but he did not wish to pursue these treatments. Physical Examination: Neck circumference: 15 inches (was 18 inches at 230 pounds).
Sleep Studies Weight (Ibs.) CPAP AHI AHI supine AHI non-supine Arousal index
Question:
230 None 60/hr 70 50 45/hr
230 12 cmH 20 5/hr 5/hr n/a 5/hr
200 None 5/hr 30 5 15/hr
190 None 10/hr 10/hr O/hr 10/hr
What treatment option do you recommend?
121
Answer:
Side sleep position and continued weight loss.
Discussion: Obesity is a major risk factor for the development of OSA. In some studies, approximately 66% of patients with OSA were obese (body weight> 120% of predicted). Neck circumference is a better predictor of OSA than body weight, indicating that nuchal obesity is more important than total body obesity. Studies suggest that obesity has direct effects on upper airway function (changes in the nature of upper airway tissues) or indirect effects secondary to changes in lung volume. One MRI study of the upper airway in OSA suggested that fat deposition adjacent to the lateral pharyngeal walls reduced the upper airway size. Another study found thickened lateral pharyngeal walls, but these changes were not secondary to fat or edema. A
A
p
NORMAL A
GSA
= anterior, P = posterior, R ,L
right and left
Patients with OSA tend to have small upper airways, although there is considerable overlap. Shape may be as important as size. The shape of the upper airway in OSA patients is different, with the the lateral dimension being the smallest (see figure). Weight loss increases the lateral dimension. The size of the upper airway varies with lung volume, probably secondary to the effects of tracheal displacement ("tracheal tug"). Obesity reduces supine lung volume and, therefore, upper airway size. Exactly how obesity and weight loss change the size and shape of the upper airway remains to be determined. Studies also have shown that the collapsibility of the upper airway is decreased by weight loss, implying that obesity increases the tendency of the upper airway to collapse. Many studies have documented that weight loss of modest proportions (5-10%) can produce signif-
122
icant improvement in sleep apnea. Even patients with mild obesity (110-115% of ideal body weight) can benefit from weight reduction. The results vary among patients; for example, a given amount of weight loss may have more effect on upper body obesity in one individual than in another. Nevertheless, weight loss decreases both the AHI and the collapsibility of the upper airway in patients with OSA. The level of nasal CPAP required to maintain upper airway patency also may decrease following weight reduction. Surgical, behavioral. and pharmacologic approaches to weight loss have all been successful in select groups of patients. The major problem to date has been maintenance of weight loss. Many patients with obstructive sleep apnea (OSA) have a significant worsening of apnea in the supine position. In this position, gravity tends to pull the tongue backward and narrow the airway. Thus, an overall apnea index may reflect moderateto-severe apnea when the patient is supine and minimal apnea in the lateral decubitus body position. In one study, approximately 55% of a large group of patients with sleep apnea had AHIs at least two times higher in the supine than in the lateral decubitus position. Unfortunately, many obese patients with severe sleep apnea still have severe apnea in the lateral decubitus position. In these patients, studies have suggested that elevation of the head of the bed (30 degrees) may be a more effective postural maneuver both to decrease the AHI and to decrease the required level of CPAP to maintain upper airway patency. Because the amount of supine sleep can dramatically affect the overall AHI, always note the amount of supine sleep when comparing two sleep studies. To this end, sleep study reports should detail the amount of supine sleep and the AHI both supine and non-supine. In the present patient, weight loss from 230 to 200 made him very position-dependent (much lower AHI in the non-supine position. As he had a low AHI in the lateral position, continued weight loss and the side-sleep position were recommended. He slept with a cylinder of firm foam sewed into a pocket on the back of at-shirt. He also continued to lose weight. A sleep study at 190 pounds showed him to have an AHI of only 5/hr in the lateral sleeping position.
Clinical Pearls l. Weight reduction can significantly improve the severity of aSA. The amount of reduction required varies widely, but can be as little as 5-10% of body weight. 2. Weight reduction (weight gain) may decrease (increase) the level of nasal CPAP required to maintain upper airway patency. 3. The major challenge of weight reduction as a treatment for aSA is maintaining the weight loss. 4. Body position has an important effect on the severity of aSA in more than 50% of patients. Always consider this effect when assessing the results of polysomnography. 5. Position therapy can be effective in selected patients. Long-term effectiveness and compliance have not been well documented. 6. Elevating the head of the bed may be a more effective postural maneuver in very obese patients.
REFERENCES I. Smith PL, Gold AR, Meyers DA. et al: Weight loss in mildly to moderately obese patients with obstructive sleep apnea. Ann Intern Med 1985; 103:850-855. 2. Schwartz AR. Gold AR, Schubert N. et al: Effect of weight loss on upper airway collapsibility in obstructive sleep apnea. Am Rev Respir Dis 1991; 144:494-498. 3. Schwab RJ. Functional properties of the pharyngeal airway: Properties of tissues surrounding the upper airway. Sleep 1996; 19:5170-S174. 4. Strobel RJ, Rosen RC: Obesity and weight loss in obstructive sleep apnea: A critical review. Sleep 1996; 19:104-115. 5. Neill AM, Angus SM, Sajkov D, McEvoy RD: Effects of sleep posture on upper airway stability in patients with obstructive sleep apnea. Am J Respir Crit Care Med 1997; 155:199-204. 6. Oksenberg A, Silverberg DS, Arons E, Radwan: Positional vs nonpositional obstructive sleep apnea patients. Chest 1997; 112:629-639. 7. Jokic R, Klimaszewski A, Crossley M, et al: Positional treatment vs continuous positive airway pressure in patients with positional obstructive sleep apnea syndrome. Chest 1999; 115:771-781.
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FUNDAMENTALS OF SLEEP MEDICINE 14
Positive Airway Pressure Titration
Positive airway pressure (continuous [CPAP] or bilevel) titration can be performed using an entire night following a diagnostic sleep study, or as the second part of a split-night sleep study following an initial diagnostic portion. Studies have suggested that an adequate positive-pressure titration can be obtained in about 60-80% of patients with a split- or partial-night study. If an adequate titration is not obtained, a repeat positive-pressure titration will be needed. While you might assume that a lack of sufficient supine or REM sleep is the cause of insufficent titration, this was not the case in one study? comparing optimal CPAP pressure on a partial and subsequent full night of CP AP titration. The Standards of Practice Committee of the American Academy of Sleep Medicine has published guidelines for appropriate candidates for split studies. Basically, there must be sufficient time remaining after a diagnosis is firmly established to perform an adequate positive-pressure titration. Note, too, that Medicare guidelines for reimbursement for CPAP require that the AHI used to qualify the patient must be based on 2 hours of recorded sleep (not monitoring). Therefore, it seems prudent to record at least 2 hours of sleep during the diagnostic portion (see table for essential elements of a good positive-pressure titration). It is important to remember that if a split study is a possiblity, patients should be educated about CPAP (several videos are available), fitted for a mask, and given an adapation period to positive pressure before the diagnostic portion begins. Education and mask fitting are rarely successful at 2 AM! The adaptation period on a low level of CPAP identifies patients with nasal congestion, those who are very pressure intolerant, and those with clasutrophobia. If nasal congestion is a problem, a full face mask (see Patient 44) may be fitted or a decision made to use heated humidity (see Patient 42) during the positive-pressure titration. Clastrophobic patients may find nasal pillows or other similar interfaces more tolerable. Pressure should be increased slowly in pressure intolerant patients. Bilevel pressure may be used. if high pressure levels are needed (see Patient 45).
Criteria for Split Titration • 2 hours of recorded sleep in diagnostic portion (so patient will qualify for Medicare payment of CPAP) • AHI > 40/hr • AHI 20--40 Ihr with significant desaturation or other factors • At least 3 or more hours remaining for CPAP titration ESSENTIALS OF POSITIVE-PRESSURE TITRATION
• • • •
Patient education about positive pressure Mask fitting CPAP training acclimitization period (identify problems early) Titration to eliminate apnea, hypopnea, snoring, desaturation, and RERAs in all body positions and sleep stages (including supine REM) • Reduction in the AHI to < 51hr if possible; at least to < lO/hr RERA = respiratory effort-related arousals
During titration the goal is to prevent apnea, hypopnea, arterial oxgyen desaturation, respiratory effortrelated arousals, and snoring in all sleep stages and body positions. In general, supine REM sleep requires
124
the highest pressure. Most diagnostic positive-pressure machines provide a flow output (CPAP flow or Vest [estimated flow]) that is obtained from a built-in pnemotachograph or other flow-measuring device. The CPAP flow signal is derived from the total flow delivered minus an estimate of leak determined by the machine. This flow signal provides information on both magnitude and shape of airflow. A flattened flow signal signifies some element of airway narrowing (airflow limitation). In general, a reasonable goal is to eliminate significant airflow limitation, especially if it precedes repetitive arousals (RERAs). Some degree of airflow limitation may be tolerated-especially in pressure-sensitive patients-if it is not associated with repetitive arousals. In Figure I, CPAP pressure is reduced (arrow), and the flattened shape of the flow signal correlates with an increase in supraglottic pressure and resistance. As pressure is increased, obstructive apneas, hypopneas, and snoringlRERAS are eliminated in that order. In Figure 2, note the snoring and slightly flattened airflow signal (arrow) on CPAP of 7 em H20. A I em H 20 increase in pressure rounds the shape of the CPAP flow tracing and eliminates snoring. Central hypopneas are sometimes noted as the patient returns to sleep after arousals, or during sleep onset. They are characterized by a round airflow profile and a reduced magnitude of flow and effort (chest and abdominal movement). They should not be treated with increases in CPAP.
~~ ;:1 12
~
11
10
=;::=~===~==::::====::::===:::===:
20
10 15 TIme (seconds)
25
FIGURE I
Positive-pressure devices also provide leak information. All mask interfaces have an intentional leak to wash out the CO 2 (usually small holes or slots in the mask). The amount of leak increases with increasing pressure. However, sudden large increases in the leak signal suggest that either mask or mouth leak is occurring. In some labs, an oral thermistor is also used, to detect mouth leak. Of note, the flow signal from the positive-pressure device registers flow via the nasal mask, but not oral flow. If the patient breathes through both the nose and mouth while using a nasal mask, the CPAP flow signal will be reduced (simulating a hypopnea) but the leak signal will increase (Fig. 3). Recording of leak information allows the sleep physician to detect such events.
,.
CPAP 7 em H20
CPAP Flow
Snore
CPAP 8 em H20 CPAP Flow
Snore
-,!~/\r-J~t-~_/~~ I 'If 18,,, ",,"'.' •• ,
1
,
FIGURE
2
$d' b
•
4.'*4
12S
In Figure 3, CPAP flow and leak are shown during a period of simulated nasal and mouth breathing. The leak information does not identify the source of the leak (mask or mouth). However, fluctuating leak without body movement suggests mouth leak. The sleep technologist can zoom in with video monitoring to see if the mouth is open. Attention to the shape of the flow profile and leak information may prevent increases in pressure to address "hypopneas" caused by mouth leaks, central hypopneas, and ineffective pressure secondary to high mask leak. The technician can reseat the mask or employ measures-such as a chin strap, full face mask, addition of heated humidity, or a change to bilevel pressure - to reduce mouth leak.
Simulated mouth leak - mimics a hypopnea
CPAP flow (Vest)
Leak
FIGURE
3
REFERENCES l. Iber C, O'Brien C, Schluter 1, et al: Single-night studies in obstructive sleep apnea. Sleep 1991; 14:383-385. 2. Sanders MH. NB Kern, 1P Costantino, et al: Adequacy of prescribing positive airway pressure therapy by mask for sleep apnea on the basis of a partial-night trial. Am Rev Respir Dis 1993; 147:1169-1174. 3. American Thoracic Society: Indications and standards for use of nasal continuous positive airway pressure (CPAP) in sleep apnea syndromes. Am 1 Resp Crit Care Med 1994; 50: 1738-1745. 4. Condos R, Norman RG, Krishnasamy I. et al: Flow limitation as a noninvasive assessment of residual upper-airway resistance during continuous positive airway pressure therapy of obstructive sleep apnea. Am 1 Respir Crit Care Med 1994; 150:475--480. 5. Montserrat 1M, Ballester E, Olivi H: Time course of stepwise CPAP titration. Am 1 Respir Crit Care Med 1995: 152: 1854-1859. 6. American Sleep Disorders Standard of Practice Committee, Chesson A. Chairman: Practice Parameters for the Indications for Polysomnography and Related Procedures. Sleep 1997;20:406--422.
126
PATIENT 36 A 55-year-old man with heavy nighttime snoring and daytime sleepiness A 55-year-old obese man was evaluated for complaints of excessive daytime sleepiness of 4-year duration. He snored heavily and was observed by his wife to stop breathing during sleep. Because of a strong suspicion for obstructive sleep apnea (OSA), the patient underwent a partial or split-night study. The first portion of the night was a diagnostic study and the second portion a nasal continuous positive airway pressure (CPAP) titration. The test was terminated at the patient's request because he no longer felt sleepy. He had some initial difficulty tolerating CPAP at 10-12.5 em Hp. Physical Examination: Obese-weight 240 pounds, height 5 feet 11 inches. HEENT: long, dependent palate; 18-inch neck circumference. Chest: clear. Cardiac: normal. Extremities: no edema.
Sleep Study CPAP(cm HP) Monitoring time (min) NREM (min) REM (min) AHI (thr) Body position
Question:
o (diagnostic)
5.0
60
240 180 10
40
75
60
Supine
10
Supine
7.5 60 50 10 50 Lateral
30
12 40 20
40 Lateral
10 Lateral
10
60
o
o
Why is this CPAP titration suboptimal?
127
Answer:
The efficacy of nasal CPAP in the supine position has not been documented.
Discussion: Nasal CPAP is probably the treatment of choice for most patients with moderate-tosevere OSA. The mechanism of action is to provide a pneumatic splint to preserve upper airway patency. The pressure level required to maintain airway patency is determined by CPAP titration: pressure is incrementally increased to find the point at which apnea, hypopnea, snoring, desaturation, and respiratory effort-related arousals are prevented (the "optimal pressure"). This pressure varies 5-20 em H20 among patients. The required pressure even varies in the same patient, depending on body posture (higher supine) and sleep stage (usually the highest pressure is needed in supine REM sleep). Thus, the optimal pressure for a patient is one that is effective in all body positions and stages of sleep. To avoid the high cost of performing two separate sleep studies and delay in treatment, many sleep centers perform partial or split-night studies. As in this case, the first portion of the night is diagnostic; the second portion is a CPAP titration. The length of time required for the diagnostic portion and the indications for initiating a CPAP titration vary between sleep centers. Practice parameters published by the American Academy of Sleep Medicine suggest that a split study should be performed when AHI > 40/hr, or AHI 20-40/hr if very significant desaturation is present. The decision to obtain a split study also is influenced by the wait time required for a repeat CPAP titration in a given locale. At least 3 or more hours of monitoring are needed during the CPAP titration. Approximately 60-80% of patients can have an adequate CPAP titration using the split-study protocol. If titration is inadequate, a repeat sleep study consisting of an entire night of positive-pressure titration is indicated. There is a certain amount of art as well as science in the CPAP titration. It also is a desensitization exercise in which the patient becomes acclimated to the mask and pressure. Sometimes the level of pressure must be reduced (at least temporarily) even if it is not the optimal pressure. Patient education before the sleep study begins can help tremendously in the adjustment process. (Education about nasal CP AP at 2 AM tends to be poorly received by most patients.) The initial acceptance of CPAP depends on an adequate mask fit. Mask and headgear fit also is best determined prior to beginning the study. The art of dealing with patient concerns and determining when to increase the pressure (and when to back off for awhile) is a challenging part of the sleep technician's job.
128
The proper endpoint for CPAP titration is still the subject of research. When initially introduced, the usual goal was prevention of apnea, hypopnea, and desaturation. Most centers continued to increase the CPAP level until snoring was eliminated. With the recognition that high upper airway resistance (high inspiratory effort) can induce arousals even if snoring is absent (upper airway resistance syndrome), upward titration of CPAP typically is continued if repiratory effort-related arousals are occurring. A few laboratories place esophageal catheters as part of routine sleep studies/CPAP titrations. Those centers titrate until esophageal pressure swings reach 5-10 em H 20 . Other centers have used the shape of inspiratory airflow (flow limitation) to identify high upper airway resistance. Flow-limited breaths are characterized by a constant or decreasing flow despite increased respiratory effort (esophageal pressure deflection). The tracing of inspiratory airflow is flat and wide rather than rounded. The pattern of flow limitation usually is noted during periods of high inspiratory effort. This method requires more accurate airflow monitoring than possible with thermocouples. Monitoring must be performed with pneumotachographs or nasal cannula attached to pressure transducers. Fortunately, most diagnostic CPAP units have an analog output derived from a flow signal measured with an internal pneumotachograph. CPAP is titrated upward until evidence of clinically significant flow limitation is eliminated. The best method of choosing the optimal CPAP pressure remains to be determined. Ultimately, the goal of CPAP titration is to produce high-quality, restorative sleep rather than endpoints related to upper airway function. In the present patient, the AHI was reduced to 10/hr-a fairly reasonable level-at a CPAP level of 12 ern H 20 . However, efficacy was not documented in the supine position. Thus, the true optimal pressure for this patient has not been determined. In retrospect, less time should have been spent on the diagnostic part of the study (a case of obvious severe OS A) and more time on the CPAP titration. In this case, you could try empiric treatment with a slightly higher pressure of 13-14 ern H 20 ; order another CP AP titration (the gold standard); or treat the patient with autoCPAP for a few weeks to establish a prescription pressure. A final alternative is to begin treatment with 12 em H 20 and increase pressure if snoring is present in the supine position or symptoms do not resolve.
Clinical Pearls 1. The goal of the CPAP titration is to determine the optimal pressure-one that is effective in all body positions and stages of sleep. 2. Body position has a major impact on the pressure required to maintain upper airway patency. The highest pressure required is usually in supine REM sleep. 3. The optimal CPAP level should not only prevent sleep-disordered breathing, but allow for maintenance of high-quality, restorati ve sleep (reduced arousals, normal sleep architecture). 4. A split-night study is economical, but reduces the time both for diagnosis and CPAP titration. Appropriate education pre-study is essential. 5. CPAP titration is an art as well as a science. The importance of education and technicianpatient rapport cannot be overemphasized.
REFERENCES 1. Pevernagie OA, Sheard JW 11": Relations between sleep stage, posture and effective nasal CPAP levels in OSA. Sleep 1992;15: 162-167. 2. Montserrat JM. Ballester E. Olivi H: Time course of stepwise CPAP titration. Am J Respir Crit Care Med 1995; 152: 1854-1859. 3. Yamashiro Y, Kryger MH: CPAP titration for sleep apnea using a split night protocol. Chest 1995; 107:62-66. 4. Oksenberg A, Silverberg OS. Arons E, Radwan H: The sleep supine position has a major effect on optimal nasal continuous positive airway pressure. Chest 1999; 116: 1000-1006.
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PATIENT 37 A 50-year-old man with problems during a CPAP titration A 50-year-old man complained of snoring and excessive daytime sleepiness. He underwent a CPAP titration after the initial diagnostic portion of his sleep study showed an AHI of 35/hr. The patient initially seemed to do well at 7 cm H 20 . However, on higher pressures his AHI was higher. The next morning he complained of a dry mouth. Figure: A 90-second tracing on 9 em H 20 is shown below. Of note, the leak on 7 cm H 20 was 5-10 Llmin.
Sleep Study (CPAP Treatment Table) DIAGNOSTIC PRESSURE 0
7 CM H 2O
9 CM H 2O
II CMHp
180 min 140 min 0 supine 35 20 0 5 57 65 85% 40
60 50 30 supine 4.8 0 0 2 2 0 94% 5
40 30 0 supine 24 0 0 2 10 2 91% 30
40 20 0 supine 30 0 0 0 10 1 90% 30
Monitoring time TST (min) REM (min) Body position AHI (zhr) Obstructi ve apneas Mixed apneas Central apneas Hypopneas Desaturations Min. SaO, Resp arousal index Uhr) TST = total
sleep time; hypopneas
Question:
= a reduction in flow associated with
an arousal or 4% desaturation
Why are there more events at pressures higher than 7 cm H 20 ?
arousal A
CPAP flow
B
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,
,
,
,
,
,
,
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,
,
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90
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FIGURE 1
130
)
Answer:
Overtitration and increased mouth leak on pressures higher than 7 em H 20 cause more events.
Discussion: CPAP treatment tables are sometimes useful for choosing an appropriate pressure for treatment. However, they do not tell the entire story. It is not uncommon for the AHI to temporarily increase as CPAP pressure increases. This is usually secondary to the effects of changes in body position or sleep stage. Higher pressure is almost always needed in the supine position and may also be required during REM sleep. Another possibility is an increase in central events. Therefore, you must look not simply at the AHI, but at the composition of events. Two other reasons that the AHI might increase at higher pressures are patient intolerance (arousals) and mask or mouth leaks. Arousals can result in central apneas or hypopneas on return to sleep. High mask or mouth leak may compromise the ability of pressure to maintain airway pressure. The set pressure is not always equal to the mask pressure. Although CPAP blowers are designed to compensate for leak, the mask pressure may be lower than the set pressure if a high leak is present. Most positive-pressure devices used in the sleep laboratory provide several analog or digital outputs that can be recorded. CP AP flow is an estimate of flow and is derived from the total flow the machine delivers minus an estimate of the bias flow or leak (Fig. 2). The leak is also available to be recorded. All CPAP mask interfaces have a port for controlled leak that washes out CO 2 and prevents rebreathing. This intentional leak increases with the amount of pressure and varies between masks. The total leak is the intentional leak + unintentional leak. Unintentional leak is due to a "mask leak" (when using a full face mask) or a "mouth leak" (if using a nasal mask). Leak is seen by the machine as an inspiratory flow onto which the variation in patient flow is superimposed. A flow-sensing device, such as a pneumotachograph, in the flow generator estimates both magnitude and shape of flow. High upper airway resistance is manifested by a flattened profile; the normal profile is rounded. Some CP AP
flow signals can also show snoring, although many do not have a sufficient high-frequency response. Nearly all units will provide a signal of the "machine pressure." This is the pressure at the machine and can differ slightly from the set pressure (value entered by technologist). The actual mask pressure may be somewhat lower during inhalation and sometimes slightly higher during exhalation. Some positive-pressure controllers provide a pressure transducer that can be connected to the mask by tubing. Actual mask pressure then can be recorded. Leak information is very useful for a number of reasons. First, a high leak may mean a poor mask seal. The mask pressure may be lower than the machine pressure. This can compromise the ability of pressure to maintain airway patency. High mask leaks can also cause arousal (noise or leaks into the eyes). A high leak can also mean that a mouth leak is present. The leak magnitude does not reveal the source of the leak. However, the pattern of leak can be very suggestive. A leak that fluctuates without any evidence of patient movement or increase in pressure suggests a mouth leak. Sometimes the technician can look for an open mouth with the monitoring lowlight camera. A thermistor over the mouth can also be used to detect leak. Unfortunately, a thermistor does not provide quantitative information about the size of the mouth leak. Mouth leak can be solely expiratory, or both inspiratory and expiratory. In Figure 3, the snore microphone detects vibration during exhalation. Also note that the expiratory portion of the flow signal is truncated (*) as exhalation is mostly via the mouth and not the nasal mask. In Figure 4, a thermistor placed outside the mask and over the mouth records flow mainly during exhalation in REM sleep. Although the value of the leak is high at 39-40 liters per minute (lpm), the patient slept undisturbed. (High leak> 0.4 liters per second or > 24 liters per minute.) Minutes before, in NREM sleep, the leak was 12 lpm. The CPAP flow detects flow via the nasal mask. If
Flow
j.;
30lpm Total flow
CPAP flow leak
o
v FIGURE
2
131
Nasal CPAP = 10 em H20
t inspiration CPAP flow Snore FIGURE
some portion of the ventilation is via the mouth, this will not register as flow. Periods of mouth breathing on CPAP can simulate a hypopnea. Usually there is no desaturation associated with such an event. Alternatively, mouth leak can actually compromise the ability to keep the airway open and result in a true hypopnea with an associated desaturation. Patients often arouse during mouth leak. Commonly, the leak dramatically decreases after arousal when the patient wakes up and closes the mouth. In the current patient, the CPAP was increased from 7 to 9 cm H 20 because of some questionable events during a brief episode of REM sleep. On 7 cm H?O, the leak had been low and constant at 5-10 lpm, and the AHI was low even during supine REM sleep. On 9 cm H?O, the leak was higher and fluctuated. There were many hypopneas without desaturation (see Figure 1, B). Many of the hypopneas were associated with arousal. Again, the definition
3
of hypopnea used here requires an arousal or a desaturation. Still looking at Figure 1, note the change in flow and leak from A to B. Flow decreases and leak increases. Leak falls back to a low value after the arousal (C). Note also that the shape of the flow is round, denoting a central hypopnea. In this case, the CPAP could have been reduced back to 7 ern H?O, a chin strap applied, or a full face mask used. The sleep technologist did apply a chin strap and start the patient on heated humidity. Heated humidity can help reduce the tendency for mouth leak in patients with nasal congestion. Unfortunately, the pressure was also increased to II cm H?O, which only worsened the situation. Although the patient had an uncomfortable night in the sleep laboratory ("they blasted my mouth open"), he was willing to try CPAP. Subsequent treatment with 7 cm Hp and heated humidity resulted in near complete resolution of symptoms.
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ROC-A1 LOC-A2 EKG
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CPAP flow chest abdomen
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132
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Clinical Pearls l. When the AHI worsens with higher positive pressure, always consider the possibility that an increase in mouth or mask leak is causing the problem. 2. Recording leak information can be very useful for both the reviewer and the technician 3. A fluctuating pattern of leak without change in body position suggests a mouth leak. 4. Mouth dryness is an important clue that a mouth leak is OCCUlTing. 5. Mouth leak can produce a pattern of flow resembling central hypopneas.
REFERENCE Berry RB: Medical therapy In Johnson JT, Gluckman JL, Sanders MH. (eds): Obstructive Sleep Apnea. London, Martin Dunniz, 2002, pp 89-1 18.
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PATIENT 38 A patient refusing to accept treatment for obstructive sleep apnea A 40-year-old man was diagnosed with moderate obstructive sleep apnea. He came to medical attention because his wife could not stand his snoring. The patient denied daytime sleepiness (Epworth Sleepiness Scale score 8/24 [normal :s 10]). Medical history included coronary artery disease and hypertension. There was no history of nocturnal angina. Although the patient did well on nasal CPAP, he declined any treatment for OSA. He stated: "My wife is the only one with a problem."
Split Sleep Study* DIAGNOSTIC PORTION TST (min) REM (min) Respiratory arousal index (lhr) AHI (lhr) AHINREM AHIREM Desaturations (number) Lowest Sa0 2 (0/0)
90 10 30 42.2 40
60 80 75
*Initial diagnostic portion. followed by CPAP titration sleep time. AHI = apnea/hypopnea index
TST = total
Question:
134
What should you tell the patient?
CPAP TITRATION
OPTIMAL CPAP (10 CM H 20 )
200 50 15 12.5 10 20 10 85
60 20 10 1.7
o 5
I 92
Answer: Discuss the the increased risk of cardiovascular events associated with untreated OSA with patient and spouse. Discussion: There are three main reasons to treat patients with OSA (see also Patient 39). The first is to relieve symptoms of daytime sleepiness and improve the quality of life (mood and concentration). The second is to prevent the sleep disturbance endured by the bed partner and the resulting social discord. The third is to prevent long-term sequelae of untreated OSA. Nasal CPAP has been shown to improve both objective and subjective sleepiness compared to sham CPAP in a randomized controlled study.' Of note, sham CPAP did improve subjective sleepiness, but not as well as effective CPAP. Only effective CPAP improved objective measures of sleepiness. Nasal CPAP can also improve the sleep of bed partners by eliminating snoring and snorting. One study of patients with OSA and their bed partners estimated that effective nasal CPAP treatment improved the sleep efficiency of the bed partner by 13%, which is the equivalent of an extra hour of sleep nightly. The frequent arousals from sleep of the bed partner of patients with OSA has been termed the "spousal arousal syndrome." The third reason for treating OSA has been the most difficult to document with convincing evidence. Data showing morbidity of untreated OSA is confounded by the influences of obesity, hypertension, and increased age. A retrospective study by He et al suggested that patients with an untreated apnea index of > 20/hr had a decreased survival that was normalized with treatment using tracheostomy or CPAP, but not UPPP. Unfortunately, the cause of death of the patients was not documented. The Sleep
Heart Health Study (SHHS) was initiated to determine the long-term impact of OSA on cardiovascular health. This study has accumulated a tremendous amount of information on a large cohort of patients using ambulatory polysomnography. Most of the cohort had mild OSA. However, even at modest AHI levels there was a moderate increase in the odds of having a stroke or congestive heart failure as the AHI increased. The evidence for an increased risk of coronary artery disease in OSA was less convincing. Follow-up cardiovascular outcomes on this cohort should provide important information. In another SHHS publication, evidence for an association of mild OSA with hypertension was presented. Patients with untreated OSA have increased sympathetic tone, and other evidence suggests OSA may contribute to atherosclerosis via a number of mechanisms. Because of the increased risk of cardiovascular complications, most clinicians recommend treatment of asymptomatic patients with moderate to severe forms of OSA. Such an approach seems especially important in patients with known cardiovascular disease. The present patient had severe OSA. The findings would likely have been even more severe if an entire diagnostic night been recorded. Even though he did well on nasal CPAP, the patient was not sleepy and did not want treatment. The long-term risks of untreated sleep apnea, including possible worsening of his coronary disease, were discussed with the patient. He was not convinced and declined nasal CPAP or consideration of other treatment options. His wife now sleeps in a separate bedroom.
Clinical Pearls I. Even asymptomatic patients with moderate to severe OSA should be offered treatment. 2. Sleep disturbance of bed partners is a frequently forgotten morbidity of untreated OSA. 3. Patients with untreated OSA and even relatively low AHIs increase their risk of cardiovascular disease.
REFERENCES I. He J, Kryger MH, Zorick FJ, et al: Mortality and apnea index in obstructive sleep apnea. Chest 1988; 94:9-14. 2. Beninati W, Harris CD, Herold DL, Shepard JW Jr: The effect of snoring and obstructive sleep apnea on sleep quality of bed partners. Mayo Clin Proc 1999;74:955-958. 3. Jenkinson C, Davies RJO, Mullins R, Stradling JR: Comparison of therapeutic and subtherapeutic nasal continuous positive airway pressure for obstructive sleep apnea: A randomised prospective parallel trial. Lancet 1999;353:2100-2105. 4. Nieto FJ, Young TB, Lind BK et al: Association of sleep-disordered breathing, sleep apnea, and hypertension in a large community-based study. Sleep Heart Health Study. JAMA 2000;283: 1829-1836. 5. Leung RST, Bradley TO: Sleep apnea and cardiovascular disease. State of the Art. Am J Resp Crit Care Med 2001: 164:21472165. 6. Shahar E, Whitney CW, Redline S, et al, for the Sleep Heart Health Study Research Group: Sleep-disordered breathing and cardiovascular disease: Cross-sectional results of the Sleep Heart Health Study. Am J Resp Crit Care Med 200 I; 163: 19-25.
13S
PATIENT 39 A 66-year-old man with mild OS A, but no symptoms A 66-year-old man was evaluated because his snoring disturbed his wife's sleep. He denied symptoms of daytime sleepiness (Epworth Sleepiness Scale score 8/24, normal). He had gained about ten pounds over the last 3 years, and his snoring and snorting had increased in severity. The patient did admit to drinking two cups of coffee to "get going in the morning." He had well-controlled hypertension, but there was no history of ischemic heart disease, heart failure, or cerebovascular disease. Physical Examination: BP 130170, HEENT: dependent palate, long edentulous uvula; neck 17inch circumference. Sleep Study: Heavy snoring noted; total sleep time supine = 80%; respiratory arousal index = 15 fhr. The table below shows the AHI using different definitions of hypopnea. AHI
Definition of Hypopnea
3fhr
> 30% reduction in airflow with at least a 4% arterial oxygen de saturation > 30% reduction in airflow with at least a 4% arterial oxygen desaturation or an arousal
8fhr
Question: CPAP?
136
The patient declined surgical and oral appliances options. Should he be treated with
Answer:
Nasal CPAP treatment of asymptomatic patients with mild OSA is controversial.
Discussion: Treatment options for patients with mild OSA include weight loss, position restriction, a UPPP, an oral appliance, nasal CPAP, or simple observation. If surgical or oral appliance options are declined, you must decide between nasal CPAP and conservative treatment (weight loss, position restriction). A consensus conference recommended CPAP treatment for all patients with a respiratory disturbance index (RDI) 2: 30/hr and for symptomatic patients with an RDI of 5-30/hr. The RDI was defined as the number of apneas, hypopneas, and respiratory effort-related arousals (RERAs) per hour of sleep. "Symptomatic" was defined as excessive daytime sleepiness, impaired cognition, mood disorders, insomnia, or documented cardiovascular diseases to include hypertension, ischemic heart disease, or stroke. Hypopnea was defined as either a 50% decrease in airflow or less than a 50% decrease in airflow + 3% desaturation or arousal. New Medicare guidelines for CPAP reimbursement are listed in the table. Many insurance providers may adopt these guidelines. The AHI does not include RERAs, and a 4% desaturation is required for hypopneas. Note that both recommendations include symptoms other than daytime sleepiness in the "symptomatic" category. The question of CP AP treatment is difficult in patients with mild OSA who are truly asymptomatic. Most recommend CPAP treatment for patients with severe OSA (AHI > 30/hr) even if symptoms or cardiovascular disease are absent. However, a study by Barbe and coworkers found no short-term benefit (quality of life measures, blood pressure, cognitive function, objective sleepiness by MSLT) in a group of patients with an AHI > 30/hr and a mean Epworth Sleepiness Scale score of 7/24 (normal). The fact that these patients were
not sleepy is probably explained by the wide variability in the susceptibility to sleep fragmentation. Moreover, some have suggested that a spouse should fill out the Epworth questionnaire, because some patients underestimate their sleepiness. As discussed in Patient 38, the other reasons for treatment of OSA besides daytime sleepiness are to alleviate socially unacceptable snoring and to prevent cardiovascular consequences of OSA. In milder OSA one might argue that cardiovascular consequences may be less likely. However, even mild increases in AHI were associated with increased risk of cardiovascular disease in the Sleep Heart Health Study. What has not been demonstrated is that CPAP treatment prevents these consequences. For milder cases of OS A, factors such as disturbance of the bedrnate's sleep, coexistent cardiovascular disease, and patient attitudes toward the problem must be considered. Of note, patients in the Barbe study were normotensive, Nasal CPAP has been shown to be effective in symptomatic patients with mild OSA. If you try nasal CPAP in asymptomatic patients, there are some factors to consider. First, adherence (formerly called compliance) is typically lower. You might want to be conservative in the pressure prescription if pressure intolerance is a problem. Adherence might be increased if the patient understands the impact of snoring on the bedpartner or their other medical conditions. Second, some asymptomatic patients actually feel better on CPAP. However, remember that in some studies the score on the Epworth Sleepiness Scale improved on sham CPAP (placbo effect). In the present case, note that classification of the patient as a simple snorer or a patient with mild OSA (AHI 2: 5/hr) depends on the definition of hypopnea. The patient felt that having his wife
Medicare Guidelines for Positive Pressure Reimbursement DEFINITIONS
Apnea = absence of airflow for 10 seconds or longer Hypopnea = 30% or more reduction in flow from baseline with at least a 4% arterial oxygen desaturation The AHI must be based on a minimum oj 2 hours of sleep recorded by polysomnography (not a cardiopulmonary study) AHI 5-14 IHR Patient must be symptomatic (i.e., documented symptoms of excessive daytime sleepiness, impaired cognition, mood disorders, or insomnia, or documented hypertension, ischemic heart disease, or history of stroke)
AHI2: 15 IHR Patient can be with or without symptoms
137
sleep with him was very important, so he agreed to try CPAP. He underwent a CPAP titration and was started on 7 em HoG and a weight-loss program. Although the patient could be considered symptomatic (documented hypertension), he did not quite meet the new Medicare guidelines of an AHI of at least 5/hr (using the Medicare definition
of hypopnea). However, he was willing to pay for his own CPAP through a rental agreement. While he found CPAP difficult to use for the first 6 weeks, he eventually felt better. His Epworth Sleepiness Scale score decreased to 5, and he no longer had to drink two cups of coffee to get going in the morning.
Clinical Pearls I. Nasal CPAP can be effective in symptomatic patients with mild GSA. 2. Treatment decisions in mild asymptomatic GSA patients are difficult. Consider the attitude of the patient, degree of bed partner sleep disturbance, and comorbid medical conditions. 3. Most recommend treatment of asymptomatic GSA patients with moderate to severe GSA (AHI > 30/hr [hypopneas not requiring desturation] or > 15/hr [hypopneas with 4 % desaturation)). 3. Remember that sleepiness may be underestimated (in addition to having the patient complete the Epworth questionnaire, also ask the significant other to complete one for the patient). 4. In new Medicare guidelines, "symptomatic" means more than daytime sleepiness. Coexistent cardiovascular disease qualifies the patient for being symptomatic. A lower AHI is required for CPAP reimbursement with patients who are symptomatic.
REFERENCES I. Redline S, Adams N, Strauss ME, et al: Improvement of mild sleep-disordered breathing with CPAP compared to conservative therapy. Am J Respir Crit Care Med 1998; 157:858-865. 2. Engleman HM, Kingshott RN. Wraith PK. et al: Randomized placebo-controlled crossover trial of continuous positive airway pressure for mild sleep apnea/hypopnea syndrome. Am J Respir Crit Car Med 1999; 159:461-467. 3. Loube 01. Gay PG, Strohl KP. et al: Indications for positive airway pressure treatment of adult obstructive sleep apnea patients. Chest 1999; 115:863-866. 4. Barbe F. Mayorala LR. Duran J. et al: Treatment with continuous positive airway pressure is not effective in patients with sleep apnea but no daytime sleepiness. Ann Intern Med 200 1;134: 1015-1023. 5. Pack AHI, Maislin G: Who should get treated for sleep apnea? Ann Intern Med 200 I; 134: 1065-1066.
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FUNDAMENTALS OF SLEEP MEDICINE 15
Positive Pressure Airway Treatment: Improving Acceptance and Adherence
Positive airway pressure (PAP) is the treatment of choice for moderate to severe obstructive sleep apnea (OSA). It is also effective in milder cases of OSA. PAP has been shown to improve subjective and objective daytime sleepiness in placebo-controlled studies. However, the major challenge to sleep physicians is to increase acceptance and adherence (formerly called compliance). Some of the first objective measures of adherence found that only 40-60% of patients used PAP devices for 4 or more hours per night. Subsequent trials in Europe have shown much better adherence when intensive programs to improve compliance were instituted. Regular contact (even by telephone) with the physician or respiratory therapists/nurses is essential to improve the chance of a good outcome. The ultimate pattern of CPAP use is often established within the first week of treatment; therefore, early intervention is essential. Involving the patient's spouse in discussions of the rationale for treatment and PAP education is helpful-afterall, the sleep of two persons is often at stake. Regular assessment of objective machine use information (adherence) and subjective sleepiness (Epworth Sleepiness Scale) is recommended. Patients are notoriously inaccurate in their estimate of their use of PAP. The simplest method of documenting CPAP use is the run time meter. An average night's use can be computed if the initial and final meter readings and the duration in days are known. This calculation is accurate, unless patients continue running the CPAP with the mask off. A better method is time at pressure, i.e., time during which pressure is actually delivered. One study suggested that, on average, time at pressure is about 90% of run time. Many CPAP machines have memory, and the information can be transferred via modem, "smart card," or serial port to a computer for analysis. In this manner, you can detect patterns of non-use and institute interventions. Several common patterns-such as no use on weekends, or removal of CPAP in early morning hours - can quickly be detected. Educate patients that the lowest Sa02 occurs in the early morning hours. If CPAP is removed to use the bathroom in the middle of the night and not replaced, instruct the patient to leave the mask in place and simply disconnect the hose from the mask.
PAP Treatment: Methods to Enhance Acceptance/Adherence • Intensive education about importance of treatment and treatment alternatives before and after the sleep study • Careful mask fitting, testing for leaks/comfort before sleep study • Pretreatment of nasal congestion, if present • Availability/routine use of humidification • Involvment of spouse in education/PAP training • Early contact or clinic follow-up • Early interventions for side effects/discomforts • Regular objective evaluation of adherence • Regular follow-up visits with the physician directing care
139
Common Side Effects of Positive Pressure Treatment and Possible Interventions" SIDE EFFECTS
INTERVENTIONS
Mask Problems Air leaks Conjuncitivits Discomfort Noise
Proper mask fitting Proper mask application (education) Different brand/type of mask
Skin breakdown
Avoid over-tightening; intervene as above for leaks Alternate between different mask types Nasal prongs/ pillows Tape barrier for skin protection
Unintentional mask removal
Low pressure alarm Consider increase in pressure
Nasal Symptoms Congestion/obstruction
Nasal steroid inhaler Antihistamines (if allergic component) Nighttime topical decongestants (oxyrnetazoline) Nasal saline Humidification (heated) Full face (Oro-nasal) mask
Epistaxis, pain
Nasal saline Humidification (heated)
Rhinitis/rhinnorhea
Nasal ipratropium bromide
Other Problems Mouth leaks; mouth dryness
Humidification (prevent increased nasal resistance) Treatment of nasal congestion Chin straps (?) Full face mask Lower pressure/bilevel pressure
Pressure intolerance
Ramp Bilevel pressure Auto-titrating device Lower prescription pressure-accept higher AHI Lower pressure + adjunctive measures (elevated head of bed, side sleeping position)
Machine noise
Long tubing with machine removed from bedroom Different brand of blower
Claustrophobia
Desensitization Nasal prongs/pillows
*See following cases for discussions relating to several of these side effects and interventions.
140
Key Points I. A systematic approach for early and frequent follow-up, including interventions for side effects, is essential to improve acceptance and adherence to positive pressure treatment. 2. Objective adherence monitoring lets you know when to intervene. 3. Frequent early contact by telephone is an effective way to indentify problems.
REFERENCES I. Engleman HM. Martin SE. Douglas NJ. Compliance with CPAP therapy in patients with the sleep apnea/hypopnea syndrome. Thorax. 1994;49:263-266. 2. Chervin RD. Theut S, Bassetti C. Aldrich MS: Compliance of nasal CPAP can be improved by simple interventions. Sleep 1997:20:284-289. 3. Hoy CJ. Vennelle M. Kingshott RN. et a1: Can intensive support improve continuous positive airway pressure use in patients with the sleep apnea/hypopnea syndrome? Am J Respir Crit Care Med 1999: 159: 1096-1100. 4. Pepin JL. Krieger J. Rodenstein D. et al: Effective compliance during the first 3 months of continuous positive airway pressure. A European prospective study of 121 patients. Am J Respir Crit Care Med 1999: 160: 1124-1129. 5. Berry RB: Improving CPAP compliance: Man more than machine. Sleep Med 2000;1: 175-178.
141
PATIENT 40 A 55-year-old man with obstructive sleep apnea still sleepy on nasal CPAP A 55-year-old man with OSA complained that his CPAP wasn't working. He had been diagnosed as having severe sleep apnea 2 months ago. He was started on nasal CPAP at 12 em H 20 based on the original split-night study. His wife denied that the patient was snoring on positive pressure ("unless he took it off during the night"). The patient denied problems with mask leaks or dry mouth. He did admit to sometimes removing the mask when he got up during the night to urinate. His Epworth Sleepiness Scale score pre-CPAP was 20, and now was 18 (normal < II). There was no history of cataplexy, hypnagogic hallucinations, or symptoms of the restless leg syndrome. Physical Examination: HEENT: dependent palate, high tongue base; neck circumference 19 inches. Machine Adherence Information (data from 3 weeks of usage): Average time at pressure: 3.5 hours. Percentage of night more than 4 hours of use: 40%. A portion of the detailed usage information for the patient is shown below. Dark bars = time at pressure.
Question:
Why is the patient still sleepy?
2/10102
•...
Tue Wed Thu Fri
•
Sat Sun 2/17102
Tue 12 14 16 18 20 22 24 2 Time
142
4
6
10 12
Answer:
Inadequate CPAP adherence.
Discussion: Patient report of CPAP usage is often unreliable. You must have objective adherence information to assess the need for further diagnostic studies or interventions. Obtaining this information should be part of the routine follow-up of patients on CPAP. Some patients try to please their physician and grossly overestimate CPAP use. Having a spouse present during the visit may allow you to gather more accurate information. However, spouses are often hesitant to disagree in front of a physician. Modem machines can give detailed use information, enabling the physician to determine certain patterns. For example, some patients have nights when no CPAP is used at all. Others discontinue CPAP use early in the morning. While simple run-time information is helpful, an occasional patient will run the machine with the mask off to fake good compliance. Time at pressure is the most reliable information. The table below lists useful questions to ask patients during routine CP AP follow-up. Snoring on CPAP is a simple way to detect the need for slightly higher pressure. A dry mouth suggests mouth leak. Question patients about mask discomfort and leak. Be assertive in demanding that home healthcare providers replace masks and filters on a regular basis. Old masks can become stiff and are more likely to leak. Patients often over-tighten their mask in an attempt to compensate for poor mask fit or seal. Do not hesitate to try different brands or types of masks. "Dissatisfaction with mask" was the leading side effect of CPAP treatment in several studies. In discussing adherence issues with patients, it is important to emphasize that many patients who ultimately do well with CPAP have difficult periods of adaptation. Reminding patients of the long-term benefits and being supportive can establish a good relationship. Have the patient join an OSA support grouphearing success stories from others may encourage him or her to persist during the adaptation period. If inadequate CPAP treatment is eliminated as a cause of persistent sleepiness, consider other sleep disorders and medical disorders. Patients with OSA can have narcolepsy, periodic leg movements in sleep, depression, and chronic pain syndromes. Questions To Ask A verage nightly use Snoring on CPAP Mask discomfort
Differential of Persistent Sleepiness on CPAP Inadequate CP AP treatment pressure too low, mask leak, mouth leak, inadequate adherence Another sleep disorder narcolepsy, insufficent sleep syndrome, restless leg syndrome/periodic leg movements in sleep Depression/mood disorder Chronic pain syndromes Medical condtions/medications There does appear to be a group of OSA patients who have persistent daytime sleepiness despite adequate CP AP adherence. Two recent studies have suggested that the addition of the wake-promoting agent modafinil can improve daytime symptoms. (See Patients 87 and 89 for a detailed discussion of modafinil.) One potential problem with modafinil is that patients may try to get by with less CPAP use. Modafinil does not prevent nocturnal hypoxemia and the impact of OSA on blood pressure and cardiovascular morbidity. The place of modafinil in the treatment of OSA remains to be determined. In the present case, the adherence pattern shows that some nights CPAP was not used at all (Wednesday). On other nights the use was rarely over 4 hours. The patient admitted he fell asleep on the couch a few nights and did not put on his CPAP. He also said that he rarely replaced the CPAP when he got up to urniate at night. Putting the mask and headgear back on seemed too difficult at 4 AM. The need for at least 4 and preferably 6 hours of nightly use to get the full benefit from CPAP was emphasized. The patient was instructed on how he could keep his head gear on and simply disconnect the hose at the mask when using the bathroom. He also admitted that by 4 AM his mask was uncomfortable. A different brand of mask was tried. On a return visit 4 weeks later, the average night adherence had increased to 5.5 hours, and the Epworth Sleepiness Scale score was now 16. Three months subsequently, the average nightly adherence was 6.5 hours, and the Epworth Sleepiness Scale score was 10/24 (normal).
Problem
Air blowing out mouth
Inadequate adherence Inadequate pressure/weight gain Wrong mask size, old mask, incorrect application Mouth leak
Air blowing out mask Dry mouth
Poor mask fit or application Mouth leak, nasal congestion
Intervention Objective adherence data Increase pressure/lose weight Changes mask, educate Chin strap, heated humidity, full face mask Refit mask/change mask, educate Treat nasal congestion, heated humditiy, treat mouth leak
143
Clinical Pearls I. Objective adherence information is essential to optimize positive pressure treatment and should be a part of every follow-up visit. 2. While the minimum acceptable usage is 4 hours per night. many patients require more use to have a full resolution of symptoms. 3. Early attention to reducing side effects and PAP discomforts is essential. The pattern of usage can be determined in the first week of treatment. 4. When patients feel discouraged. remind them that adaptation to CPAP treatment often takes several months. CPAP support groups may help. 5. In patients with persistent daytime sleepiness and adequate CPAP therapy. first eliminate the possibility that other sleep disorders are present. If none can be documented, consider treatment with modafinil.
REFERENCES I. Kribbs NB, Pack AI, Kline LR. et al: Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am Rev Respir Dis 1993;147:887-895. 2. Weaver TE. Kribbs NB. Pack AI. et al: Night to night variability in CPAP use over the first three months of treatment. Sleep
1997;20:278-283. 3. Meurice JC, Paquereeau 1. Neau JP. et al: Long-term evolution of daytime somnolence in patients with sleep apnea/hypopnea syndrome treated by continuous positive pressure. Sleep 1997:20: I 162-1166. 4. Pack AI. Black JE. Schwartz JR. Matheson JK: Modafinil as adjunct therapy for daytime sleepiness in obstructive sleep apnea. Am J Respir Crit Care Med 200 I: 164: 1675-1681. 5. Kingshott RN. Vennelle M. Coleman EL. et al: Randomized. double-blind, placebo-controlled crossover trial of modalinil in the treatment of residual excessive daytime sleepiness in the sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med
2001; 163:918-923.
144
PATIENT 41 A 50-year-old man unable to sleep on CPAP due to mask leak and claustrophobia A 50-year-old man was found to have mild obstructive sleep apnea (AHI = IO/hr and minimium SaO, 90%) on a previous partial-night sleep study. During that study, no REM sleep and minimal supine sleep were recorded during the diagnostic portion. During the CPAP titration portion of the study he was able to sleep briefly on 10 cm H,O during REM in the supine position. The AHI was 5/hr in that circumstance. The patient was unable to sleep on CPAP for the last 2 hours of the study. He tried nasal CPAP at home, but experienced symptoms of claustrophobia and mask leak. Another size of the same brand of mask was tried without success. The patient discontinued CPAP, but complained of persistent moderate daytime sleepiness (Epworth score 18/24). His primary care physician then ordered a full-night diagnostic study, followed by an MSLT, because it was felt that mild OSA could not explain the severe symptoms. Severe OSA was noted, and the MSLT was cancelled. =
Sleep Study Time in bed Total sleep time (TST) Sleep period time (SPT) WASO (min) Sleep latency (min) REM latency (min) Arousal index (lhr) Respiratory arousal index (lhr)
420 min 320 min 400 min 78 min 2 min 200 min 40 35 40 35.5 70
AHI (lhr) AHI NREM (lhr) AHI REM (lhr)
Sleep stages
%SPT
Stage Wake Stage I Stage 2 Stage 3 and 4 Stage REM
19.5 10 60 0 10.5
AHI supine (lhr) AHI non-supine (lhr) TST supine
70 10 50%
WASO = wake after sleep onset
Questions:
Why is the AHI so much higher on the second (full-night) study? What would you rec-
ommend?
145
Answer: The patient has severe OSA (underestimated by the previous partial-night study), and nasal CPAP should be tried again with a different mask and desensitization to address the claustrophobia. Discussion: The diagnostic portion of splitnight studies often underestimates the true severity of OSA, as sufficient supine or REM sleep may not be recorded. Many patients have a much higher AHI in those circumstances. In addition, the final REM periods of the night tend to have more disturbed ventilation and are the time of the most severe desaturation in many patients. The diagnostic portion of split-night studies do not record sleep during the final REM periods of the night. Problems with the mask interface are the most common side effect of positive-pressure treatment in most studies. These include discomfort, mask leak, skin abrasion (from over-tightening the mask), and conjunctivitis (air leak into the eyes). Patients frequently report increased leak when they change body positions. A number of mask alternatives are available (see figure for a few examples). Because of the cost, some providers of durable medical equipment are reluctant to change masks. This is a poor strategy, because a well-fitting mask is essential for adequate adherence. Different brands, sizes, and types should be tried. Patients having problems with leak at the top of the nose (bridge) may have a better seal with a nasal pillows (prongs) type inter-
A,
146
face. These fit directly into the nostrils and do not cover the bridge of the nose. Claustrophobia is a challenging problem for sleep physicians. Some patients will tolerate a nasal pillows (Breeze TM) or nasal cannula type interface (Nasal Aire TM) better than a mask that fits over the entire nose. Others may find bilevel pressure easier to tolerate than CP AP. A structured or unstructured desenzitization to CPAP/mask can be tried: the patient first wears the mask at low pressure during wakefulness for increasing periods of time. He or she then starts wearing the mask and CPAP during the night If necessary, pressure lower than the optimal pressure can be used initially. In the CUITent case, the diagnostic portion of the split-night study underestimated the true severity of OSA because little REM or supine sleep was recorded. The MSLT was cancelled as the results would not help make a diagnosis of narcolepsy until the sleep apnea was adequately treated. The patient was started on nasal pillows as the mask interface and a program of desensitization with a pyschologist. After several weeks he was able to use the CPAP for the entire night and noted resolution of his symptoms (Epworth score 10/24).
Ultramirage" (ResMed ); B, Nasal pillows/Breeze" (Mallincrokdt); C, Nasal Aire (lnnoMed)
Clinical Pearls 1. The severity of GSA may be underestimated by split- or partial-night studies. 2. Problems with the mask interface are the most frequent side effect of positive-pressure treatment. 3. The clinician must be aggressive in trying different sizes, types, and brands of interfaces until an adequate one is found (trial and error). 4. Claustrophobia may be approached by using nasal pillows type interfaces and desensitization.
REFERENCES I. Nino-Murcia G, McCann CC, Bliwise DL, et al: Compliance and side effects in sleep apnea patients treated with nasal continuous positive airway pressure. West J Med 1989; 150: 165-169. 2. Rolfe l.Dlson LG, Sanders NA: Long-term acceptance of continuous positive airway pressure in obstructive sleep apnea. Am Rev Respir Dis 1991;144:1130-1133. 3. Hoffstein V, Viner S, Mateika S, Conway J: Treatment of obstructive sleep apnea with nasal continuous positive airway pressure. Patient compliance, perception of benefits, and side effects. Am Rev Respir Dis 1992; 145:841-845. 4. Edinger JD, Radtke RA: Use of In vivo desensitization to treat a patient's claustrophic response to nasal CPAP. Sleep 1993;16:678-680.
147
PATIENT 42 A 55-year-old man having difficulty with CPAP because of nasal congestion A 55-year-old man was diagnosed as having severe obstructive sleep apnea (AHI = 55/hr). After CPAP titration, treatment with nasal CPAP was initiated. Unfortunately, the patient developed severe nasal congestion and was unable to continue treatment. He had a long history of mild nasal congestion that worsened during the spring. He was treated with a nonsedating antihistamine and nasal steroid medications, without much improvement. He reported waking up several hours after starting nasal CPAP and being unable to breathe through his nose. A very dry mouth usually was noted at that time. Cold (passover) humidity was added without any improvement in symptoms. Physical Examination: HEENT: edematous nasal mucosa, no polyps; large tongue, edematous uvula; 18-inch neck circumference. Chest: clear. Cardiac: normal. Extremities: no edema.
Question:
148
What further therapy would you consider?
Answer:
Heated humidification and aggressive decongestant therapy may ease CPAP side effects.
Discussion: Nasal symptoms are common in patients with OSA before treatment, and nasal obstruction itself may be a contributing factor in the development of sleep-disordered breathing. After starting treatment with nasal CPAP, many patients report new or increased nasal symptoms. Of patients using nasal CPAP, 30-50% experience nasal side effects including congestion, dry nose and throat, sore throat, and even bleeding from the nose. These side effects can dramatically reduce adherence and can result in cessation of therapy. It is unclear how nasal CPAP increases or causes nasal symptoms. In some patients, the necessity of nasal respiration draws attention to de novo nasal symptoms. In others, airway pressure on the nasal mucosa induces rhinitis by reflex mechanisms. Patients with rhinitis may respond to inhaled, anticholinergic medication (ipratropium bromide). However, in most patients nasal congestion rather than rhinitis is the major problem. The etiology of worsening nasal congestion is not known with certainty but may be related to mucosal drying. Cold, dry air appears to induce release of mediators from mast cells. Some degree of mouth breathing may initiate a unidirectional airleak (out the mouth), and the loss of moisture from the system overwhelms the capacity of the nasal mucosa to humidify inspired air. Further drying of the nasal mucosa results in more nasal congestion and even higher nasal resistance, which, in turn, promotes more mouth breathing. Thus, a vicious cycle develops. In many patients on CPAP, adequate humidification of air can break this cycle. It also can improve symptoms of nasal congestion. While passover cold humidification (air blown over water) may be adequate in mild cases, most patients with significant symptoms require heated humidification. The absolute amount of moisture delievered is
~100
o
£
:g
Leaks
much higher with heated humdity. In the figure, note how the relative humdity falls abruptly during leaks (mouth leaks). Even heated humdity does not prevent a decrease in relative humidity during leaks; however, the actual value is much higher than without humidification. A recent study found that heated humidity increased nightly use of CPAP by about 30 minutes in a group of unselected patients. Patients were more satisfied with CPAP when using cold or heated humidity. A few patients prefer cold humidity. However, because many patients benefit from heated humidity, several companies are now selling CPAP units with built-in heated humidifiers. Another approach to mouth leaks is to use chin straps. Their efficacy has not been studied systematically, but a few patients improve with their use. Interestingly, recent studies suggest that patients with a prior uvulopalatopharyngoplasty may have a greater tendency for mouth leaks on CPAP. This finding seems reasonable, as the absence of a mouth leak in most patients using nasal CP AP probably is due to the forward movement of the palate against the tongue (sealing off the oral passages from flow). In patients with nasal congestion who fail a trial of heated humidification, topical nasal vasoconstrictors (oxymetazoline) can be tried (at bedtime only). Most physicians are aware that topical nasal vasoconstrictors cannot be used continuously without inducing rebound nasal congestion. Patients who do not respond to these interventions may benefit from a full face mask or nasal surgery. In the present patient, heated humidification was added to the nasal CPAP circuit, and the symptoms of nasal congestion improved. The patient resumed treatment and only rarely required a topical nasal vasoconstrictor at bedtime. He continued the use of an inhaled nasal steroid medication.
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Heated humidification reduces the drop in relative humidity caused by mouth leaks. 149
Clinical Pearls I. Nasal symptoms are a major cause of adherence problems with nasal CPAP therapy. 2. Mouth leaks may further increase nasal resistance by setting up a unidirectional flow out the mouth (leak) and drying the nasal mucosa. 3. If initial therapy for nasal congestion with nasal steroids and nonsedating antihistamines (if an allergic component is suspected) fails, or the patient complains of dry nose/ mouth, then heated humidification should be added to the CPAP circuit. 4. Heated humidification is more effective than cold humidity in most patients with significant symptoms of dryness or nasal congestion. Several brands ofCPAP units with builtin heated humidity are available. 5. Topical vasoconstrictors can be used to treat nasal congestion as a last resort at bedtime only.
REFERENCES I. Kribbs NB, Pack AI, Kline LR, et al: Objective measurement of patterns of nasal CPAP use by patients with obstructive sleep apnea. Am J Resp Crit Care Med 1993; 147:887-895. 2. Richards GN, Cistulli PA, Ungar RG, et al: Mouth leak with nasal continuous positive airway pressure increases nasal airway resistance. Am J Respir Crit Care Med 1996; 154: 182-186. 3. Massie CA, Hart RW, Peralez K, Richards GN: Effects of humidification on nasal symptoms and compliance is sleep apnea patients using continuous positive airway pressure. Chest 1999; 116:403-408. 4. Martins de Araujo MT, Vieira SB. Vasquez EC, Fleury B: Heated humification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy. Chest 2000; 117: 142-147.
150
PATIENT 43 A 30-year-old man unable to tolerate nasal CPAP because of "too much pressure" A 30-year-old man with severe obstructive sleep apnea stopped using nasal continuous positive airway pressure (CPAP) because the prescribed pressure of 14 ern H 20 was "too high." Using the ramp option, he was able to fall asleep on his side, but he woke up later and was unable to tolerate CPAP at the prescription pressure. He also felt that the beginning pressure when the ramp option was activated was "not enough pressure" when he tried to fall asleep on his back. A summary of his original CPAP titration (selected pressure levels) is shown below. When the patient changed from the left lateral to supine position, a CPAP level of 7 cm H 20 was no longer adequate, and it was increased to 10 em H20 . At this pressure there were few events until the patient entered REM sleep. The CPAP level was increased to 14 em H 20 to maintain airway patency during supine REM sleep.
Sleep Study-CPAP Titration
Pressure (em H2O) Body position REM (min) AHI (events/hr) AHI, NREM AHI, REM
Question:
0 Left 0 55 55 n/a
7 Left 0 5 5 n/a
7 Supine 0 50 30 n/a
10 Supine 10 IS 5 40
14 Supine 30 5 0 5
What measures could make treatment with nasal CPAP acceptable to this patient?
151
Answer:
Auto-adjusting CPAP.
Discussion: Several approaches are available when patients have difficulty tolerating the prescribed CPAP pressure. The ramp mode on many commercial CPAP units allows a slow increase in airway pressure from a low setting (around 3---4 cm H 20 ) to the prescribed pressure, so that the patient can fall asleep at lower pressures. The ramp period (time to reach set pressure) is adjustable on most units. If the patient awakens during the night, the ramp mode can be reinitiated. Two important points: (I) The mask seal must be tested at the final (prescribed) pressure before the ramp is initiated. If this is not done, mask leaks may appear as the pressure increases. (2) The low initial pressure is a problem for some patients. These patients may have trouble falling asleep due to difficulty breathing through the system even when awake. Some CPAP units allow an increase of the initial pressure in the ramp mode. If not, a short ramp period may be better tolerated than a long one. However, no study has demonstrated that the ramp option really improves acceptance or adherence to CP AP therapy. Auto-adjusting CPAP (APAP) units are now available that attempt to provide the lowest effective pressure in any circumstance. These units apply a variety of detection methods-searching for apnea, hypopnea (airflow), airway vibration (snoring), and airflow flattening as indicators of airway narrowing or closure. The machines use different algorithms to determine how much the pressure should be increased and how fast. When no events are detected, the units slowly lower the level of pressure. This continuous titration of pressures may lower the mean pressure required to maintain airway patency. For example, while sleeping in the lateral decubitus position a pressure level of 5 em Hp might be adequate. When supine (perhaps 40% of the night), the required pressure increases to 10 ern H 20 . Thus, the mean pressure is 7 em H 20 instead of a single setting of 10ern HoO. In most APAP units one can also set the minimum and maximum allowable pressure. This may be useful as some patients develop episodes of mouth or mask leak, which cause transient large increases in pressure. Several studies found that APAP devices improve adherence to positive pressure treatment (increased mean nightly use). Others have failed to find an advantage of APAP with respect to adherence. Of note, the difference between the mean nightly pressure on APAP and the fixed CPAP pressure was small in some studies. One might expect APAP to have the biggest advantage in those patients who have considerable variability in the pressure needed during the night (effects of posture and sleep stage). Indeed one study did find that patients with sleep stageor body position-dependent OSA may be a sub-
152
group showing increased adherence to positive pressure on APAP. APAP devices also have memory capability; detailed use, pressure, and leak information can be transferred to a computer for analysis. Most devices also report a machine-determined average AHI for each night (events/time at pressure). Additionally, the machine can detect problems with high leak. Another approach to intolerance of a level of CP AP is to switch to bileveI pressure. This method can allow maintenance of airway patency with a lower pressure during expiration and may be especially useful in patients who mainly complain of difficulty exhaling. Bilevel pressure is detailed in another case (see Patient 45). Other remedies: adjunctive therapy may decrease the level of pressure required to maintain airway patency; weight loss can minimize the tendency of the upper airway to collapse; the simultaneous use of an oral appliance can sometimes improve the efficacy of a given level of CPAP; and aggressive treatment of nasal resistance (congestion) can reduce the required mask pressure. Note that the pressure level at the mask is not the inspiratory pressure level in the oropharynx or hypopharynx, due to a pressure drop across the nose. Studies have shown that postural change can decrease the CPAP pressure required to keep the airway open. Sleeping in the lateral position can decreased the required pressure in some patients. However, this posture can be ineffective in very obese patients. Moreover, it is difficult to constrain patients to sleep on their sides. Alternatively, a recent study found that modest head elevation (30%) reduced the pressure required to maintain upper airway patency by almost 5 cmH 20 . A final approach is simply to accept a lower pressure than the optimal pressure determined during the CP AP trial. For example, the present patient did well at 10 ern H 20 in the supine position until he entered REM sleep. He may be better served by using nasal CP AP at a lower-than-optimal pressure than by stopping therapy altogether. Five events per hour in NREM sleep is much better than 55 per hour (no CPAP), even if maintenance of airway patency in REM is incomplete. With an AHI 5/hr in NREM and 40/hr in REM, the overall AHI is likely to be around 16/hr (assuming 20% REM sleep). In many other treatments for OSA, an AHI of 15/hr in a patient with 55/hr at baseline would be considered a fairly good response. Accepting less-than-perfect treatment results is especially important for patients with severe GSA, in whom the only effective alternatives are tracheostomy or extensive upper airway surgery (not always available). Over time, many pa-
tients adapt to CPAP and may accept a slow increase in pressure to a level that maintains an open airway in all circumstances. In the current case, the patient required much lower pressure during NREM sleep in the lateral sleeping position than during REM in the supine position. He was treated with an APAP device with a minimum pressure of 7 cm H20 and a maximum pressure of 15 em H20. Below is pressure information transferred from the device's memory for one night. You can see the wide variation in pressure and the fact that the average pressure (around 10 cm
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Clinical Pearls L Auto-adjusting CPAP and bilevel pressure are treatment alternatives in patients unable to use nasal positive pressure at the optimal pressure due to pressure intolerance. 2. Adjunctive measures such as postural changes and weight loss can improve the efficacy of a given level of CPAP. 3. Many patients are better served by using a less-than-optimal CPAP pressure rather than no effective therapy at all. With chronic treatment, higher levels of CPAP may eventually be accepted by many patients.
REFERENCES I. Schwartz AR. Gold AR, Schubert N: Effect of weight loss on upper airway collapsibility in obstructive sleep apnea. Am Rev Respir Dis 1991; 144:494-498. 2. Meurice lC, Marc I, Series F: Efficacy of auto-CPAP in the treatment of obstructive sleep apnea/hypopnea syndrome. Am 1 Resp Crit Care Med 1996 ;153:794-798. 3. Neill AM. Angus S, Sajovo D, McEvoy RD: Effects of sleep posture on upper airway stability in patients with obstructive sleep apnea. Am 1 Resp Crit Care Med 1997; 155: 199-204. 4. Hudgel, DW, Fung C: A long-term randomized, crossover comparison of auto-titrating and standard nasal continuous airway pressure. Sleep 2000;23:645-648. 5. Series F, Marc I: Importance of sleep stage and body position depnedence of sleep apnea in determining benefits to auto-CPAP therapy. Eur Resp 1. 200 I; 18: 170-175. 6. Berry RB, Parish 1M, Hartse KM: The use of auto-titrating CPAP for treatment of adults obstructive sleep apnea. An American Academy of Sleep Medicine Review. Sleep 2002;25: 148-173.
153
PATIENT 44 A 55-year-old man unable to use nasal CPAP due to intractable nasal congestion A 55-year-old man with a long history of nasal congestion was diagnosed as having severe obstructive sleep apnea (AHI = 70/hr). He underwent a nasal CPAP titration but the procedure was terminated at the patient's request because he could not breathe thorough his nose. He already was being treated with a non-sedating antihistamine and a nasal steroid inhaler. In the past he reported improvement with oxymetazalone (a topical nasal vasoconstrictor), but he developed dependence on this medication (rebound). He refused to consider surgical treatments for OSA. Physical Examination: Nose: slightly deviated septum, moderate mucosal edema and erythema, no polyps. Tongue: large, difficult to see oropharyngeal aperture.
Question:
154
What treatment options are available for this patient?
Answer:
Consider full face mask CPAP, also called oronasal CPAP.
Discussion: Occasionally a patient with OSA is unable to tolerate the initial CP AP titration due to difficulty with nasal breathing. While medical treatment of nasal congestion or surgical treatment of structural obstruction may ultimately improve the condition, the loss of a CPAP titration opportunity in the sleep laboratory is expensive. Other patients may complain of intractable nasal obstruction once CPAP treatment is initiated, and are unable to continue treatment. In both cases, application of CPAP by a full face mask (oronasal CPAP) provides a useful treatment alternative, allowing patients to breathe through both the nose and mouth. Two studies have shown that full face CPAP (see top figure) works in patients unable to tolerate nasal CPAP due to nasal obstruction. Full face masks require some unique features compared to nasal masks. First, quick removal must be possible
should the patient need to vomit. Second, there must be a valve to allow entry of room air in case the source of air fails (CPAP unit failure). Third, a good seal may be more difficult to obtain than with a nasal mask because there is a larger area to be covered and sealed. Many edentulous patients have a less rigid face, and this makes obtaining a good seal over the lower face difficult. Nevertheless, the full face mask may be the only method some patients will tolerate. After completion of CPAP titration in the laboratory, intensive treatment of the nose may allow some patients to be switched to nasal CPAP. The addition of heated humidity helps many patients with nasal congestion. As a last resort, you can try a topical decongestant (only at night) or refer the patient for nasal surgery. However, chronic treatment with full-face CPAP is the best alternative for some patients with nasal obstruction. Full face masks also can be useful in patients with a large oral leak. Chin straps may address this problem in some individuals. In others, the addition of humidification and treatment of nasal congestion may decrease the tendency to open the mouth during sleep. However, a patient not responding to these measures may benefit from oronasal CPAP. Of note, by preventing mouth leak and loss of humidity, a full face mask also helps prevent nasal dryness. Another, recently introduced mask alternative that might be useful in patients with nasal congestion is an oral interface (Oracle™-Fisher and Paykel Healthcare). The device consists of two flaps: a soft seal positioned inside the cheeks (see figure below, B) and a snap flap positioned outside the cheeks (C). Airflow passes over a tongue guide (A) that rests above the tongue. This device requires that heated humidity be used with CPAP, as the usual humidification provided by the nasal passages is bypassed. A leak port is present to vent carbon dioxide. Nasalleak may be a problem in a few patients, but in most the palate seals off the nasal passages once pressure is sufficient. Initial studies suggest that the optimal pressure with this interface is similar to that of a nasal mask in most patients. However, you might still want
155
to perform an in-lab titration because proper technique and some adaptation is essential. The utility of this device remains to be proven. As mentioned above, nasal surgery to correct obstruction (septoplasty, turbinoplasty) is another option to improve tolerance to nasal CPAP in patients with intractable nasal congestion. One study reported a decrease in the level of CPAP needed in severe OSA after nasal surgery. Another study of radiofrequency treatment of turbinate hypertrophy
noted an increase in self-reported CPAP adherence. However, the control group in this study was very small. More study of this promising technique (which can be performed as an outpatient procedure) is needed. The present patient underwent a repeat CP AP titration with a full face mask. At 15 ern HoO, the AHI was reduced to 5/hr. The patient currently is using CP AP with a full face mask and is experiencing good improvement of symptoms.
Clinical Pearls I. When patients are unable to tolerate nasal CPAP titration due to nasal obstruction, titration with a full face mask should be tried to avoid losing a night in the sleep lab. 2. In cases of intractable nasal congestion, full face (oronasal) CPAP may be the only treatment option that is tolerated. 3. CPAP via a full face mask can be useful in patients with a large, oral air leak that does not respond to chin straps, heated humidity, and treatment of nasal congestion. 4. A new oral mask interface (Oracle TM) may also work in patients unable to use a nasal mask. 5. Nasal surgery to increase CPAP adherence is generally a last resort. Improvement has been seen in selected patients with severe nasal obstruction.
REFERENCES 1. Prosise GL, Berry RB: Oral-nasal continuous positive airway pressure as a treatment for obstructive sleep apnea. Chest 1994; 106:180-186. 2. Sanders MH. Kern NB, Stiller RA, et al: CPAP therapy via oronasal mask for obstructive sleep apnea. Chest 1994; 106:774-779. 3. Friedman M. Tanyeri H. Lim JW. et al: Effect of improved nasal breathing on obstructive sleep apnea.Otolaryngol Head Neck Surg 2000: 122:71-74. 4. Martins de Araujo MT, Vieira SB. Vasquez EC. Fleury B: Heated humidification or face mask to prevent upper airway dryness during continuous positive airway pressure therapy. Chest 2000; 117:142-147. 5. Powell NB, Zonate AI. Weaver AM. et al: Radiofrequency treatment of turbinate hypertrophy in subjects using continuous positive airway pressure: A randomized, double-blind, placebo-controlled clinical pilot trial. Laryngoscope 200 I; III: 1783-1790. 6. Anderson FE, Smith NC, Kingshott RN. et a1: Efficacy of oral CPAP in the management of obstructive sleep apnea. Sleep 2002, 25:A220.
156
PATIENT 45 A 45-year-old man with intolerance to nasal CPAP because of difficulty exhaling A 45-year-old man was diagnosed as having severe obstructive sleep apnea (AHI 80/hr). He underwent a nasal CPAP titration, and the optimal pressure was determined to be 13 em H 20 . Treatment with nasal CPAP at this pressure was initiated. However, the patient returned complaining that the pressure was too high. He stated that it was especially uncomfortable to exhale against the pressure. Review of the CPAP titration showed that at 12 em H 20 the patient still had 25 hypopneas per hour in NREM sleep. Rather than lower the pressure, the patient underwent a trial with bilevel pressure. Figure: Events such as this were common at an expiratory positive airway pressure (EPAP) of IO ern H 20 and an inspiratory positive airway pressure (lPAP) of 12 em H 20 . This level of pressure can be designated as 12/10 em H 20 . Bands around the patient's chest and abdomen were used to detect respiratory effort.
Question:
What adjustment would you make to the pressure levels?
Arousal
EEG
Machine Flow Chest Abdomen
-
Arterial oxygen saturation
------
Desaturation
FIGURE 1
157
Answer:
Increase inspiratory positive airway pressure.
Discussion: Separately adjustable IPAP and EPAP (bilevel pressure) was introduced with the goal of being able to use lower expiratory pressures and still maintain upper airway patency during sleep. Some patients with OSA who are treated with nasal CPAP complain of great difficulty breathing out against the expiratory pressure. With bilevel pressure, airway patency usually can be maintained with a lower level of expiratory pressure. As CP AP is titrated upward, upper airway occlusion (apnea) typically converts to upper airway narrowing (hypopnea). Further increases in pressure distend the airway until significant upper airway narrowing is prevented (no hypopnea or snoring). The usual paradigm for bilevel pressure titration is to increase both pressures (IPAP = EP AP) until apnea is prevented. Then the IPAP is increased until hypopnea and snoring are prevented. Another approach is to start with IPAP = 6 em H 20 and EPAP = 4 em H 20 and then sequentially increase first IPAP and then EP AP until the desired result is effected. With bilevel pressure, the EP AP must be high enough to prevent airway collapse during expiration (prevent apnea), and the higher IPAP must sufficiently open the airway during inspiration to prevent hypopnea (airway narrowing). In Figure 2, apnea is still present at an IPAP/EPAP of 15/10 ern H 20 (A). An increase in EPAP to 12.5 cm H 20 (B) resolves the apnea. When originally introduced, bilevel pressure units were much more expensive than CPAP units. The first units were introduced with the trade name BIPAP, and this term is commonly (but incorrectly) used to refer to the bilevel pressure treatment modality. Today several bilevel units are marketed, and the cost - while still much higher than for CPAPhas decreased. Should all OSA patients be treated with bilevel pressure? One study of patient preferences found no significant advantage to bilevel pressure over traditional CP AP. In this study, the mean difference between IPAP and EP AP was about 4 ern H?O. Probably the most cost-effective approach is to-begin treatment with CPAP, and if
158
patients are unable to tolerate the device and complain of high pressure, then bilevel pressure can be tried. Such a plan assumes that the difference between IPAP and EPAP is likely to be significant (> 2 cm H 20) at the optimal pressure settings. Other patients in whom bilevel pressure may be useful are those with hypoventilation secondary to muscle weakness, lung disease, or abnormal ventilatory control. Some patients with the obesity hypoventilation syndrome (OSA plus hypoventilation) also may have better nocturnal gas exchange with bilevel pressure than CPAP. The IPAP-EPAP pressure difference is equivalent to pressure-support ventilation by nasal mask. Thus, a bilevel pressure setting of 15/5 is equi valent to ventilating a patient with a positive end expiratory pressure of 5 and a pressure support of 10 ern H?O. Obviously, some patients with hypoventilation still require traditional ventilatory support and intubation/tracheostomy. In patients with milder, more stable illness, however, bilevel pressure may work quite well and can prevent the need for mechanical ventilation. Patients with the overlap syndrome (OS A + chronic obstructive pulmonary disease) may also find bilevel pressure more comfortable. These patients already have difficulty exhaling secondary to their lung disease. Bilevel pressure also may be helpful in patients with intractable mouth leak. In some of these patients, high pressures tend to blow the mouth open, especially during exhalation. Although never systematically studied, clinical experience suggests that in selected patients, mouth leak can be improved by a switch to bilevel pressure. In the present patient, hypopnea was present at a bilevel pressure of 12/10. Note that chest and abdominal movements are in-phase before (see Figure I; A) and out-of-phase during (B) the event. Hypopnea resolved after the IPAP was increased to 16 ern H?O. Treatment was begun with bilevel pressure of 16/10 rather than a CP AP at 14 cm H 20. The patient tolerated this therapy and noted an improvement in daytime sleepiness.
inspiration
A flow
t
10 • 0 1.0
(Us)
15
pressure (em H2O)
10 inspiration
B flow
1.0
(Us)
0 1.0
pressure (em H2O)
FIGURE
15 12.5 2. Obstructive apnea abolished by an increase in EPAP.
Clinical Pearls 1. Bilevel pressure treatment allows separate adjustment of the IPAP and EPAP pressure levels; thus, upper airway patency can be maintained with an EPAP level lower than the required level of CPAP. 2. The level of EPAP is titrated to prevent apnea; the level of IPAP is titrated to prevent hypopnea and snoring. 3. Despite theoretical advantages, bilevel pressure has not been demonstrated to improve adherence over traditional nasal CPAP in unselected patients. In individual cases (pressure intolerant patients, patient on high pressure levels, or those describing difficulty exhaling on CPAP), bilevel pressure may improve acceptance and adherence to positive pressure treatment. 4. Bilevel pressure can provide a form of pressure support ventilation, which is useful in patients with hypoventilation. 5. Patients with COPD or those with neuromuscular weakness may tolerate bilevel pressure better than CPAP.
REFERENCES I. Sanders MH, Kern N: Obstructive sleep apnea treated by independently adjusted inspiratory and expiratory positive airway pressures via nasal mask. Chest 1990; 98:317-324. 2. Reeves-Hache MK, DW Hudgel, R Meek, et al: Continuous versus bilevel positive airway pressure for obstructive sleep apnea. Am J Respir Crit Care Med 1995; 151:443-449. 3. Resta 0, Guido P, Picca V, et a1: Prescription of nCPAP and nBiPAP in obstructive sleep apnea syndrome. Respir Med 1998; 92:820-827. 4. Series F, Marc I: Effects of inspiratory and expiratory positive pressure difference on airflow dynamics during sleep. J Appl PhysioI1998;85: 1855-1862.
159
PATIENT 46 A 60-year-old man with a suboptimal CPAP titration A 60-year-old man with a long history of snoring and daytime sleepiness underwent a partial-night sleep study. The diagnostic portion of the study revealed severe obstructive sleep apnea. Unfortunately, the patient had difficulty tolerating nasal CPAP. He slept poorly and did not achieve REM sleep or much supine sleep on CPAP. He was reluctant to undergo another sleep study because he found the monitoring leads to be very uncomfortable. Other treatment alternatives were discussed with the patient, but he did not want either surgery or an oral appliance. An autotitration study at home was ordered. Figure: Below is a single-night profile of pressure, leak, and events detected by the machine. In the bottom tracing, left axis = duration of each apnea (vertical line with ball on top); right axis = AHI.
Question:
What treatment do you recommend?
PRESSURE
cmH20 10
----------- ~- ----- - -----~ --- - --- - - - - ~ ------ - - -- - -;- ---- ------- ~ --- - - . --- -- -:- - - - - - - - - - - I
0.8
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I
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I/sec
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APNEA EVENTS DURATION + Alii
60
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,
:
:
:
,
I
,
,
.,
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160
, ,
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,
,
Answer:
Treatment with fixed CPAP at 9-10 em H 20 .
Discussion: The need for retitration of CPAP is a frequently encountered problem in sleep medicine. The causes include a suboptimal initial titration or the return of excessive daytime sleepiness in a patient initially treated successfully with CPAP. The ideal CPAP titration is one that demonstrates elimination of apnea, hypopnea, arterial oxygen desaturation, and respiratory effort-related arousals in all body positions and sleep stages. However, this ideal is frequently not attained-especially with partialnight sleep studies. While an attended positive-pressure titration in a sleep laboratory is the standard of care, patients in some communities may not have convenient access to a sleep laboratory, or the wait for a traditional study may be several months. Autotitrating CPAP (APAP) may provide an answer for many such patients. APAP units differ in the respiratory variables that are targeted (apnea, hypopnea, snoring, airflow limitation, impedance) or in the algorithms used to determine pressure increases or decreases. Usually pressure is slowly increased until targets such as apnea, hypopnea, or snoring are eliminated. The machines then slowly decrease pressure until events are again noted. Using this approach, the lowest pressure needed for a given situation is administered. Most units have a memory and it is possible to transfer stored information to a computer for analysis. Nearly all devices give information about the amount of time spent at various pressures during one or more nights. Many also provide a profile of individual nights with leak, pressure. and residual event information. The physician can review the pressure information and select a single pressure for fixed CPAP treatment with a conventional CPAP unit. Typically either the P90 or P95 (90 or 95 th percentile pressure) is selected. These are the pressures exceeded only 10% or 5% of the time. Some devices include software that automatically eliminates periods of high leak for this analysis. The reviewer can also judge if an adequate titration was effected.
Of note, the AHI is really an index based on machine time at pressure, as the machine cannot determine whether the patient was really asleep. The machines also cannot differentitate between central and obstructive apnea. The former may not be improved by increases in CPAP. Some machines handle this problem by not increasing above a certain pressure for apneas not accompanied by snoring or airflow flattening. Most studies of APAP titrations excluded patients with frequent central apneas or those likely to have this problem (congestive heart failure). The literature documents the efficacy of attended APAP titrations. In such studies, the technologist could intervene for high mask leaks. This is important, as leaks may mimic events and prevent adequate titrations, There is less information about unattended APAP titrations. However, such titrations are certainly possible if proper patient training and mask fitting are performed. On the basis of current literature, patients likely to have central sleep apnea (congestive heart failure) or those likely to require oxygen (patients with COPD or low awake SaO,) are not ideal candidates for unattended titratiton, Unattended APAP titrations are usually not reimbursed. but many home healthcare companies may be willing to provide the service if CPAP units will ultimately be purchased from them. The present patient underwent an autotitration study at home for 5 days. A summary of the data for the entire period of time is shown below. Note that a leak over 0.4 Llsec is considered high for the device used. You cannot assess whether supine or REM sleep was obtained on the basis of the supplied data. However, 5 nights of monitoring should give a reasonable mix of all body positions and sleep stages. The auto-titration seemed acceptable, and the patient was started on 10 em H 20 (P95) using a traditional CPAP device. His wife reported that he never snored while using CPAP.
Auto-Titration Study in Present Patient Days monitored:
5
Maximum leak:
0.8 Llsec
Minimum pressure limit (cm H 20 ):
5
Median leak:
0.15 Llsec
Maximum pressure limit (ern H 20 ): Maximum pressure (ern H 20 ):
15
Average use:
5 hr 20 min
12
AHI:
5.6/hr
P95 (ern H 20 ):
10.1
161
Clinical Pearls 1. Auto-titrating CPAP can be used in the unattended setting to help select an optimal fixed pressure for CPAP treatment. 2. Judicious patient selection, adequate mask fit, and patient training are needed to increase the likelihood of a good result. 3. The physician should verify from the machine data that an adequate auto-titration was effected (reasonable leak, low overall AHI, good compliance). Simply accepting one computer generated number (P95) is not sufficient. 4. Patients with significant lung disease, significant central apnea, or congestive heart failure are not good candidates for unattended auto-titration. 5. If auto-titration fails, a traditional (attended in laboratory) CPAP titration should be ordered.
REFERENCES I. Stradling J. et al: Automatic nasal CPAP in the laboratory: Patient outcomes. Thorax 1997;52:72-75. 2. Teschler H. Berthon-Jones M: Intelligent CPAP systems: Clinical experience Thorax I998;53:S49-54. 3. Fletcher EC. et al: Unattended home diagnosis and treatment of obstructive sleep apnea without polysomnography. Arch Fam Med 2000;9: 168-174. 4. Series F: Accuracy of unattended home CPAP titration in the treatment of obstructive sleep apnea. Am J Resp Crit Care Med. 2000;162:94-97. 5. Berry RB. Parish JM. Hartse KM: The use of auto-titrating CPAP for treatment of adults with obstructive sleep apnea. An American Academy of Sleep Medicine Review. Sleep 2002;25: 148-173. 6. Littner J. Hirshkowitz M. Davila D. et al: Practice parameters for the use of auto-titrating continuous positive airway pressure devices for titrating pressures and treating adult patients with obstructive sleep apnea syndrome. Sleep 2002;25: 143-147.
162
PATIENT 47 A 55-year-old obese man with desaturation during a nasal CPAP trial A 55-year-old, very obese man was suspected of having severe obstructive sleep apnea. He underwent a partial-night study, and an AHI of 80/hr was noted during the initial 2-hour diagnostic portion (CPAP = 0). The patient underwent a nasal CPAP titration. At 16 em Hp, apnea and hypopnea were absent, and repetitive arousals did not occur. The arterial oxygen saturation was slightly reduced (to approximately 92%). However, further increases in the level of CPAP produced mask leaks and were not tolerated by the patient. Subsequently, moderate arterial oxygen desaturation developed, despite uninterrupted sleep and no apnea or hypopnea. Figure: Tracing on nasal CPAP at 16 ern H20 .
Question:
What is occurring?
C
a
4 -
2-
A A
1
1
ROC-A 1 LaC - A 2 chin EMG
CPAP flow Chest Abdomen SaO 2
80%
5 sec FIGURE
1
163
Answer:
This is an episode of nonapneic hypoventilation in REM sleep exacerbated by REM re-
bound.
Discussion: Early in the clinical use of nasal CPAP in patients with severe OSA, it was appreciated that periods of hypoventilation and desaturation could occur during REM sleep despite a patent upper airway. The first night the upper airway is stabilized, long periods of REM sleep (REM rebound) and high REM density can occur in some patients. These features of REM rebound occur because the patient has been REM-deprived as a consequence of repeated arousals. Thus, prevention of upper airway obstruction prevents arousal-despite the presence of severe hypoxia and hypercapnia. This fact demonstrates that stimuli involved with airway obstruction (inspiratory effort rather than simply hypoxia/hypercapnia) playa significant role in the arousal process. Deterioration in gas exchange during REM periods with a high REM density represents an exaggeration of normal changes that occur in ventilation during REM sleep. In normal individuals, tidal volume falls during bursts of eye movements in REM sleep because of associated reductions in phrenic nerve activity (less diaphragmatic activity) and loss of intercostal muscle respiratory pump function (REM-associated skeletal muscle hypotonia). Periods of REM sleep with the most eye movements are associated with the greatest changes in ventilation. Obese patients with a large mechanical load on the respiratory pump and/or daytime hypoxia and hypercapnia may develop significant hypoventilation and hypoxia during these periods of high REM density. The failure to arouse despite severe hypoxemia is probably secondary to an increased arousal threshold (prior sleep fragmentation) and the lack of stimuli associated with increased respiratory effort during apnea (the airway is patent on CPAP). There are limited treatment options for these REM-rebound-associated periods of severe desaturation. A further increase in CPAP pressure can be attempted, but it may not be tolerated by the patient, or it may be associated with increased mask
164
leaking. Another option is to add supplemental oxygen to the nasal CPAP treatment. The oxygen flow is titrated to obtain an SaO? > 85-90%. Alternatively, bilevel pressure support may be a solution. Unfortunately, in some patients with severe OSA the expiratory positive airway pressure (EPAP) may have to be quite high (e.g., 18 cm H,O) to maintain upper airway patency. The maximum IPAP is limited to 20 ern H 20 on many machines, which reduces the amount of pressure support (IPAP-EPAP) that can be provided. While some machines can deliver up to 30 em H 20, pressures over 20 cm H 20 are rarely tolerated by patients and make obtaining an adequate mask seal difficult. Finally, volume-cycled ventilation via nasal or full face mask can be attempted. This has been reported to work in patients with severe hypercapnia and OSA. Fortunately, after several days of treatment, respiration during REM sleep on nasal CPAP usually improves. The reduction in REM rebound may reduce the REM density, and baseline gas exchange (daytime and sleeping PC0 2) may improve in hypercapnic patients. For example, there is a parallel shift of the ventilatory response curve to PCO, to the left during wakefulness (higher ventilation at the same PC0 2 ) after days to weeks of CPAP treatment. Thus, patients started on both nasal CPAP and oxygen may no longer need the oxygen after several weeks of treatment. In the present case, Figure I shows a high REM density and a low Sa0 2 despite regular airflow. Figure 2 shows a plot of Sa0 2 during the diagnostic and CPAP = 16 em Hp portions of the study. Note that with the onset of REM sleep on CPAP, desaturation occurred until supplemental oxygen was added at 2 Umin. The patient was discharged on nasal CPAP and 2 Umin oxygen via the nasal mask at night. After 2 months, a repeat sleep study showed adequate nocturnal saturations (> 88%) during REM sleep using only nasal CPAP.
CPAP = 0
50°2 (%)
CPAP =16
95 90 85 80
------
75
------
70
------
-------
-b-:-1REM - - -- - - --
------
8
60 min ( )
REM FIGURE
2
Clinical Pearls I. During initial nasal CPAP treatment of some patients with GSA, there may be a dramatic REM rebound associated with long periods of REM sleep with a high REM density. 2. Severe hypoxemia and hypercapnia may be associated with REM periods during initial CPAP treatment-despite maintenance of upper airway patency. This is especially common in patients with severe GSA who have significant obesity and/or daytime hypercapnia or hypoxemia. 3. Treatment of these episodes may require the addition of supplemental oxygen, a switch to bilevel pressure, or, in extreme cases, volume-cycled positive-pressure ventilation via nasal (or full face) mask.
REFERENCES I. Krieger J. Weitzenblum E. Monassier JP. et al: Dangerous hypoxemia during continuous positive airway pressure treatment of obstructive sleep apnea. Lancet 1983; 2: 1429-1430. 2. Gould GA. Gugger M. Molloy J. et al: Breathing pattern and eye movement density during REM sleep in humans. Am Rev Respir Dis 1988: 138:874-877. 3. Waldhorn RE: Nocturnal nasal intermittent positive pressure ventilation with bi-Ievel pressure in respiratory failure. Chest 1992; 101:516-521. 4. Piper AJ. Sullivan CE: Effects of short-term NIPPY in the treatment of patients with severe obstructive sleep apnea and hypercapnia. Chest 1994; 105:434-440.
165
PATIENT 48 A 30-year-old woman with fatigue and mild daytime sleepiness A 30-year-old woman complained of fatigue and mild daytime sleepiness of 2-year duration. Her general internist was unable to find an explanation for her fatigue. The patient's Epworth Sleepiness Scale score is 14/24 (mild sleepiness). Her husband reported that she snored heavily, especially in the supine position. She had gained 20 pounds over the last 2 years. The diagnosis is determined to be mild-to-moderate obstructive sleep apnea. Nasal CPAP titration is recommended to the patient, but she refuses this treatment. Physical Examination: Height 5 feet 3 inches, weight 135 pounds. HEENT: dependent palate, long edematous uvula, tongue normal, prominent pharyngeal tonsils, dentition poor; 14-inch neck circumference. Chest: clear. Cardiac: normal. Extremities: trace edema. Laboratory Findings: CBC and thyroid studies: normal.
Sleep Study AHI Supine Lateral decubitus
Question:
25/hr 40/hr 5/hr
35/hr O/hr
Which of the treatment options shown below would you recommend?
Option A
Option B
166
Arousal index PLM index
Answer: Option B (uvulopalatopharyngoplasty), rather than option A (laser-assisted palatoplasty or uvulopalatoplasty), is the recommended procedure for OSA. Discussion: Uvulopalatopharyngoplasty (UPPP) is an operation that removes residual tonsillar tissue, the uvula, a portion of the soft palate, and redundant tissue from the pharyngeal area. Its disadvantages include the need for general anesthesia and considerable postoperative pain. The most frequent complication is velopharyngeal insufficiency, which is manifested as some degree of nasal reflux when drinking fluids. This usually resolves within a month of surgery. Other potential complications include voice change, postoperative bleeding, and nasopharyngeal stenosis (secondary to scarring). A few cases of severe postsurgical bleeding or upper airway obstruction requiring reintubation have been reported. It is prudent to admit patients to the intensive care unit after surgery for close observation if severe OSA is present. Significant apnea and desaturation can occur during the recovery period in patients with severe obstructive sleep apnea (OSA). These problems often can be managed with nasal CPAP. However, the major problem with UPPP is lessthan-perfect efficacy as a treatment for OSA. UPPP does not address airway narrowing behind the tongue or in the hypopharynx; therefore, it is not universally effective in preventing sleep apnea. It is much more effective in decreasing the incidence or loudness of snoring (vibration of the soft palate). In general, 40-50% of all patients undergoing UPPP have about a 50% decrease in their AHI, to less than 20/hour. Frequently, the number of apneas decreases, and the number of hypopneas increases. One study reported that a significant number of initial responders to UPPP may later relapse, especially if there is weight gain. Thus, patients treated with UPPP should be restudied if symptoms or signs of sleep apnea return. Several methods have been studied to determine if responders can be identified preoperatively. These methods include cephalometric radiographs, computerized axial tomography, fluoroscopy, fiber optic endoscopy of the upper airway during Mueller maneuvers (precipitating airway collapse), and upper airway pressure monitoring during sleep. In some of these methods the patient is upright, and in most the patient is awake; therefore, it is not surprising that predictions of what happens during sleep are less than perfect. Patients with obstruction only in the palatal area are the most likely to respond to UPPP. However, no method can predict with certainty which patients will benefit from this surgery. Interestingly, a few studies have determined that the site of greatest upper airway narrowing in UPPP failures is the retropalatal area.
Presumably, postsurgical changes secondary to either palatal edema or scarring are to blame. Laser-assisted palatoplasty or uvulopalatoplasty (LAP or LAUP) was introduced recently as a treatment for snoring. In this procedure only a small portion of the uvula/soft palate is removed. Usually two trenches on either side of the uvula are cut. Some also remove the end of the uvula. With time and scarring, the palate stiffens and elevates. This procedure can be done on an outpatient basis using local anesthesia. It is generally considered a treatment for snoring, but has been used for the upper airway resistance syndrome (UARS) and milder cases of sleep apnea when suitable upper airway anatomy exists. The long-term efficacy of LAP remains to be established. The standard of practice committee of the Amercian Academy of Sleep Medicine was unable to recommend this procedure for sleep apnea based on the current published evidence. Somnoplasty (radiofrequency energy ablation), another relatively new outpatient method of palatoplasty for treatment of snoring (and possibly UARS), appears to be well tolerated (possibly less pain), but is no more effective than traditional UPPP. Repeated treatments may be needed. Several other procedures that utilize cautery or injection of sclerotic agents to stiffen the palate have also been tried. UPPP is considered less effective than nasal CPAP because it is less likely to eliminate apnea and normalize sleep. However, when nasal CPAP is refused or not tolerated, UPPP can be a treatment alternative-especially in mild-to-moderate apnea. With disease of this severity, there usually is a reasonable chance of obtaining a postoperative AHI less than 15/hr. If UPPP fails, there is always the option of again trying nasal CPAP. However, one study suggested that when nasal CPAP is used after UPPP, air leak via the mouth may be more likely. The present patient had mild-to-moderate sleep apnea, and she refused a trial of nasal CPAP. Weight loss may dramatically reduce the severity of apnea in this patient, but weight loss is difficult to achieve and even more difficult to maintain. Oral appliances are an option (see Patients 51 and 52). However, the patient had poor teeth. When she performed an inspiratory maneuver with the mouth closed and nose blocked, nasopharyngoscopy revealed collapse mainly in the retropalatal area; thus, the patient was considered a reasonable candidate for UPPP. A polysomnogram 3 months after UPPP showed an AHI lO/hr with an arousal index of 15/hr. The patient reported a great improvement in symptoms. Attempts at weight loss continued to be unsuccessful. 167
Clinical Pearls I. UPPP has roughly a 40-50% chance of reducing the AHI by 50%, to less than 20/hr. 2. Patients with obstruction only in the retropalatal area are more likely to respond to UPPP. 3. LAUP is a treatment for snoring, but is generally not recommended for OSA. 4. Because subjective improvement often exceeds the objective response after UPPP, a polysomnogram three to four months after surgery is needed to document efficacy in all but the mildest cases. 5. An experienced surgeon and careful monitoring during the postoperative period are essential to reduce immediate complications of this procedure. 6. A significant number of initial responders to UPPP may relapse, especially if weight gain occurs. Patients should be restudied if signs or symptoms of sleep apnea return.
REFERENCES I. Hudgel DW. Harasick T. Katz RL. et al: Uvulopalatopharyngoplasty in obstructive apnea: Value of preoperative localization of site of upper airway narrowing during sleep. Am Rev Respir Dis 1991; 143:942-946. 2. Launois SH. Feroah TR. Campbell WN. et al: Site of pharyngeal narrowing predicts outcome of surgery for obstructive sleep apnea. Am Rev Respir Dis 1993;147: 182-189. 3. Larsson LH. Carlsson-Norlander B. Svanborg E: Four year follow-up after uvulopalatopharynoplasty in 50 unselected patients with obstructive sleep apnea syndrome. Laryngoscope 1994; 104: 1362-1368. 4. American Sleep Disorders Association. Standards of Practice Committee: Practice parameters for the treatment of obstructive sleep apnea in adults: The efficacy of surgical modifications of the upper airway. Sleep 1996; 19: 152-155. 5. Sher AE. Schechtman KB. Piccirillo JF: The efficacy of surgical modifications of the upper airway in adults with obstructive sleep apnea syndrome. Sleep 1996; 19: 156-177. 6. Powell NB. Riley RW. Troell RJ, et al: Radiofrequency volumetric tissue reduction of the palate in subjects with sleep-disordered breathing. Chest 1998; 113: 1163-1174. 7. Littner M, Kushida CA, Hartse K. et al: Practice parameters for the use of laser-assisted uvulopalatoplasty. Sleep 200 1;245:603-619.
168
PATIENT 49 A 50-year-old man with a return of snoring 6 months after uvulopalatopharyngoplasty A 50-year-old man underwent uvulopalatopharyngoplasty (UPPP) as treatment for severe snoring. A sleep study presurgery showed an AHI of 10/hr, but the patient denied any symptoms of excessive daytime sleepiness. After surgery, the patient initially reported a considerable decrease in the loudness of his snoring. However, over the next 4 months he began to feel increasingly sleepy during the day. He also reported a sore throat and problems breathing through his nose. His wife stated that his snoring had returned and that she noticed some periods of time when he did not breathe followed by "gasping for air." Physical Examination: Vital signs: normal. HEENT: see figure. Note the patient's palatal area (A) and a more typical UPPP result (B).
Sleep Study
Total sleep time AHI Type of events Obstructive/mixed apnea Central apnea Hypopnea
Question:
A
Before UPPP
After UPPP
420 min 10/hr
430 min 50/hr
10
60
90
40
o
o
What is causing the worsening symptoms after UPPP?
B
169
Diagnosis:
Nasopharyngeal stenosis has worsened the patient's sleep apnea.
Discussion: It appears that patients with upper airway narrowing localized to the retropalatal area have the best results with UPPP. Thus, in patients for whom UPPP has failed, the most prominent areas of obstruction would be expected in the hypopharynx. A few studies have found, however, that the most common major site of narrowing postsurgery in failed UPPP cases is still the retropalatal area. This recurrence of narrowing may be secondary to edema-swelling of the palatal edge at the surgical site. A less common but severe complication of UPPP is the formation of nasopharyngeal inlet stenosis, which can markedly worsen airway obstruction during sleep. The time it takes for stenosis to develop is variable. Causes are believed to include technique (e.g., simultaneous adenoidectomy, excessive removal of the posterior tonsillar pillars), scarring in keloid-forming patients, wound dehiscence, wound infection, or treatment of postsurgical bleeding with electrocautery. The best way to treat this problem is
unclear. However, repair with a CO 2 laser has been reported. The laser causes less damage to deeper tissues and hopefully less chance of repeat scarring. One aspect of UPPP sometimes overlooked is that postoperative pain can be quite intense (see table). Patients should be warned of this prior to surgery. Velopharyngeal incompetence usually is a self-limited problem (resolves in a few months). There also may be a change in the voice (especially the singing voice). The delayed complications are return of snoring and return or worsening of sleep apnea. A worsening of OSA has been reported after both UPPP and LAUP. The present patient was referred to an ENT surgeon for evaluation. Treatment was performed with a CO? laser, and the involved area partially opened. At 3 months the patient's symptoms of sleepiness had improved, and a repeat sleep study showed a reduction of the AHI to 20/hr (still worse than presurgery). The patient has declined treatment with nasal CPAP or oral appliances.
Complications From UPPP IMMEDIATE
DELAYED
Pain-can be severe Velopharyngeal incompetence (fluid out nose during swallowing) Voice change Globus sensation - "mucus in back of throat" Worsening of apnea in postoperative period
Return of snoring Worsening of OSA Nasopharyngeal stenosis
Clinical Pearls 1. The severity of obstructive sleep apnea can worsen after UPPP. Close follow-up by both the surgeon and the sleep specialist is essential. 2. Nasopharyngeal inlet stenosis is a rare but severe complication of UPPP. Recurrence of retropalatal narrowing probably is a more common problem.
REFERENCES I. Shepard JW Jr, Thawley SE: Evaluation of the upper airway by computerized tomography in patients undergoing uvulopalatopharyngoplasty for obstructive sleep apnea. Am Rev Respir Dis 1989; 140:711-716. 2. Fairbanks DNF: Uvulopalatopharyngoplasty complications and avoidance strategies. Otolaryngol Head Neck Surg 1990; 102:239-245. 3. Van Duyne J, Coleman JA: Treatment of nasopharyngeal Inlet stenosis following uvulopalatopharyngoplasty with CO 2 laser. Laryngoscope 1995; 105:914-918. 4. Ryan CF. Love LL: Unpredicatable results of laser assisted uvulopalatoplasty in the treatment of obstructive sleep apnea. Thorax 2000; 55:399--404. 5. Sasse SA. Mahutte CK, Dickel M. Berry RB: The characteristics of five patients with obstructive sleep apnea whose apnea-hypopnea index deteriorated after uvulopalatopharygoplasty. Sleep Breath 2002;6:77-84.
170
PATIENT 50 A 55-year-old man with severe daytime sleepiness and limited treatment options A 55-year-old man was referred for severe daytime sleepiness of at least 3-year duration (Epworth Sleepiness Scale score 22/24-severe). He had been previously evaluated and found to have severe obstructive sleep apnea (OSA). At that time he was started on nasal CPAP and (later) bilevel pressure, but he could not tolerate these treatments. The patient subsequently underwent a uvulopalatopharyngoplasty (UPPP), with limited improvement in his symptoms. He was unable to lose weight, but did discontinue drinking alcohol. He was treated with an oral device, but found this very uncomfortable despite many adjustments. He fell asleep at work and was passed over for promotion. His driver's license had been suspended after two sleep-associated traffic accidents. Physical Examination: Height 5 feet 8 inches, weight 220 pounds. HEENT: large tongue, wellhealed palatal defect; mild retrognathia; short neck, 18-inch circumference. Chest: clear. Cardiac: distant heart sounds. Extremities: I + pedal edema. Neurologic: patient asleep in the waiting room. Sleep Study (post UPPP): AHI 80/hr, no position dependence. Type of events: mixed/obstructive apnea 50%, central apnea 5%, hypopnea 45%. Arterial oxygen saturation: 200 desaturations, minimum Sa0 2 = 75%. Cardiac: sinus arrhythmia rare premature ventricular contractions.
Question:
What treatment do you recommend?
171
Answer:
Trachesotomy or complex upper airway surgery is recommended.
Discussion: Patients with severe sleep apnea who do not tolerate nasal CPAP are a difficult problem for the sleep physician. UPPP may be tried, but it has only a 40-50% chance of reducing the AHI by 50%. Thus, many patients with severe OSA will continue to have an AHI > 20/hr after UPPP. Weight loss can be prescribed, but this treatment takes time, and successful maintenance of weight loss is uncommon. Some patients with severe OSA will respond to treatment with an oral appliance. However, for many patients with severe OSA, treatment options beyond nasal CPAP are limited to tracheostomy or upper airway surgery more complex than a UPPP. Tracheostomy is a highly effective treatment for OSA. However, it is cosmetically unacceptable to many patients. The indications used in one large series included: (1) disabling sleepiness with severe consequences, (2) cardiac arrhythmias with sleep apnea, (3) cor pulmonale, (4) AHI > 40/hr, (5) frequent desaturations below 40%, and (6) no improvement after other therapy. Today this treatment is usually reserved for patients with the obesity hypoventilation syndrome/recurrent hypercapnic respiratory failure who are not adherent to CPAP or bilevel therapy. Tracheostomy also may be used for perioperative airway protection in selected cases for patients undergoing upper airway surgery. A non-cuffed 6 French tube usually suffices for treatment of obstructive sleep apnea.
Tracheostomy has significant complications in patients with OSA. For example, anesthesia and intubation tend to be more difficult. Postoperative complications include stoma infection/granulation tissue, accidental decannulation, obstruction of the tube when the head is turned or hyperextended, recurrent purulent bronchitis, and psychosocial difficulties (depression). A longer-than-usual tracheostomy tube may be needed for very obese patients with thick necks. The end of the tracheostomy tube typically is plugged during the day and, because of its small size, air flows around it between the lungs and the upper airway. If resistance to flow around the tube is a problem, a fenestrated tube (hole at bend of the superior end of the tube) can be used. During sleep, the tracheostomy tube is unplugged to bypass the upper airway obstruction. However, note that very obese patients can still occlude the tracheostomy opening with "triple chins." Because of the ineffectiveness of UPPP in many patients with OSA and the morbidity involved with tracheostomy, new procedures to target retroglossal and hypopharyngeal obstruction have been developed. A systematic surgical approach is advocated, such as the one used at Stanford University (Fig. I). Patients are first classified, according to site of obstruction, by use of fiberoptic pharyngoscopy and lateral cephalometric radiographs. Pharyngo-
Presurgical Evaluation (Physical Examination, Cephalometric analysis, Fiberoptic phoryngoscopy)
-+
+
UPPP
(Type 1 - retropalatalj
L
Phase I (Site of obstruction)
+
\1,
UPPP +GAHM
GAHM
(Type 2 - retropalatal-hypopharynx)
(Type 3-hypopharynx)
!
Post-operative PSG (6 mol (Failure)
..
-+
Phase II MMO FIGURE I. Stanford two-phase protocol. GAHM = Genioglossus Advancement with Hyoid Myotomy MMO = Maxillary-Mandibular Osteotomy
172
scopy with the MUller manuever (inspiration with the nose occluded) shows collapse at the retropalatal or retroglossal/hypopharyngeal area. On cephalometrics, OSA patients tend to have long, soft palates; small posterior air spaces « 10 mm behind the tongue); mandibular deficiency; and a long distance to the hyoid. A Type 1 obstruction is at the retropalatal area. Type 3 is at the hypopharyngeal area (behind the tongue or lower). Type 2 is a combined obstruction (palatal + hypopharynx). Type I patients are ideal candidates for UPPP. Type 3 are candidates for genioglossus advancement (GA), with or without hyoid myotomy (UM). Type 2 patients are candidates for combined UPPP and GAUM. A postoperative polysomnogram is performed in 6 months, and treatment failures are then offered maxillary mandibular osteotomy (MMO), also called MMO with advancement (MMA). Because an occasional patient with type 2 obstruction will improve with UPPP, in some centers a retrolingual procedure is added only after UPPP fails. In some other centers, patients with severe mandibular deficiency or very small posterior airspaces are offered UPPP + MMO as the first procedure, or MMO after UPPP fails. In the genioglossus advancement (GA; Fig. 2) procedure, the attachment of the genioglossus at the geniotubercle of the mandible is advanced by making a limited rectangular mandibular osteotomy to include the geniotubercle (site of attachment of genioglossus and geniohyoid on the mandible). The rectangular piece of bone with muscular attachments is advanced and rotated to prevent retraction back into the mouth. When initially introduced, the second component of the surgery - hyoid myotomy (HM) with suspension-consisted of a release of the hyoid from its inferior muscular attachments and suspension from the anterior mandible. Today, the hyoid is often attached to the superior border of the thyroid cartilage. This modification has increased the response rate to around 80%. Some sur-
geons perform only the GA at the first surgery, with the HM performed only if needed at a subsequent operation. The GAHM does not require any change in dental occlusion. Complications of GAHM include transient anesthesia of the lower anterior teeth (all) and, rarely, tooth injury. The next level of complexity is maxillomandibular osteotomy and advancement (Fig. 3). The maxilla and mandible are advanced together, and both upper and lower teeth are moved to maintain occlusion. The procedure increases the retrolingual and, to a small extent, the retropalatal segments of the upper airway. The maxilla is moved by a Le Fort I osteotomy and the mandible by a sagittal-split osteotomy. Numbness of the chin and cheek areas is an expected complication that resolves in 6-12 months in most patients. In some institutions, MMO is performed only after UPPP and GAHM (whether performed simultaneously or sequentially) fails. In others, MMO + adjunctive procedures is the first surgery offered, especially in patients with facial-skeletal deficiency who are healthy enough to undergo the more extensive procedure. Response rates up to 90% have been published. Obviously, GAHM and MMO should be done by maxillofacial surgeons with considerable experience in these operations. Such procedures are usually available only at large tertiary-referral hospitals. In an attempt to avoid surgery involving the mandible or maxilla, procedures directed at the tongue have also been developed. Laser midline glossectomy (LMG) and lingualplasty (LP) increase the retroglossal airway by removing tongue tissue. UPPP + LP appears to be the most effective. Postoperative bleeding and odynophagia are potential complications. Recently, temperature-controlled radiofrequency tongue base reduction has also been attempted. This procedure can be performed on an outpatient basis. An initial study showed good success, but one patient developed a tongue base ab-
Genioglossus Advancement FIGURE
Hyoid myotomy and suspension 2
173
Maxillary Mandibular Osteotomy (MMO) FIGURE
3
scess. The long-term efficacy remains to be established. The present patient had persistent, disabling daytime sleepiness and moderate-to-severe oxygen desaturations after UPPP. When presented with the options of tracheostomy or more complex upper airway surgery, he chose the latter. He was evaluated with cephalometric radiographs and fiberoptic pharyngoscopy and found to have a very small posterior airspace and evidence of mandibular deficiency. The options of trying GAHM first or proceeding directly to MMO were discussed with the patient. He very much wanted only one surgery, and an MMO was performed. A sleep study performed 6 months after surgery revealed an AHI of 9/hr overall with minimal drops in the Sa0 2. The patient's Epworth score was reduced to 12/hr (mild sleepiness). His performance at work improved, and he was quite satisfied with treatment.
Clinical Pearls I. The most reliable treatment for severe OSA in patients refusing or not tolerating nasal CP AP is tracheostomy. 2. Unless upper airway obstruction is localized to the retropalatal area, UPPP alone often is ineffective in severe OSA. 3. GA or GAHM may increase the effectiveness of UPPP by preventing obstruction in the retroglossal/hypopharyngeal region. 4. MMO is an extensive procedure available only in a few specialized centers but can be effective in severe OSA patients who have failed UPPP or UPPP + GAHM.
REFERENCES I. Guilleminault C. Simmons B. Motta J, et al: Obstructive sleep apnea syndrome and tracheostomy. Arch Intern Med 1981; 141:985-988. 2. Riley RW, Powell NB, Guilleminault C: Obstructive sleep apnea and the hyoid: A revised surgical procedure. Otolaryngol Head NeckSurg 1994; 111:717-721. 3. American Sleep Disorders Association: Practice parameters for the treatment of obstructive sleep apnea in adults: The efficacy of surgical modifications of the upper airway. Sleep 1996; 19:I52-155. 4. Sher AE. Schechtman KB, Piccirillo JF: The efficacy of surgical modifications of the upper airway in adults with obstructive sleep apnea syndrome. Sleep 1996; 19: 156-177. 5. Li KK, Powell NB, Riley RW: Surgical managment of obstructive sleep apea. In Lee-Chiong TL, Sateia MJ, Caraskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002, pp 435--446.
174
PATIENT 51 A 40-year-old man with sleep apnea unable to tolerate nasal CPAP A 40-year-old man was evaluated for complaints of loud snoring and daytime sleepiness. Although he was able to function fairly well, he sometimes fell asleep in large business meetings. His work required him to travel frequently. The patient reported only occasional ethanol use. He had lost 15 pounds on a diet, which improved his snoring and sleepiness somewhat. After examination, the diagnosis is determined to be mild-to-moderate sleep apnea. The patient had read extensively about sleep apnea and wanted to avoid nasal CPAP if possible. He was recently divorced and feared use of this device would impair his social life. In addition, he wanted to avoid surgery if possible. Physical Examination: Height 5 feet 10 inches, weight 220 pounds. Blood pressure: normal. HEENT: slight retrognathia, palate edematous but otherwise normal; 16-inch neck circumference. Cardiac: normal. Extremities: no edema. Sleep Study: AHI 30/hr, PLM index O/hr.
Question:
What treatment option is illustrated below?
175
Answer:
An oral appliance.
Discussion: Oral appliances can be effective treatment in patients with snoring or mild-tomoderate obstructive sleep apnea (OSA). Some patients with severe apnea also will respond. The importance of oral appliances for treatment of OSA is highlighted by the establishment of the American Academy of Dental Sleep Medicine. Oral appliances work either by retaining the tongue in a forward position (tongue-retaining device), or by moving the mandible forward and thereby indirectly moving the tongue (mandibular-advancing device). Patients with a posteriorly placed mandible might be expected to improve the most. However, the amount of forward movement of the tongue (supine position) probably is the most critical element in determining effectiveness. Many types of oral appliances are available. The effectiveness of several has been confirmed by welldesigned studies. The tongue-retaining devices secure the tongue in a forward position by holding the tongue tip in a soft bulb (with negative pressure). The bulb is held anterior to the lips and teeth by a flange on the mouthpiece behind the bulb portion of the device. Most dental devices require fitting by a trained dentist to obtain the dental impression and bite registration, and the device is fabricated in a dental laboratory. A few devices composed ofthermolabile material can be molded to the patient's teeth in the office ("boil and bite"). However, the involvement of a dentist is recommended because if the mandible is moved too far forward, temporomandibular joint (TMJ) problems can occur. With careful fitting of oral appliances, TMJ problems should not be common. However, these devices generally are not recommended for patients with preexisting TMJ problems.
Oral devices frequently induce excess salivation, at least initially, as well as some mild discomfort in the morning. Thus, adherence to treatment is a problem with oral devices as with nasal CPAP. Studies in which both nasal CPAP and oral appliances were effective have revealed that many patients prefer treatment with an oral appliance. Unlike nasal CPAP, a sleep study is not needed for initial titration. The patient is begun on a conservative amount of advancement, which is usually increased slowly over several weeks until the desired result is obtained (e.g., no snoring). Once the device has been optimally adjusted, a sleep study is recommended for those with moderate or severe OSA to ensure effectiveness. Rarely, oral appliances worsen the severity of sleep apnea. The patient should be followed by a dentist to ensure that TMJ or occlusion problems do not develop. There is some preliminary evidence that oral appliances may induce some shift in the dentition after 3-5 years of use. In the present case, nasal CP AP would be effective but was not acceptable to the patient. Other suitable treatment options included uvulopalatopharyngoplasty and other types of upper airway surgery, or oral appliances. Respecting the patient's wish to avoid surgery if possible, he was referred to a dentist experienced in making oral appliances. An impression of the patient's teeth was made; a bite registration was taken; and a dental laboratory prepared a Herbst device. This device allows forward movement of the jaw. It is attached to the teeth on both maxilla and mandible and is unlikely to fall out during the night. The patient reported reduction in both his snoring and amount of daytime sleepiness, and planned to continue a weight-loss program.
Clinical Pearls I. An oral appliance can be effective treatment in mild-to-moderate OSA. 2. Some patients with severe OSA will also have a good response to oral appliances. 3. Patients with TMJ problems are poor candidates for oral appliances. 4. Involvement of a dentist is crucial in preventing complications of oral appliances. 5. A sleep study is recommended for patients with moderate to severe OSA who are using an oral appliance, once stabilization is achieved. A study is also indicated in patients with milder OSA who do not experience improved symptoms.
176
REFERENCES I. American Sleep Disorders Association: Practice parameters for the treatment of snoring and obstructive sleep apnea with oral appliances. Sleep 1995; 18:511-513. 2. Schmidt-Nowara W, Lowe A. Wiegand L. et at: Oral appliances for the treatment of snoring and obstructive sleep apnea: A review. Sleep 1995; 18:501-510. 3. Ferguson KA. Ono T, Lowe AA. et al: A randomized crossover study of an oral appliance vs nasal-continuous positive airway pressure in the treatment of mild-moderate obstructive sleep apnea Chest 1996; 109: 1269-1275. 4. Henke KG. Frantz DE. Kuna ST: An oral elastic mandibular advancement device for obstructive sleep apnea. Am J Respir Crit Care Med 2000; 161:420-425. 5. Lowe AA: Oral appliances for sleep breathing disorders. In Kryger M, Roth T, Dement W (eds): Principles and Practice of Sleep Medicine, 3rd edition. Philadelphia, WB Saunders Co, 2000, pp 929-939.
177
PATIENT 52 A 45-year-old man still experiencing daytime sleepiness after uvulopalatopharyngoplasty A 45-year-old man was diagnosed with severe sleep apnea (AHI 60/hr). He underwent a nasal CPAP titration, but did not tolerate this treatment. After several treatment options were discussed, the patient decided to have uvulopalatopharyngoplasty (UPPP). Postoperatively, the patient initially noted improvement in snoring and daytime sleepiness. However, 4 months after the UPPP he began to experience increased symptoms of daytime sleepiness and fatigue. The patient admitted that he had gained about 20 pounds since surgery. A repeat sleep study was ordered. Physical Examination: Blood pressure 160/90, pulse 88, respirations 16. HEENT: well-healed UPPP palatal defect, moderate-size tongue. Chest: clear. Cardiac: normal. Extremities: no edema.
Sleep Study
Total sleep time AHI Type of events Obstructive/mixed apnea Central apnea Hypopnea
Question:
178
BEFORE UPPP
6 MONTHS AFfER UPPP
340 min 60/hr
360 min 40/hr
100% 0% 0%
What treatment would you recommend?
40% 0% 60%
Answer:
Consider an oral appliance and weight loss for persistent OSA.
Discussion: The sleep physician frequently is confronted with the problem of treatment in patients who experience inadequate improvement after UPPP. Another common scenerio is initial improvement after UPPP with subsequent redevelopment of symptoms. Patients may also worsen after UPPP, possibly secondary to scar tissue at the site. There are several treatment options: • Ask the patient to lose weight. Weight loss of just 10-20% of body weight can dramatically reduce the AHI in some patients (see Patient 35). Certainly weight gain should be avoided in any patient undergoing UPPP. Because weight loss is difficult (and often slow) to achieve and maintain, it should not be relied upon as the sole treatment for obstructive sleep apnea except in the mildest cases. • Consider repeat surgery on the palate (rarely performed unless the initial surgery was very conservative). • Try nasal CPAP. Unfortunately, many patients undergo UPPP because they declined CPAP. However, some will reconsider this decision and submit to a nasal CPAP titration. While one study has suggested that mouth leaks are more common on nasal CPAP following UPPP, nasal CPAP may work -especially if the required pressure is not high. Heated humidity may help patients tolerate mouth leak.
• Proceed to more advanced surgical treatment (see Patient 50). • Try an oral appliance as treatment for OSA. The rationale for trying an oral appliance in UPPP failures is that the UPPP should have decreased obstruction at the retropalatal area, and the oral applicance should reduce obstruction behind the tongue and in the hypopharynx. At least one study has reported success in many patients for whom UPPP failed. Of note, Henke and coworkers found that an oral appliance was effective in some patients with predominantly retropalatal obstruction. The mechanism of this action is not known. This is relevant, as the retropalatal area remains the smallest part of the upper airway in many patients after UPPP. In the present patient, a sleep study 6 months after UPPP showed persistent, significant sleep apnea. In the table, note that the amount of obstructi ve and mixed apnea decreased, and the amount of hypopnea increased. The patient declined nasal CPAP treatment and was referred to a dentist. A Herbst appliance (see Patient 51) was constructed. Using this device, the patient's symptoms improved. A repeat sleep study with the device in place showed an overall AHI of 15/hr. While this was not a perfect result, the patient felt better and still declined a trial of nasal CPAP. He was referred to a dietician and started a structured weight-loss program.
Clinical Pearls I. Patients who undergo UPPP should be followed closely. In some patients, symptoms of obstructive sleep apnea return after an initial improvement. 2. OSA can actually worsen after UPPP in some patients. 3. Nasal CPAP treatment may be more difficult in patients with a previous UPPP due to an increased tendency for mouth leaks. 4. Oral appliances may be a satisfactory treatment for some patients in whom UPPP failed. OA can be effective even if the major site of obstruction is retropalatal. 5. Weight loss can be a useful adjunctive therapy no matter which mode of treatment is selected in patients with even mild obesity.
REFERENCES I. Mortimore IL, Bradley PA, Murray JAM, et al: Uvulopalatopharyngoplasty may compromise nasal CPAP therapy in sleep apnea syndromes. Am J Respir Care Med 1995; 154: 1759-1762 2. Millman RP, Rosenberg CL, Carlisle CC, et al: The efficacy of oral appliances in the treatment of persistent sleep apnea after uvulopalatopharyngoplasty. Chest 1998; 113:992-996. 3. Henke KG, Frantz DE, Kuna ST: An oral elastic mandibular advancement device for obstructive sleep apnea. Am J Resp Crit Care Med 2000; 161:420--425. 4. Sasse SA, Mahutte CK, Dickel M, Berry RB: The characteristics of five patients with obstructive sleep apnea whose apnea-hypopnea index deteriorated after uvulopalatopharygoplasty. Sleep Breath 2002;6:77-84.
179
PATIENT 53 A 50-year-old man needing objective confirmation of his ability to stay awake A 50-year-old man was suspended from his job as a truck driver when he was diagnosed as having severe obstructive sleep apnea (GSA). The patient had never had an automobile accident, but had fallen asleep at the wheel while waiting for his truck to be loaded. A multiple sleep latency test (MSL T) performed at that time showed a mean sleep latency of 4.5 minutes. Following treatment with nasal CPAP, the patient noted marked symptomatic improvement. However, his company required that he have repeat testing before reinstatement.
Sleep Study (on prescribed level of nasal CPAP) Time in bed Total sleep time Sleep period time (SPT) Sleep efficiency (%) Sleep latency REM latency Arousal index
440 min (378-468) 404 min (340-439) 425 min (414-453) 92 (88-96) 10 min (0-19) 80 min (69-88) 10/hr
Sleep Stages
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
5 (2-7) 13 (4-12) 49(51-72) 15 (0-13) 18 (17-25)
AHI PLM index ( ) =
normal values for age, PLM = periodic leg movement
MSLT:
Question:
180
3/hr « 5) O/hr
Mean sleep latency 9 minutes (still in the abnormal range); no REM sleep in five naps. What would you recommend to document an adequate ability to stay awake?
Answer:
The "maintenance of wakefulness" test documents ability to stay awake.
Discussion: The multiple sleep latency test is a measure of the tendency to fall asleep during normal waking hours. However, the patient being tested is not trying to stay awake. When the MSLT is performed on patients with OSA before and after treatment, the mean sleep latency usually shows only modest improvement and still may not be in the normal range (> 10 minutes), despite dramatic symptomatic improvement. Similarly, patients with narcolepsy who are treated with stimulants tend to have only modest improvements in mean sleep latency. Thus it was appreciated that the MSLT may not be a sensitive measure of ability to maintain wakefulness, nor of improvement in this ability after treatment. The maintenance of wakefulness test (MWT) was designed to test the patient's ability to stay awake. The patient is seated upright in bed in a dimly lighted room and asked to remain awake for 20 or 40 minutes. The usual EEG, EOG, and EMG monitoring is performed to detect sleep. The test is terminated if sleep is noted, or after 20 or 40 minutes if the patient maintains wakefulness. The test is repeated four to five times across the day, and the mean sleep latency is determined (20 or 40 minutes if no sleep is recorded). When both the MSLT and MWT were administered to a group of patients with excessive daytime sleepiness, the correlation was significant but low. Several individuals did not fall asleep during the
MWT, but had some degree of daytime sleepiness as assessed by the MSLT. In another study, the MWT sleep latency increased from 18 to 31 minutes in a group of patients with OSA after adequate treatment. One normative study has suggested that a normal MWT latency should be more than 19 minutes on a 40-minute test (or 11 minutes on an abbreviated 20-minute MWT). The MWT latency required for a person to safely pursue an occupation critically dependent on alertness has not been standardized. Furthermore, the ability to stay awake is not the same as maintaining alertness. Studies using driving simulators have attempted to provide a performance-based test of alertness. Test results showed decreased alertness in patients with OSA and in patients with narcolepsy, as compared to a control group. However, these results did not correlate with MSLT results, and half of each group performed as well as controls. While these studies are important first steps, they have not been validated by performance tests of the real thing. Thus, for now, clinical judgement still is required. The present patient remained awake over four MWT tests (40 minutes). He was reinstated with the provision that he must comply with nasal CPAP therapy, submit to periodic checks of objective adherence to treatment, and undergo a repeat MWT in 6 months.
Clinical Pearls I. The maintenance of wakefulness test (MWT) is a more sensitive measure of improvement in the ability to stay awake after treatment in patients with disorders of excessive daytime sleepiness than the mutiple sleep latency test (MSLT). 2. The MWT and MSLT, although correlated, give discordant results in an appreciable number of patients. 3. MWT criteria for clearance in occupations requiring alertness have yet to be established.
REFERENCES I. Poceta, JS, Timms RM. Jeong D. et al: Maintenance of wakefulness test in obstructive sleep apnea syndrome. Chest 1992; 101:893-902. 2. Sangal RB, Thomas L, Mitler MM: Maintenance of wakefulness test and multiple sleep latency test: Measurements of different abilities in patients with sleep disorders. Chest 1992; 101:898-902. 3. George CFP. Boudreau AC, Smiley A: Comparison of simulated driving performance in narcolepsy and sleep apnea patients. Sleep 1996; 19:711-717. 4. Doghramji K, Miller MM, Sangal RB, et al: A normative study of the maintenance of wakefulness test (MWT). Electroencephalogr Clin Neurophysiol 1997; 103:554-562.
181
PATIENT 54 A 45-year-old man falling asleep at the wheel while driving A 45-year-old man was evaluated for complaints of severe, excessive daytime sleepiness (Epworth score 22/24) . He had a long history of heavy snoring. Recently, he had fallen asleep several times while stopped at traffic lights and stop signs. He admitted to having a recent automobile accident, but claimed this was not secondary to his sleepiness. A partial-night study (diagnostic/nasal CPAP titration) was planned. Nasal CPAP titration was attempted after 2 hours of monitoring, but the patient refused to continue. The study was completed as a diagnostic study. Physical Examination: Height 5 feet 8 inches, weight 230 pounds. Blood pressure 150/80, pulse 88. HEENT: large tongue; l7-inch neck circumference. Chest: clear. Cardiac: S4 gallop. Extremities: trace edema. Neurologic: oriented to person, place, and time (but asleep in the waiting room). Sleep Study Time in bed (monitoring time) Total sleep time (TST) Sleep period time (SPT) WASO Sleep efficiency (0/0) Sleep latency REM latency
( ) = normal
values for age, PLM
426 min (390-468) 369 min (343-436) 410 min (378-452) 41 min 87 (85-97) I min (2-18) 120 (55-78)
Sleep Stages
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
10(1-12) 20 (5-11) 60 (44-66) 0(2-15) 10 (19-27)
AHI PLM index
80/hr IO/hr
= periodic leg movement
Question: Should this patient be reported to the appropriate licensing agency as having a medical condition making driving hazardous?
182
Answer:
This patient has severe OSA, and he should not drive until adequately treated.
Discussion: The question of whether or not to report a patient to state authorities as having a medical condition making driving hazardous is one of the most difficult problems facing sleep physicians. The patient has a right to confidentiality, but the physician has ethical and legal obligations to the driving public. Large financial tort settlements have been brought successfully against some physicians for failure to report a person with a medical condition who was subsequently involved in a serious traffic accident. Each state has its own laws, and local medical societies have guidelines. However, in the end, the decision rests with the treating physician. In some states, such as California, reporting is done to a health agency rather than directly to the motor vehicle licensing agency. Note that reporting does not always result in the loss of the patient's license. What is the increase in risk of having an automobile accident for the patient with OSA? This is difficult to estimate, but one study found a two to three times greater risk. Clearly, not all patients with sleep apnea are at high risk of having an auto accident. It appears that the presence of sleep apnea plus a history of a previous accident (or frequent falling asleep at the wheel) identifies a group of patients with especially high risk. A committee of the American Thoracic Society has issued the following reasonable recommendations: "In those jurisdictions in which conditions such as excessive daytime sleepiness caused by sleep apnea may be construed as reportable events, we recommend reporting to licensing bureaus if: (a) the patient has excessive daytime sleepiness, sleep apnea, and a history of a motor vehicle accident or equivalent level of clinical concern; and (b) one of the following circumstances exists-
(i) the patient's condition is untreatable or is not amenable to expeditious treatment (within 2 months of diagnosis); or (ii) the patient is not willing to accept treatment or is unwilling to restrict driving until effective treatment has been instituted." The committee also noted that it is the physician's responsibility to notify every patient with sleep apnea that driving when sleepy is risky. Some form of written documentation that the patient understands this warning is prudent. To date there is no objective test that can quantify a patient's degree of driving impairment. The multiple sleep latency test quantifies sleepiness, but does not predict ability to stay awake. One study did not find a correlation between MSL T results and reported accidents. The maintenance of wakefulness test is a better test of the ability to remain awake, but it does not assess alertness or the ability to drive. There have been promising attempts at developing driving simulators, but the results of these performance tests have not correlated with actual driving ability. Studies have shown that the risk of traffic accidents does appear to be reduced with nasal CPAP therapy (if patients are compliant). In the present case, the sleep study showed severe OSA. Note the absence of stages 3 and 4 sleep and the decrease in REM sleep. Unfortunately, the patient did not tolerate a nasal CP AP titration. After being confronted with the sleep study results, he still declined CPAP and other effective treatments. He said he would try to lose weight. The patient was asked to sign a document confirming that it was recommended that he not drive until adequately treated. His condition was reported to the local health department for eventual submission to the appropriate agency.
Clinical Pearls I. Patients with OSA who fall asleep at the wheel or have had previous accidents are at increased risk of having a sleep-related automobile accident. 2. Patients at risk should be advised not to drive until adequate treatment has begun. 3. Reporting of patients to appropriate state authorities is prudent when they refuse to comply with effective therapy or restrict their driving until adequately treated. 4. Studies have suggested that nasal CPAP treatment can reduce the risk of auto accidents if patients are adherent to treatment.
183
REFERENCES I. Findley LJ, Unverzagt ME, Suratt PM: Automobile accidents involving patients with obstructive sleep apnea. Am Rev Respir Dis 1988; 138:337-340. 2. American Thoracic Society Official Statement: Sleep apnea, sleepiness, and driving risk. Am J Respir Crit Care Med 1994; 150:1463-1473. 3. Cassel W, Ploch C, Becker D, et al: Risk of traffic accidents in patients with sleep disordered breathing: Reduction with nasal CPAP. Eur Respir J 1996: 9:2602-2611. 4. George CFP, Boudreau AC, Smiley A: Simulated driving performance in patients with obstructive sleep apnea. Am J Respir Crit Care Med 1996: 154:175-181. 5. George CF: Reduction in motor-vehicle collisons following treatment of sleep apnea with nasal CPAP. Thorax 200 I ;56:508-512.
184
PATIENT 55 A 30-year-old man with severe snoring A 30-year-old man being considered for laser-assisted palatoplasty (LAP) as a treatment for snoring was referred by an ENT surgeon for evaluation. The patient denied symptoms of daytime sleepiness. His wife had not noticed episodes of apnea or gasping for breath, although she currently slept in a separate bedroom. The snoring was causing considerable marital problems for the patient. There was no history of nasal congestion except during upper respiratory tract infections. The patient did admit to drinking one or two alcoholic beverages with supper most nights. Loud snoring was noted during most of the sleep study except when the patient was in REM sleep. Physical Examination: Vital signs: normal. HEENT: long edematous uvula; 15 ~-inch neck circumference. Chest: clear. Cardiac: normal. Extremities: no edema. Figure: Tracings during periods when the patient was snoring and sleeping quietly are shown below. Sleep Study Time in bed (monitoring time) Total sleep time Sleep period time (SPT) WASO Sleep efficiency Sleep latency REM latency
440 min (414--455) 411.5 min (400--443) 420 min (405--451) 8.5 min 94 (95-99) 2.5 min (2-10) 90 min (70-100)
( ) = normal values for age. hypopnea = decrease in airflow
Question:
Sleep Stages
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
2 (0-3) 12 (2-9) 60 (50-64) 10 (7-18) 16 (20-27)
Arousal index (lhr) AHI
IO/hr 3/hr
+ either arousal or 4% desaturation
What is your diagnosis?
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,
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nasal pressure Snore
chest abdomen
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185
Diagnosis:
Simple snoring.
Discussion: While snoring is a cardinal symptom of obstructive sleep apnea (GSA), not all snorers have a significant number of apneas and hypopneas nor the upper airway resistance syndrome (UARS). Recall that a diagnosis of UARS requires that the patient be sleepy. In fact, most snoring patients have minimal apnea, normal sleep architectures, and no daytime sleepiness. They are said to have simple snoring. Snoring may be defined as a vibratory, sonorous noise made during inspiration and, less commonly, expiration. It is associated with a vibration (fluttering) of the soft palate and other pharyngeal structures. Snoring is difficult to quantify but may be described on the basis of intensity or vibratory qualities. It is associated with a narrowing of the upper airway. Anything that narrows the upper airway, increases nasal resistance, or decreases upper airway muscle tone worsens snoring. Thus, nasal congestion, the supine posture, and ethanol or hypnotics may have this effect. There is a definite male predominance, although a considerable number of women also snore. Simple snoring is common and tends to increase with age. Some studies have suggested that up to 60% of men and 40% of women over the age of 40 are habitual snorers. Snoring intensity is loudest in slow wave sleep and softest in REM sleep. During snoring, the esophageal pressure can be quite negative, and systemic blood pressure may increase (or not fall as it normally does in NREM sleep). A possible association between snoring and hypertension is still debated. However, patients with heavy snoring are at risk for developing GSA. Many sleep laboratories find it useful to record snoring on the polygraph tracings by using a microphone near the patient's neck. However, sometimes the technician will hear snoring over the intercom/audio monitor even though the snoring microphone does not detect it. When nasal pressure or a
thermocouple pneumotach
pneumotachograph is used to monitor airflow, vibrations in the airflow tracing during snoring may be seen (Fig. I)-provided the pressure amplifier is sufficiently sensitive and the high filter setting on the amplifier is not too low (70- 100). If thermistors or thermocouples are used to detect airflow, these vibrations will not be seen. In Figure 2, note the evidence of snoring (5) in the pneumotachograph but not the thermistor tracings. The "pneumorach" tracing shows a flat profile during snoring. Snoring vibrations also are reflected in esophageal pressure tracings; note the higher esophageal pressure deflections (compared to initial, non-snoring breath). If snoring is heavy, very negative esophageal pressures may be reached. In some patients, chin EMG activity increases at inspiration (phasic) during snoring episodes (Fig. 3). Before attempting to treat snoring, first assess whether significant sleep apnea is present. Although patient assessment of daytime sleepiness is a poor predictor of GSA, it is not economically feasible to study every patient with snoring. A large neck circumference and bedrnate-witnessed gasping or apnea are the best historical predictors of GSA. If either of these is present or the patient reports significant daytime sleepiness, a sleep study is indicated. Most clinicians also feel that if snoring is severe enough to warrant surgery, then a sleep study is indicated even if daytime sleepiness is not present. The rationale for this recommendation is that if moderate to severe GSA is present, then UPPP is not the treatment of choice. Even if mild GSA is present, most would not recommend an LAUP. An LAUP is usually reserved for simple snoring. The treatment options for simple snoring are similar to those for mild GSA: weight loss, the side sleep position, upper airway surgery, an oral appliance, or nasal positive airway pressure. In the present case, the wife's observations were
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esophageal pressure
-+ Inspiration 0
j
-10 -20 -30 -40
FIGURE
186
2
em H O 2
not helpful because she slept in another bedroom. The history of heavy habitual snoring prompted a sleep study. Long periods of heavy snoring and airflow limitation (flat nasal pressure profile) were seen. Note that the airflow by thermistor shows no changes, but there is paradoxical movement in the chest and abdominal tracings (Fig. I). However, the patient had a normal AHI, arousal index, and sleep architecture.
He was not sleepy. Therefore, he was diagnosed as having simple snoring. It is possible that the sleep study underestimated the severity of sleep apnea because the patient did not drink his usual alcoholic beverages beforehand. In any case, because he desired "to get this problem fixed quickly," he was treated with a laser-assisted palatoplasty and counseled to avoid weight gain and abstain from alcohol.
Quiet
Snoring
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~~
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3
Clinical Pearls 1. Snoring patients without symptoms and signs of GSA or UARS (no daytime sleepiness) are classified as having simple snoring. 2. Patients with simple snoring may be at risk for eventual development of frank GSA and therefore should be educated about the symptoms and signs of GSA. 3. Snoring severe enough to warrant surgical intervention deserves evaluation with a sleep study. 4. Snoring can be detected with snore microphones, and high-frequency oscillations sometimes can be seen in the nasal pressure signal (with appropriate amplifer setting). Snoring may be associated with pardoxical breathing and high esophageal pressure deflections. 5. Snoring is usually loudest and most frequent during slow wave sleep.
REFERENCES 1. Lugaresi E, Cirignolla F, Coccanga G, et al: Some epidemiological data on snoring and cardiorespiratory disturbances. Sleep 1980; 3:221-224. 2. Stoohs R, Guilleminault C: Snoring during NREM sleep: Respiratory timing. esophageal pressure and EEG arousal. Respir Physio11991; 85:151-167. 3. Krespi YP, Pearlman SJ, Keidar A: Laser-assisted uvulopalatoplasty for snoring. J Otolaryngol 1994; 17:744-748. 4. Hoffstein V: Snoring. Chest 1996; 109:201-222. 5. Littner M, Kushida CA, Hartse SE, et al: Practice parameters fo the use oflaser-assisted uvulopalatoplasty, An update 2000. Sleep 2001; 24:603-619.
187
PATIENT 56 A 30-year-old choir singer with heavy snoring A 30-year-old woman was evaluated for complaints of heavy snoring that had significantly worsened over the last year. Interestingly, there had been no weight gain or change in nasal congestion to explain the sudden onset of snoring. Snoring was noted during the sleep study in all body positions and was a major embarassment for the patient. She also complained of mild sleepiness (Epworth Sleepiness Scale score 13) and reported fatigue, dry skin, and cold intolerance. The patient had originally seen an ENT surgeon who offered her laser-assisted palatoplasty. However, she sings in her church choir and was hesitant to undergo the operation because of the possibility of a change in her singing voice. In fact, she was concerned that her singing voice had deepened recently. The patient denied drinking alcohol. Physical Examination: Blood pressure 130/80 mmHg, pulse 70, temperature 37°C. General: mildly obese; slightly hoarse voice. HEENT: large tongue, edematous palate; possible thyromegaly, 15-inch neck circumference. Chest: clear. Cardiac: normal. Abdomen: obese. Extremities: trace pedal edema. Neurologic: slow relaxation phase of deep tendon reflexes in ankle. Sleep Study Time in bed (monitoring time) Total sleep time Sleep period time (SPT) WASO Sleep efficiency (0/0) Sleep latency REM latency
440 min (425-462) 411.5 min (394-457) 420 min (414-453) 8.5 min 94 (90-100) 2.5 min (0-19) 90 min (69-88)
Sleep Stages
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
12 (0-6) 8 (3-6) 50 (46-52) 15 (7-21) 15 (21-31)
Arousal index Respiratory arousal index
30/hr 25/hr
AHI AHI NREM/REM AHI supine/non-supine
15/hr 14/hr / 20/hr 20/hr / 5/hr
( ) = normal values for age, hypopnea = reduction in airflow
Question:
188
+ arousal or 4% desaturation
What treatment would you recommend?
Answer:
Thyroid replacement and nasal CPAP or an oral appliance.
Discussion: Hypothyroidism has been demonstrated to cause or exacerbate obstructive sleep apnea. While some sleep centers routinely obtain thyroid studies in all patients with suspected OSA, a recent study found hypothyroidism in less than 1% of these screened patients. Therefore, routine thyroid studies probably are indicated only if symptoms and signs are suggestive of hypothyroidism. Thyroid studies also may be indicated if the subsequent sleep study provides no explanation for sleepiness and fatigue, or if patients with OSA do not respond to treatment. The group of OSA patients at highest risk for coexistent hypothyroidism is older women. While hypothyroidism is present in a low percentage of patients with OSA, a much higher percentage of patients with known hypothyroidism have OSA. One study of patients newly diagnosed with hypothyroidism revealed OSA in 9 of II patients. Treatment of hypothyroidism may dramatically improve OSA. In one study, the mean AHI fell from 78/hr to l2/hr after patients became euthyroid. However, restoration of the euthyroid condition in patients with OSA does not reliably reverse sleep apnea in all patients. Moreover, initiation of even low doses of thyroid replacement in untreated patients with OSA and coronary artery disease has been reported to cause nocturnal angina. Therefore, treatment of OSA should be begun when thyroid replacement is initiated. After the euthyroid state is attained, a repeat sleep study can determine if continued treatment of OSA (other than thyroid replacement) is required. Some patients do, in fact, experience complete reversal of sleep apnea following adequate treatment of hypothyroidism, even if body weight remains constant. The reason hypothyroidism exacerbates OSA is unclear and possibly multifactorial.
Upper airway muscle myopathy, narrowing of the upper airway by mucoprotein deposition in the tongue (macroglossia), and abnormalities in ventilatory control are possible mechanisms. Treatments for snoring or mild OSA include weight loss, avoidance of the supine sleeping position, upper airway surgery (LAUP for snoring, UPPP for snoring or mild OSA), an oral appliance, or nasal CPAP. Although nasal CPAP is rarely used for isolated snoring, it can be quite effective (see figure); increased pressure can eliminate snoring (S).
nasal mask pressure 5sec
S S S S S
-, Increased CPAP
In the present patient, the sleep study revealed mild to moderate OSA and heavy snoring, with an overall AHI of 15/hr. An elevated thyroid-stimulating hormone of 18 mIU/L « 6 is normal) and a low free T4 documented primary hypothyroidism. Treatment was begun with low doses of thyroid replacement. The patient did not want surgery or an oral appliance. She underwent a CPAP titration and began nasal CPAP treatment with 5 em H20. The thyroid replacement was gradually increased until the euthyroid state was attained. A repeat sleep study (off nasal CPAP) several months later revealed an AHI < 5/hr and minimal snoring. Nasal CPAP therapy was discontinued, and the patient's snoring remained minimal.
Clinical Pearls 1. Hypothyroidism is a predisposing condition for the development of OSA and should be considered in all patients with OSA. 2. Routine thyroid screening may not be cost-effective in all patients with suspected OSA. 3. Restoration of the euthyroid state does not eliminate sleep apnea in all patients with OSA and hypothyroidism. 4. Treatment of both OSA and hypothyroidism should be initiated. A repeat sleep study several months after the euthyroid state is restored determines if continued OSA treatment (other than thyroid replacement) is necessary. 5. Although nasal CPAP is less commonly used for simple snoring or mild OSA, it can be effective. 6. Snoring while using nasal CPAP treatment is a clue that the prescribed pressure should be increased.
189
REFERENCES I. Berry RB, Block AJ: Positive nasal airway pressure eliminates snoring as well as obstructive sleep apnea. Chest 1984: 85: 15-20. 2. Rajagopal KR, Abbrecht PH, Derderian 55, et al: Obstructive sleep apnea in hypothyroidism. Ann Intern Med 1984; 101:
491-494. 3. Rauscher H, Formanek D, Zwick H: Nasal continuous positive airway pressure for non-apneic snoring? Chest 1995; 107:58-61. 4. Winkelman JW, Goldman H, Piscatelli N, et al: Are thyroid function studies necessary in patients with suspected sleep apnea? Sleep 1996; 19:790-793.
190
PATIENT 57 A 50-year-old man with severe hypertension A 50-year-old-man with a history of severe hypertension (previous systolic blood pressure 180-190 mmHg) was admitted to the intensive care unit (lCU) when his physician noted a blood pressure of 2301130 mmHg in the office. At the time of admission the patient was being treated with lisinopril and amlodipine for his hypertension, but he had run out of medication. During the first night in the ICU the patient had periods of obvious obstructive apnea and swings in blood pressure. He adamantly denied symptoms of daytime sleepiness. Physical Examination: Height 5 feet 11 inches, weight 220 pounds. Blood pressure 180/95 mmHg. HEENT: edematous soft palate and uvula; 16-inch neck circumference. Chest: clear. Cardiac: S4 gallop. Extremities: 1 + edema, right arterial line in place. Laboratory Finding: EKG: left ventricular hypertrophy. Figure: Airflow and arterial blood pressure were recorded on a two-channel chart during the night in the ICU.
Question: ness?
Should this patient be treated for a sleep disorder even though he denies daytime sleepi-
200 Blood pressure (mm Hg)
o
20 sec
Airflow
191
Diagnosis:
Obstructive sleep apnea and nocturnal worsening of systemic hypertension.
Discussion: Reversal of excessive daytime sleepiness is not the only reason patients with significant OSA should be treated. Retrospective studies have suggested that when the apnea index is greater than 20/hr, untreated OSA is associated with a decreased survival rate. Further, this decrease is not secondary to links with other disorders, such as obesity and hypertension, because effective treatment of OSA resulted in a normal cumulative 5-year survival. While prospective studies of the impact of OSA and CPAP treatment on life expectancy are needed, it seems likely that untreated, significant OSA does shorten survival. The question is: How? One possibility is that OSA causes or worsens the known morbidity and mortality associated with systemic hypertension. In normal subjects, heart rate and systemic blood pressure fall during NREM sleep. Patients with OSA have increases in heart rate and systemic and pulmonary arterial blood pressure following apnea termination during sleep. Depending on the frequency of apnea during the night, many patients with OSA (with and without daytime hypertension) fail to show a mean fall in blood pressure during the night ("non-dippers"). The etiology of the post-apnea surges in blood pressure is complex, but activation of the autonomic nervous system (increased sympathetic activity) and arousal probably are the major causes. There is conflicting evidence about whether hypoxia also plays a role. Most hypertensive patients without OSA still have a dip in blood pressure during sleep. Conversely, many hypertensive and nonhypertensive patients with OSA are non-dippers (no sleep-associated fall in blood pressure). Studies have suggested that patients with both daytime and nocturnal hypertension (non-dippers) appear to have an increased risk of developing left ventricular hypertrophy. Thus, OSA may worsen the impact of hypertension on the heart and perhaps the peripheral vasculature. Does OSA cause daytime hypertension? A canine model showed that nocturnal hypertension could be induced by periodic acoustic arousal to mimic the periodic arousals of OSA. However, only nocturnal intermittent airway occlusions to simulate OSA resulted in both nocturnal and daytime hypertension. This suggests a role for intermittent hypoxia or airway occlusion as one cause of daytime hypertension. Chronic intermittent hypoxia given to rodents has been shown to increase
192
unstimulated (resting) blood pressure. While some epidemiologic studies have linked daytime hypertension to OSA, others have not. The biggest problem is separating out the coexisting factors of age and obesity. Certainly there is a 50-60% incidence of hypertension in most series of patients with OSA. Peppard and coworkers found a dose-response relationship between the AHI at baseline and the presence of hypertension at a 4-year followup. Other cross-sectional studies have found only a modestly increased risk of hypertension as AHI increases. However. even if OSA does not cause systemic hypertension (only an association), as noted above, it may worsen the consequences. Can treatment of OSA favorably alter the impact of hypertension? Several studies have shown a reduction in nocturnal blood pressure on nasal CPAP in OSA patients with daytime hypertension. In some patients, daytime blood pressure also may improve, although most patients still require treatment of hypertension with medication. Pepperell and coworkers found that the 24-hour mean arterial blood pressure fell by 3.3 mmHg in a group of moderate to severe patients with OSA using nasal CPAP. Both daytime and nighttime blood pressure fell. Based on prospective studies of the effects of hypertension, the authors reasoned that a fall in blood pressure of 3.3 mmHg would be expected to be associated with a stroke risk reduction of 20%, and a coronary artery disease event reduction of about 15%. The patients who used nasal CPAP more than 5 hours per night, those with an AHI > 40/hr, and those on antihypertensive medications had the largest falls in mean blood pressure. Whether nasal CPAP treatment favorably alters the development of left ventricular hypertrophy remains to be determined. In the present case, the chart recorder documented numerous apneas associated with a surge in blood pressure after apnea termination. The patient initially refused a complete sleep study. However, after discussion about the cardiovascular consequences and increased mortality associated with untreated sleep apnea, he agreed. A split-night study showed an AHI of 80/hr. Treatment with nasal CPAP at 12 cm HzO reduced the AHI to 8/hr. After a month of treatment with nasal CPAP, the patient reported an improved energy level. While antihypertensive therapy was still needed, improved control was noted, with systolic blood pressures in the 140-150 mmHg range.
Clinical Pearls I. Reversal of daytime sleepiness is not the only reason patients with significant GSA should be treated. 2. GSA prevents the normal sleep-associated fall in systemic blood pressure. 3. The presence of GSA appears to increase the risk of having systemic hypertension. However, even if GSA is only an association rather than a cause of hypertension, GSA likely worsens the severity or the consequences of hypertension in many patients. 4. Effective treatment of GSA prevents the cyclic nocturnal increases in blood pressure and may improve daytime blood pressure control and/or the long-term consequences of hypertension.
REFERENCES J. He J, Kryger MH. Zorick Ff, et at: Mortality and apnea index in obstructive sleep apnea. Chest 1988; 94:9-14. 2. Verdecchia P, Schiallica G. Guerrier M. et al: Circadian blood pressure changes and left ventricular hypertrophy in essential hypertension. Circulation 1990; 81:528-536. 3. Suzuki M. Guilleminault G. Otsuka K. er al: Blood pressure "dipping" and "non-dipping" in obstructive sleep apnea syndrome patients. Sleep 1996; 19:382-387. 4. Brooks D. Horner RL. Kozar LF. et al: Obstructive sleep apnea as a cause of systemic hypertension. Evidence from a canine model. 1 Clin Invest 1997; 99:106-109. 5. Peppard PE. Young T. Palta M. et al: Prospective study of the association between sleep-disordered breathing and hypertension. N Engl1 Med 2000; 342: 1378-1384. 6. Fletcher EC: Invited review: Physiological consequences of intermittent hypoxia: systemic blood pressure. 1 Appl Physiol 2001; 90: 1600-1605. 7. Pepperell1CT. Ramdassingh-Dow S. Crosthwaite N. et al: Ambulatory blood pressure after therapeutic and subtherapeutic nasal continuous positive airway pressure for obstructive sleep apnea: a randomized parallel trial. Lancet 2002;359:204-210. 8. Peker Y. Hedner 1. Norum 1. et al: Increased incidence of cardiovascular disease in middle-aged men with obstructive sleep apnea: A 7-year follow-up. Am 1 Respir Crit Care Med 2002; 166: 159-165.
193
PATIENT 58 A 55-year-old man with premature ventricular contractions during sleep A 55-year-old man was undergoing coronary angiography. Before the procedure he was given midazolam (a potent benzodiazepine), and he fell asleep. During this time, heavy snoring and pauses in breathing were noted. The patient was referred for sleep evaluation. His angiogram had shown significant threevessel coronary artery disease. Physical Examination: Blood pressure 135/88 mmHg, pulse 80 and regular. HEENT: large uvula, edematous pharynx; 16-inch neck circumference. Chest: clear. Cardiac: S4 gallop. Extremities: no edema. Sleep Study: AHI 40/hr. Minimum arterial oxygen saturation: 85% during NREM, 75% during REM. Figure: A sample tracing from the sleep study is shown.
Question:
Are the premature ventricular contractions (PVCs) being caused by obstructive sleep apnea?
C4- A1 O 2 -A 1 ROC-A 1 LOC - A 2 chin EMG EKG
Airflow Chest Abdomen
194
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Diagnosis:
Severe obstructive sleep apnea is present, but frequent and unifocal PYCs are unrelated.
Discussion: In normal individuals, the heart rate falls during NREM sleep. This is thought to be due to parasympathetic predominance during sleep. In patients with OSA, the heart rate varies in cycles: slowing with apnea onset, increasing slightly during apnea, and increasing more dramatically in the post-apneic period. These changes are illustrated below in a tracing from another patient. The numbers under the EKG tracing are the instantaneous heart rates. Although these cycles are referred to as bradytachycardia, the heart rate remains between 60 and 100 in many patients. In one series, 25% of OSA patients showed true bradycardia (60 bpm) and tachycardia (> 100 bpm). Bradyarrhythmias including heart block (2nd degree-mobitz types 1 and 2, and 3rd degree) occur in a minority of OSA patients (usually < 10%). Early studies attributed the slowing of heart rate during apnea to increased vagal tone and hypoxia. The slowing was diminished by atropine and supplemental oxygen. The increased vagal tone during apnea is the result of hypoxic stimulation of the carotid body. With resumption of respiration, inflation of the lungs decreases vagal tone, and the hypoxic influences on sympathetic tone are unmasked (tachycardia). More recent studies have not consistently found a reduction in heart rate in the last part of apnea. Instead, they have focused on tachycardia as the primary event at apnea termination, with a subsequent fall in heart rate as sympathetic activity diminishes after the initial burst. These studies suggest that the individual differences in the effect of apnea on heart rate may be secondary to differences in the response of the carotid body to hypoxia. C4 - A1 O2-A1 ROC-A 1
The cycles of heart rate slowing may have little significance, except in cases of significant bradycardia or heart block. However, the periods of tachycardia and elevated blood pressure post-apnea increase myocardial oxygen demand at the same time that hypoxemia exists, predisposing to ischemia and possibly tachyarrhythmias. In normal individuals, sleep usually is a time of reduced tachyarrhythmias and ischemia. Patients with OSA may not enjoy the same protection. While PYCs are not uncommon in patients with OSA, they typically are unrelated to apnea or desaturation. In one series of 400 patients with OSA, PYCs were more frequent during sleep in only 14% of patients. In another study, a clear association between PVC frequency and the severity of nocturnal desaturation was found only when the SaO z was < 60%. Heart rate variability has recently been used as a tool to study the balance of parasympathetic and sympathetic tone in patients with OSA. During wakefulness, OSA patients show less heart rate variability than normal individuals. This is thought to be secondary to an increase in sympathetic tone that is still present during the day. After successful treatment with CPAP, the heart rate variability may increase, which suggests a drop in sympathetic activity. In the present patient, PYCs were noted during the middle of apnea rather than during periods of desaturation and arousal post-apnea. A 24-hour Holter monitor showed that the PVC rate was lower during the nocturnal hours. The patient underwent a nasal CPAP titration and was treated with 10 ern H,O pressure. He reported less daytime sleepiness. -A coronary bypass surgery has been scheduled.
~~~
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LOC - A 2 chin EMG EKG
~+W+AAUUH~~ 85
66
63
67
70 85
92
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--------~----
---------80%
195
Clinical Pearls I. pves in patients with OSA usually are unrelated to sleep apnea unless the SaO~ is less than 60%. 2. The most common cardiac rhythm during sleep in patients with OSA is a periodic slowing and speeding of the sinus rate. Although the rhythm is sometimes called bradytachcardia, the heart rate often remains at 60-100 bpm in many patients. The heart rate slows at apnea onset and increases following apnea termination. 3. Untreated OSA patients have decreased heart rate variability that increases after effective treatment.
REFERENCES I. Zwillich C, Devlin T, White D, et al: Bradycardia during sleep apnea. Characteristics and mechanisms. J Clin Invest 1982; 69: 1286-1292. 2. Guilleminault C, Connoly SJ, Winkle RA: Cardiac arrhythmia and conduction disturbances during sleep in 400 patients with sleep apnea syndrome. Am J Cardiol 1983; 52:490--494. 3. Shepard JW, Jr. Garrison MW, Grither DA, et al: Relationship of ventricular ectopy to oxyhemoglobin desaturation in patients with obstructive sleep apnea. Chest 1985; 88:335-340. 4. Becker H, Brandenburg U, Peter JH, et al: Reversal of sinus arrest and atrioventricular conduction block in sleep apnea during nasal continuous positive airway pressure. Am J Resp Crit Care Med 1995; 151:215-218. 5. Sato F, Nishimura M, Sinano H, et al: Heart rate during obstructive sleep apnea depends on individual hypoxic chemosensitivity of the carotid body. Circulation 1997;96:274-281. 6. Leung RST, Bradley TD: Sleep Apnea and Cardiovascular Disease. State of the Art. Am J Resp Crit Care Med 200 I; 164: 2147-2165. 7. Khoo MC, Belozeroff V, Berry RB, Sassoon CS: Cardiac autonomic control in obstructive sleep apnea: Effects of long-term CPAP therapy. Am J Respir Crit Care Med 2001; 164:807-812.
196
PATIENT 59 A 30-year-old pregnant woman with onset of snoring A 30-year-old woman in the third trimester of her first pregnancy was noted by her husband (a physician) to snore heavily during the night. This occurred although she spent nearly all of the night sleeping in the lateral decubitus position. The patient had gained about 25 pounds during the pregnancy. During regular visits with her obstetrician, all fetal monitoring indicated a healthy pregnancy. There was no history of snoring prior to the pregnancy. Because the patient had been complaining of fatigue and was taking frequent naps, her husband was concerned that she might have obstructive sleep apnea (GSA). He had not heard any pauses in breathing during sleep. The patient denied falling asleep while watching television or reading during the day. Physical Examination: General: healthy, gravid appearance. HEENT: moderately congested nasal mucosa; edematous palate and uvula; 15-inch neck circumference. Extremities: trace edema.
Question:
Should a sleep study be performed?
197
Answer:
A sleep study is unnecessary for snoring associated with pregnancy.
Discussion: Pregnancy is associated with a number of physiologic changes that affect respiration during wakefulness and sleep. In the first trimester, increased sleepiness and total sleep time and decreased stages 3, 4, and REM sleep are common. In the second trimester sleep normalizes. In the third trimester, sleep commonly is disturbed again, secondary to frequent urination, backache, fetal movement, leg cramps, and heartburn. The restless leg syndrome can appear or become worse during pregnancy. A high level of progesterone (a respiratory stimulant) in the third trimester is associated with a lowering of the arterial PCO,. Growing abdominal girth results in an upward displacement of the diaphragm. In addition, edema develops in the nasal passages and pharynx. These last two changes result in snoring in up to 30% of all pregnant women. Sleep Problems During Pregnancy Daytime sleepiness Insomnia Snoring Restless leg syndrome Narcolepsy Obstructive sleep apnea Possible worsening of pre-eclampsia by snoring/upper airway resistance syndrome Although snoring is common in pregnant women, overt OSA is uncommon. A few cases of severe OSA have been reported. However, this condition may be underdiagnosed. Some pregnant patients with OSA continued to have sleep apnea after delivery; thus, pregnancy probably worsened but did not cause sleep apnea in these patients. One recent study suggested that airflow limitation can worsen blood pressure during pregnancy in patients with preeclampsia in the absence of overt apnea.
198
Thus, indications for sleep monitoring when snoring is present might include witnessed apnea, severe hypertension, previous pregnancy with fetal growth retardation, and severe hypersomnia or insomnia. If sleep apnea is present, therapeutic options are somewhat limited. Severe cases probably should be treated with nasal CPAP. Close monitoring of both fetus and patient is essential. There is some evidence to suggest that severe OSA in the mother causes retardation of infant fetal growth, but this has not been determined conclusively. If narcolepsy is present during pregnancy, the recommended stimulant treatment is pemoline, which is a category B drug. Category B means no controlled human studies have been published but animal studies show no risk to fetus, or animal studies show an adverse effect on the fetus but wellcontrolled studies in pregnant women failed to demonstrate a risk to the fetus. Of note, pemoline has been associated with liver failure and is no longer considered a first-line medication in nonpregnant patients with narcolepsy. Most of the medications used for the restless leg syndrome are category C or D, and physicians generally recommend only conservative management, such as iron and folate supplements. Diphenhyramine and zolpidem, category B drugs, address insomnia, but little experience is available. Therefore, most would recommend using no medications if possible, especially in the first trimester. In the present patient, the absence of respiratory pauses and symptoms of daytime sleepiness suggested that simple snoring was present. Regular obstetric care showed no evidence of fetal compromise. Therefore, the patient and husband were reassured and informed that if snoring persisted after delivery or if symptoms of daytime sleepiness were noted, then a sleep study would be performed.
Clinical Pearls 1. Snoring during pregnancy (especially in the last trimester) is common. 2. Development of overt sleep apnea during pregnancy is not common. 3. Indications for a sleep study in a pregnant woman who snores include witnessed apnea, severe hypertension, and previous or current unexplained pregnancy with fetal growth retardation. 4. If patients with OSA become pregnant, potential harm to the developing fetus is possible, and a sleep evaluation is warranted. 5. Limited data suggests that nasal CPAP is the OSA treatment of choice during pregnancy. Close fetal monitoring is essential. 6. The restless legs syndrome may develop or worsen during pregnancy.
REFERENCES 1. Charbonneau M, Falcone T, Cosio, MG, et al: Obstructive sleep apnea during pregnancy. Am Rev Respir Dis 1991; 144:461--463. 2. Feinsilver SH. Hertz G: Respiration during sleep in pregnancy. Clin Chest Med 1992; 13:637-644. 3. Loube DI, Poceta JS, Morales MC, et al: Self-reported snoring during pregnancy: Association with fetal outcome. Chest 1996; 109:885-889. 4. Edwards N, Blyton DM, Kirjavainen T, et al: Nasal continuous positive airway pressure reduces sleep induced blood pressure increments in preeclampsia. Am J Respir Crit Care Med 2000; 162:252-257. 5. Santiago JR, Nolledo MS, Kinzler W, Santiago TV: Sleep and sleep disorders in pregnancy. Ann Intern Med 2001;134:396--408
199
PATIENT 60 A 45-year-old man with snoring and hypercapnia A 45-year-old obese man was evaluated for severe, bilateral pedal edema of I-year duration. The patient had smoked one pack of cigarettes per day for 10 years, but he denied a history of cough or wheezing. There was no history of hypertension, chest pain, or myocardial infarction. The patient's wife reported that he snored heavily. However, the patient denied excessive daytime sleepiness. Physical Examination: Height 5 feet 9 inches, weight 275 pounds. Blood pressure 130/85 mmHg, pulse 80 and regular. Neck: short, 18-inch circumference. Chest: clear to auscultation. Cardiac: distant heart sounds, no murmurs. Extremities: 3 + pedal edema. Laboratory Findings: Spirometry: FEV I 3.0 L (77% of predicted), FVC 3.4 L (70% of predicted), FEV/FVC 0.88. Arterial blood gas (room air): pH 7.35, PC0 2 52 mmHg, P0 2 55 mmHg, HC0 3 33 mmol/L. Chest radiograph: borderline cardiomegaly. Sleep Study: AHI 66/hr. Minimum oxygen saturation 40%. Number of desaturations to < 85%: 300.
Questions:
200
What is the diagnosis? What treatment will reduce the level of hypercapnia?
Diagnosis:
Obesity hypoventilation syndrome. Nasal CPAP or tracheostomy reduces hypercapnia.
Discussion: The diagnosis of obesity hypoventilation syndrome (OHS) requires that the patient be obese and hypoventilate for reasons other than lung disease or neuromuscular weakness. Most patients with OHS have obstructive sleep apnea (OSA). An occasional patient experiences worsening of daytime hypoventilation during sleep without discrete apneas or hypopneas. Patients with OHS sometimes are called Pickwickian. This term is best avoided because some physicians use it to refer to all patients with OSA. The combination of obesity, snoring, and unexplained CO 2 retention always suggests the possibility of OHS. The absence of a history of severe daytime sleepiness does not rule out this diagnosis. Many patients underestimate the severity of their daytime sleepiness. Note that only about 15% of patients with OSA have significant daytime CO 2 retention, and these patients form two groups: those with OHS and those with overlap syndrome (OSA + chronic obstructive pulmonary disease). These groups tend to have especially severe nocturnal oxygen desaturation and evidence of cor pulmonale. The etiology of CO 2 retention in OHS is multifactorial. Patients with OHS have reduced ventilatory responses to hypercapnia and hypoxia. In addition, they have a lower chest wall compliance (increased work of breathing) than patients with a similar amount of obesity without hypoventilation. After adequate therapy of the OSA with tracheostomy or nasal CPAP, the hypercapnic ventilatory response changes. There is a parallel shift of the ventilation versus PCO z curve to the left, reflecting a higher ventilation at a given PCO z (slope un-
changed). This type of alteration in the hypercapnic ventilatory response is probably due to prevention of nocturnal worsening of CO 2 retention and the associated retention of HC0 3 . Removal of the depressant effects of chronic hypoxia on ventilatory drive also may be a factor. In any case, daytime PCO z usually decreases after treatment. Adequate treatment of patients with OHS usually requires nasal CPAP or tracheostomy. In cases of severe daytime hypoxia, daytime oxygen and the addition of oxygen to nasal CPAP at night may be required until clinical improvement occurs. Although diuretic therapy often is prescribed, the cornerstone of treatment for cor pulmonale is relief of hypoxia (and the associated pulmonary arterial vasoconstriction). Medroxyprogesterone (Provera), a respiratory stimulant that takes several days to reach maximal effect, has been used to treat patients with OHS. Treatment usually improves the level of daytime CO, retention, nocturnal oxygenation, and signs of cor pulmonale. However, this agent does not reduce the AHI nor improve symptoms of daytime sleepiness. Side effects of medroxyprogesterone include decreased libido (decreased testosterone levels), alopecia, and hyperglycemia. For these reasons, it is no longer the treatment of choice in these patients. In the present patient, the spirometric results (mild restrictive pattern) made COz retention secondary to lung disease unlikely. The presence of obesity, severe sleep apnea, and high daytime PC0 2 is consistent with OHS. After several weeks of treatment with 14 em H 20 of nasal CPAP, the daytime PC0 2 fell to 45 mmHg.
Clinical Pearls I. Unexplained CO 2 retention, obesity, and OSA suggest obesity hypoventilation syndrome (OHS). 2. Patients with OHS may present with signs of cor pulmonale rather than major complaints of excessive daytime sleepiness. 3. Adequate treatment of OSA frequently reduces the level of daytime CO 2 retention and improves the nocturnal arterial oxygen saturation and cor pulmonale. 4. Medroxyprogesterone reduces the daytime PC0 2 level in patients with OHS, but does not improve the AHI. Positive airway pressure is the treatment of choice for patients with OHS.
REFERENCES I. Sullivan CE, Berthon-Jones M, Issa FG: Remission of severe obesity-hypoventilation syndrome after short-term treatment during sleep with nasal continuous positive airway pressure. Am Rev Respir Dis 1983; 128:177-81. 2. Rajagopal KR, Abbrecht PH, Jabbari B: Effects of medroxyprogesterone acetate in obstructive sleep apnea. Chest 1986; 90:815-821. 3. Rapoport OM, Garay SM, Epstein H, et al: Hypercapnia in the obstructive sleep apnea syndrome. Chest 1986; 89:627-635. 4. Berthon-Jones M, Sullivan CE: Time course of change in ventilatory response to C02 with long-term CPAP therapy for obstructive sleep apnea. Am Rev Respir Dis 1987; 135:144-147.
201
PATIENT 61 A 55-year-old man with hypercapnic respiratory failure A 55-year-old man was admitted to the intensive care unit (ICU) with hypercapnic respiratory failure. The patient's wife reported that he snored heavily, had apneic episodes at night, and had been sleepy during the day for several years. Prior to admission, he had become increasingly somnolent and his ankles had swollen. There was no history of chest pain or fever. A previous pulmonary function test revealed only mild restrictive ventilatory dysfunction: FEV I 2.56 L (70% of predicted), FVC 3.33 L (72% of predicted), FEV/FVC 0.77. Physical Examination: Height 5 feet 9 inches, weight 250 pounds. HEENT: large tongue, dependent palate; IS-inch neck circumference. Chest: a few rales at the bases, no wheezes. Cardiac: distant heart sounds. Abdomen: very obese. Extremities: 3 + pedal edema. Neurologic: easily arousable, but very sleepy. Laboratory Findings: Chest radiograph: enlarged pulmonary arteries, no evidence of pulmonary edema. EKG: sinus rhythm, right axis deviation. Echocardiogram: normal left ventricular function, dilated right ventricle, increased estimated pulmonary arterial pressure (40 mmHg). Arterial blood gas (room air): pH 7.24, PC0 2 70 mmHg, P0 2 45 mmHg, HC0 3 30 mmol/L.
Question:
202
What is the cause of the patient's respiratory failure?
Diagnosis:
Obesity hypoventilation syndrome with acute worsening of chronic respiratory failure.
Discussion: Patients with the obesity hypoventilation syndrome (OHS) or the overlap syndrome (OSA + chronic obstructive pulmonary disease [COPD]) sometimes present with hypercapnic respiratory failure and hypoxemia. There usually is evidence of a chronic component and a history of slow deterioration with increasing somnolence and evidence of right heart failure. The diagnosis should be suspected in any obese, hypercapnic patient or in any hypercapnic patient with COPD who has an FEY I > I L. With COPD alone, hypercapnia is unusual until the FEY I falls below I L (40% of predicted). It is important to recognize the existence of OSA in patients with OHS or overlap syndrome because adequate treatment of the sleep apnea (usually tracheostomy or nasal CPAP) results in a reduction of daytime PC0 2 and an improvement in oxygenation and cor pulmonale. When sleep monitoring equipment is available in the ICU, the presence of sleep apnea can be precisely documented in stable patients. Sometimes simple observation confirms the diagnosis, but more often empiric treatment is begun, and a confirmatory sleep study is obtained after the patient's condition improves. There are several therapeutic approaches. If the patient is somnolent or the pH low on admission, nasal bilevel pressure with oxygen can be started immediately. If the patient is alert and the respiratory acidosis is well compensated, controlled oxygen therapy can be employed during the day and empiric treatment with nasal bilevel pressure or CPAP plus oxygen can be used during sleep. The level of positive pressure is titrated until obstructive apnea is prevented andlor the arterial blood gases are stabilized. One approach might be to start with a bilevel pressure of 8/4 and then titrate upward as needed. If patients have difficulty keeping their mouth shut, a full face mask can be used. Elevation of the head of the bed will minimize the amount of positive pressure required. The addition of heated humidity may help if patients have mouth leak. Of note, if significant leak is present, the high flow provided by the machine may reduce the effective FiO, supplied by the addition of oxygen. The Fi0 2 is adjusted to keep the Sa02 > 90-92%. It is not unusual to require 4-6 L per minute of oxygen or more to the positive pressure device tubing. When using bilevel pressure, remember that the level of end-expiratory positive airway pressure (EPAP) is titrated to prevent upper airway closure. When the patient is awake, a low level of EPAP usually suffices (3-5 em H,O). During sleep, the level can be increased until airway obstruction is prevented. The inspiratory positive airway pressure (IPAP) level is titrated above the EPAP level to pre-
vent hypopnea and to assist ventilation. The IPAPEPAP difference is the level of pressure support. As in any chronically hypoventilating patient, the immediate goal of noninvasive ventilation is to stabilize the pH rather than normalize the PC0 2 . Another alternative is to use positive-pressure volume-cycled ventilation (assist control mode) via nasal or full-face mask. The ventilator must be leak-tolerant; chin strips may be needed with a nasal mask to reduce mouth leak. Positive end-expiratory pressure is added to prevent upper airway closure. The Fi02 (inspired oxygen concentration) is increased to maintain adequate oxygenation. While noninvasive mask CPAP, bilevel, or volume ventilation will suffice in many patients, obtunded or rapidly deteriorating patients are best treated with endotracheal intubation and mechanical ventilation. Remember that there is considerable risk in treating patients with impaired conciousness with mask positive-pressure ventilation (aspiration, bloating). Clinical judgment is needed to determine if an acutely ill patient can be handled with mask ventilatory support. Close observation and monitoring is essential, which almost always requires an ICU setting. Acute respiratory acidosis even with a chronic component should not be treated on a general medical floor. Patients presenting with respiratory failure secondary to the OHS usually have signs of cor pulmonale (right heart failure). Treatment with diuretics may be employed; however, the main treatment of this problem is prevention of hypoxemia and the associated pulmonary arterial vasoconstriction. In the present patient, the restrictive pattern on spirometry was not severe enough to account for CO 2 retention. The history was highly suggestive of OHS. The patient was alert enough to attempt nasal ventilation, and he was started on bilevel pressure via nasal mask at an IPAP/EPAP of 10/3 cm Hp, with the addition of oxygen titrated to keep the Sa02 above 90%. IPAP/EPAP was increased to ISIS ern H20 over the first hour. The PC0 2 stabilized at 65 mmHg with the Sa02 above 90%. Treatment included diuretics. Over the next 3 days, edema decreased, and the PC0 2 gradually improved to 50 mmHg; supplemental oxygen was no longer required during the day. A partial-night sleep study revealed an AHI of 80/hr and demonstrated that bile vel pressure of 17/12 was needed to maintain upper airway patency during sleep when the patient was supine. Supplemental oxygen at I Llmin was required to maintain an oxygen saturation> 90%. The patient eventually was discharged on this treatment. When seen in clinic 3 weeks later, the daytime PC0 2 had improved to 45 mmHg.
203
Clinical Pearls 1. Patients with OHS or the overlap syndrome may present with a mixture of acute and chronic ventilatory failure. 2. Conservative therapy with oxygen and nasal CPAP, bilevel pressure. or volumecycled positive pressure ventilation (by mask) may avoid the need for intubation. If mouth leaks are a problem. try a full-face mask. Heated humidity may also improve tolerance to treatment if mouth leaks are present. 3. During sleep, the level of nasal CPAP or bilevel pressure can be titrated to prevent upper airway closure and hypopnea and desaturation. A formal sleep study and pressure titration can be performed once the patient's condition stabilizes.
REFERENCES I. Sullivan CEo Berthon-Jones M. Issa FG: Remission of severe obesity-hypoventilation syndrome after short-term treatment during sleep with nasal continuous positive airway pressure. Am Rev Respir Dis 1983; 128:177-181. 2. Shivaram U. Cash ME. Beal A: Nasal continuous positive airway pressure in decompensated hypercapnic respiratory failure as a complication of sleep apnea. Chest 1993; 104:770-774. 3. Piper AJ. Sullivan CE: Effects of short-term NIPPV in the treatment of patients with severe obstructive sleep apnea and hypercapnia. Chest 1994; 105:434-440.
204
PATIENT 62 A 57-year-old man with severe obstructive sleep apnea treated with oxygen An obese 57-year-old man was admitted to the intensive care unit twice in the same year for hypercapnic respiratory failure and congestive heart failure. Mechanical ventilation was required on one occasion, and on the other he was treated with bilevel pressure and oxygen by nasal mask. A sleep study performed after one admission showed an AHI of 80/hr and severe arterial oxygen desaturation. The patient responded to nasal CPAP, but refused treatment with this therapy. He was treated with nocturnal oxygen at 3 Umin. However, 3 months after his last admission, the patient was again admitted with hypercapnic respiratory failure and a weight gain of 30 pounds over 2 months. His wife had problems waking him up during the week prior to admission. Physical Examination: Blood pressure 160/90 mmHg, pulse 88. Height 5 feet 10 inches, weight 300 pounds. HEENT: massive tongue; 18-inch neck circumference. Chest: rales at bases. Cardiac: S4 gallop. Extremities: massive edema to upper thigh. Laboratory Findings: Arterial blood gas: pH 7.30, PC0 2 80 mmHg, P0 2 55 mmHg, HC0 3 38.4 mmollL on 4 Umin oxygen. Thyroid studies: normal. Spirometry: FEV I 2.5 L (66% predicted), FVC 3.0 L (62% predicted), FEV /FVC 0.83.
Question:
What long-term treatment do you recommend?
205
Answer:
Tracheostomy and oxygen are recommended for this patient with obesity hypoventilation
syndrome.
Discussion: Oxygen is not the treatment of choice in patients with OSA, because while oxygen may decrease the severity of nocturnal desaturation, it has only a minor impact (slight decrease) on the frequency of apnea and therefore the severity of daytime sleepiness. In severe cases, nocturnal desaturation may persist despite oxygen administration. In addition, oxygen induces modest increases in apnea duration. Interestingly, oxygen tends to decrease central and mixed apneas and increase obstructive apneas. In patients with cor pulmonale secondary to OSA who refuse more effective therapy, oxygen sometimes can result in clinical improvement. In patients with the overlap syndrome (OSA + COPD), oxygen can considerably worsen nocturnal hypercapnia. However, even in these patients, oxygen treatment may be the only alternative if nasal CPAP or other effective treatment for OSA is refused. Tracheostomy, although rarely used today, still has a place in the treatment of patients with very severe OSA. When such patients refuse other treatment, tracheostomy is preferable to an early death
from repeated bouts of severe cor pulmonale and respiratory failure. In some patients with OHS or the overlap syndrome, nocturnal desaturation persists during sleep even if upper airway obstruction is abolished. These patients have low baseline POz values in the supine position and may hypoventilate during sleep even with a patent upper airway. In such patients, treatment with both tracheostomy (or nasal CPAP) and oxygen may be necessary, at least initially. The level of hypercapnia and oxygenation may subsequently improve with adequate treatment of the cor pulmonale and OSA. Thus, not all patients require long-term oxygen therapy. After the third visit in the ICU in I year, the present patient was advised to have a tracheostomy or face possible early death. He underwent the procedure and was treated with nocturnal oxygen after a nocturnal oximetry study showed persistent desaturation post-tracheostomy. Over the subsequent month, the patient's daytime PCO z fell to 45 mmHg, and his edema improved tremendously. Two years have passed since his last bout of respiratory failure.
Clinical Pearls 1. Oxygen treatment in patients with OSA may improve nocturnal desaturation, but does not significantly decrease the AHI or the severity of daytime sleepiness. Therefore, it should be used as a treatment of last resort. 2. Patients with severe obesity, OHS, or the overlap syndrome may still have nocturnal desaturation even if upper airway patency is restored. (Supplemental oxygen is added to the trachostomy or nasal positive airway pressure tubing). 3. Tracheostomy still is a valid treatment for patients with severe, life-threatening OSA who refuse other effective therapy.
REFERENCES I. Smith PL. Haponik EF, Bleecker ER: The effects of oxygen in patients with sleep apnea. Am Rev Respir Dis 1984; 130:958-963. 2. Fletcher EC, Brown DL: Nocturnal oxyhemoglobin desaturation following tracheostomy for obstructive sleep apnea. Am J Med 1985; 79:35-42. 3. Gold AR, Schwartz AR, Bleecker ER, et al: The effect of chronic nocturnal oxygen administration upon sleep apnea. Am Rev Respir Dis 1986; 134:925-929. 4. Fletcher EC, Munafo DA: Role of nocturnal oxygen therapy in obstructive sleep apnea. Chest 1990; 98: 1497-1504.
206
PATIENT 63 A 5-year-old child with behavior problems. A 5-year-old boy had developed behavior problems over the last 6 months. He often refused to go the bed at night and would not obey his kindergarten teacher. He bullied his fellow students and stole their toys, In addition, he seemed hyperactive and was unable to pay attention during class activities.. The child's parents reported that he had restless sleep and sometimes snored. There was no history of daytime sleepiness. The child had been evaluated by his pediatrician, who felt that his tonsils were only mildly enlarged. The patient was diagnosed as having the attention deficit/hyperactivity disorder and was being treated with methylphenidate, This resulted in minimal improvement in behavior. The pediatrician ordered a sleep study, Physical Examination: Normal weight and development. HEENT: mild to moderate tonsillar enlargement. Resting awake Sa02 96%, end-tidal PC0 2 36 mmHg. Figure: The tracing below was noted on the sleep study. The end-tidal PC0 2 tracing is not a capnogram, but the average of recent peak end-tidal PC0 2 values (see Patient 64 for an example of a capnogram).
Question:
What is causing this child's behavior problems?
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207
Answer:
Obstructive sleep apnea/hypopnea syndrome.
Discussion: Obstructive sleep apnea in children usually does not present with complaints of daytime sleepiness. In fact, complaints are often of inattentive, hyperactive, and aggressive behavior. Some children who have received a diagnosis of attention-deficit/hyperactivity disorder (ADHD) are later found to have OSA. In fact, some patients evaluated in sleep centers have already been placed on methylphenidate for ADHD! While tonsillar enlargement is the etiology in most cases of pediatric OSA, the severity of the disease does not correlate with tonsillar size. The relative size and and structure of the other components of the upper airway as well as upper airway muscle activity are important for determing the effect of a given degree of tonsillar hypertrophy. Many children with large tonsils have no problems, while others with only moderate tonsillar enlargement have severe disease. Many children with sleep-disordered breathing have discrete apneas or hypopneas only during REM sleep. During NREM, there are often long periods of obstructive hypoventilation sec-
ondary to high upper airway resistance. When airflow is monitored with thermistors, obstructive hypoventilation may only be detected by a low oxygen saturation or a high end-tidal PCO). However, nasal pressure monitoring often clearly -shows a severe pattern of airflow limitation (see figure). The present patient exhibited symptoms of hyperactivity rather than daytime sleepiness. Although snoring was not prominent, long episodes of obstructive hypoventilation occurred. Note that the thermistor really does not look abnormal. However, the nasal pressure signal clearly shows a pattern of severe airflow limitation. If nasal pressure was not used, the only clues for hypoventilation would be the low Sa0 2 , paradoxical motion of the chest and abdomen, and high end-tidal PC0 2 . The end-tidal CO 2 signal is not the usual capnograph, but is the last measured end-tidal PC0 2 value. The child was referred for tonsillectomy and adenoidectomy. His sleep and behaviors were noticeably improved only a few weeks after surgery, and he was weaned off methylphenidate.
Important Differences Between Adult and Pediatric GSA CHILDREN
Clinical Findings Peak age Sex ratio Etiology Excessive daytime sleepiness Neurobehavioral Sleep Study Findings Sleep architecture Obstruction Cortical arousal
ADULTS
Preschoolers (4-6) Equal Adenotonsillar hypertrophy Uncommon
Over 45 Men> women Obesity, upper airway size Very common
Hyperactivity, developmental delay
Impaired vigilance, cognitive impairment
Normal Obstructive hypoventilation or cyclic obstruction < 50% of apneas
Decreased SWS and REM Cyclic obstruction
Tonsillectomy and adenoidectomy
CPAP
At termination of most apneas
Usual Treatment
SWS
208
=
slow wave sleep (stages 3 and 4)
Clinical Pearls I. Children with GSA often present with symptoms suggestive of ADHD rather than excessive daytime sleepiness. 2. The severity of sleep-disordered breathing does not correlate with the degree of tonsillar hypertrophy. 3. The peak incidence of pediatric GSA is in preschoolers (ages 4-6). 4. The predominant pattern of breathing abnormality is often obstructive hypoventilation without frequent arousals.
REFERENCES I. Marcus CL: Sleep-disordered breathing in children. Am 1 Resp Crit Care Med 200 I; 164: 16-30. 2. American Academy of Pediatrics: Clinical Practice Guideline: Diagnosis and Managment of Childhood Obstructive Sleep Apnea Syndrome. Pediatrics 2002; 109:704-712. 3. Chervin RD. Archbold KH. Dillon lE. et al: Inattention. hyperactivity. and symptoms of sleep-disordered breathing. Pediatrics 2002; 109:449-456.
209
PATIENT 64 A 6-year-old boy with large tonsils A 6-year-old boy was referred for evaluation of heavy snoring of 2-year duration. His parents had not noted apnea, but were concerned that he seemed to be "working hard to breathe during sleep" and was often sweaty during the night. While he was not sleepy during the day, he had trouble concentrating and was doing poorly in school. In the past the patient had been well-behaved, but he had become irritable and emotionally labile. Physical Examination: HEENT: bilateral, large tonsils (almost "kissing") with obstructed pharyngeal airway; boggy mucosa in nose. Otherwise unremarkable. Sleep Study: AHI 5/hr, long periods of increased end-tidal peo z to 55 mmHg, SaOz 92-93%. Figure: A sample tracing from a period of heavy snoring is shown below.
Question:
Should this patient have a tonsillectomy?
PetC02 Chest Abdomen 1 sec
210
Answer:
A tonsillectomy plus adenoidectomy (T&A) should be performed.
Discussion: While excessive daytime sleepiness was the main presenting complaint in several initial studies of children with OSA, more recent studies have found this complaint in only a minority ofpatients. Snoring is common in children with OSA, although it is not universally present. As in adults, simple snoring is much more common than OSA. Parents may notice restless sleep with increased inspiratory effort and diaphoresis in a child with OSA. Daytime symptoms of mouth breathing, behavioral problems, or poor progress in school may be noted. Rarely, developmental delay occurs. With the exception of children with craniofacial abnormalities, most OSA in children is secondary to obstruction from adenotonsillar hypertrophy. Interestingly, the severity of the disorder does not correlate with tonsil size. Some children have large tonsils and snoring, yet little impairment in breathing. Polysomnographic findings in children with sleep apnea also can differ from those in adults. In adults, apnea in defined as a cessation of airflow for 10 seconds or more, and the normal AHI is considered to be < 5/hr. In children, any cessation in airflow greater than two normal respiratory cycles is considered an apnea, and an AHI ~ l/hr is considered to be abnormal. Many children with OSA exhibit relatively few discrete apneas or hypopneas; instead they show long periods of hypo ventilation and desaturation. For this reason, pediatric sleep laboratories often use end-tidal PC0 2 monitoring to assess the periods of hypoventilation. An increase in end-tidal PC0 2 to 55 mmHg of any duration or > 50 mmHg for longer than 10% of the total sleep time (or> 45 mmHg for longer than 60%) is considered abnormal. Today, most large sleep centers have special monitoring rooms for pediatric patients. These rooms feature children's decor and an extra bed in the room for a parent to stay. In most children with OSA, the treatment of
choice is removal of enlarged adenoids and tonsils. Tonsillectomy generally is considered a routine surgery in children and is often performed as an outpatient procedure. However, in children with OSA, postoperative complications of T&A can occur in 16-27% of patients. Complications include upper airway obstruction, pulmonary edema, and respiratory depression from sedati ves and narcotics. One study suggests that the presence of any of the following is an indication for postoperative monitoring overnight in the hospital with oximetry: age < 2 years, craniofacial abnormalities, failure to thrive, morbid obesity, cor pulmonale, AHI > lO/hr, nadir Sa02 > 70%, and daytime hypoventilation. Overnight monitoring in a pediatric ICU should be considered for patients with elevated daytime PC0 2 . Nasal CPAP has been used in the postoperative setting to help maintain upper airway patency. Postoperative polysomnograms 6-8 weeks after T&A are recommended for patients with additional risk factors (obesity, craniofacial abnormalities, cor pulmonale) or very high AHI values pre-op to ensure an adequate response. Nasal CPAP is problematic in young children, but has been used sucessfully in patients not responding to adenotonsillectomy. In severe cases of childhood OSA with hypoventilation and craniofacial abnormalities, tracheostomy may be indicated. In the present patient, despite an AHI of only 5/hr, there were long periods of snoring, shallow breathing, and increased end-tidal PC0 2, as well as desaturation. The patient was referred to an ENT surgeon, and tonsillectomy plus adenoidectomy was performed. After surgery, the patient was monitored in the hospital overnight with oximetry, but there were no signs of desaturation. Within days his disposition, behavior, and school work improved, and he slept better.
211
Clinical Pearls 1. In children, the most common cause of OSA is hypertrophy of the adenoids and tonsils. Tonsillectomy plus adenoidectomy (T&A) is the treatment of choice in most cases. 2. After T&A, high-risk children with OSA should be monitored in the hospital overnight with oximetry. 3. In children, an AHI 2:: l/hr is considered abnormal. 4. In a pediatric study, the sleep environment should be suitable for children. Arrange for a parent to sleep in the same room with younger children. 5. Monitoring end-tidal PCO? may be useful in detecting periods of obstructive hypoventilation in pediatric patients with sleep-disordered breathing.
REFERENCES I. Rosen GM, Muckle RP, Mahowald MW, et al: Postoperative respiratory compromise in children with obstructive sleep apnea syndrome: Can it be anticipated') Pediatrics 1994; 93:784--788. 2. Carroll JL, Loughlin GM: Obstructive sleep apnea in infants and children: Diagnosis and management. In Ferber R, Kryger M (eds): Principles and Practice of Sleep Medicine in the Child. Philadelphia, WB Saunders, 1995; pp 193-230. 3. Marcus CLK, Ward SL, Mallory GB, et al: Use of nasal continuous positive airway pressure as treatment of childhood obstructive sleep apnea. J Pediatr 1995; 127:88-94. 4. American Thoracic Society: Standards and indications for cardiopulmonary sleep studies in children. Am J Respir Crit Care Med 1996; 153:866-878. 5. Schechter MS: Technical report: Diagnosis and management of childhood obstructive sleep apnea syndrome. Pediatrics 2002; 109:E69.
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PATIENT 65 A 20-year-old woman with daytime sleepiness since childhood A 20-year-old woman with moderate mental retardation was evaluated for persistent heavy snoring and leg edema. The patient had a long history of obstructive sleep apnea. Her condition deteriorated after she visited with her parents for 2 months and gained 30 pounds. Before this vacation, she was cared for at an institution for mentally retarded children and was doing well on nasal CPAP of 12 em H 20. Physical Examination: Height 60 inches, weight 210 pounds. HEENT: upsloping palpebral fissures, crowded oropharynx/dependent palate; 17-inch neck circumference. Extremities: 2 + pitting edema, short calves. Neurological: oriented to person and place, but not date; evidence of mild retardation, but able to answer questions appropriately. Figure: This tracing occurred during stage 2 sleep in the initial, diagnostic portion of the study, off positive pressure. TcPC0 2 = transcutaneous PC0 2 . Later in the study, frank obstructive apneas were noted. The awake TcPC0 2 was 50 mmHg.
Question: Why is the Sa0 2 so low (74-79%) and the transcutaneous PC0 2 so high (70 mmHg) when no discrete breathing events are noted?
C4-A2 02-Al ROC-A1
LOC-A2 chin l-chin3 -'*-...-........----"""""! EKG airflow
nasal pressure chest
abdomen
Sa02
------------~--~~-------~~
TcPC02
213
Answer:
Hypoventilation associated with the Prader-Willi syndrome.
Discussion: The Prader-Willi syndrome (PWS) is characterized by hypothalamic obesity, hyperphagia, hypogonadism, mental retardation, hypotonia (muscle weakness), and behavioral and sleep disorders. The prevalence of this disorder is 1 per 10,000 to 25,000 live births. The syndrome is associated with failure of expression of genes on the long arm of the paternally derived chromosome 15. There is a deletion of the long arm of this chromosome in approximately 50-70% of patients. PWS patients have a characteristic habitus including short stature, up-sloping palpebral fissures, and short arms and legs. Growth hormone secretion is abnormal. Some have compulsive behaviors. Daytime sleepiness may be an intrinsic manifestation of the disease, and in some patients it is worsened by sleep-disordered breathing. Some patients have sleep-onset REM. One important characteristic of patients with this syndrome is an insatiable appetite leading to massive obesity. In evaluating alterations in ventilatory control it has been difficult to separate intrinsic problems from those associated with severe obesity. However, the hypoxic ventilatory response was found to be absent or reduced in PWS patients with or without obesity. This is believed to be secondary to peripheral chemoreceptor dysfunction, although central processing of chemoreceptor information may be involved as well. The hypercapnic ventilatory responses appear to be decreased mainly in obese patients. The arousal response to hypoxia during sleep is virtually absent, and the arousal response to hypercapnia is impaired. Obese patients with Prader-Willi may have severe forms of OS A, with severe hypoxia and hypercapnia during sleep. They may also have daytime hypercapnia. Patients demon-
214
strating hypoventilation may require noninvasive venti lation. Treatment of OSA in these patients usually consists of weight loss and some form of positivepressure therapy or upper airway surgery. Weight reduction often results in considerable improvement. As PWS patients have mental retardation, weight loss is usually only possible in a very structured environment. Special group homes experienced in caring for persons with PWS have had success with weight loss. Positive-pressure treatment usually consists of nasal CPAP or bilevel pressure. Very severe cases may require nocturnal ventilatory support via tracheostomy - at least until weight loss has been effected. Recently, growth hormone replacement has been shown to improve muscle strength, decrease body fat, and improve ventilatory control in these patients. In the present case, the tracing shows what appears to be relatively normal airflow. However, the arterial oxygen saturation is very low and the transcutaneous PC0 2 high. In fact, the awake PC0 2 was also high. This patient has daytime hypoventilation that worsened during sleep. Later during the short diagnostic portion of the sleep study, traditional obstructive hypopneas and apneas were noted, with even more severe arterial oxygen desaturation. The patient required a combination of bilevel pressure 16/10 ern Hp and supplemental oxygen at 21pm to prevent nocturnal desaturation. After 2 months of treatment and an intensive weight-loss program (30pound weight loss), the daytime transcutaneous PC0 2 returned to normal, and nocturnal oxygen was no longer needed (demonstrated by nocturnal oximetry). The patient continued treatment on bilevel pressure of 16/10 em H 20, although lower levels might have sufficed.
Clinical Pearls 1. Prader-Willi Sydrome (PWS) is associated with severe obesity, obstructive sleep apnea, and abnormal ventilatory control. 2. The ventilatory response to hypercapnia and daytime CO 2 retention (if present) may normalize with weight loss and treatment of OSA. 3. Most patients have an abnormality in chromosome 15. 4. Food restriction (weight control) is an essential component of treatment. 5. Obese PWS patients with OSA often have very severe desaturations and hypercapnia during sleep.
REFERENCES I. Arens R, Gozal D. amlin KJ, et al: Hypoxic and hypercapnic ventilatory responses in Prader-Willi syndrome. J Appl Physiol
1994;77:231-2236. 2. Lindgren AC, Hellstron LG. Ritzen EM, Milerad J: Growth hormone treatment increased CO, response, ventilation. and central inspiratory drive in children with Prader-Willi syndrome. Eur J Pediatr 1999; 158:936-940. 3. Manni R, Politini L, Nobili L, et al: Hypersomnia in the Prader-Willi syndrome: Clinic-electrophysiological features and underling factors. Clin NeurophysioI2001; 112:800-805.
215
PATIENT 66 A 55-year-old man with chronic obstructive pulmonary disease and nocturnal desaturation A 55-year-old man with severe chronic obstructive pulmonary disease (CapO) underwent nocturnal oximetry monitoring to determine if nocturnal desaturation might explain the presence of cor pulmonale. He admitted to snoring, but denied daytime sleepiness. Physical Examination: Height 5 feet 10 inches, weight 180 pounds. Blood pressure 130/90 mmHg, pulse 85, temperature 37°C, respirations 20/min. HEENT: edentulous, otherwise normal; 15Yz-inch neck circumference. Chest: decreased breath sounds. Cardiac: no murmurs or gallops. Extremities: I + pedal edema. Laboratory Findings: Spirometry: FEV I 1.1 L (29% of predicted), FVC 2.5 L (52% of predicted), FEV /FVC 0.44. Arterial blood gas (room air): pH 7.43, PC0 2 38 mmHg, P0 2 65 mmHg, HC0 3 25 mmol/L. Figure: A tracing from the nocturnal oximetry monitoring is shown below.
Question:
What is causing the nocturnal arterial oxygen desaturation?
0~
....C
0
:.;:::; CO L.. :::J .-
100
80 70
m
60
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50
0> >0-
40
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X 0
m
.~
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t
m
- -
•
90
30 20 10
11
PM
12
1
2
AM
time FIGURE 1
216
3
4
5
6
7
Answer:
Chronic obstructive pulmonary disease.
Discussion: Patients with capo can have arterial oxygen desaturation during sleep for several reasons. First, the normal sleep-associated 8- to 10mmHg fall in P0 2 has much greater significance if the baseline presleep PO? value is on the steep part of the oxyhemoglobin saturation curve (P0 2 50-60 mmHg). At this point, a normal fall in P02 during NREM sleep results in significant arterial oxygen desaturation. Second, periods of sleep apnea of varying significance may occur. (See Patient 70 for a discussion of the overlap syndrome [CaPO + OSA]). Third, nonapneic arterial oxygen desaturation can be abrupt and severe during REM sleep in patients with capo. The REM-associated desaturations are believed to be secondary to hypo ventilation during periods of hypopnea, as well as to an increase in ventilationperfusion (V/Q) mismatch. Often, the hypopneic periods are not well-defined and consist of small, variable tidal volumes over periods of time as long as several minutes. During REM sleep, the diaphragm is the only active muscle of inspiration (REM-associated skeletal muscle hypotonia). In patients with capo, diaphragmatic function often is compromised secondary to hyperinflation. In addition, neural drive to the diaphragm may fall during bursts of eye movements in REM sleep, producing hypopnea (or central apnea). An increase in VIQ mismatch during these episodes also may contribute to hypoxemia. The increase in V/Q mismatch is believed to be secondary to a decrease in functional residual capacity during these REMrelated hypopneic episodes. Patients with capo may have REM-associated desaturations without having sleep apnea even if
their daytime P0 2 is 60 mmHg. As expected, these REM-associated desaturations occur every 90-120 minutes during the night. The most severe and longest periods of desaturation typically occur in the early morning hours, when REM periods are longer and the REM density (number of eye movements per minute) is greater. In contrast, the pattern of arterial oxygen desaturation on an all-night plot in patients with OSA shows a saw-tooth pattern consistent with repetitive, discrete episodes of desaturation. Several studies have determined equations to predict the severity of nocturnal desaturation in capo patients based on awake measurements. In general, patients with lower Sa02 and higher PC0 2 are more likely to have significant nocturnal desaturation. However, there is considerable individual variation. In the present patient, the nocturnal oximetry showed a fall in Sa02 to below 85% (Fig. I), with further episodes of steep desaturation (black bars) probably associated with REM sleep. A complete sleep study was performed because of the history of snoring (despite the fact that the oximetry was not suggestive of sleep apnea). The dramatic falls in Sa0 2 were associated with hypopneic breathing during REM sleep. The baseline Sa02 again fell to less than 85% for the majority of NREM sleep. The AHI was only 10/hr. A tracing from NREM sleep (Fig. 2) shows low Sa02 despite regular airflow. In contrast, a tracing from REM sleep shows irregular, small tidal volumes; reduced chest wall motion (chest wall muscle hypotonia); and a lower Sa0 2• The patient was treated with nocturnal oxygen, and improvement in pedal edema was noted. (See Patient 68 for a discussion of the treatment of nocturnal oxygen desaturation associated with capo.)
217
NREM
~~
REM
~~~~
~~Vi~ LOC - A 2
~ ~~'1;J~
chin EMG ur,," I'~ •• , H'.
10 I
.1..
Airflow Chest
Abdomen
85% 75% FIGURE 2
Clinical Pearls I The usual pattern of nocturnal desaturation due to COPD is a fall in baseline 5a0 2 during NREM sleep, with more dramatic falls occurring during episodes of REM sleep. 2. A saw-tooth pattern in the 5a02 tracing suggests that substantial sleep apnea is present. 3. REM-associated desaturation in patients with COPD usually is secondary to periods of hypoventilation (hypopnea) rather than apnea. I
REFERENCES I. Fletcher EC, Gray BA, Levin DC: Nonapneic mechanisms of arterial oxygen desaturation during rapid-eye-movement sleep. J Appl Physiol 1983; 54:632-639. 2. Hudgel DW, Martin RJ, Capehart M. et al: Contribution of hypoventilation to sleep oxygen desaturation in chronic obstructive pulmonary disease. J Appl Physiol 1983; 55:669-677. 3. Douglas NJ. F1enley DC: Breathing during sleep in patients with obstructive lung disease. Am Rev Respir Dis 1990; 141: 1055-1069.
218
PATIENT 67 A 60-year-old man with leg swelling A 60-year-old man with a long history of heavy smoking and chronic obstructive pulmonary disease (COPD) was referred for evaluation. He had failed to qualify for home oxygen therapy on a recent examination. The patient had bouts of mild pedal edema during courses of steroid therapy for exacerbations of COPD. These bouts responded to diuretics. There was no history of snoring, and the patient denied daytime sleepiness. He used inhaled bronchodilators only on an as-needed basis. Physical Examination: Height 5 feet 8 inches, weight 160 pounds. Blood pressure 140/89 mmHg, pulse 78. HEENT: edentulous; 15 YJ-inch neck circumference. Chest: bilateral wheezing. Cardiac: distant sounds. Extremities: I + pedal edema. Laboratory Findings: ABO (room air): pH 7.42, PCO z 38 mmHg, PO z 62 mmHg, HC0 3 23 mmol/L. Spirometry: FEV I 1.6 L (46% of predicted), FVC 3.2 L (73% of predicted), FEV/FVC 0.50. Chest x-ray: possible mild enlargement of the pulmonary arteries.
Question:
Should this patient have polysomnography or nocturnal oximetry?
219
Answer:
Nocturnal oximetry suffices in this case.
Discussion: Some degree of nocturnal arterial oxygen desaturation is common in patients with moderate-to-severe capo. One study found that daytime measurements of lung function could predict nocturnal desaturation. Although there was considerable variability, the lower the SaO z and the higher the PCO z, the more likely nocturnal desaturation was to occur. The study also found that the survival of patients with greater-than-predicted nocturnal desaturation was no worse than that of patients with less nocturnal desaturation. The authors concluded that sleep studies were not useful in patients with capo unless sleep apnea was suspected. Another study of capo patients with daytime paz > 60 mmHg found that 27% showed some desaturation during sleep, although most of the desaturations were during REM sleep and often brief. Desaturation could not be predicted on the basis of daytime studies. In a subsequent investigation, modest improvements in daytime pulmonary artery pressures were documented in a group of patients with daytime paz > 60 mmHg and nocturnal oxygen desaturation who received oxygen treatment. However, it is not clear that these improvements are clinically significant. To date, there appears to be no clear benefit to diagnosing or treating isolated periods of REM-associated nocturnal desaturation. With the current state of knowledge, the clinician must individualize the decision for sleep studies and nocturnal oxygen treatment in patients with capo not qualifying for 24-hour oxygen treatment on the basis of daytime paz. A sleep study is indicated if obstructive sleep apnea (or another cause of excessive daytime sleepiness) is suspected. Patients with significant unexplained cor pulmonale might benefit from some type of sleep study. The usual criteria for continuous oxygen therapy are a daytime paz :S; 55 mmHg or 55-59 mmHg plus
evidence of end-organ damage (cor pulmonale). Patients who qualify for oxygen on the basis of these criteria do not need a sleep study unless sleep apnea is suspected or they have failed to respond to oxygen treatment. For patients with a daytime paz 2: 60 mmHg and evidence of significant cor pulmonale, a sleep study could provide documentation of significant nocturnal desaturation. However, there are no clear criteria for what constitutes significant nocturnal desaturation, and the optimal type of sleep study is not known. It probably is reasonable to use nocturnal oxygen to treat capo patients with a daytime paz > 60 mm Hg who have significant desaturation « 85%) in both NREM and REM sleep-especially if cor pulmonale is present. However, no clear benefit of doing so has been documented. The type of sleep study used to evaluate for nocturnal desaturation often depends on local resources. Oximetry alone may suffice in many cases. However, if the tracings suggest the presence of sleep apnea, a full sleep study (and nasal CPAP titration) may be required. The clinician should remember that oxygen is not the only treatment for nocturnal desaturation. In the original Nocturnal Oxygen Treatment Trial, 21 % of the patients screened no longer met criteria when they were placed on intensive bronchodilator therapy. Some patients with minimal acute improvement in the FEY I and FYC have steady improvement in oxygenation when treated with smoking cessation and bronchodilator therapy. In the present patient, sleep apnea was not suspected, and nocturnal oximetry revealed only brief periods of mild desaturation (to 85%), probably associated with stage REM sleep. The baseline SaO z remained above 92% for most of the night. The patient was treated with more aggressive bronchodilator therapy, including the long-acting inhaled beta agonist salmetrol.
Clinical Pearls 1. The clinical suspicion of sleep apnea is the main indication for a sleep study in patients with capo. 2. In patients not qualifying for continuous oxygen treatment, sleep monitoring may be indicated if significant, unexplained cor pulmonale is present. 3. The criteria for what constitutes significant nocturnal desaturation and the benefits of treating such desaturation (in the absence of daytime hypoxemia) remain to be demonstrated.
220
REFERENCES 1. Nocturnal oxygen Therapy Trial Group: Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease. Ann Intern Med 1980; 93:391-398. 2. Cannaughton JJ, Catterall JR, Elton RA: Do sleep studies contribute to the management of patients with severe chronic obstructive pulmonary disease? Am Rev Respir Dis 1988; 138:341-344. 3. Fletcher EC, Luckett RA, Goodnight-White S, et al: A double-blind trial of nocturnal supplemental oxygen for sleep desaturation in patients with chronic obstructive pulmonary disease and a daytime P0 2 above 60 mmHg. Am Rev Respir Dis 1992; 145: 1070-1076.
221
PATIENT 68 A 55-year-old man with chronic obstructive pulmonary disease and severe pedal edema A 55-year-old man with severe capo was referred for evaluation of cor pulmonale. He did not qualify for home oxygen on a recent examination. The patient denied daytime sleepiness, but complained of frequent awakenings. His wife noted that he frequently snored, but she had never observed episodes of apnea. Physical Examination: Pulse 90, blood pressure 130/90 mmHg. Height 5 feet 8 inches, weight 170 pounds. Chest: bilateral wheezing. Cardiac: regular rate and rhythm. Extremities: 3 + pedal edema. Laboratory Findings: Spirometry: FEV I 1.0 L (27% of predicted), FVC 3.0 L (64% of predicted), FEV ,/FVC 0.33 (80-120% of predicted). Chest radiograph: hyperinflation, large pulmonary arteries. Arterial blood gas (room air): pH 7.42, PC0 2 45 mmHg, P0 2 62 mmHg, HCO) 25 mmol/L. Sleep Study Time in bed Total sleep time Sleep period time (SPT) Sleep efficiency (%) Sleep latency REM latency AHI
445 min (378-468) 350 min (340-439) 425 min (361-453) 79 min (88-96) 10 min (1-22 min) 2.5 min (65-104) 4/hr«5)
( ) = normal values for age
Question:
222
What treatment do you recommend?
Sleep Stages
%SPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
18 (2-7) 13 (4-12) 49 (51-72) 5 (0-13) 15(17-25)
Mean Sa0 2
NREM REM
84% 70%
Answer:
Optimize treatment of COPD and initiate low-flow nocturnal oxygen.
Discussion: Low-flow oxygen by nasal cannula can prevent the typical, nonapneic arterial oxygen desaturation manifested by patients with COPD, without substantially increasing the nocturnal PC0 2• However, oxygen is expensive and therefore should be prescribed only when it is likely to be worth the cost. The benefits of chronic 24-hour oxygen therapy in patients with COPD have been well documented by the Nocturnal Oxygen Treatment Trial (NOTT) and other studies of patients meeting the standard criteria of a daytime P0 2 :5 55 mmHg breathing room air. The value of 55 mmHg was chosen because below this point pulmonary arterial pressure starts to increase significantly secondary to hypoxic vasoconstriction. In the NOTT study, patients also received oxygen if the P0 2 was 55-59 mmHg and evidence of end-organ damage was present (edema, hematocrit> 55%, or P pulmonale on EKG). Today most physicians would consider evidence of significant cor pulmonale or neurologic dysfunction an indication for oxygen treatment in this group with borderline oxygenation. In the group of patients meeting criteria for 24hour oxygen, sleep studies are not indicated unless sleep apnea is suspected. However, the clinician often is faced with the difficult question of what to do about patients not meeting any of the above criteria (daytime P0 2 2:: 60 mmHg). Some patients may benefit from nocturnal oxygen therapy if significant and prolonged nocturnal desaturation is present. However, one study comparing patients with mild daytime hypoxemia could find no difference with respect to mortality or development of pulmonary
hypertension between groups with and without nocturnal desaturation during short-term follow-up up to 6 years. Indeed, criteria for what constitutes significant nocturnal desaturation have not been standardized (see Patient 67). While low-flow supplemental oxygen induces little increase in CO 2 in most stable COPD patients during sleep, this is not the case if significant sleep apnea also is present (the overlap syndrome). When such patients are treated with oxygen, varying amounts of desaturation persist, the apneas tend to lengthen, and the nocturnal PCO? may increase significantly. Patients with the overlap syndrome also may complain of a morning headache after oxygen is initiated. Oxygen alone is not the optimal treatment for this group of patients. (See Patient 70 for a detailed discussion of the overlap syndrome.) In the present patient, a sleep study was ordered because of the history of snoring (to rule out OSA). The study revealed a low AHI and relatively few discrete desaturations (changes in Sa0 2 2:: 4%). However, the baseline Sa0 2 during NREM sleep was below 85% and even lower in REM sleep (64 min). An echocardiogram was consistent with cor pulmonale (right ventricle dilation, normal left ventricle function). Therefore, it was believed that the patient would benefit from nocturnal oxygen therapy. A separate oximetry study documented that oxygen at a flow rate of 2 Llmin maintained a saturation above 90% for all but a few brief desaturations (probably in REM sleep). The patient was begun on nocturnal oxygen therapy and his pedal edema improved. He also reported improved sleep quality
Clinical Pearls 1. The criteria for treatment of COPD with a daytime PO? 2:: 60 mmHg and nocturnal desaturation are not well defined. Patients with significant desaturation in both NREM and REM sleep may benefit from oxygen treatment, especially if evidence of significant cor pulmonale is present. 2. Low-flow oxygen treatment for COPD-associated nocturnal desaturation usually does not cause significant increases of nocturnal CO 2 unless significant sleep apnea is present.
REFERENCES I. Nocturnal Oxygen Therapy Trial Group: Continuous or nocturnal oxygen therapy in hypoxemic chronic obstructive lung disease. Ann Intern Med 1980; 93:391-398. 2. Goldstein RS, Ramcharan V. Bowes G. et al: Effect of supplemental nocturnal oxygen on gas exchange in patients with severe obstructive lung disease. N Engl J Med 1984; 310:425-429. 3. Douglas NJ. Flenley DC: Breathing during sleep in patients with obstructive lung disease. Am Rev Respir Dis 1990; 141:1055-1069. 4. Chaouat A. Weitzenblum E. Kessler R. et al: Outcome of COPD patients with mild daytime hypoxemia with or without sleeprelated oxygen desaturation. Eur Resp J 2001; 17:848-855.
223
PATIENT 69 A 60-year-old "pink puffer" with insomnia A 60-year-old man with severe chronic obstructive pulmonary disease (COPO) was referred for complaints of poor sleep. He had difficulty falling asleep and then awakened several times during the night. Sometimes the awakenings were associated with dyspnea. There was no history of snoring or daytime sleepiness. The patient's medications included theophylline 300 mg bid and albuterol by metered-dose inhaler. Physical Examination: Height 5 feet 10 inches, weight 150 pounds. Blood pressure 150/80 mmHg, pulse 95. General: thin, nervous; no acute distress. HEENT: unremarkable; IS-inch neck circumference. Chest: hyperresonant to percussion, diminished breath sounds. Cardiac: distant heart sounds. Extremities: no edema. Laboratory Findings: Spirometry: FEV I 1.5 L (40% of predicted), FVC 2.8 L (59% of predicted), FEV/FVC 0.54, OLCO 15 ml/min/mmHg (44% of predicted). Chest radiograph: hyperinflation. ABG (room air): pH 7.43, PC0 2 38 mmHg, P0 2 65 mmHg. Theophylline level: 11.5 mg/ml.
Question:
224
What treatment do you recommend?
Answer:
Try a long-acting inhaled bronchodilator.
Discussion: The sleep of patients with COPO is poor, with low sleep efficiencies and, often, reduced amounts of slow wave and REM sleep. Patients may complain of frequent awakenings. Many different approaches have been tried to improve sleep in these patients, but all of the approaches share one limitation: no one actually knows what is waking patients up. For example, isolated hypoxemia is a poor arousal stimulus. One study suggested that supplemental oxygen improves sleep, while another did not find an improvement. Cough or wheezing also could awaken patients. However, cough usually does not occur during sleep. Nocturnal dyspnea is another possible cause of disturbed sleep. Patients with COPO have an exaggeration of the normal diurnal variation in lung function, with FEV I worsening around 6 AM. Many bronchodilators taken at bedtime may have worn off by the time they are most needed. Sustained-action theophylline might have an advantage; however, this drug's stimulant properties could disturb sleep. Studies have suggested that the advantages may balance the side effects in some patients. Moreover, the stimulatory side effects vary in severity among individuals. Salmeterol, a long-acting beta-agonist, has the potential of being an effective bronchodilator with less central nervous system stimulation. The effects of theophylline and salmeterol on sleep quality have not been directly compared in COPO patients, but one study of patients with asthma showed only a minimal advantage with salmeterol (slightly fewer arousals). Thus, both of these medications may be useful in patients with COPO and nocturnal/early morning dyspnea. Another alternative is to use an increased dose of ipratropium bromide at bedtime (4 puffs qhs). This
medication has few systemic side effects, and the higher dose may give a longer duration of effective bronchodilation. One study of ipratropium (0.02% solution) nebulized qid found an improvement in nocturnal oxygenation and an increase in REM sleep compared to placebo in a group of patients with moderate to severe COPO. A new, long-acting anticholinergic, tiotropium, is now available in the U.S. and may be useful in treating nocturnal symptoms in patients with COPO. Some patients with COPO may still complain of disturbed sleep despite optimal medical management. They often request sleeping pills, and many take over-the-counter medications. The question arises: Are hypnotics safe in these patients? Numerous studies of hypnotic medications have found minimal worsening of nocturnal saturation. One important caveat is that most of the patients in these studies were stable (no acute exacerbations) and nonhypercapnic. Hypnotics can worsen obstructive sleep apnea; therefore, recipients should not have the overlap syndrome. This said, one would probably want to use shorter-acting benzodiazepines (triazolam, temazepam) or the nonbenzodiazepines zolpidem or zaleplon. Other alternatives would be to use sedating tricyclic antidepressants (Sinequan and others) in low doses. Certainly each case must be individualized. Question patients carefully about morning confusion or memory loss. In the present case, the patient reported that theophylline made him "jumpy." He was switched from theophylline to salmeterol (2 puffs every 12 hours). He also was given a limited supply of zolpidem 5 mg to use on occasional nights when he was unable to fall asleep. On this regimen the patient noted improved sleep most nights.
Clinical Pearls I. Patients with COPO have poor sleep quality with a low sleep efficiency and reductions in REM and slow wave sleep. 2. There is conflicting evidence about whether oxygen therapy improves sleep quality in hypoxemic patients. 3. In many patients the benefits of long-acting bronchodilator medications may balance potential side effects secondary to central nervous system stimulation. 4. Some patients with complaints of insomnia on theophylline may improve on longacting inhaled beta-agonists. Ipratropium bromide may also be useful. 5. Short- or intermediate-duration benzodiazepine hypnotics and the nonbenzodiazepine hypnotics usually result in only minimal worsening in breathing during sleep in stable nonhypercapnic patients with COPO. Caution still is indicated.
225
REFERENCES I. Calverly PMA, Brezinova V, Douglas NJ, et al: The effect of oxygenation on sleep quality in chronic bronchitis and emphysema. Am Rev Respir Dis 1982; 126:206-210. 2. Berry RB, Desa MM, Branum JP, et al: Effect of theophylline on sleep and sleep-disordered breathing in patients with chronic obstructive pulmonary disease. Am Rev Respir Dis 1991; 143:245-250. 3. Girault C, Muir JF, Mihaltan F, et al: Effects of repeated administration of zolpidem on sleep, diurnal and nocturnal respiratory function, vigilance, and physical performance in patients with COPD. Chest 1996; 110:1203-1211. 4. Selby C, Engleman HM, Fitzpatrick MF, et al: Inhaled salmeterol or oral theophylline in nocturnal asthma. Am J Respir Crit Care Med 1997; 155:104-108. 5. Martin RJ, Bartelson BL, Smith P, et al: Effect of ipratropium bromide treatment on oxygen saturation and sleep quality in COPD. Chest 1999;115: 1338-1345.
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PATIENT 70 A 52-year-old man with chronic obstructive pulmonary disease and pedal edema A 52-year-old man was being treated for severe COPD with bronchodilators and continuous oxygen therapy at 1 Llmin. Despite this treatment he had severe, persistent pedal edema and CO 2 retention. Large doses of diuretics had not improved the pedal edema. His wife reported that he snored and fell asleep in front of the television during the day. The patient attributed this to poor sleep at night. Physical Examination: Height 5 feet 9 inches, weight 200 pounds. Blood pressure 150/90 mmHg, pulse 88. HEENT: edematous uvula, dependent palate; 17-inch neck circumference. Chest: bilateral wheezes. Cardiac: distant heart sounds. Extremities: 3+ pedal edema. Laboratory Findings: Spirometry: FEY I 1.7 L (46% of predicted), FYC 3.0 L (64% of predicted), FEY /FYC 0.57. ABG: pH 7.36, PC0 2 55 mmHg, P0 2 58 mmHg on 1 Llmin of oxygen by nasal cannula. Chest radiograph: large pulmonary arteries, no pulmonary edema. Figure: Below is a trace of the initial part of a nocturnal recording of Sa0 2 (on oxygen at 1 Llmin by nasal cannula).
Question:
Would complete polysomnography be useful?
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227
Answer: Yes. A sleep study (diagnostic/nasal positive airway pressure titration) is indicated in this patient with the overlap syndrome. Discussion: This patient fits the classic description of the "blue bloater" variant of COPD (hypercapnia plus cor pulmonale). Recently, it has been appreciated that many such co PO patients also have obstructive sleep apnea (OS A). Such patients are said to have the overlap syndrome (COPD+ OSA). This combination has important consequences in terms of morbidity and treatment. A low baseline PO z and/or ventilation-perfusion mismatch secondary to COPD results in more significant oxygen desaturation during apnea. Thus, OSA patients with COPD tend to have more severe arterial oxygen desaturation and cor pulmonale. Most OSA patients do not have daytime CO? retention. Those that do usually have a component of COPD or the obesity hypoventilation syndrome. However, the presence of OSA may impair ventilatory drive, so that while patients with hypercapnic COPD usually have an FEV I < I L, overlap patients may retain CO 2 with more moderate degrees of airflow obstruction. The amount of CO? retention in overlap patients does not necessarily correlate with the AHI. One study comparing hypercapnic and nonhypercapnic patients with the overlap syndrome found no difference in the FEV I and AHI between the two groups. The hypercapnic group was heavier and had a history of heavy ethanol use. The authors hypothesized that the hypercapnic patients had depressed respiratory drives possibly secondary to the effects of alcohol. As effective treatment of OSA in patients with the overlap syndrome can result in a reduction of daytime PCO z, nocturnal CO z retention secondary to apnea probably is contributory to the development of hypercapnia in overlap patients. What are the implications of this combination of diseases (COPD + OSA)? The most obvious is that both diseases need to be treated for optimal results. Thus, the daytime gas exchange of the patient with OSA and mild COPO may improve when bronchodilator therapy is added to treatment of OSA (nasal CPAP or bilevel therapy). In the patient with
228
COPD and significant sleep apnea, treatment with oxygen alone may not adequately prevent nocturnal oxygen desaturation. In this group, low-flow oxygen also can result in significant nocturnal increases in CO? Studies suggest that oxygen alone does not improve right-sided heart failure if apnea is not adequately treated. Conversely, OSA patients with low POz values when awake may need oxygen plus nasal positive pressure to prevent nocturnal desaturation. When the upper airway obstruction of hypercapnic patients with the overlap syndrome is adequately treated, the daytime PCO z frequently improves. As previously discussed in Patient 45, some patients with COPD find bilevel pressure more tolerable than CPAP. When should a sleep study be ordered in a patient with known COPD? The major indication is a suspicion of sleep apnea (snoring, daytime sleepiness). Another is evaluation of a patient already using nocturnal oxygen who is not showing improvement in cor pulmonale. If resources are limited, a simple overnight pulse oximetry test may show the sawtooth pattern suggestive of sleep apnea. However, this approach can be more costly in the long run if a nasal positive airway pressure titration is then required. In the present patient, oximetry showed the sawtooth pattern of desaturation consistent with OSA (refer to figure). The worsening of SaO z at A is probably secondary to an episode of REM sleep. Note the low baseline SaO z and the persistence of decreased SaO z after each event. The patient underwent polysomnography while receiving his usual oxygen. An AHI of 50/hr was documented. Nasal CPAP was titrated, and apnea and hypopnea were abolished at 10 em HzO. Addition of oxygen at 2 Umin was needed to maintain SaO z above 90%. Treatment with a combination of nasal CPAP and oxygen was begun, and the patient's daytime sleepiness and pedal edema improved. After I month of nasal CPAP, the daytime PCO z had decreased to 45 mmHg.
Clinical Pearls I. A saw-tooth pattern on the Sa0 2 trace in a patient with capo suggests that OSA also is present. 2. If a capo patient with only moderately severe airflow obstruction has daytime COo retention, suspect the presence of the overlap syndrome. 3. In the overlap syndrome, adequate treatment of both capo and OSA is required. 4. Supplemental oxygen therapy of nocturnal desaturation alone is not optimal treatment for most patients with capo and significant OSA. 5. Nasal positive airway pressure (CPAP or bilevel pressure) plus oxygen if needed is probably the most effective therapy for patients with capo and significant OSA who have a low P0 2 when awake.
REFERENCES I. Bradley TD, Rutherford R, Lue F. et al: Role of diffuse airway obstruction in the hypercapnia of obstructive sleep apnea. Am Rev Respir Dis 1986; 134:920-924. 2. Fletcher EC. Schaaf JW. Miller J, Fletcher JG: Long-term cardiopulmonary sequelae in patients with sleep apnea and chronic lung disease. Am Rev Respir Dis 1987; 135:525-533. 3. Chan CS. Grunstein RR. Bye PTP. et al: Obstructive sleep apnea with chronic airflow limitation: Comparison of hypercapnic and eucapnic patients. Am Rev Respir Dis 1989; 140:1274-1278. 4. Sampol G. Sagales MT, Roca A. et al: Nasal continuous positive airway pressure with supplemental oxygen in coexistent sleep apnea-hypopnea syndrome and severe chronic obstructive pulmonary disease. Eur Respir J 1996; 9:111-116.
229
PATIENT 71 A 35-year-old woman with asthma and poor sleep at night A 35-year-old woman had been treated for moderate-to-severe asthma since age 15. Her medications included sustained-action theophylline 450 mg qam and 300 mg at 6 PM, inhaled albuterol 2 puffs qid, and inhaled f1uticasone 220 meg/spray 2 puffs bid. Her symptoms were improved with higher doses of f1uticasone, but she was worried about potential side effects. During several severe exacerbations the patient was treated with oral prednisone. She had gained about 15 pounds in the last 2 years. Over the past year, the patient had reported frequent awakenings with shortness of breath. In the morning she felt sleepy and somewhat wheezy. The patient's roommate reported loud snoring and gasping for air during the night. Physical Examination: Height 5 feet 2 inches, weight 130 pounds. General: slightly "cushinoid" appearance. HEENT: edematous uvula and palate; 15-inch neck circumference. Chest: bilateral expiratory wheezes. Cardiac: normal. Extremities: no edema. Laboratory Findings: Spirometry (3 PM): FEY I 1.8 L (63% of predicted), FYC 3.0 L (90% of predicted), FEY/FYC 0.60. Theophylline level (12 noon): 12.0 mg/ml. Peak Flow Diary (Umin) 6 AM 10 PM A WAKENINGS* 6 AM 10 PM A WAKENINGS* Day I Day 2 Day 3
200 225 225
300 325 300
3 2 3
Day 4 Day 5 Day 6
225 180 200
325 300 300
• Awakenings are from the preceding night.
Questions:
230
What is your diagnosis? What other evaluation do you suggest?
4 3 3
Answers: Nocturnal asthma (documented diurnal variation in airflow). Consider a sleep study to rule out obstructive sleep apnea. Discussion: Nocturnal worsening of symptoms and sleep disturbance are significant problems for patients with asthma. In one study, up to 40% experienced symptoms every night. There is a normal circadian variation in airway function, with the highest airflow in the late afternoon (4 PM) and the lowest in the early morning (4 AM). This normal variation is exaggerated in patients with obstructive airway diseases: FEY 1 or peak flow can fall as much as 20-40% in the morning hours ("morning dippers"). The etiology of this variation is multifactorial and includes circadian changes in the amounts of circulating steroids and, possibly, inflammatory mediators in the lungs, as well as changes in cholinergic tone. Sleep also appears to have an adverse effect on asthma, independent of other factors. The easiest way to diagnose severe nocturnal worsening of asthma is to have the patient record peak flow measurements at bedtime and upon awakening. Treatment of patients with nocturnal asthma should begin with inhaled corticosteroids. This medication has been shown to reduce the circadian fluctuation in airway tone. Patients with continued nocturnal symptoms despite an adequate dose of inhaled corticosteroids can then be treated with a long-acting bronchodilator. Theophylline has been proven effective despite the stimulatory effects of the medication. In dosing theophylline, the goal should be to obtain the highest levels during the time of greatest airflow obstruction (at night and early morning). Long-acting oral beta agonists have also proven helpful. However, long-acting inhaled beta agonists (salmeterol and formoterol) are probably the most popular long-acting bronchodilators. These drugs are effective treatment for nocturnal asthma and may cause less systemic stimulation and sleep disruption than theophylline. Interestingly, in terms of sleep quality (arousals), Selby and coworkers found only a slight advantage for salmeterol compared to theophylline: the falls in morning flow rates were similar, but awakenings
were less frequent on salmeterol. Weigand et al found salmeterol to be more effective than theophylline at preventing the morning drop in flow rates. The drugs did not differ in polysomnographic findings, but patients perceived better sleep with salmeterol than theophylline. In any case, the longacting beta agonists require less attention to dosing than theophylline. While asthmatics generally have a greater response to beta-agonists than anticholinergic medications, vagal tone is increased at night. Studies have shown an improvement in nocturnal peak flow after ipratropium bromide. A higher bedtime dose (4 puffs) may be needed for a more prolonged duration of action. Finally, asthmatic patients may have other sleep disorders. If obstructive sleep apnea (OSA) is present, adequate treatment may improve the control of asthma as well as symptoms of daytime sleepiness. The reasons that OSA may worsen asthma are at present unknown. In the current case, the peak flow diary confirmed severe morning dipping. The theophylline dosing was changed to 450 mg at 10 PM and 300 mg qam to provide the highest levels when needed. The patient reported fewer nocturnal symptoms, but felt her sleep was not as sound (more awakenings). Theophylline was changed to salmeterol, 2 puffs every 12 hours, with inhaled albuterol as needed between salmeterol doses. Morning peak flows improved to 250-325 Llmin, and the patient reported a decrease in the number of prolonged awakenings to one or less per night. Despite these changes, complaints of falling asleep during the day persisted. A sleep study revealed an AHI of 30/hr. During the second half of the sleep study, a nasal CPAP titration documented elimination of snoring and apnea at 7 em Hp. Treatment with nasal CPAP resulted in improvement in symptoms of daytime sleepiness and further improvement in nocturnal symptoms of asthma.
231
Clinical Pearls I. The degree of diurnal variation in airflow can most easily be documented by peak flow measurements at bedtime and on awakening. 2. When OSA is present in asthmatic patients, adequate treatment of OS A may improve the asthma. 3. The addition of a long-acting bronchodilator is indicated if patients with nocturnal asthma do not respond to inhaled steroids, or if the required dose of inhaled steroids is higher than desired. 4. Long-acting inhaled beta agonists taken at bedtime have been shown to improve morning flow rates as well as, if not better than, theophylline. Patients may also perceive better sleep quality. 5. If theophylline is used, dosing should be such that the highest levels are during the night or the early morning hours.
REFERENCES I. Chan CS. Woolcock AI. Sullivan CE: Nocturnal asthma: Role of snoring and obstructive sleep apnea. Am Rev Respir Dis 1988;
137:1502-1504. 2. Beam WR, Weiner DE. Martin RI: Timing of prednisone and alterations of airways inflammation in nocturnal asthma. Am Rev Respir Dis 1992; 146:1524-1530. 3. Martin RI: Nocturnal asthma: Circadian rhythms and therapeutic interventions. Am Rev Respir Dis 1993; 147:525-528. 4. Selby C. Engleman HM, Fitzpatrick MF, et al: Inhaled salmeterol or oral theophylline in nocturnal asthma? Am I Respir Crit Care Med 1997; 155:104-108. 5. Weersink ElM. Douma RR, Postma DS. et al: Fluticasone propionate, salmeterol xinafoate, and their combination in the treatment of nocturnal asthma. Am I Resp Crit Care Med 1997; 155:1241-1246. 6. Weigand L. Mende CN, Zaidel G, et al: Salmeterol vs theophylline. Sleep and efficacy outcomes in patients with nocturnal asthma. Chest 1999;115:1525-1532.
232
FUNDAMENTALS OF SLEEP MEDICINE 16
Central Sleep Apnea
Central apnea is defined as a cessation in airflow of 10 seconds or longer that is associated with an absence of respiratory effort. Patients with CSA comprise less than 15% of patients with sleep apnea evaluated at most sleep centers. Some central apneas are common in patients with obstructive sleep apnea (OSA). However, the diagnosis of central sleep apnea (CSA) syndrome requires that the majority of apneic events be central in nature. The exact proportion of central events required is not clear; some physicians diagnose CSA when 50-80% of the events are central. Of note, many patients who exhibit central apneas also exhibit central hypopneas (reduction in airflow associated with a reduction in inspiratory effort) or simply hypoventilate during sleep with relatively few discrete events. Unless you measure esophageal pressure, it may be difficult to differentiate central from obstructive hypopnea. However, central hypopneas usually exhibit a rounded nasal pressure signal profile (Fig. 1).
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The CSA syndrome affects a heterogeneous mix of patients that can be subdivided into a group with daytime hypoventilation (hypercapnic) and a group without hypoventilation (non-hypercapnic; see table). The group with hypoventilation includes patients with a defect in ventilatory control (primary central alveolar hypoventilation) and patients with neuromuscular disorders. These patients usually have a history of bouts of respiratory failure and cor pulmonale. The nonhypercapnic group is composed of patients with Cheyne-Stokes breathing (usually secondary to congestive heart failure [CHF]) and patients in whom no obvious cause for the CSA exists (idiopathic CSA).
Patients With Central Sleep Apnea Syndrome HYPERCAPNIC
Idiopathic central hypoventilation Neuromuscular diseases Brainstem disease
NON-HYPERCAPNIC
Idiopathic central sleep apnea Cheyne-stokes breathing • Associated with congestive heart failure • Associated with neurological disease Sleep at high altitude During nasal CPAP titration
233
Cheyne-Stokes breathing (CSB) is a specific type of periodic breathing that is associated with a crescendo-decrescendo pattern of ventilation, with central apneas (Fig. 2) or central hypopneas at the nadir. Arousals tend to occur near the maximum point of ventilatory effort (sometime after apnea cessation) in Cheyne-Stokes breathing. In idiopathic central apnea, arousals tend to occur at apnea termination, and ventilatory drive returns abruptly (see Fig. 2). Most cases of Cheyne-Stokes breathing secondary to CHF also have a longer cycle time (longer ventilatory phase between apneas) and a long delay in the nadir in Sa0 2 (long circulation time). The length of the ventilatory phase tends to correlate with the length of circulation time (decreased cardiac output). The apnea length depends on the amount of hypocapnia at sleep onset.
Cheyne-Stokes Breathing A
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Patients may develop central apnea during positive-pressure titration. In some patients with combined OSA and Cheyne-Stokes breathing secondary to heart failure, CSB-CSA will be manifest once the obstructive component is eliminated with positive pressure. In other OSA patients undergoing positive-pressure titration, central apneas may occur following arousals from respiratory effort-related arousals (inadequate pressure) or from arousals secondary to excessive pressure or mouth leak. In the first case, higher pressure may eliminate the events. Of note, early studies of OSA patients after tracheostomy documented persistent central apneas that tended to resolve over time. Sleep Apnea and Congestive Heart Failure. The interaction between sleep apnea and the heart has attracted considerable attention. It has been realized that complaints of shortness of breath and frequent awakening at night are not necessarily secondary to paroxysmal nocturnal dyspnea due to CHF.
Types of Sleep Apnea in Patients with CHF Obstructive sleep apnea Mixed obstructive and central sleep apnea Central sleep apnea and Cheyne-Stokes breathing (CSA-CSB) One recent study of 450 men and women with CHF identified risk factors for the presence of obstructive and central sleep apnea. Risk factors for CSA included male sex, atrial fibrillation, age> 60, and hypopcapnia (PC0 2 < 38 mmHg) during wakefulness. Risk factors for OSA included a high body mass index (BMI) in men and increased age in women. Studies have suggested that the presence of CSA in patients with CHF means a worse prognosis. Treatment of patients with OSA and cardiomyopathy has been shown to improve cardiac function. Treatment of patients with CHF and CSA with nasal CPAP was associated with a significant improvement in left ventricular ejection fraction at 3 months and a relative risk reduction of 81 % in mortality-cardiac transplantation rates."
234
REFERENCES I. Bradley TO. McNicholas WT. Rutherford R. et al: Clinical and physiologic heterogeneity of the central sleep apnea syndrome. Am Rev Respir Dis 1986; 134:217-221. 2. Malone S. Liu PP. Holloway, et al: Obstructive sleep apnea in patients with dilated cardiomyopathy: Effects of continuous positive airway pressure. Lancet 1991; 33: 1480-1484. 3. Javaheri S. Parker Tl. Wexler L. et al: Occult sleep-disordered breathing in stable congestion heart failure. Ann Intern Med 1995;122: 487-492. 4. Hanly PI, Zuberi-Khokhar NS: Increased mortality associated with Cheyne-Stokes respiration in patients with congestive heart failure. Am I Resp Crit Care Med 1996; 153:272-276. 5. Sin DO. Logan AG. Fitzgerald FS et al: Effects of continuous positive airway pressure on cardiovascular outcomes in heart failure patients with and without Cheyne-Stokes respiration. Circulation 2000; 102:61--66. 6. Van AT. Bradley TO. Liu PP: The role of continuous positive airway pressure in the treatment of congestive heart failure. Chest 2001; 120:1675-1685.
235
PATIENT 72 A 58-year-old man with daytime sleepiness A 58-year-old man complained of daytime sleepiness of 2-year duration. His wife reported that he occasionally snored and was a "restless sleeper." There was no history of muscle weakness, orthopnea, pedal edema, or respiratory failure. Physical Examination: Blood pressure 150/85 mmHg, pulse 80, temperature 37°C, respiratory rate 15. General: thin. HEENT: unremarkable; 15-inch neck circumference. Chest: clear to auscultation and percussion. Cardiac: normal. Extremities: no edema. Neurologic: normal. Sleep Study: AHI 35/hr. No periodic limb movements. Figure: Over 70% of the respiratory events (apneas and hypopneas) were similar to the one illustrated below.
Question: What is the cause of the patient's daytime sleepiness?
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236
Diagnosis: Idiopathic central sleep apnea. Discussion: Central sleep apnea (CSA) occurs because the PCO? is below the apneic thresholdthe level of PCO~ during sleep below which ventilation is absent. -The apneic threshold is usually only 1-2 mmHg below the awake PCO? values. Most patients in stable sleep have PC02 levels around 5 mmHg higher than the wake values. Hyperventilation during wakefulness does not cause apnea because of the presence of the wakefulness stimulus-a poorly defined but important component of ventilatory drive that is lost during sleep. During NREM sleep, ventilation depends on metabolic control. If the PC0 2 falls below the apneic threshold for any reason (even in normals), central apnea is the result. The presentation of idiopathic CSA is somewhat variable, including complaints of insomnia, daytime sleepiness, or choking during the night. In a recent series, the symptom of excessive daytime sleepiness was the major presenting complaint. Snoring may occur in idiopathic CSA, but is less prominent than in OSA. Patients with idiopathic CSA also tend to be thinner than those with OSA. Of the patients with non-hypercapnic CSA, Cheyne-Stokes breathing is more common than idiopathic CSA. In one study, only 5% of over 300 patients with sleep apnea had idiopathic CSA. Polysomnography in idiopathic CSA typically reveals frequent, isolated central apneas or runs of central apneas (one form of periodic breathing). A run of central apneas may follow arousal from a non-respiratory stimulus. Central apneas during NREM sleep occur most commonly in stage I or 2 sleep. Central apnea is believed to occur because the PC0 2 level is below the apneic threshold (the lowest PC0 2 triggering ventilation during sleep). This is consistent with the findings that most patients with idiopathic CSA have relatively low PC0 2 values when awake and asleep, and that central apneas usually follow periods of increased ventilation. In Figure 2, a central apnea (*) follows a big breath (arrow). Patients with idiopathic CSA also have increased ventilatory responses to CO 2 compared to normal individuals. In a recent study, an increase in the baseline
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awake PC0 2-by either CO 2 administration or the addition of dead space-decreased the amount of central apnea. The periods of increased ventilation triggering central apneas often are associated with arousal. Arousal may trigger a transient increase in ventilation and a fall in PC0 2. This transient fall in PC0 2 is then associated with a central apnea as the patient returns to sleep (below the apneic threshold). Thus, arousal may initiate or predispose to continuation of central apnea. In some patients with idiopathic CSA, central apnea occurs mainly in the supine position. Some investigators have hypothesized that reflexes triggered by upper airway collapse may inhibit respiration in these patients. These may be the reasons that some patients with CSA respond to nasal CPAP treatment. In the present patient, over 70% of the respiratory events were central apnea (Fig. 1). Note the absence of movement in the chest and abdominal tracings. The predominance of central apneas that were not of the Cheyne-Stokes type and the absence of symptoms or signs of congestive heart failure resulted in a diagnosis of idiopathic CSA. (See Patient 73 for a discussion of treatment for idiopathic CSA).
237
Clinical Pearls 1. Idiopathic eSA occurs in nonhypercapnic patients without an obvious associated disease (neurologic disorder or congestive heart failure). 2. While many patients with idiopathic eSA complain of excessive daytime sleepiness and have a history of snoring, some complain primarily of insomnia (frequent awakenings). 3. Idiopathic eSA is uncommon and these patients comprise less than 5% of patients with sleep apnea. 4. Patients with idiopathic eSA have low daytime peo 2 levels. Arousal from sleep may trigger several large breaths with a subsequent central apnea.
REFERENCES I. Dempsey JA. Skatrud JB: A sleep-induced apneic threshold and its consequences. Am Rev Respir Dis 1986; 133: 1163-1 170. 2. Xie A, Wong B, Phillipson EA, et al: Interaction of hyperventilation and arousal in pathogenesis of idiopathic central sleep apnea. Am J Respir Crit Care Med 1994; 150:489-495. 3. Xie A, Rutherford R, Rankin F, et al: Hypocapnia and increased ventilatory responsiveness in patients with idiopathic central sleep apnea. Am J Resp Crit Care Med 1995; 152: 1950-1955. 4. Xie A, Rankin F. Rutherford R, et al: Effects of inhaled CO, and added dead space on idiopathic central sleep apnea. Am Rev Respir Dis 1997; 82:918-926. -
238
PATIENT 73 A 55-year-old man with central sleep apnea A 55-year-old man with complaints of frequent awakenings and moderate daytime sleepiness was evaluated by polysomnography. He snored occasionally, and his wife had noted some brief pauses in his breathing during the night. There was no history of leg jerks or symptoms of congestive heart failure. The patient's only medication was an angiotensin-converting enzyme inhibitor for hypertension. Physical Examination: Blood pressure 150/85 mmHg, pulse 80 and regular. HEENT: dependent palate. Cardiac: normal. Chest: clear, no rales. Extremities: no edema. Sleep Study: AHI 30/hr. Respiratory events: obstructive apnea 5%, mixed apnea 15%, central apnea 75%, hypopnea 5%. Figure: A sample tracing is shown below.
Question:
What treatment do you recommend?
15 sec
A
90%
239
Answer:
Nasal CPAP is effective treatment in some patients with idiopathic central sleep apnea.
Discussion: There is no uniform consensus about the best treatment for patients with idiopathic CSA (central sleep apnea). This group is heterogeneous, and treatment must be individualized. Because idiopathic CSA is relatively rare, no longterm studies of the effectiveness of any treatment have been published. Treatments of Idiopathic CSA Nasal CPAP Triazolam Acetazolamide Oxygen therapy (selected patients)
Triazolam, a benzodiazepine, reduced the frequency of idiopathic CSA in one study, probably by decreasing the number of arousals or the amount of hyperventilation associated with arousal. Obviously, sedatives are contraindicated in the hypercapnic forms of CSA. Nasal CPAP also has been reported to decrease central apnea in patients with idiopathic CSA. The mechanisms by which CPAP works are unknown. Two possibilities are that nasal CPAP slightly increases the sleeping PC0 2 or prevents upper airway reflexes from initiating apnea. The level of CPAP required to prevent central apnea may exceed the level necessary to prevent obstructive events. Patients who snore or have central apnea mainly in the supine position might be assumed to be the best candidates for CPAP treatment. Of note, one case report found that CP AP
helped but bilevel pressure worsened central sleep apnea. The authors hypothesized that CP AP worked by inducing a modest increase in PC0 2 during sleep. As noted in Patient 72, the addition of dead space or inhaled CO 2 has been shown to decrease central apnea in patients with idiopathic CSA. In patients with OSA, central apneas can sometimes appear on CPAP (usually post arousal) or when CPAP induces repetitive arousals from sleep (levels of CPAP presumably too high). Various respiratory stimulants have been tried as treatments for idiopathic CSA, with variable amounts of success. The best evidence is for use of acetazolamide (Diamox), which is a carbonic anhydrase inhibitor. Acetazolamide induces a metabolic acidosis and reduces the pH even if the PC0 2 also decreases slightly. One study found modest success with a dose of 250 mg given I hour before bedtime: the AHI was reduced by approximately 50% and symptoms improved, although sleep efficiency was not significantly better. Oxygen therapy also has been reported to decrease the amounts of nocturnal desaturation and central apnea in selected patients. In the present patient, apnea was noted to be predominantly central. In the tracing, the small oscillations at A represent movement from cardiac contractions. He snored, and therefore treatment with CPAP was tried. The patient underwent a CP AP titration, and at 10 em HoO the AHI was reduced to 8/hr. Treatment with nasal CPAP resulted in improvement of symptoms.
Clinical Pearls I. Idiopathic central sleep apnea is rare, present in 5% or less of patients with sleep apnea. 2. No consensus exists about the best treatment for idiopathic CSA. Treatment must be individualized. 3. Nasal CPAP may be effective in some patients with idiopathic CSA. 4. Alternative treatments include acetazolamide, hypnotics, and oxygen therapy.
REFERENCES I. Issa FG. Sullivan CE: Reversal of central sleep apnea using nasal CPAP. Chest 1986; 90: 165-171. 2. Hoffstein V. Slutsky AS: Central sleep apnea reversed by continuous positive airway pressure. Am Rev Respir Dis 1987; 135:1210-1212. 3. Bonnet MH. Dexter JR. Arand DL: The effect of triazolam on arousal and respiration in central sleep apnea patients. Sleep 1990; 13:31-41. 4. DeBacker WA. Verbacken J. Willemen M et al: Central apnea index decreases after prolonged treatment with acetazolamide. Am J Resp Crit Care Med 1995: 151:87-91. 5. Franklin KA. Eriksoon P. Sahlin C. et al: Reversal of central sleep apnea with oxygen. Chest 1997; Ill: 163-169. 6. Hommura F. Nishimura M. Oguri M, et al: Continuous versus bilevel positive airway pressure in a patient with idiopathic central sleep apnea. Am J Respir Crit Care Med 1997; 155: 1482-1485.
240
PATIENT 74 A 70-year-old man with daytime sleepiness and pedal edema A 70-year-old man was evaluated for complaints of waking at night gasping for air and daytime sleepiness over several years. The patient's wife also reported that he snored while supine and occasionally stopped breathing. He was being treated for hypertension and occasional episodes of leg swelling. Physical Examination: Blood pressure 130/80 mmHg, pulse 90, respiratory rate 15. General: no acute distress. Cardiac: S3 gallop, PMI laterally displaced. Chest: rales at the lung bases. Extremities: 1+ pedal edema. Sleep Study: AHI 52/hr. Respiratory events: obstructive apnea 0%, mixed apnea 75%, central apnea 15%, hypopnea 10%. Figure: A mixed apnea characteristic of this patient is shown in the tracing below.
Question:
Is this a typical case of obstructive sleep apnea?
Airflow 5a02 chest abdomen
vVVlf
1J1Jwv-98%
88%
~ 5 sec
B
l'
A
241
Diagnosis: Obstructive (mixed) sleep apnea with underlying Cheyne-Stokes breathing due to congestive heart failure. Discussion: Sleep-disordered breathing is common but often unrecognized in patients with congestive heart failure. At least three forms of sleep apnea exist in these patients: (I) Cheyne-Stokes breathing (CSB) with central apnea, (2) traditional obstructive sleep apnea (OSA), and (3) a combination of CSB and OSA, producing mixed and central apneas. Many clinicians fail to suspect sleep apnea because complaints of poor sleep are attributed to dyspnea secondary to congestive heart failure. Recognition of sleep-disordered breathing is important because treatment not only improves nocturnal oxygenation and sleep quality, but may improve cardiac function. Patients with CSB+OSA can mimic the typical OSA presentation, with complaints of excessive daytime sleepiness and mixed apnea on polysomnography. The presence of CSB may be overlooked until treatment is attempted with nasal CPAP. Once the obstructive component is prevented, the repetitive central apneas of CSB are unmasked. Typical evidence of CSB is a crescendo-decrescendo pattern of ventilation with central apnea or hypopnea at the nadir in ventilatory effort. However, the return of ventilatory effort following central apnea is associated with upper airway closure in some patients. This causes an obstructive portion of apnea following the central part. In some patients, apnea is mixed in the supine position (predisposing to airway closure) and purely central (CSB pattern) in the lateral decubitus position.
Some differences in mixed apnea between the two disorders are notable. The mixed apnea ofCSB tends to have a longer central than obstructive component. Also, in typical OSA a number of totally obstructive apneas usually are present. When CSB is secondary to congestive heart failure, the nadir in arterial oxygen saturation is delayed secondary to an increased circulation time. Finally, mixed apnea in patients with typical OSA resolves once upper airway obstruction is prevented. In contrast, patients with CSB have an underlying instability in ventilatory control that causes persistence of CSB. Although neurologic disease can cause CSB, congestive heart failure is by far the most common cause. The present patient had mixed apnea with a long central component and a short obstructive portion (see figure, area A). The small, rapid deflections in the abdominal tracing represent cardiac contractions (B). The most interesting finding was the unusual position of the nadir (88%) in arterial oxygen saturation. At first glance the nadir appears to occur before, rather than after, apnea termination. However, the illustrated nadir is actually the consequence of the preceding apnea (not shown). The severity of congestive heart failure was unappreciated by the physicians taking care of the patient. A subsequent nuclear medicine study (multiple gated acquisition) revealed a left ventricular ejection fraction of 30%. (See Patients 75 and 76 for discussions on the treatment of CSB with and without an obstructive component).
Clinical Pearls I. Cheyne-Stokes breathing may present as a sleep apnea syndrome, with mixed and central apneas and daytime sleepiness. 2. A delay in the nadir of the arterial oxygen saturation is a clue that a long circulation time is present. This is evidence of significant cardiac dysfunction. 3. Sleep-disordered breathing in patients with congestive heart failure (obstructive sleep apnea, CSB, or a combination) frequently is unrecognized and may negatively impact patient outcome if not adequately treated.
REFERENCES 1. Dowdell WT. lavaheri S. McGinnis W: Cheyne-Stokes respiration presenting as sleep apnea syndrome. Am Rev Respir Dis 1990; 141:871-879. 2. lavaheri S. Parker Tf, Wexler L. et al: Occult sleep-disordered breathing in stable congestive heart failure. Ann Intern Med 1995; 122:487-492.
242
PATIENT 75 A 60-year-old man with severe congestive heart failure and daytime sleepiness A 60-year-old man with known congestive heart failure (left ventricular ejection fraction 30%) was referred for complaints of daytime sleepiness. His wife denied hearing snoring but had noted her husband gasping for air and breathing irregularly during sleep. The patient also noted paroxysmal nocturnal dyspnea and had been admitted several times for exacerbations of congestive heart failure. Physical Examination: Pulse 85 and regular, blood pressure 110170 mmHg. HEENT: normal palate; no jugular venous distention; IS-inch neck circumference. Chest: bilateral rales. Cardiac: S3 gallop, grade 2 holosystolic murmur at the apex. Extremities: 2 + pedal edema. Laboratory Findings: Arterial oxygen saturation (room air): 94%. Sleep Study: AHI 50/hr (70% central apneas, 30% hypopneas), arousal index 40/hr, desaturation index 30/hr « 85%), mean Sa0 2 at desaturation 85%. Figure: This sample tracing of airflow and arterial oxygen saturation (Sa0 2) shows multiple central apneas. Vertical arrows mark the timing of arousals.
Question:
What is the diagnosis?
20 sec Airflow
243
Diagnosis:
Central apnea with Cheyne-Stokes breathing secondary to heart failure.
Discussion: Cheyne-Stokes breathing (CSB) is defined as a crescendo-decrescendo pattern of breathing with central hypopnea or apnea at the nadir. It is caused by an instability in ventilatory control. The two most common causes of CSB are congestive heart failure (CHF) and neurologic disease (cerebrovascular accidents). The vast majority of CSB is secondary to CHF; the incidence of CSB in patients with severe CHF of any cause is as high as 40-50%. CSB often is unsuspected, as typical patients only exhibit it during sleep. The etiology of CSB in patients with CHF was formerly attributed to delayed feedback of changes in blood gases to the ventilatory controllers (long circulation time), thus producing an "overshoot" in ventilation. During sleep, when the PCO? drops below the apneic threshold, central apnea occurs. One would expect the CHF patients with CSB to have longer circulation times (as a consequence of worse cardiac function). However, when groups of CHF patients with and without CSB were compared, the main difference was not the degree of cardiac dysfunction (left ventricular ejection fraction), but the slightly lower daytime peo z levels in CSB patients. Other studies have shown that patients with CSB have lower PCO? during sleep, higher LV filling pressures, and higher hypercapnic ventilatory drives. Higher ventilatory drives would predispose to an overshoot in ventilation. Higher filling pressures may stimulate pulmonary receptors (stiff lungs), which may also increase ventilation. In some patients, the sleeping PCO z decreases during the night possibly secondary to increasing LV filling (and pulmonary capillary) pressures. In this patient, CSB may appear only in the second or last third of the night. CSB may be associated with frequent arousal from sleep and daytime sleepiness. Unfortunately, clinicians typically assume that these symptoms are secondary to dyspnea associated with CHF. Interestingly, the arousals associated with CSB often occur at the zenith of ventilatory effort (see figure, arrows), rather than at apnea termination. Significant arterial oxygen desaturation is common in CSB patients, despite a normal daytime SaO z' Neither oxygen desaturation nor repetitive activation of the sympathetic nervous system is beneficial to patients already suffering from cardiac dysfunction. It is not surprising that the presence of CSB in patients with CHF signals a worse prognosis. The optimal treatment of CSB associated with CHF is not yet known. Certainly treatment starts with optimization of cardiac function. Other treatments for CSB associated with CHF include posi-
244
tive airway pressure and oxygen therapy. Theophylline also lowers the amount of CSB; however, treatment may not reduce the number of arousals and there is a concern about inducing arrhythmias with this medication. Thus, this medication is rarely used for CSB and CHF. Nasal CPAP can reduce the amount of CSB acutely in a few patients. However, chronic treatment with CPAP for I or more months is required in most patients. Acutely, an optimal pressure cannot be identified with a CPAP titration in most patients. The usual strategy is to start treatment with 5 ern HzO or a higher pressure if needed to eliminate any component of obstruction. Pressure is then increased to 10-12 em H?O as tolerated over several weeks. If patients are not sleepy, a period of "desensitization" to CPAP during the day may be needed befor CPAP is started. A pressure of 10-12 ern H?O was shown to be effective in several studies. The mechanisms by which CPAP reduces CSB are thought to include a modest increase in PCO}' an increase in oxygen stores (less desaturation), and a long-term improvement in cardiac function. Bilevel pressure can also be tried, although using too high a IPAP-EPAP difference could actually worsen CSB by augmenting a tendency to overshoot. However, in pressure-sensitive patients, CPAP may not be tolerated, and bilevel is an option. Oxygen treatment (2-4 Ipm) by nasal cannula has also been shown to reduce CSB and associated arousals and desaturation. Adaptive servo-ventilation (ASV) is a new, noninvasive ventilatory mode developed with the goal of rapid improvement in CSB (even on the first treatment night). In this method, a low level of EPAP (about 5 cm HzO) is used (sufficient to prevent obstruction), and the level of IPAP varies (4-10 cm H 20 ) depending on the previous level of ventilation. The IPAP-EPAP difference increases during low periods of ventilation and decreases during high levels of ventilation. Thus, the amount of ventilatory support "adapts" to stabilize ventilation. The device also uses a back-up rate of IS/min. One study comparing oxygen, nasal CPAP, bilevel pressure (mean pressure 13/5 em HzO) with a back-up rate, and ASV found that all reduced the amount of central apnea, but ASV was the most effective. It reduced the central apnea index from around 35/hr to less than 5/hr. This form of ventilation is promising, but is not yet available for clinical use. Does treatment of CSB with CPAP improve cardiac function or survival? Short-term studies have shown improvement in cardiac function and a reduction in sympathetic tone with CPAP. One
study also suggests that CPAP can improve survival in patients with CHF and central sleep apnea (see Fundamentals 16). This may be secondary to reduction in hypoxia, sympathetic tone, and a decrease in afterload. A multicenter trial is underway in Canada to compare conventional care to CPAP in patients with severe CHF (CANPAP study)
to determine if CPAP reduces mortality in these patients. The present patient was treated with ongoing nasal CPAP at 10 cm H20 . He reported improved sleep quality, and over the next several weeks noted a dramatic decrease in pedal edema although his medications were unchanged.
Clinical Pearls I. The type of central apnea that includes Cheyne-Stokes breathing (CSB) is common and often unsuspected in patients with significant congestive heart failure (CHF). 2. CSB can present with symptoms of daytime sleepiness and disturbed sleep. 3. Adequate treatment of CSB associated with CHF can improve sleep, cardiac function, and perhaps even the long-term prognosis of these patients. 4. The best treatment for patients with CHF and CSB plus central sleep apnea is not known. Nasal CPAP or oxygen are current treatment options. 5. A level of nasal CPAP that effectively reduces CSB acutely often cannot be identified. The usual approach (assuming no OSA is present) is to start with a low level ofCPAP (5 ern H20 ) and increase to 10-12 cm H20 over several weeks as tolerated.
REFERENCES I. Hanly PJ. Millar TW, Steljes DO, et al: The effect of oxygen on respiration and sleep in patients with congestive heart failure. Ann Int Med 1989: 111:777-782. 2. Naughton M, Bernard D, Tam A, et al: Role of hyperventilation in the pathogenesis of central sleep apnea in patients with congestive heart failure. Am Rev Respir Dis 1993; 148:330-338. 3. Jahavheri S, Parker TJ, Wexler L, et al: Effect of theophylline on sleep-disordered breathing in heart failure. N Engl J Med 1996; 335:562-567. 4. Teschler H, Dohring J, Wang Y, Berthon-Jones M: Adaptive pressure support servo-ventilation. A novel treatment for CheyneStokes respiration in heart failure. Am J Resp Crit Care Med 2001: 164:614--619. 5. Yan AT, Bradley TD. Liu PP: The role of continuous positive airway pressure in the treatment of congestive heart failure. Chest 2001; 120:1675-1685.
245
PATIENT 76 A 60-year-old man with obstructive sleep apnea and numerous central apneas on CPAP A 60-year-old man with a diagnosis of obstructive sleep apnea (OSA) was referred from another sleep laboratory for a nasal CPAP titration. His previous sleep study showed an AHI of 60/hr. Figure: A tracing of a central apnea at a CPAP level of 12 ern HoO is shown below.
Sleep Study-CPAP Trial
10
12
15
60
60
20
30
50
50
40
35
30
0
0
0
0
0
0
% mixed apnea
100
50
0
0
0
0
% central apnea
0
0
0
100
100
100
% hypopnea
0
50
100
0
0
0
Desaturations < 85%
40
30
10
0
0
0
Arousal index (/hr)
40
35
20
10
10
10
CPAP(cm HP) NREM (min) AHI (lhr) % obstructive apnea
Question:
0
5
120
60
55
7.5
What is causing the central apnea?
Nasal CPAP 12 em H
2O
Airflow
N\)
Chest Abdomen Sa0 2
246
90%
96%
Diagnosis:
Cheyne-Stokes breathing presenting as obstructive sleep apnea (mixed apnea).
Discussion: When patients with OSA (mixed apnea) and underlying Cheyne-Stokes breathing (CSB) are treated with nasal CPAP, the CSB tends to be unmasked. In typical cases of mixed apnea, CPAP abolishes the obstructive component by preventing upper airway obstruction. However, in patients with OSA plus CSB, the centraL component persists secondary to the underLying eSB. The sudden appearance of repetitive central apnea during a CPAP titration may be a surprise if the underlying CSB was not appreciated on the diagnostic study. Note that central apneas also may appear during upward titration of CPAP if high levels of pressure trigger arousal and hyperventilation (followed by central apnea on return to sleep). However, these central apneas will not be of the Cheyne-Stokes type. Cheyne-Stokes breathing also may not be appreciated when central hypopnea rather than apnea is noted at the nadir in ventilation. If the flow signal is used from the positive-pressure devices, the shape of inspiratory flow is usually rounded during central hypopnea (see Fundamentals 16). The first goal of CPAP titration in these patients is to prevent upper airway obstruction. As discussed in Case 75, further upward titration of CPAP usually does not abolish CSB, but may reduce desaturation and arousal. Acute reduction of CSB may be secondary to increases in PCO, or a reduction in the severity of desaturation. When no level of CPAP abolishes CSB, one approach is to treat with pressure at 10-12 em H 20 (or a higher
level if needed to prevent upper airway obstruction). Several studies have shown that treatment during sleep with this level of nasal CPAP in patients with congestive heart failure (CHF) produces long-term improvements in cardiac function-by improving oxygenation, decreasing afterload, and decreasing sympathetic stimulation from frequent arousals. Improvements in cardiac function should eventually decrease the amount of CSB. However, one study of similar patients showed no improvement in symptoms of cardiac function when nasal CPAP at a level of 7.5 em H 20 was compared with placebo after 2 weeks. This result emphasizes that treatment must be individualized and monitored carefully. It may also take longer than 2 weeks to see an improvement. Long-term effects of CPAP may depend on the preload status of the patient. In the present case, the CPAP trial shows a conversion from mixed apnea to hypopnea and finally to central apnea as the level of CPAP increased. Further upward titration did not eliminate the central apneas, but the number of arousals was decreased, and oxygenation was much improved. Examination showed a crescendo-decrescendo pattern of breathing with central apneas or hypopneas at the nadir, consistent with CSB. An echocardiogram revealed unsuspected cardiac dysfunction. CPAP at 12 em H 20 was prescribed, and on a repeat sleep study 2 months later the AHI was reduced to IO/hr. Improved cardiac function also was evident.
Clinical Pearls 1. CPAP therapy may uncover Cheyne-Stokes breathing (CSB) in patients with congestive heart failure once the obstructive component has been eliminated. 2. CSB (central apnea) usually persists despite upward titration of CPAP. 3. The goals of CPAP therapy in patients with both upper airway obstruction and CSB secondary to heart failure are to prevent airway obstruction, improve oxygenation, and provide a pressure sufficient to improve cardiac function (10-12 em H 20 in most patients).
REFERENCES 1. Takasaki Y, Orr D, Popkin J, et al: Effect of nasal continuous positive airway pressure on sleep apnea in congestive heart failure. Am Rev Respir Dis 1989; 140: 1578-1584. 2. Dowdell WT, Javaheri S, McGinnis W: Cheyne-Stokes respiration presenting as sleep apnea syndrome. Am Rev Respir Dis 1990; 141:871-879. 3. Bradley TD, Holloway RM, McLaughlin PR, et al: Cardiac output response to continuous positive airway pressure in congestive heart failure. Am Rev Respir Dis 1992; 145:377-382. 4. Davies RJO, Harrington KJ, Ormerod OJM, et al: Nasal continuous positive airway pressure in chronic heart failure with sleep disordered breathing. Am Rev Respir Dis 1993; 147:630-634. 5. Yan AT, Bradley TD, Liu PP: The role of continuous positive airway pressure in the treatment of congestive heart failure. Chest 2001;120: 1675-1685.
247
PATIENT 77 A 12-year-old boy with daytime CO 2 retention A 12-year-old boy underwent a sleep study to determine if his noninvasive nocturnal ventilation with bile vel pressure was adequate to prevent severe desaturation or nocturnal hypercapnia. As a young child he had undergone tracheosotomy and home ventilation. Currently the patient was using nasal bilevel ventilatory support only at night. During prior evaluations his respiratory muscle strength and lung function had been normal. Physical Examination: HEENT: healed tracheostomy scar; no tonsillary enlargement. ABG on room air: pH 7.34, PC0 2 55 mmHg, P0 2 65 mmHg, HC0 3 30 mmol/L. Figure: Tracing was obtained during NREM sleep, off bilevel pressure support.
Question:
What is the diagnosis?
! airflow
Arousal
J, Awakening
!VVVVVVVIN\Arv-IINJV\I\/\/'vv"vwv-"/'/IIVWV'f',t.rVI!W.fJ\fWWJ\NVWN
chest abdomen
Sa02 (
)
180 seconds
248
Answer:
Congenital central hypoventilation syndrome.
Discussion: Congenital central hypoventilation syndrome (CCHS), also known as idiopathic CCHS, was formerly called Ondine' curse. CCHS is a congenital form of severe central hypoventilation of undetermined etiology. The hypoventilation is not on the basis of neuromuscular disease or lung disease: the defect is in the central metabolic control of breathing. The voluntary control of breathing is intact, and the peripheral chemoreceptors have normal responses to hypercapnic and hypoxia. However, there is an absence or severe decrease in the hypoxic or hypercapnic ventilatory responses. The defect is believed to be in the central integration of chemoreceptor information. Most patients with CCHS present at birth with apnea or erratic spontaneous breathing. They typically have cyanosis. Other patients present soon after birth with pulmonary hypertension or respiratory failure. The hypoventilation is worse during sleep, but also usually is present during wakefulness. The additional drive to breath during wakefulness (wakeful drive) is the reason most patients hypoventilate less during wake. Some children may require 24-hour ventilatory support. There is a higher than expected frequency of neuroblastoma and Hirschsprung' s disease with CHHS; other causes of central hypoventilation syndrome are listed in the table. Late-onset CCHS is a rare syndrome in which patients present at ages 2-4 and have associated hypothalamic abnormalities. Sleep studies in CCHS typically show a reduc-
tion in tidal volume and breathing rate, but frank central apnea is not common. Unlike other breathing disorders, some patients with CHHS have worse breathing problems during NREM than REM sleep. This may be explained by the fact that metabolic control of respiration occurs during NREM sleep. Ventilation during REM sleep is less related to hypoxic and hypercapnic stimuli. Patients with CCHS will arouse from high levels of hypoxic hypercapnia. Central Hypoventilation Syndromes in Children Primary Congenital CHS Late-onset CHS Secondary Obesity hypoventilation Associated with brainstem lesions*
*Amold-Chiari type I or II, achondroplasia with stenosis of the foremen magnum. hypoxic encephalopathy, trauma, meningoencephalitis, poliomyelitis, tumor In the present case the tracing shows central hypoventilation and hypopnea during sleep. Note the decrease in Sa02• The patient was placed back on bilevel pressure of 16/9 via a nasal mask (see figure below), On this level of support the patient did well during NREM and REM sleep. This is an example of a milder case of CCHS in which the patient does not require ventilatory support during the day.
Bllevel19/6 em H20 bilevel now vVY'{IlV\Yo/YY'N'{'{'lvY'IV'vYNvYN-..'Y'V''JY'fV'VY'{VVV'N\'Y'NYY''/VV'{V'V\ chest
abdomen 5002
98% (
)
180 seconds
249
Clinical Pearls I. Congenital central hypoventilation syndrome (CCHS) is secondary to a defect in the metabolic control of ventilation. The hypoventilation is not due to lung disease, upper airway abnormality, or neuromuscular weakness. 2. Sleep studies of CCHS show periods of central hypopnea and hypoventilation (rare central apnea). 3. Noninvasive pressure support (bilevel) with or without oxygen during sleep may suffice in some cases. Others need 24-hour ventilatory support via tracheostomy. 4. In some patients with CCHS, the hypoventilation is more severe in NREM than REM sleep.
REFERENCES I. American Thoracic Society: Idiopathic congenital central hypventilation syndrome: Diagnosis and management. Am J Resp Crit Care Med 1999;160:368-373. 2. Marcus CL: Sleep-disordered breathing in children. Am J Resp Crit Care Med 2001; 164:16-30.
250
PATIENT 78 A 75-year-old man with a history of polio A 75-year-old man was seen for complaints of daytime somnolence and pedal edema. At age 30 he had a severe case of poliomyelitis with weakness in the arms and legs. After partial recovery, he enjoyed good health until the last few years. About 2 years ago, unexplained pedal edema began to occur. An arterial blood gas test (room air) at that time revealed: pH 7.36, PCO z 50 mmHg, pOz 65 mmHg, HCO) 25 mmol/L. The patient was started on nocturnal oxygen, at 2 L/min by nasal cannula at night, and his pedal edema improved. No sleep study was performed at that time. The patient's wife reported that he rarely snored or gasped for air at night. Over the last few months, the patient had become increasingly somnolent during the day, and his ankles began to swell. Physical Examination: Vital signs: unremarkable. HEENT: edentulous, otherwise normal. Chest: clear to ausculation and percussion. Cardiac: no murmurs. Abdomen: normal. Extremities: 2 + pedal edema. Neurologic: mild-to-moderate symmetric reduction in strength in the arms and legs; gag reflex intact. Laboratory Findings: ABG (room air): pH 7.34, PCO z 60 mmHg, PO z 55 mmHg, HCO) 27 mmol/L.
Question:
What evaluation and treatment would you suggest?
251
Answer:
Sleep study with titration of bilevel positive airway pressure.
Discussion: Patients with a distant history of poliomyelitis may experience a worsening of the muscle weakness later in life (post-polio syndrome). Respiratory muscle weakness can result in hypoventilation during the day, with a worsening during sleep. The associated desaturation during sleep may result in findings consistent with cor pulmonale. During NREM sleep, periods of central apnea, hypopnea, obstructive apnea, or regular breathing with hypoventilation may occur. During REM sleep, more profound arterial oxygen desaturation usually is noted. Transcutaneous PC0 2 monitoring reveals an increase in PC0 2 during NREM sleep and a further increase during REM sleep. The treatment of this syndrome must be individualized. Milder cases may respond to oxygen administration. As hypoventilation worsens, some degree of ventilatory support, such as bilevel pressure via nasal mask, is indicated. The level of expiratory positive airway pressure (EPAP) is titrated to maintain upper airway patency. The level of inspiratory positi ve airway pressure (IP AP) is adjusted to provide a level of pressure support (pressure support = IPAP - EPAP). The level of pressure support is adjusted until the spontaneous tidal volume is in a normal range (400-500 cc). Oxygen can be added if de saturation persists despite pressure support of ventilation. Negative-pressure ventilation via body wrap or
cuirass also has been used successfully in some patients. One potential problem is the development of upper airway obstruction because upper airway muscle activity is not coordinated with the negativepressure breaths. If patients do not improve adequately with the aforementioned approaches, the next step is positivepressure, volume-cycled ventilation via nasal mask. Mouth leaks may require chin straps or a full face mask. In very severe cases, tracheostomy and volume ventilation can be employed. Even then, many patients may only require ventilatory support at night. Nocturnal ventilation can improve the daytime PC0 2 by preventing hypoxic depression of ventilatory drive and resting the respiratory muscles. In the present patient, a sleep study revealed desaturation to 80% without discrete hypopneas during NREM sleep. During REM sleep, central apneas and arterial oxygen desaturation to 50% were noted. During the second part of the night, bilevel pressure was titrated to a level of 15/5 ern H 20, and oxygen at 2 Llmin was added to prevent desaturation. Using this approach, nocturnal desaturation was prevented. After I week of treatment the patient felt more awake, and his daytime PC0 2 decreased to 50 mmHg. He was followed carefully so that the amount of pressure support could be increased or volume-cycled ventilation via mask instituted if a progressive rise in PC0 2 was noted.
Clinical Pearls I. Respiratory failure can develop many years after the initial infection in patients with a history of poliomyelitis. 2. Patients with neuromuscular disorders may experience severe nocturnal hypoventilation (with or without obstructive or central sleep apnea) and symptoms of cor pulmonale and daytime sleepiness. 3. Nocturnal ventilatory assistance with bilevel pressure or volume-cycled ventilation via nasal or full face mask can prevent nocturnal hypoventilation and allow many patients to function during the day without ventilatory support.
REFERENCES 1. Bach JR. Alba MS: Management of chronic alveolar hypoventilation by nasal ventilation. Chest 1990; 97:52-57. 2. Steljes DG. Kryger MH. Kirk BW, Millar TW: Sleep in postpolio syndrome. Chest 1990; 98: 133-140. 3. Waldhorn RE: Nocturnal nasal intermittent positive pressure ventilation with bi-Ievel positive airway pressure (BIPAP) in respiratory failure. Chest 1992; 10 I :516-521. 4. Meyer TI, Hill NS: Noninvasive positive-pressure ventilation to treat respiratory failure. Ann Intern Med 1994; 120:760-770. 5. Claman DM, Piper AM, Sanders MH, et al: Nocturnal noninvasive positive pressure ventilatory assistance. Chest 1996; 110:
1581-1588.
252
FUNDAMENTALS OF SLEEP MEDICINE 17
The Restless Leg Syndrome and Periodic Leg Movements in Sleep
Restless Leg Syndrome (RLS). RLS is characterized by paresthesias (abnormal sensations) and dysesthesias (uncomfortable sensations) in the limbs that compel the person to move to relieve the sensation and that are exacerbated by rest. The symptoms occur primarily in the evening or at night. In 1995, the International RLS Study Group published the primary and associated features of the syndrome (see table). The primary features are required to make the diagnosis of the RLS. The associated features are not required to make the diagnosis, but are frequently present and support the diagnosis. International RLS Study Group Criteria for Diagnosis of RLS PRIMARY FEATURES
ASSOCIATED FEATURES
• Unpleasant limb sensations: desire to move the limbs usually associated with paresthesias/ dysesthesias (abnormal/unpleasant sensations)
• Sleep disturbance and consequences: difficulty initiating or maintaining sleep; less commonly, excessive daytime sleepiness
• Motor restlessness: patient is compelled to move
• Invo!unatary movements during wake or sleep (PLMS)
• Symptoms precipitated by rest and relieved by activity: symptoms are worse or exclusively present at rest (i.e., sitting or lying) with at least partial and temporary relief by activity • Symptoms worse in the evening or at night
• Normal neurologic exam in primary RLS; in secondary forms, possible evidence of neuropathy • Clinical course: onset any age, usually chronic and progressive, remissions may occur, can be exacerbated by or exclusively during pregnancy • Family history: sometimes present; suggestive of autosomal dominant pattern
The unpleasant sensations associated with RLS have been described as a creepy or crawling feeling, burning, bone ache, pulling, electrical current, throbbing legs, "heeby jeebies," or worms crawling under the skin. Sometimes sensations are absent, and there is only an irresistible urge to move ("Elvis legs"). Other patients report that the legs just move without an associated urge to move. About 20% of patients report the unusual sensations to be painful. Of note, about 20-30% also report similar sensations in the arms (usually in more severely affected patients). One study found that 10% of adults experienced RLS symptoms either often or very often. The prevalence of RLS symptoms increases with age and may be as high as 10-25% in adults over age 65 (depending on whether patients with only occasional symptoms are included). The differential diagnosis of RLS is discussed in Patient 80. Periodic Leg Movements (PLMs). PLMs are repetitive, stereotypic dorsiflex ions of the big toe with fanning of the small toes, accompanied by flexion of the ankles, knees and thighs that recur at intervals of
253
5-90 seconds with a duration of 0.5-5 seconds. The leg movements resemble the triple flexion or Babinski response. At least four movements must be counted per episode to meet the polysomnographic criteria for PLMs. Some clinicians recommend counting all leg movements whether or not they meet this criteria and whether or not they occur in wakefulness or sleep. Technical information on the recording of leg movements during sleep is discussed in Patient 79. Periodic leg movements in sleep (PLMS) occur most commonly in stages 1 and 2, but can also occur in stages 3,4, and-less commonly-during REM sleep. Periodic leg movements should not be confused with hypnic jerks (sleep starts), which are whole-body jerks at sleep onset. Patients with frequent leg movements may remember awakenings, but rarely are aware of the leg movements themselves. Bed partners usually report that patients jerk or kick during the night. The PLM index is the number of periodic leg movements per hour of sleep. It is said that a PLM index of > 5/hr is abnormal, but this cutoff is arbitrary and not based on scientific data. These movements are present in 5-6% of all adults and 30-86% of adults over 60 years of age. PLMS may be an asymptomatic finding, especially in older patients. The term periodic leg movement disorder (PLMD) is used to identify the syndrome of leg movements + symptoms (insomnia or excessive daytime sleepiness). The disorder is diagnosed when these symptoms are present in association with an abnormal PLM index and/or PLM arousal index. This assumes that no other disorder can explain the symptoms. While PLMD is thought to be the etiology in about 10-12% of patients seen in sleep centers for insomnia complaints, only 2-3% of patients presenting with excessive daytime sleepiness are thought to have PLMD as the major cause of their sleepiness.
International Classification of Sleep Disorders Criteria for PLMS Severity SEVERITY
PLM INDEX (lHR)
Mild Moderate Severe
5-24 25-49 ~ 50
PLM AROUSAL INDEX (lHR) Not specified Not specified > 25 /hr
While the terms "restless leg syndrome" and "periodic limb/leg movements in sleep" are often used interchangeably, such usage is inaccurate. RLS is a clinical diagnosis, and PLMS is usually a polysomnographic diagnosis. It is estimated that 70-90% of patients with RLS will have PLMS on a sleep study. In contrast, only 30% or less of patients with PLMS have RLS. There seems to be little doubt that RLS is a distinct clinical entity with significant morbidity, deserving treatment. However, whether isolated PLMD (no RLS) is really a clinical syndrome that warrants treatment has been called into question (see reference 4 and Patient 80). Causes of RLS/PLMS. RLS is often divided into primary RLS (no other disease present) and secondary RLS (secondary to an indentifiable cause). The cause of primary RLS is not known. There may be an abnormality in iron transport into the CNS or in use of iron as it relates to dopaminergic neurons. Examples of secondary RLS include end-stage renal failure (with or without dialysis), pregnancy, iron-deficiency (with or without anemia), and certain drugs. It is prudent to check serum iron, total iron-binding capacity, and ferritin in patients with RLS. RLS associated with renal failure is not helped by dialysis, but is cured by a renal transplant. The RLS of pregnancy commonly vanishes or improves with delivery. The RLS of iron deficiency may improve with iron supplementation. A number of medications can cause or worsen RLS, including selective serotonin reuptake inhibitors. However, the occasional patient with RLS improves on SSRIs. Bupropion is an antidepressant that increases dopamine and may be an alternative in patients with the onset or worsening of RLS on other antidepressants. If the onset of RLS can be linked to the start of medication, try a switch to an alternate medication. The causes of PLMS are the same as RLS. In addition, PLMs can be seen during CPAP titration for OSA and are also seen in patients with narcolepsy, OSA, and the REM behavior disorder. PLMs have also been noted upon withdrawal from anticonvulsants, barbiturates, and hypnotics. For a detailed discussion of the treatments of RLS and PLMS, see Patients 82 and 83.
254
Causes and Associations of PLMS
Classification of Restless Leg Syndrome Primary Secondary Iron deficiency Renal failure Pregnancy Drugs (caffeine, tricyclic antidepressants, serotonin reuptake inhibitors, dopamine blockers [compazine, metaclopramide])
Any cause of RLS Withdrawal of anticonvulsants, barbituates, hypnotics Associated with narcolepsy, GSA, CPAP titration
Key Points 1. The restless leg syndrome (RLS) is characterized by symptoms that occur during wakefulness and that meet certain criteria. 2. Periodic limb movements in sleep (PLMS) is diagnosed when the PLM index is > 5/hr. For a leg movement to be counted as a PLM, it must occur in a sequence of a least four leg movements separated by 5 to 90 seconds. 3. The PLM Disorder (PLMD) is defined as PLMS + symptoms of insomnia or daytime sleepiness. Some have questioned whether PLMD is a real clinical entity. PLMs occur in many aysmptomatic individuals. 4. About 70-90% of patients with RLS have PLMS on a given night. 5. Many patients with PLMS do not have RLS.
REFERENCES I. American Sleep Disorders Association: International Classification of Sleep Disorders: Diagnostic and Coding Manual. Lawrence. KS. Allen Press. 1990. pp 65-71. 2. Ancoli-Israel S. Kripke DF. Klauber MR. et al: Periodic leg movements in sleep in community-dwelling elderly. Sleep 1991; 14:496-500. 3. Waters AS: Toward a better definition of the restless leg syndrome. The International Restless Leg Syndrome Study Group. Mov Disord 1995; 10:634-632 4. Phillips B. Young T. Finn L. et al: Epidemiology of restless leg symptoms in adults. Arch Intern Med 2000; 160:2137-2141. 5. Mahowald MW: Assessment of periodic leg movements is not an essential component of an overnight sleep study. Am J Resp Crit Care Med 2001; 164:1340-1341.
255
PATIENT 79 A 50-year-old man with snoring and leg kicks A 50-year-old man with a history of snoring and leg kicks during sleep underwent a sleep study. The tracings shown below were obtained.
Question 1: Note the right and left leg EMGs on separate channels (Fig. I). How many PLMs are present in this 60-second tracing? Question 2: Note the 180-second segment with repetitive obstructive apneas (Fig. 2). The right and left leg EMGs are displayed on a single channel. How many PLMs are shown?
C4-A1 ~"'~~~*",Mf,\J~-WJ~~~ 02-A1 Nfl.t.~I,.,M.J¥-Lf'lf'\Al"'''f~V.~AtM''W.f'~'t¥'N1
ROC-A1 '~IfYI~~NJw.(~~r..Ilk'iv0rrf\\~ LOC-A2 ~'I"rI'o/~~II.Af'~ chin EMG ---.--------.-----...;.--......, R Leg EMG
----. -----~,.------1.,."""",--
~
~
""'"
t-
--~-~
L Leg EMG
5 sec FIGURE I
C4-Al 02-Al ROC-A1 LOC-A2 chin EMG
airflow
-
- -
-
_._..
.
.
--
---.
....
""".
~.
chest
abdomen
R. L Leg EMG
(
)
30 seconds FIGURE
256
2
Answers: In Figure I, four PLMs are shown. In the first pair of leg movements, the left leg movement starts more than 5 seconds after the onset of the right leg movement, and is therefore considered a separate movement. In Figure 2, none of the leg movements are considered PLMs because they all are associated with the termination of obstructive apnea. Discussion: The International Classification of Sleep Disorders states that the diagnosis of periodic limb movement disorder (PLMD) requires symptoms (excessive daytime sleepiness/insomnia) + PLMs noted on a sleep study. Other sleep disorders may be present, but cannot account for the leg movements. There should also be no evidence of a medical or psychiatric disorder that could account for the complaint. As discussed in Patient 84, the presence of leg movements in patients with OSA has a questionable impact on sleepiness in most patients unless the restless leg syndrome is present. Some have suggested that PLMD is not a true sleep disorder, but simply a polysomnographic finding. The diagnosis of periodic leg movements in sleep (PLMS) requires monitoring of leg EMGs. Surface electrodes usually are placed over the anterior tibialis muscle (anterior lateral calf). Movements may occur in one or both legs; therefore, monitoring of both legs is suggested. This dual monitoring can be performed using a single polygraph channel (Fig. 2) or in separate tracings (Fig. I). Usually two electrodes are placed on each anterior tibialis muscle about 2-4 ern apart. Then each leg EMG can be recorded in a bipolar manner as the voltage between the two electrodes. If the legs are displayed on a single channel, the voltage difference between one electrode on each leg is measured. The other electrodes are held in reserve in case one of those monitored fails. A burst of anterior tibialis muscle activity with a duration between onset and resolution of 0.5 to 5 seconds, with an amplitude of at least 25% of the bursts recorded during patient biocalibration (voluntary toe dorsiflexion), is scored as a leg movement (LM). A leg movement is considered part of a PLM sequence if it belongs to a group of four or more leg movements separated by more than 5 and less than 90 seconds (most separations are 20-40 seconds). This defining separation is from the onset of one leg movement until the onset of the second. In contrast, the inter-LM interval is from LM offset to the next LM onset. Leg movements following arousals or those associated with apnea termination are not counted as PLMs in most laboratories. Others also do not count LMs occurring during crescendo snoring, but those occurring in the middle of an apnea are counted in some centers. In the two-channel method of display, simultaneous movements in both legs are counted as one movement, unless the start of the second move-
ment is more than 5 seconds after the start of the first (some use 5 seconds after the offset of the initial LM). Of note, an American Sleep Disorders Association (ASDA) task force actually recommended that all LMs be counted, and those that are part of a PLM sequence, associated with respiratory events, or occuring during wake be tabulated separately. However, most sleep laboratories simply count only those LMs that occur during sleep, are part of a PLM sequence, are not felt to be associated with respiratory events, and do not follow an arousal. A leg movement must be preceded by at least 10 seconds of sleep to be considered a PLM in sleep. To be scored as a PLM with arousal, an arousal must occur simultaneously with a LM or follow it by less than 3 seconds. The total number of PLMs, the number of PLMs with arousal, and the PLM index and PLM arousal index are usually determined. The PLM index is the number of periodic leg movements per hour of sleep, and the PLM arousal index is the number of PLMs associated with arousal per hour of sleep respectively. The PLM arousal index has been thought to be a better indicator of the impact of PLMs on sleep than the PLM index. This said, many leg movements are associated with EEG changes that do not meet ASDA arousal criteria. For example, K complexes with or without alpha bursts are frequently seen. Some of these can be associated with changes in airflow, heart rate, or blood pressure in the absence of cortical arousal. Of note, the PLM arousal index has not been shown to correlate with objective measures of sleepiness. The International Classification of Sleep Disorders offers a grading system for severity of PLMS: a PLM index < 5 is considered normal; 5-24 is mild; 25-49 is moderate; and 2= 50/hr is severe. A PLM arousal index > 25/hr is also considered severe. However, these cutoffs are entirely arbitrary and are not based on any outcomes data. Normative data on the PLM and PLM arousal index are not available. One must always use clinical correlation (presence or absence of symptoms) in determining the importance of PLMS. In the present case, Figure 1 shows three pairs of right and left leg movements. However, in the first pair the left leg movement starts 5 seconds after the right and is considered a separate movement. The other pairs are each considered to represent one leg movement. As noted above, some centers require 5 seconds from offset to onset of the next LM to con-
257
sider LMs to be separate events. Using this criterion, only three PLMs would be counted in this patient. In Figure 2, all leg movements are associated with the termination of apnea. Hence, most centers
would not score them as PLMs. Note that in this patient, the leg EMG shows a much more brisk change at apnea termination than the chin EMG. This is a frequent finding in some patients.
Clinical Pearls I. The rules for scoring leg movements and periodic leg movements vary between sleep laboratories. 2. Simultaneous leg movements in right and left legs are counted as one movement. 3. In order to be considered a periodic leg movement in sleep, a leg movement must occur during sleep in a sequence of four or more movements, each separated by more than 5 and less than 90 seconds (time between leg movement onsets). Leg movements that follow an arousal are not counted. 4. The PLM index and PLM arousal index are computed by dividing the number of PLMs or the number of PLMs associated with arousal (arousal simultaneous or following the LM by < 3 seconds) by the hours of sleep. 5. It has been said that a PLM index of 5 or less is normal, but this cutoff is arbitrary. Many asymptomtic individuals have a higher PLM index. 6. The PLM arousal index may be a better indicator of the impact of PLMS on sleep quality, but a normal range for the PLM arousal index has not been established.
REFERENCES 1. Coleman RM: Periodic movements in sleep (nocturnal myoclonus) and the restless leg syndrome. In Guilleminault C (ed): Sleep and Waking Disorders: Indications and Techniques. Boston, Butterworth Publishers, 1932, pp 265-295. 2. Diagnostic Classification Steering Committee, Thorpy MJ, Chair: International Classification of Sleep Disorders. Rochester, Minnesota, American Sleep Disorders Association, 1990. 3. The ASDA Task Force: Recording and scoring leg movements. Sleep 1993; 16:749-759. 4. Walters AS: Assessment of periodic leg movements is an essential component of an overnight sleep study. Am J Respir Crit Care Med 2001; 164: 1339-1340. 5. Marshall B. Davila DG: Monitoring limb movements during sleep. In Lee-Chiong TL, Sateia MJ, Caraskadon MA (eds): Sleep Medicine. Philadelphia, Hanley & Belfus, 2002.
258
PATIENT 80 A 56-year-old man with crawling sensations in his legs at bedtime A 56-year-old man reported an inability to fall asleep at night secondary to a crawling sensation in both legs. These unpleasant sensations frequently started an hour before bedtime when he was seated or recumbent in bed. The discomfort was relieved by moving his legs or walking, but it returned as soon as he became inactive. After great difficulty falling asleep, the patient experienced frequent and prolonged awakenings during the night. His wife reported that he kicked and jerked during sleep, but did not snore. Because of these problems, the patient was quite fatigued. An evaluation by the patient's primary care physician revealed no evidence of anemia, iron or folate deficiency, or renal failure. Physical Examination: Neurologic: intact position and vibration sense; sensation to pin and touch normal; deep tendon reflexes normal and symmetric. Laboratory Finding: Hct 40%.
Questions:
What is the diagnosis? Should a sleep study be ordered?
259
Diagnosis: Restless leg syndrome. A sleep study is not needed unless other sleep pathology (e.g., sleep apnea) is suspected. Discussion: The diagnosis of the restless leg syndrome (RLS) is based primarily on clinical history from the patient and bed partner. The essential elements of RLS (see Fundamentals 17) should be present. The differential diagnosis of RLS includes paresthesia due to neuropathy, neuroleptic akathisia, claudication, and the painful legs and moving toes syndrome (see table). In RLS, symptoms are worse in the evening and at night, exacerbated by inactivity and the supine position, and temporarily improved by activity. The neurological exam as well as EMG and nerve conduction studies are normal in most patients with RLS (unless the patient also has a coexistent neuropathy). Paresthesias or dysesthesias from a neuropathy are usually not relieved by moving or walking, and generally are not worse at night. EMG and nerve conduction studies are usually abnormal. Neuroleptic akathisia is characerized by repetitive restless movement such as body rocking, marching in place, or movement of the extremities. Movements may not be worse at night or when lying down. There is always a history of prior or current neuroleptic use (phenothiazines). The movements are associated with inner restlessness, but not dysesthesia/paresthesia. The painful legs and moving toes syndrome is characterized by semi-continuous toe movements not necessarily influenced by activity. The pain is often not worse at night, EMG studies are abnormal, and MRI imaging may reveal evidence of nerve root compression. While many patients focus on the specific symp-
DYSESTHESIA/ PARESTHESIA
WORSE IN THE EVENING/ NIGHT
toms of RLS, others complain of difficulty falling asleep or maintaining sleep (insomnia). Most patients with RLS have periodic leg movements in sleep (PLMS). However, a history of leg jerks at night does not eliminate the possibility that sleep apnea is also present. Remember that PLMS and obstructive sleep apnea (OSA) frequently coexist, and that OSA patients can also complain of insomnia. Therefore, a sleep study is indicated if the patient being evaluated for RLS snores, or if daytime sleepiness persists after adequate treatment of RLS. Otherwise, a sleep study is not needed to diagnose RLS. The etiology of RLS is unknown. The condition has been associated with iron deficiency (less commonly, folate or B 12 deficiency), vascular insufficiency, uremic neuropathy, and caffeine abuse. Some of the described associations are based on relatively few anedoctal reports. When sleep monitoring is performed in patients with RLS, there are quasi-periodic movements of the legs during wakefulness, and the sleep latency is prolonged. After sleep onset, PLMs are noted in 70-90% of patients. In the present patient, clear-cut symptoms of RLS were present, and there was no reason to suspect sleep apnea (no daytime sleepiness or snoring). Therefore, a sleep study was not ordered. The patient was started on pramipexole .125 rng at 9 PM (usual bedtime was II PM). The dose was increased to .25 mg after 1 week. The patient reported nearly complete relief of his symptoms. (For a detailed discussion of the treatment of RLS and PLMS, see Patients 82 and 83.)
IMPROVED By MOVEMENT
STUDIES
NEUROLEPTIC USE
RLS
Usually
Always
Temporarily
Neuro exam, EMG often normal
No
Neuropathy
Usually
Sometimes
No
Decreased sensation, abnormal EMG/nerve conduction
No
Neuroleptic akathisia
No
Not usually
Not usually
Variable
Yes
Claudication
Pain
Not usually
Walking may worsen
Decreased pulses
No
Painful toes, moving leg syndrome
Pain
Not usually
No
Abnormal EMG, MRI shows lumbosacral radiculopathy
No
260
Clinical Pearls I. 2. 3. 4. tient
The diagnosis of RLS usually can be made by history and physical examination. Iron-deficiency with or without anemia should be excluded in patients with RLS. Most patients with RLS have PLMS during sleep. A sleep study should be ordered if snoring or if daytime sleepiness is present in a pawith a clinical diagnosis of RLS. Sleep apnea frequently coexists with PLMS.
REFERENCES I. Diagnostic Classification Steering Committee. Thorpy MJ, Chair: International Classification of Sleep Disorders. Rochester, Minnesota, American Sleep Disorders Association, 1990. 2. Walters AS, Hening W, Rubinstein M, et al: A clinical and polysomnographic comparison of neuroleptic-induced akathisia and the idiopathic restless leg syndrome. Sleep 1991; 14:339-345. 3. Waters AS: Toward a better definition of the restless leg syndrome. The International Restless Leg Syndrome Study Group. Mov Disord 1995; 10:634-632.
261
PATIENT 81 A 40-year-old man who kicks in his sleep A 40-year-old man was referred because his wife complained that he kicked in his sleep and constantly disturbed her. The patient remembered awakening several times each night, but never noticed any discomfort at those times. He admitted that at bedtime he did have an irresistible urge to move his legs. However, this delayed his sleep only rarely. The patient's wife said he regularly snored at night, but this did not bother her. The snoring was worse when the patient complained of nasal congestion. His Epworth sleepiness scale was 10/24 (normal). Physical Examination: HEENT: normal except for a mildly dependent palate and long uvula. Sleep Study: Total sleep time 360 minutes. Mild snoring, AHI 5/hr, AHI during REM l5/hr. Lowest sao, 92%. Figure: There were 240 events similar to the two identified (A and B) in the tracing below. Twenty percent of these events were associated with arousal. Note that fewer PLMs occurred in the lateral sleeping position.
Question:
What is the diagnosis?
C3-A2 Ol-A2 ROC-Al LOC-A2 EKG chin EMG Snore airflow chest
abdomen R,L Legs
Sa02
262
Diagnosis:
Periodic leg movements in sleep (PLMS) associated with snoring airflow limitation.
Discussion: Periodic limb (leg) movements in sleep (PLMS), also known as nocturnal myoclonus, consists of stereotypic periodic leg (arm) movements during sleep that mayor may not be associated with arousals. (See Fundamental 17 and Patient 79 for a detailed description of these movements.) The conventional wisdom once was that if the movements were associated with a sufficient frequency of arousals, the combination could result in either daytime sleepiness or insomnia (periodic limb movement disorder [PLMDJ). Recently, however, the idea that isolated PLMD (no RLS) is really a sleep disorder requiring treatment has been challenged. First, PLMS is very common in elderly patients and could simply be a polysomnographic finding. Second, the PLM arousal index does not correlate with measures of excessive sleepiness. Even in patients with insomnia and PLMs, it is not clear that the PLMs are actually the cause of the syndrome. Third, PLMs are common in patients with obstructive sleep apnea and narcolepsy. In one study of patients with sleep-disordered breathing, a higher PLM arousal index actually was associated with less daytime sleepiness. Another study of patients with the upper airway resistance syndrome found an association between respiratory effort-related arousals and PLMs. This suggests that PLMS could be a manifestation of upper airway narrowing in some patients. Despite the controversy about the diagnosis of PLMD, there is probably a subgroup of patients with PLMS in whom treatment of the leg movements does improve sleep. While leg movements may be associated with EEG changes consistent with cortical arousal, often other, more subtle changes are present-such as a K complex with alpha waves (K-alpha). Sometimes only an "autonomic" arousal is present, with an increase in heart rate or blood pressure. One study of the arousals associated with PLMs showed that the arousals actually followed the PLMs in less than 25% of the cases (other arousals preceded or were coincident with leg movements). Some have suggested that the PLMs and arousals are simply both manifestations of periodic arousals that mayor may not be associated with dopamine dysfunction. In patients with heavy snoring and airflow limitation as well as PLMs, it is often difficult to know if these are two separate entities, or if airflow limi-
tation (increased respiratory effort) is causing the PLMs. In some patients with mild OSA and frequent PLMs, treatment with nasal CPAP abolishes the PLMs-suggesting that the sleep-disordered breathing was causing the PLMs. In others, PLMs may persist once the upper airway is stabilized. In such cases, first ensure that respiratory effortrelated arousals are abolished (increase in CPAP as needed). Then consider pharmacological treatment of PLMs-but only if the patient is still symptomatic after adequate treatment of OSA. Some have suggested that PLMs are simply a peripheral manifestation of periodically occurring central arousals, rather than the cause of the arousals. PLMs certainly can disturb the sleep of bedmates. It could be argued that PLMs without RLS could be treated to improve the sleep quality of the bedmate. While the area will likely remain controversial, it is probably prudent not to assume that an elevated PLM index explains symptoms of daytime sleepiness until you have carefully excluded other causes. For example, PLMs are common in patients with narcolepsy. Additionally, you should probably be conservative in treatment of PLMs in the absence of RLS. In the present patient with PLMS, the tracing is typical in that it shows PLMs associated with airflow limitation and snoring. The second PLM is followed by a K complex in the EEG tracings and a slight improvement in airflow, although cortical arousal is not evident. The PLM index was 40/hr (240/6), and the PLM arousal index was (8/hr). The patient was diagnosed as having mild OSA (REM related) and frequent PLMs, with a mildly increased PLM arousal index. He was absolutely asymptomatic and felt he had no problems. The couple was given three options: (l) sleep in separate beds, (2) trial of treatments for mild OSA, (3) trial of treatments for PLMS. Sleeping in separate beds was unacceptable and the patient was reluctant to try dopaminergic agents. He underwent a weight loss program (IO-pound weight loss), and his nasal congestion was treated with nasal steroids. On this treatment regimen the patient snored less and seemed to kick much less at night. He and his wife were satisfied. However, improvement in the PLM index was not documented by a repeat sleep study because of financial considerations.
263
Clinical Pearls I. Periodic leg movements in sleep are common in asymptomatic elderly patients and patients with narcolepsy and obstructive sleep apnea. Be cautious in ascribing complaints of daytime sleepiness or insomnia to PLMS. 2. In the absence of RLS, asymptomatic PLMS probably do not need treatment, unless the sleep of the bedmate is disturbed and other measures (separate beds) are not acceptable to the couple. 3. In some patients, PLMs may be a marker for airflow limitation/snoring and/or respiratory effort-related arousals. Treatment of snoring/UARS/mild GSA may be the best way to decrease PLMs in these individuals.
REFERENCES I. Mendelson WB: Are periodic leg movements associated with clinical sleep disturbance? Sleep 1996; 19:219-223. 2. Exner EN, Collop NA: The association of upper airway resistance with periodic limb movement. Sleep 2000: 24: 188-192. 3. Karadeniz D, Ondze B. Besset A. Billiard M: EEG arousals and awakenings in relation with periodic leg movements during sleep. J Sleep Res 2000; 9:273-277. 4. Montplasir J, Michaud M, Denesle R, Gosseline A: Periodic leg movements are not more prevalent in insomnia of hypersomnia. but are specifically associated with sleep disorders involving a dopaminergic impairment. Sleep Medicine 2000; I: 163-167. 5. Mahowald MW: Assessment of periodic leg movements is not an essential component of an overnight sleep study. Am J Resp Crit Care Med 200 I; 164: 1340-1341. 6. Chervin RD: Periodic leg movements and sleepienss in patients evaluated for sleep-disordered breathing. Am J Respir Crit Care Med 2001; 164:1454-1458.
264
PATIENT 82 A 50-year-old man who kicks during sleep A 50-year-old man was evaluated because he kicked all night in bed, disturbing his wife's sleep. He described a feeling of "pins and needles" in his legs in the evening that sometimes made falling asleep difficult. He constantly moved his legs while trying to fall asleep. His wife reported that he snored occasionally. The patient denied symptoms of daytime sleepiness, and his Epworth Sleepiness Scale score was 9/24 (normal). There was no history of recent weight gain or cataplexy. The patient remembered awakening several times each night but never noticed any discomfort at those times. He was treated with c1onazepam I mg qhs, but this made him sleepy in the morning, and his wife reported that there was no improvement in his leg kicking during sleep. Physical Examination: Normal. Sleep Study: Total sleep time 360 minutes. AHI lO/hr. Figure: There were 240 events similar to the two identified (A and B) in the tracing below during 6 hours of sleep. Only 5% of the events were associated with arousal.
Question:
What treatment would you recommend?
EKG
R,l leg EMG
265
Answer:
Dopamine agonist for the restless leg syndrome and periodic leg movements in sleep.
Discussion: Many of the same drugs used to treat restless leg syndrome (RLS) are used to treat patients with the periodic leg movement disorder (see table). When treating patients with RLS (with or without periodic leg movements [PLMs]), the goal is to relieve symptoms and improve sleep quality. In patients with isolated leg movements in sleep (PLMS) but no RLS, the goal is to im-
in the morning. A controlled-release form of the medication can be used to avoid these problems. A more significant problem is the development of augmentation, i.e., symptoms of the RLS have earlier onset and spread to other areas of the body. Augmentation is more common when RLS is present (versus isolated PLMS) and with a dose in excess of 300 mg of levodopa. This problem is han-
Treatment Options for PLMD and RLS PLMD
RLS
Mild or intermittent
Carbidopa/levodopa Benzodiazepines
Moderate
Carbidopa/levodopa Dopamine agonists Benzodiazepines
Severe
Dopamine agonists Benzodiazepines Narcotics
Nonpharmacological * Carbidopa/levodopa Benzodiazepines Dopamine agonists Anticonvulsants Benzodiazepines Narcotics Dopamine agonists Benzodiazepines Narcotics Anticonvulsants Combination/rotating agents
PLMD = periodic leg movement disorder
*Avoid
alcohol. caffeine: do leg stretching, exercise; take warm baths
prove sleep. The leg movements are not felt to be harmful except for disturbing the sleep of bedpartners. Dopaminergic medications (dopamine precursors and dopamine agonists) are probably the most effective and widely used treatments for PLMS and RLS. They reduce the frequency of PLMs, decrease RLS symptoms, and improve sleep quality. Carbidopa/levodopa (Sinemet and others) works because L-DOPA, a dopamine precursor, enters the central nervous system and is converted to dopamine. Carbidopa, a decarboyxlase inhibitor, does not enter the central nervous system. It prevents peripheral conversion of DOPA to dopamine, thereby decreasing peripheral side effects and increasing availability of L-DOPA in the brain. A typical dose of carbidopa/levodopa is 25/100 to 100/300 taken at bedtime and repeated during the night if needed. The medicine is started at a low dose of 25/100 and increased gradually. Compared to dopamine agonists, CD/LD requires only a short time to onset of action, but has a short half life. This agent is very useful for for rapid treatment of symptoms such as may occur on long airplane or car trips. However, the short half life of CD/LD often results in recurrence of symptoms during the night and a rebound in symptoms
266
died by a switch to dopamine agonists. In general, chronic CD/LD treatment of RLS/PLMS does not lead to the dyskinesias seen in Parkinson's disease (possibly because the daily dose is much lower). Pergolide (Permax) is an effective ergotamine dopamine agonist, but it is often associated with significant nausea and nasal congestion as well as constipation and orthostatic hypotension. These side effects can be controlled with dromperidone 10-30 mg a day (available in Canada but not the U.S.), which is a dopamine receptor blocker that does not cross the blood-brain barrier. Pergolide is less commonly used today. Pramipexole and ropinirole, non-ergotamine dopamine agonists, are available and effective. Their popularity is increasing because they are associated with much less nausea than ergotamine dopamine agonists (bromocriptine and pergolide); have a longer half life than CD/LD (no repeat dosing during the night); and are less likely to lead to augmentation. They are started at low doses (e.g., 0.125 mg of pramipexole or 0.25 mg of ropinirole) and titrated upward slowly to minimize side effects such as nausea and postural hypotension. Because the time to peak level is longer than CD/LD, it is important to give these agents 1-2 hours before bedtime (or symptom onset). Side effects include nau-
sea, postural hypotension, and daytime sleepiness. Leg edema has also been reported with pramipexole. If augmentation occurs with pramipexole, it can usually be handled by splitting the dose and giving a portion of the medication earlier in the evening (e.g., 0.125 mg at 6 PM and 9 PM). The dose of pramipexole must be reduced in renal insufficiency. Benzodiazepines have variable effectiveness in RLS and PLMs. Some studies reported that they improved sleep in patients with PLMS, but not the frequency of leg movements. Others showed an improvement in PLM frequency. Benzodiazepines should be used with caution-if at all-in patients with OSA. Clonazepam is the most commonly used benzodiazepine for RLS/PLMS. Unfortunately, it has a long half-life and can cause early morning grogginess. Other benzodiazepines such as triazolam and temazepam also improve sleep in patients with RLS. Clonazepam should be started low (0.125--0.25 mg) and titrated up slowly to minimize early morning grogginess. Giving the drug 1-2 hours before bedtime may decrease morning grogginess and give adequate blood levels at sleep onset. Narcotics (oxycodone, propoxyphene, and others) are also effective in RLS, but are usually reserved for severe cases. Two problems are the potential for abuse and the development of tolerance. One longterm study of narcotics in RLS did not find these po-
tential factors to be major problems. However, these drugs might worsen sleep apnea, and some evidence for this problem was found in the study. Anticonvulsants (carbamazepine and gabapentin) are said to be effective in RLS, although less so than dopaminergic agents. There is not sufficient documentation of efficacy in PLMS to recommend their use ifPLMS occur without RLS symptoms. Anticonvulsants typically are used in RLS patients who have accompanying neuropathic pain, or in patients who cannot tolerate the other agents. Gabapentin can cause daytime fatigue and somnolence. Carbamazepine can cause nausea, dizziness, and, rarely, aplastic anemia and agranulocytosis. In patients with very severe RLS, combinations of agents (dopaminergic, benzodiazepines, narcotics) are frequently required. Some clinicians combine opiates and dopamine agents so that a lower dose of each agent is effective, resulting in fewer side effects. Another approach is to use different medications on alternate weeks. In the present case, although RLS symptoms were not a problem for the patient, reducing the PLMS was essential to keep his wife in the same bed. He was started on pramipexole 0.125 mg 2 hours before sleep, and this was increased to 0.25 mg I week later. His wife reported a great reduction in leg kicking. The patient did not experience daytime sleepiness on this treatment.
Comparison of Pharmacologic Treatments for RLS and PLMS
TIME To PEAK LEVEL (MIN)
HALFLiFE (HRS)
MODE OF ELIMINATION
INITIAL DOSE
DOSING ADJUSTTIMING OF MENT DoSE (MIN) (INCREASED MAXIMUM BEFORE EVERY DOSE X DAYS) HS
Dopamine precursors
CD/LD
30
1.5-3
hepatic
251100 mg 30-60 min 3-7 days
(Sinemet) CD/LDCR (Sinemet CR)
120
6-8
hepatic
25/10050/200 mg
45-60
3-4
hepatic
20 mg
60
27
renal
120
8-12
renal
2.5 mg 45-60 min 3 days 1/2 to I 0.05 mg 60 min 2-3 days one at supper or hs .125 mg 120 min 2-3 days
60-120
about 6
hepatic
.25 mg
60-120 min
3 mg
Dopamine agonists Bromocriptine (Parlodel) Pergolide (Permax) Pramipexole (Mirapex) Ropinirole (Requip)
120 min
3-7 days
2-3 days
300 mg of LD* 300 mg of LD*
1-2 mg
1.5 mg
(continued) 267
Comparison of Pharmacologic Treatments for RLS and PLMS (Continued)
TIME To PEAK LEVEL (MIN)
HALFLiFE (HRS)
MODE OF EUMINATION
INITIAL DOSE
DOSING ADJUSTTIMING OF MENT DOSE(MIN) (INCREASED EVERY BEFORE MAXIMUM X DAYS) DOSE HS
Benzodiazepines 60-120
19-39
hepatic
.125.25 mg
60-120 min
3-5 days
4mg
Carbamazepine (Tegretol)
4-5 hrs
hepatic
200
at hs
3-6 days
400 mg
Gabapentin (Neurotonin)
variable
variable 12-17 hrs with repeated dosing 5-7 hrs
renal
100 (100-400)
at hs
3-6 days
1200 mg
Clonazepam (Klonopin)
Anticonvulsants
CD/LD = carbidopa/levodopa, CR = controlled release. HS *Toavoid augmentation
=
hour of sleep(bedtime)
Clinical Pearls I. Treatment of PLMS with clonazepam improves sleep quality (reduces arousals), but often does not reduce the frequency of leg movements. 2. Early morning somnolence, a common side effect of clonazeparn, may limit the usefulness of this medication. 3. Dopaminergic agents reduce the number of PLMs and improve sleep quality. Many clinicians consider these medications the treatment of choice. 4. Carbidopa/levodopa has a rapid onset of action, but a short duration. It may cause augmentation of symptoms in high doses. 5. The dopamine agonists pramipexole and ropinerol are less likely to cause nausea than pergolide and bromocriptine. 6. Pramipexole and ropinerol have a longer duration of action than regular preparations of carbidopa/levodopa. However, these dopamine agonists should be given 1.5 to 2 hours before bedtime (or symptom onset).
REFERENCES I. Mitler, MM. Browman CPo Menn SJ.et al: Nocturnal myoclonus: Treatment efficacy ofclonazepam andtemazepam. Sleep 1986; 9:385-392. 2. Peled R. Lavie P: Double-blind evaluation of clonazepam on periodic legmovements in sleep. J Neurol Neurosurg Psych 1987; 50: 1679-1681. 3. Doghramji K. Browman CPo Gaddy JR. et al: Triazolam diminishes daytime sleepiness andsleep fragmentation in patients with periodic leg movements in sleep. J ClinPsychopharmacol 1991; 11:284-290. 4. Practice parameters for the treatment of the restless legs syndrome and periodic limb movement disorder. Sleep 1999; 22:961-968. 5. Henning W. Allen RA. Early C. et al:The treatment of restless legssyndrome andperiodic limb movement disorder. Sleep 1999; 22:970-999. 6. Montplaisir J. Nicolas A. Denesle R. et al: Restless leg syndrome improved by pramipexole: A double-blind randomized trial. Neurology 1999; 52:938-943. 7. OndoW: Ropinirole for restless legssyndrome. Mov Disord 1999; 14:138-140. 8. Happe S. Klosch G. Saletu B. et al: Treatment of idiopathic restless leg syndrome with gabapentin. Neurology 200 1; 57:1717-1719. 9. Walters AS.Winkelmann J. Trenkwalder C. et al: Long-term follow-up on restless legs syndrome patients treated with opioids. Mov Disord 2001; 16:1105-1109.
268
PATIENT 83 A 72-year-old man with worsening symptoms during treatment for restless legs A 72-year-old man was diagnosed as having the restless leg syndrome (RLS) on the basis of a history of crawling sensation in both legs. These unpleasant sensations frequently started 30 minutes before bedtime when he was seated or recumbent in bed. The discomfort usually was relieved by moving his legs or walking, but the sensations returned once he became inactive. The patient was started on one-half pill of carbidopa/levodopa 25/100 mg, and the dose was slowly increased to three pills 90 minutes before bedtime over several weeks. This treatment initially resulted in good control of his symptoms. However, he began to notice severe RLS symptoms in the early evening that involved his arms as well as his legs. Physical Examination: Unremarkable. Neurologic: no involuntary movements, normal muscle tone, sensation intact.
Question:
What treatment do you recommend?
269
Answer:
Discontinue carbidopa/levodopa and try a dopamine agonist.
Discussion: Dopamine precursors (carbidopa/ levodopa [CD/LD]) and dopamine agonists (see table in Patient 82) are the most widely used agents for RLS and PLMS. CD/LD is short acting and can result in a rebound in symptoms in the early morning. The dose can either be repeated during the night or a continuous release form of the medication can be used. However, treatment of RLS/PLMS with CD/LD eventually results in some augmentation of symptoms in up to 80% of patients with RLS and in 30% of patients with PLMS and no RLS. The augmentation effect describes: (I) earlier onset of the usual bedtime symptoms (early evening or late afternoon), (2) increased severity of symptoms, and (3) spread of symptoms to the arms. Augmentation is more likely to occur at doses of more than 300 mg of levodopa. It may temporarily improve with an increase in dosage, but the symptoms eventually occur again. Augmentation usually responds to discontinuing the medication and switching to another agent. The usual approach is to wean CD/LD and switch to a dopamine agonist. Some clinicians wean CD/LD while starting the dopamine agonist (overlap), although this may not be necessary. Despite the problem of augmentation, CD/LD can be effective in mild or intermittent RLS. It has a more rapid onset of action, although a shorter half life, than dopamine agonists. Patients who get RLS symptoms only on long plane or car trips might find this medication useful.
The dopamine agonist pramipexole (Mirapex) is effective for both RLS and PLMs, and is less likely to cause augmentation than CD/LD. Side effects include nausea (less than pergolide), postural hypotension, somnolence, headache, and (rarely) lower extremity edema. If augmentation occurs, it often can be handled by starting the medicine earlier in the evening. Side effects can be minimized by starting with a low dose (0.125 mg about 2 hours before bedtime or before typical symptom onset). The dose can be increased by 0.125 mg every 2-3 days to a maximum of 1.5 mg. Some patients find splitting the medication (e.g., one at 6 PM, one at 8 PM) effective if nausea or augmentation is a problem. Pramipexole is excreted by the kidneys and the dose should be decreased in patients with renal failure. Also, use the lowest dose possible. Ropinirole (Requip) has a slightly shorter time to peak level and half-life than pramipexole, and is cleared by hepatic metabolism. The usual starting dose is 0.25 mg 1-2 hours before bedtime or symptom onset, with dose increases every 2-3 days to a maximum of 3 mg. Side effects include nausea, postural hypotension, and sleepiness. In the present patient, carbidopa/levodopa was discontinued, and the early evening symptoms as well as the spread to his arms gradually ceased. The patient was begun on pramipexole 0.125 mg at 8 PM (typical symptoms started at 10 PM). The dose was increased over 1 week to to 0.25 mg at 8 PM, with resolution of symptoms.
Clinical Pearls 1. Augmentation of RLS symptoms can occur while on treatment with carbidopa/ levodopa, but usually responds to a discontinuation of medication and a switch to a dopamine agonist. 2. Augmentation is more likely in patients with RLS than with PLMS alone. The lowest effective dose of carbidopa/levodopa should be used to decrease the risk of augmentation. 3. In patients with moderate to severe RLS, it may be prudent to begin treatment with a dopamine agonist rather than CD/LD, to avoid augmentation. 4. Alternative treatments for RLS include other dopamine agonists, opiates, anticonvulsants, and benzodiazepines. 5. Augmentation can occur with dopamine agonists, but is less likely than with dopamine precursors.
270
REFERENCES I. Monteplaisir J, Lapierre 0, Warnes H, et al: The treatment of the restless leg syndrome with or without periodic leg movements in sleep. Sleep 1992; 15:391-395. 2. Becker PM. Jamieson AO, Brown WD: Dopaminergic agents in restless leg syndrome and periodic leg movements of sleep: Response and complications of extended treatment in 49 cases. Sleep 1993; 16:713-716. 3. Walters AS, Wagner ML. Hening WA, et al: Successful treatment of the idiopathic restless leg syndrome in a randomized doubleblind trial of oxycodone versus placebo. Sleep 1993; 16:327-332. 4. Allen RP, Earley CJ: Augmentation of the restless leg syndrome with carbidopallevodopa. Sleep 1996; 19:205-213. 5. Earley CJ, Yaffee JB, Allen RP: Randomized, double-blind. placebo-controlled trial of pergoIide in restless legs syndrome. Neurology 1998; 51: 1599-1602. 6. Montplaisir J, Nicolas A, Denesle R, et al: Restless leg syndrome improved by pramipexole: A double-blind randomized trial. Neurology 1999; 52:938-943. 7. Walters AS, Winkelmann J, Trenkwalder C, et al: Long-term follow-up on restless legs syndrome patients treated with opioids. Mov Disord 2001; 16:1105-1109.
271
PATIENT 84 A 58-year-old man with sleep apnea and leg jerks during sleep A 58-year-old man was diagnosed as having severe obstructive sleep apnea (GSA) on an initial study. He then underwent a nasal CPAP titration, after which he remarked that he had had the "best night of sleep in years." However, there was a drastic change in his PLM index on CPAP. Physical Examination: Vital signs: normal. HEENT: large tongue, dependent palate; 16-inch neck circumference. Chest: clear. Cardiac: normal. Extremities: no edema. Neurologic: sensation in extremities intact. Figure: A sample tracing is shown below. The airflow is flow signal from the CPAP machine in the sleep laboratory
Sleep Studies» AHI PLM index PLM-arousal index Arousal index
Diagnostic
CPAP Titration (12 em H20)
66/hr IO/hr 5/hr 50/hr
IO/hr 60/hr IO/hr 15/hr
,', All indices are the number of events per hour of sleep.
Question:
What is your diagnosis?
C3-A2 01-A2 ROC-A1 LOC-A2 EKG chin EMG
airflow chest abdomen
R,L Legs
5002
272
Diagnosis:
Periodic leg movements associated with nasal CPAP treatment of OSA.
Discussion: A significant increase in periodic limb (leg) movements in sleep (PLMS) has been reported in patients with OSA following the initiation of nasal CPAP. The etiology of this change is unknown, but several possibilities have been suggested. One is that the severe fragmentation of sleep by apnea (pre-CPAP) did not allow manifestation of the PLMS, and treatment with CPAP unmasked the PLMS by allowing continuous sleep. Another is that the rebound in sleep following initial CPAP treatment results in less spontaneous patient movement, and the stasis or pressure on the nerves due to immobility leads to PLMS. Many patients spend more time supine when treated with CPAP than in the untreated state. Whatever the etiology, the clinician must decide whether to treat the PLMS or follow the patient's symptoms after nasal CPAP therapy is initiated. In some patients on nasal CPAP, the large increase in PLMS is transient. In others, the PLM-arousal index is low, and the impact on sleep is insignificant. In such cases, observation is adequate, and if symptoms of daytime sleepiness resolve, no additional treatment is necessary. However, if daytime sleepiness persists or returns after treatment of OSA is initiated, PLMS could be one cause of treatment failure. Note that the mere presence of PLMS should not exclude consideration of other causes of persistent daytime sleepiness such as inadequate pressure, poor compliance, inadequate sleep, and narcolepsy
(which often coexists with PLMS). The patient's bedpartner should be questioned about the frequency of body movements while the patient is on nasal CPAP. Repeat sleep monitoring to determine the PLM-arousal index (with the patient on nasal CPAP) may be needed for clarification and to document that the level of CPAP is adequate. If treatment of PLMS is indicated, special treatment consideration is necessary in patients with PLMS and significant OSA. Benzodiazepines, a common treatment for PLMS, have the potential to worsen sleep apnea. The risk probably is small if the patient is on an adequate amount of nasal CPAP. However, the effect of benzodiazepines on the efficacy of nasal CPAP has not been specifically studied. In addition, there is always the possibility that the medication will be taken on nights when CPAP is not used. Therefore, dopaminergic treatment of PLMS with carbidopa/levodopa or dopamine agonists is the logical choice. Certainly, benzodiazepines are absolutely contraindicated in patients with hypoventilation and CO 2 retention. In the present case, the PLM-arousal index was modest, and the patient noted a marked improvement in daytime sleepiness almost immediately after starting nasal CPAP. His wife reported that he did not kick at night and was "as cool as a cucumber." Good control of his symptoms persisted on nasal CP AP therapy, and no treatment for the PLMS was initiated.
Clinical Pearls I. A large increase in PLMS can follow initiation of nasal CPAP therapy in OSA patients. 2. In many patients with OSA and PLMS, treatment of the OSA alone can result in a complete resolution of symptoms. PLMS treatment is usually not needed unless the restless legs syndrome is present. 3. When adequate treatment of OSA (nasal CPAP) fails to abolish symptoms of daytime sleepiness, PLMS may be one cause of persistent sleepiness. However, the mere presence of PLMS should not discourage the clinician from excluding other causes of persistent daytime sleepiness. 4. Benzodiazepines can worsen OSA. Dopaminergic agents should be used when treating PLMS or the restless legs syndrome in patients with sleep apnea.
REFERENCES I. Fry JM. Diphillip MA. Pressman MR: Periodic leg movements in sleep following treatment of obstructive sleep apnea with nasal CPAP. Chest 1989; 96:89-91. 2. Yamashiro Y. Kryger MH: Acute effect of nasal CPAP on periodic limb movements associated with breathing disorders during sleep. Sleep 1994; 17:172-175. 3. Berry RB. Kouchi K. Bower J, et al: Effect oftriazolam in obstructive sleep apnea. Am J Resp Crit Care Med 1995; 151:450-454. 4. Guilleminault C. Phillip P: Tiredness and somnolence despite initial treatment of obstructive sleep apnea syndrome. Sleep 1996; 19:5 117-S 122. 5. Chervin RD: Periodic leg movements and sleepienss in patients evaluated for sleep-disordered breathing. Am J Respir Crit Care Med 2001; 164:1454-1458.
273
FUNDAMENTALS OF SLEEP MEDICINE 18
Narcolepsy
Narcolepsy is a neurological disorder characterized by excessive daytime sleepiness (EDS) and symptoms related to the abnormal regulation of REM sleep (see table). Hallmarks of the disorder are a short REM latency and inappropriate intrusion of REM sleep physiology into wakefulness: cataplexy (loss of muscle tone during periods of high emotion), hypnagogic hallucinations (dreaming at sleep onset), and sleep paralysis (loss of muscle tone at sleep onset or on awakening). Some patients also develop episodes of automatic behavior (up to 30 minutes of semi-purposeful behavior with amnesia for interval) during periods of reduced alertness. The short periods of decreased vigilance may be experienced by the patient as a "blackout" and be mistaken for a seizure.
Tetrad of Narcolepsy SYMPTOMS
Excessive sleepiness Cataplexy Hypnagogic hallucinations Sleep paralysis
ApPROXIMATE PREVALENCE
100% 70% 66% 60%
The prevalence of the disorder is 0.03-0.05% in the general population. The most common age of onset is adolescence, but a second peak occurs near 40 years of age. The disorder can also occur in children. About 10% of cases start before age 10 and 5% after age 50. Usually daytime sleepiness is the first symptom, followed in months to years by other symptoms. Cataplexy is the only symptom that is specific for narcolepsy, but it is present in only about 70% of cases. Patients with primary narcolepsy have a normal neurological examination. However, secondary or "symptomatic" narcolepsy can occur in patients with head trauma, stroke, multiple sclerosis, brain tumors, neurodegenerative disorders, and CNS infections. Narcolepsy was found to be associated with the presence of the human leukocyte antigens (HLA) DR2 and DQ6 in the Japanese population. About 95% of Caucasians with narcolepsy also are HLA-DR2 positive. However, the incidence of HLA-DR2 in African-American narcoleptics is lower. The antigen DQB I*0602 is the most sensitive marker for narcolepsy across all ethnic groups. Unfortunately, antigen testing is not that useful in making a diagnosis of narcolepsy because (I) most individuals positive for the antigen do not have narcolepsy, (2) antigen-negative cases of narcolepsy have been reported, and (3) the group of narcoleptics without cataplexy are less likely to be antigen positive. The latter group provides the greatest difficulty in making a diagnosis. The current thinking is that having certain genes may predispose a person to the development of narcolepsy. In 1998, two peptides secreted by the hypothalmus and similar to secretin were identified (hypocretin [HCRT] 1 and 2). Another group identified two peptides that bound to two G protein--coupled receptors on the hypothalamus. These proteins stimulated food intake and were called orexin A and B ("orexin" is Greek for "appetite"). Ultimately it was found that the hypocretin and oxrexin peptides were identical. The hypocretin-secreting cells are found only in the hypothalamus. They project to the hypothalamus but also to many other brain areas. Two major pathways have been identifed to the cortex and two to the brainstem. The descending pathways are to areas known to affect the sleep-wake cycle. One especially important projection is to the the locus ceruleus (LC). This is the location of norepinephrine-secreting neurons that are important in maintaining wakefulness. 274
Binding Affinities HCRT HCRT I PEPTIDE HCRT 2 PEPTIDE
I RECEPTOR
High Low
HCRT
2 RECEPTOR High High
Hypocretin knockout mice were found to have narcoleptic-like behavior (decreased HCRT production). Dogs with canine narcolepsy-cataplexy were found to have a mutation of genetic coding for the hypocretin-2 receptor. Thus, disorders that decrease either production of HCRT or abnormalities of the HCRT receptor could cause narcolepsy. These findings suggested an important genetic influence on narcolepsy. However, the inheritance of human narcolepsy is more complex that canine narcolepsy. For example, when looking at identical twins, when narcolepsy involves one of the pair, the other exhibits narcolepsy in only 25-30% of the cases. Thus, a combination of genetic susceptibility and some environmental trigger or infectious/autoimmune disorder may ultimately determine if narcolepsy develops. The link between the HCRT system and human narcolepsy has been further supported by the findings that seven of nine patients with narcolepsy had low HCRT-I levels in the cerebrospinal fluid. Another study of narcoleptic brains showed an absence of hypocretin-secreting neurons in the hypothalamus. Nishino et al have hypothesized that human narcolepsy involves a disruption of hypocretin neurotransmission. This could invol ve HCRT secretion, the number of HCRT receptors, or HCRT receptor function (for example an abnormal receptor or blocking antibodies). Physiologically, the loss of hypocretin stimulation of the locus ceruleus may be very important for development of the manifestations of narcolepsy. The LC cells are active during wakefulness but cease functioning during REM sleep or prior to and during cataplexy.
Key Points I. Narcolepsy is a disorder associated with daytime sleepiness the intrusion of REM sleep physiology into wakefulness. 2. Narcolepsy is associated with certain HLA markers, but genetics alone cannot explain why some patients develop the disorder. 3. Dysfunction of the hypocretin system appears to playa key role in the development of narcolepsy. 4. Secondary narcolepsy can be associated with head trauma, stroke, multiple sclerosis, brain tumors, neurodegenerative disorders, and CNS infections. 5. Cataplexy, the only symptom specific for narcolepsy, is present in only 70% of patients.
REFERENCES I. Mignot E, Hayduk R, Black J et al: HLA DQB I*0602 is associated with cataplexy in 509 narcoleptic patients. Sleep 1997; 20: 1012-1020. 2. de Lecea L, Kilduff TS. Peyron C. et al: The hypocretins: Hypothalamus-specific peptides with neuroexcitatory activity. Proc Natl Acad Sci USA 1998; 95:322-327. 3. Sakurai T, Amemiya A, Ishii M, et al: Orexins and orexin receptors: A family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell 1998; 92:573-585. 4. Nishino S. Ripley B, Overeem S, et al: Hypocretin (orexin) deficiency in human narcolepsy. Lancet 2000; 355:39-40. 5. Thannickal TC, Moore RY, Nienhuis R, et al: Reduced number of hypocretin neurons in human narcolespy. Neuron 2000; 27:469-474. 6. Brooks SN, Mignot E: Narcolepsy and idiopathic hypersomnia. In Lee-Chiong TL, Carskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus. 2002, pp 193-20 l.
275
PATIENT 85 A 30-year-old man with daytime sleepiness and episodes of weakness A 30-year-old man was evaluated for excessive daytime sleepiness of 5-year duration. There was no history of snoring or observed apnea. The patient recalled feeling weak in the knees when he laughed or was embarrassed. The patient's wife reported that sometimes he kicked the covers at night. Rarely, the patient felt he could not move for awhile as he was falling asleep at night. Physical Examination: Normal. Sleep Study Time in bed Total sleep time Sleep period time (SPT) Sleep efficiency % Sleep latency REM latency Arousal index AHI
( ) = normal
values for age. PLM
Question:
276
480 min (414--455) 350 min (400--443) 425 min (405--451) 73 (95-99) 10 min (2-10 min) 2.5 min (70-100) 20/hr l/hr « 5)
= periodic leg movement
What is the likely diagnosis?
Sleep Stages
%SPT
Stage Wake Stage 1 Stage 2 Stages 3 and 4 Stage REM
18 (0-3) 13 (2-9) 49 (50-64) 5 (7-18) 15 (20-27)
PLM index PLM-arousal index
30/hr 10/hr
Diagnosis:
Narcolepsy.
Discussion: Narcolepsy is a disorder of unknown etiology that causes excessive daytime sleepiness and usually is associated with cataplexy as well as other phenomena linked to REM sleep. A relatively young age of onset (10-30 years old) is typical; in 70-80% of cases, symptoms start before age 25. Interestingly, 5% of cases start after age 50. The history of cataplexy (episodes of weakness preceded by high emotion such as laughter, surprise, or embarrassment) is strong evidence for narcolepsy. This symptom is the only member of the classic tetrad of narcoleptic symptoms (sleep attacks, cataplexy, hypnagogic hallucinations, and sleep paralysis) that is pathognomonic for a narcolepsy. Cataplexy is present in about 70% of patients with narcolepsy. The entire tetrad is present in only 10-15% of patients. Sleep paralysis is characterized by an inability to move while still awake at sleep onset (hypnagogic) or, less commonly, on awakening (hypnopompic). This symptom can occur in normal individuals, especially after periods of sleep deprivation. Hypnagogic hallucinations ("awake dreaming") are vivid sensory sensations occurring while awake at sleep onset (termed hypnopompic just after awakening). The sensations may include visual imagery (a person or animal in the room) or auditory hallucinations. Sleep attacks are sudden periods of irresistable daytime sleepiness. While this is a classic symptom of narcolepsy, many patients complain of sleepiness throughout the day. Sleep attacks also can be a symptom of other disorders, such as sleep apnea. Daytime naps are said to be more refreshing in narcolepsy than OSA. However, not all studies have documented this difference. The onset of sleep attacks may precede cataplexy by several years (rarely, by as many as 40 years), making the diagnosis of narcolepsy more difficult. Additionally, even when present, episodes of cataplexy may be uncommon and subtle, so that obtaining an unequivocal history of cataplexy is not a simple task. Some characteristics of cataplexy may help the clinician differentiate this symptom from other episodes of a vague weak feeling or passing out. Consciousness is always maintained during attacks of cataplexy. The episodes rarely last more than afew minutes (not hours). The weakness of cataplexy is symmetric. although weakness may involve only the muscles of the neck or face (head bobbing forward, jaw dropping, or a facial droop). Other patients report buckling knees and falling. Episodes of cataplexy can be terminated by hypnagogic hallucinations and then sleep. The frequency of cataplexy is highly variable, from daily to a few times per year. Polysomnography in narcolepsy usually reveals
sleep fragmentation and often PLMS. The sleep latency is usually short, but problems with sleep maintenance are common. A short REM latency (time from sleep onset to the first REM sleep) of 20 minutes or less (termed sleep-onset REM), is the characteristic finding on polysomnography, although it is not always present (about 40-50% of the time). Again, this symptom can occur with other disorders, such as sleep apnea, depression, withdrawal of REMsuppressing medication, and prior REM deprivation of any cause. A diagnosis of narcolepsy can be made by history in a patient with daytime sleepiness (daily lapses into sleep for at least 3 months) and unequivocal cataplexy. A nocturnal sleep study and multiple sleep latency test (MSLT) are still recommended for confirmation and to rule out other sleep disorders. If cataplexy is not present, the diagnosis of narcolepsy depends on a nocturnal polysomnogram to rule out other causes of daytime sleepiness (e.g., sleep apnea, PLMS), and demonstration of either a short nocturnal REM latency « 20 minutes) orby MSLT performed on the following day-a mean sleep latency < 5 minutes and two or more naps with REM sleep. An additional important requirement is that the physician exlude other factors (e.g., recent medication changes, poor sleep) that could explain the findings. (See Patient 86 for a detailed discussion of the use of the MSLT in the diagnosis of narcolepsy.) Of note, an MSLT showing a short sleep latency but fewer than two REM periods does not rule out narcolepsy. Patients with narcolepsy and cataplexy have only a 70-80% chance of having a diagnostic MSLT on a given day. In addition, patients with obstructive sleep apnea can have two or more REM onsets on an MSLT. Some patients with narcolepsy have an MSLT with two REM onsets and a slightly longer mean sleep latency (5-8 minutes). The sleep latency of patients with narcolepsy does tend to be shorter than patients with OSA (see figure, next page), although there is considerable overlap. The importance of a short nocturnal REM latency in making the diagnosis of narcolepsy is often overlooked. While present only 40-50% of the time, Aldrich et al found a REM latency < 20 minutes to have as high a positive predictive value for narcolepsy as an MSLT with a mean sleep latency < 5 minutes and two REM onsets. Again, you must rule out other explanations, such as OSA, for a short nocturnal REM latency. However, in that study only I% of patients with OSA had a nocturnal REM latency < 20 minutes. The present patient noted a young age of onset and had symptoms consistent with cataplexy and
277
sleep paralysis. The sleep study showed a short REM latency, a low sleep efficiency, reduced slow wave sleep, and PLMS. PLMS is not uncommon in narcoleptics and can disturb sleep enough to contribute to the symptoms of daytime sleepiness. However,
PLMS does not typically result in a short REM latency. In the present patient, a PLM arousal index of lO/hr, while mildly disturbing sleep, is unlikely to be responsible for the severe symptoms. All of these findings are highly suggestive of narcolepsy.
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4 8 12 16 Mean sleep latency (min) -
Narcolepsy
20
c:::::J Sleep-related breathing disorder
Mean Sleep Latency in Patients with Narcolepsy and Sleep-related Breathing Disorders
Clinical Pearls 1. Cataplexy is the only pathognomonic symptom of narcolepsy. Unfortunately, sleep attacks may precede symptoms of cataplexy by several (rarely, many) years, and not all patients with narcolepsy have cataplexy. 2. Attacks of cataplexy are characterized by maintenance of consciousness and rarely last more than a few minutes. Weakness is symmetric, but may involve only the neck or facial muscles. 3. In the absence of unequivocal cataplexy, the diagnosis of narcolepsy depends on a sleep study to rule out other explanations for daytime sleepiness and demonstration of a short REM latency on the nocturnal sleep study and/or a diagnostic MSLT. 4. Neither a short nocturnal REM latency nor an MSLT meeting criteria for narcolepsy are very sensitive for the diagnosis. A short nocturnal REM latency is present only 40-50% of the time in patients with confirmed narcolepsy. An initial MSLT meeting criteria for narcolepsy is present only 70-80% of the time in patients with narcolepsy and cataplexy. 5. A short nocturnal REM latency and MSLT meeting diagnostic criteria for narcolepsy can occur in other disorders-especially OSA.
REFERENCES I. Mosko SS. Shampain OS. Sassin JF: Nocturnal REM latency and sleep disturbance in narcolepsy. Sleep 1984; 7: 115-125. 2. Aldrich MS. Chervin RD. Malow BA: Value of the multiple sleep latency test for the diagnosis of narcolepsy. Sleep 1997; 20:620-629. 3. Thorpy M: Current concepts in the etiology. diagnosis and treatment of narcolepsy. Sleep Medicine 200 I; 2:5-17. 4. Guilleminault C. Anagnos A: Narcolepsy. In Kryger MH. Roth T. Dement WC (eds): Principles and Practice of Sleep Medicine. Philadelphia. WB Saunders. 2000. pp 676-686.
278
PATIENT 86 A 23-year-old man with daytime sleepiness, but no symptoms of cataplexy A 23-year-old man complained of severe daytime sleepiness present for at least 2 years. If the patient was able to take a nap, he usually awoke feeling refreshed. There was no history of cataplexy or hypnagogic hallucinations, and the patient denied snoring. However, he did remember a few episodes of sleep paralysis during which he was aware of having awakened but could not move for a few minutes. The patient provided a sleep log (diary) documenting at least 7 hours of sleep each night. A sleep study and multiple sleep latency test (MSLT) were ordered. Physical Examination: Normal. Sleep Study Time in bed Total sleep time Sleep period time (SPT) Sleep efficiency % Sleep latency REM latency Arousal index
( ) = normal
values for age, PLM
440 min (430-454) 390 min (405-434) 425 min (410-439) 88 (91-99) 10 min (3-26 min) 40 min (78-99) 20/hr
= periodic
MSLT Nap 1 Nap 2 Nap 3 Nap 4 Nap 5 - - - - - - - - - _ . ---------Mean
Question:
Sleep Stages
%SPT
Stage Wake Stage 1 Stage 2 Stages 3 and 4 Stage REM
13 (3-6) 49 (40-51) 15 (16-26) 15 (22-34)
AHI PLM index
O/hr « 5) O/hr
leg movement
Sleep Latency (min)
-
8 (0-1)
3.5 2.0 3.5 1.0 4.0 -------------. 2.8 (min)
REM Latency (min) 5 3 None 3 None 3 of 5 naps with REM
What is the cause of the patient's daytime sleepiness?
279
Diagnosis:
Narcolepsy, on the basis of the MSLT.
Discussion: The MSLT can help support the diagnosis of narcolepsy, but the characteristic findings are neither absolutely sensitive nor specific for this disorder (see table). The findings must be analyzed with the results of the previous nocturnal polysornnogram, the clinical history, and the patient's recent medication and sleep history in mind. The usual MSLT criteria for narcolepsy include a mean sleep latency < 5 minutes, documenting severe daytime sleepiness, and REM sleep present in two or more of five naps. However, narcoleptic subjects occasionally have two or more REM onsets and a slightly longer mean sleep latency (5-10 minutes). Only about 60-80% of patients with classic narcolepsy (excessive daytime sleepiness plus cataplexy) have a positive MSLT on anyone day. Therefore, a negative MSLT does not rule out the possibility of narcolepsy. In such cases, a history of unequivocal cataplexy still allows the diagnosis of narcolepsy. In cases where the polysomnogram does not suggest another cause for daytime sleepiness, and the MSLT documents a short sleep latency but insufficient REM periods, there are three major possibilities: narcolepsy, idiopathic hypersomnolence, and mild OSA/upper airway resistance syndrome. This scenario assumes that insufficient sleep (during the sleep study or in the prior week) and acute withdrawal of stimulants are not responsible for the short sleep latency on the MSLT. In a study by Aldrich et al (see reference 3), a diagnosis of narcolepsy was made in patients with no cataplexy by repeating the MSLT. Unfortunately, this may not always be possible for financial considerations. Additionally, an MSLT meeting criteria for narcolepsy is not specific for this diagnosis. REM onsets are seen in other sleep pathology, such
as obstructive sleep apnea. While a much lower percentage of patients with OSA have an MSL T meeting criteria for narcolepsy, these patients make up the majority of patients studied in sleep laboratories. This is why the preceding nocturnal polysomonography is absolutely essential to rule out sleep apnea or sleep disturbance (decreased REM sleep) that may alter the REM latency. It is recommended that sleep apnea be treated before performing an MSLT (see Patients 90 and 91). A sleep diary should reveal if recent sleep deprivation caused a false positive MSLT. A drug history (and often a urine drug screen) helps clarify if medication or medication withdrawal altered the MSL T results. All drugs affecting sleepiness or REM sleep should be withdrawn for 2-3 weeks before testing, if possible. In the present case, the patient reported sleep attacks and sleep paralysis, but neither of these symptoms is specific for narcolepsy. The sleep study showed a slightly shortened REM latency, but not as short as is typical in narcolepsy. Neither sleep apnea nor PLMS was recorded, and the amount of sleep (and REM sleep) was adequate. Thus, the sleep study did not indicate a reason for daytime sleepiness or REM onsets. The MSLT met criteria for narcolepsy, as the patient exhibited severe sleepiness (sleep latency < 5 minutes), and three of five naps included REM sleep. The sleep log and medication history showed no reasons to suspect another cause for these findings. Thus, a diagnosis of narcolepsy was well-supported, despite an absence of cataplexy. Some have suggested that narcolepsy should be subdivided into a classic syndrome with cataplexy and a syndrome without cataplexy (excessive daytime sleepiness and positive MSLT). However, at the present time both are treated in the same manner.
MSLT Findings in Narcolepsy and Sleep-Disordered Breathing NARCOLEPSY WITH CATAPLEXY
Polysomnograph: SOREM period MSLT: A: 2 + SOREM periods B: Mean sleep latency < 5 minutes Both A and B
NARCOLEPSY WITHOUT CATAPLEXY
SLEEPDISORDERED BREATHING
33%
24%
1%
74% 87%
91% 81%
7% 39%
67%
75%
4%
SOREM = sleep-onset REM Data from Aldrich MS, Chervin RD, Malow BA: Value of the multiple sleep latency test for the diagnosis of narcolepsy. Sleep 1997; 20:620-629.
280
Clinical Pearls 1. MSLT testing can help support a diagnosis of narcolepsy. However, a negati ve test does not eliminate the possibility that narcolepsy is present. 2. A positive MSLT is not specific for narcolepsy and must be interpreted in light of information from the prior nocturnal polysomnogram, a medication history, and the recent pattern and amount of sleep. 3. The MSLT criteria for narcolepsy are a mean sleep latency < 5 minutes and REM sleep present in two or more of five naps.
REFERENCES I. American Sleep Disorders Association: The clinical use of the multiple sleep latency test. Sleep 1992; 15:268-276. 2. Bassetti C. Aldrich MS: Narcolepsy. Neurol Clin 1996; 14:545-569. 3. Aldrich MS. Chervin RD. Malow BA: Value of the multiple sleep latency test for the diagnosis of narcolepsy. Sleep 1997; 20:620-629. 4. Chervin RD. Aldrich MS: Sleep-onset REM periods during multiple sleep latency testis in patients evaluated for sleep apnea. Am J Resp Crit Care Med 2000; 161:426-431.
281
PATIENT 87 A 25-year-old man with narcolepsy who is still sleepy on medication A 25-year-old man was diagnosed with narcolepsy on the basis of symptoms of excessive daytime sleepiness and cataplexy. A polysomnogram revealed no apnea or periodic leg movements in sleep. A multiple sleep latency test showed a mean sleep latency of 3 minutes and REM sleep in two of five naps. The patient was started on methylphenidate (Ritalin) 10 mg tid, but still had severe daytime sleepiness in the early afternoon. He filled out a sleep diary which showed that some nights he only slept for 6 hours due to late bedtimes. He also admitted to taking an additional pill at night to allow him to study into the latenight hours. Physical Examination: Normal.
Question:
282
What treatment would you recommend?
Answer: Longer sleep time, improved sleep hygiene, and increased medication-especially before the most sleepy periods of the day. Discussion: The treatment of narcolepsy can be divided into treatment of daytime sleepiness and treatment of cataplexy/hypnagogic hallucinations. The treatment of daytime sleepiness begins with evaluation of the polysomnogram to determine if arousals from PLMS or sleep apnea could be worsening daytime sleepiness. Next, sleep hygiene and the amount of sleep must be optimized. Regular bedtime and an adequate sleep period are essential. Any sleep disturbance magnifies symptoms of narcolepsy. Those patients who find a short nap restorative may benefit from regularly scheduled naps during the day. A number of stimulant medications, including indirect sympathomimetics, are available to treat the daytime sleepiness of narcolepsy by increasing the synaptic availability of norepinepherine and dopamine (see table). Adequate control of daytime sleepiness can be attained in about 60-80% of patients. Methamphetamine, dextroamphetamine, and methylphenidate appear to be the more efficacious medications. Methylphenidate is less expensive, has a shorter half-life, and is the preferred stimulant for moderate-to-severe narcolepsy. Milder cases may be treated with pemoline, which is not a schedule II medication and often is better tolerated than the other stimulants. It has a long half-life, and the once-a-day dosing may also increase compliance. However, pemoline is no longer a first-line agent because it has been associated with severe liver damage. There are several potential problems with the use of stimulant medications. First, tolerance may develop, requiring escalating doses and leading to ineffectiveness at the highest dose. In some patients, effectiveness can be restored by a "drug holiday"no medications for several days. Unfortunately, severe sleepiness may occur during that time. Second, the medications can increase blood pressure, although this effect is not usual in normotensive patients. Third, side effects of stimulants include nervousness, irritability, headache, decreased appetite, and insomnia. Thus, they should not be taken near bedtime, especially methamphetamine and dextroamphetamine, both of which have a relatively long half-life. Fourth, attacks of paranoia or hallucinations have been reported with amphetamines, but major psychiatric side effects are rare in the absence of underlying psychiatric disorders. The peak action of dextroamphetamine, methamphetamine, and methylphenidate is 1-3 hours from ingestion, so the medications should be taken at least I hour before the time of desired effective-
ness. If a sleep attack has begun before medication is taken, then a nap may be the best treatment in some patients. Also note that methylphenidate has a much shorter half-life than the amphetamines and must be taken several times a day (bid to tid). However, methylphenidate appears less likely to produce side effects than the amphetamine drugs. All of these medications are schedule II drugs. Modafinil is a new wake-enchancing nonstimulant medication that is now available in the United States. Its mechanism of action is not known, but the action is not specific to patients with narcolepsy. It has been shown to be effective at decreasing subjective and objective measures of sleepiness in narcolepsy in double-blind placebo-controlled studies. There is no evidence that tolerance develops or that the drug impairs sleep quality. It has a number of advantages including once daily dosing, low abuse potential, and the fact that it is not a schedule II medication. While generally felt to have fewer side effects that methylphenidate and other stimulants, this has never been proven in a randomized comparison. In addition, modafinil has not been shown to be more effective than stimulants. The general impression of most clinicians is that it may be less effective than methylphenidate. The drug is fairly expensive (thirty 200-mg tablets cost about $150). Unlike the indirect sympathomimetics, withdrawal of modafinil does not result in a rebound of REM and slow wave sleep (see Patient 89 for details). Another alternative that can be tried in patients not tolerating stimulants is the irreversible MAO type B inhibitor selegiline. At doses of 10--40 mg/day, this drug has been shown to improve narcoleptic symptoms. Unfortunately, at doses over 20 mg/day it loses its MAO inhibitor selectivity, and a low tyramine diet is indicated to avoid the risk of hypertensive reactions. The drug also has anticataplectic activity in addition to its alerting ability. Patients who experience intolerable side effects with other agents may benefit from this medication as long as they are willing to adhere to a low tyramine diet. In the present case, the problem was not side effects but persistent sleepiness. The dose of methylphenidate was changed to 10 mg every morning, 20 mg before lunch, and 10 mg at 4 PM, with improvement in early afternoon symptoms. As an alternative, on nonworking days the patient was encouraged to take an early-afternoon nap. He also was encouraged to get 7-8 hours of sleep each night and to avoid any stimulant medication after supper.
283
Medications Used to Treat Excessive Daytime Sleepiness
DRUG
BRAND NAME
Pemoline
Cylert
Methylphenidate"
Ritalin
DOSE 18.75-37.5 mg qd (18.75.37.5 mg tabs) 5-10 mg bid or tid (5, 10,20 mg tabs)
MAXIMUM DOSE (DAILY)
HALF-LIFE
SELECTED SIDE EFFECTS
150 mg
12 hrs (adults)
Hepatitis. liver failure
100 mg
2-4 hrs
Nervousness. tremulousness, headache, palpitations Nervousness, tremulousness, headache. palpitations Nervousness, tremulousness, headache, palpitations Nausea. dizziness, confusion, dry mouth Headache, drug interactions, nervousness
Dextroamphetamine" Dexedrine Dextrostat Others Methamphetamine* Desoxyn
5 mg qd to bid (5, 10 mg tabs)
60mg
10-30 hrs
5 mgqd (5, 10 mg tabs)
60 mg
12-34 hrs
Selegiline**
Eldepryl
10-20 mg (5-10 mg bid)
20mg
9-14 hrs
Modafinil'
Provigil
200 or 400 mg qd (100,200 mg tabs)
400 mg
10-12 hrs
*Schedule II medication **Low tyramine diet (MAOI) 'Only modafinil is FDA-approved asa narcolepsy treatment.
Clinical Pearls I. With proper dose titration, stimulant medication can control sypmptoms of daytime sleepiness in 60-80% of narcoleptic patients. 2. Non-pharmacological measures such as good sleep hygiene, adequate sleep, and daytime naps are an essential part of treatment of daytime sleepiness in patients with narcolepsy. 3. It is essential to plan dosing according to the time profile of symptoms and to avoid medication-induced insomnia or sleep disturbance. 4. The largest doses should be taken 1-2 hours before the periods of maximum sleepiness. 5. If patients fail to respond to treatment, the coexistence of other sleep disorders such as obstructive sleep apnea should be considered. 6. Modafinil may be better tolerated than stimulants in some patients with narcolepsy.
REFERENCES
I. Mitler M. Aldrich MS, Koob GF, et al: ASDA standards of practice: Narcolepsy and its treatment with stimulants. Sleep 1994; 17:352-371.
Mitler M, Harsch J, Hirshkowitz M, et al: Long-term efficacy and safety of modafinil for the treatment of excessive daytime sleepiness associated with narcolepsy. Sleep 1994; 17:352-371. 3. Bassetti C,Aldrich MS: Narcolepsy. Neurol Clin 1996; 14:545-569. 4. U.S. Modafinil in Narcolepsy Study Group: Randomized trial of modafinil for the treatment of pathological somnolence in narcolepsy. Ann Neurol 1998; 43:88-97. 5. U.S. Modafinil in Narcolepsy Study Group: Randomized trial of modafinil asa treatment forthe excessive daytime somnolence of narcolepsy. Neurology 2000; 53:1166-1175. 6. Littner M, Johnson SF, McCall MV, et al,Standard of Practice Committee of the AASM: Practice parameters forthe treatment of narcolepsy: An update 2000. Sleep 200 I; 24:451--466. 2.
284
PATIENT 88 A 25-year-old man with frequent episodes of cataplexy A 25-year-old man who was diagnosed with narcolepsy experienced almost daily episodes of cataplexy that commonly were associated with laughter or surprise. At these times, the patient felt weakness in his legs; a few times he almost fell to the ground. The episodes varied in frequency, but were increased after periods of irregular sleep. In addition to cataplexy, the patient also was troubled by hypnagogic hallucinations, which consisted of seeing a stranger in the room as he was falling asleep. While he realized the imagery was not real, the patient sometimes felt quite anxious about the episodes. He was treated with imipramine (a tricyclic antidepressant), with decreases in the frequency of the episodes of cataplexy and hypnagogic hallucinations. However, at a dose that controlled his cataplexy, he found the medication intolerable secondary to side effects (especially dry mouth). When he abruptly stopped the medicines, he noted a significant increase in the episodes of cataplexy. Physical Examination: Normal.
Question:
What treatment would you recommend?
285
Answer:
A trial of fluoxetine or other selective serotonin reuptake inhibitor.
Discussion: Cataplexy is the only manifestation of narcolepsy that is virtually pathognomonic for this disorder. This symptom is characterized by sudden bilateral loss of muscle tone at moments of emotion (e.g., surprise, laughter, anger, embarrassment). The severity varies from minor facial drooping with eye closure, slurred speech, and a sagging jaw to loss of postural muscle tone and falling. The loss of muscle tone is not always instantaneous; it may progress over a few minutes. Duration of a cataplectic episode usually is about I minute, but it can last up to 20 minutes in the rare patient. During cataplexy, consciousness is preserved. However, the patient can enter a period of sleep and dream during the attacks, or can have hallucinations. The frequency of cataplectic episodes varies widely between patients with narcolepsy. In general, patients with the most severe cataplectic episodes tend to have them frequently, and they are very disturbing. In some patients, cataplexy is infrequent and requires no treatment. Cataplexy typically is treated more successfully than daytime sleepiness. Hypnagogic hallucinations are images occurring while the patient is still awake at sleep onset or on awakening (hypnopompic). They usually are visual, but may include or feature exclusively other senses, such as smell and hearing. Images may be simple or complex and bizarre. Patients typically know the hallucinations are not real, but are still quite frightened. The most common hypnagogic hallucination is a stranger or animal in the room. The usual treatment for cataplexy is low doses of tricyclic antidepressants. Protriptyline (5-30 mg daily) is a non sedative medication, but it is commonly associated with anticholinergic side effects. Urinary retention is a typical side effect in older patients. Imipramine (Tofranil) (25-200 mg daily) and clomipramine (75-125 mg daily) are other effective tricyclics. Successful treatment of cataplexy with serotonin reuptake inhibitors in their usual antidepressant doses has also been reported. For example, fluoxetine (Prozac), a selective serotonin reuptake inhibitor (20-80 mg daily) was effective. However, fluoxetine can cause sleep disturbance, thereby worsening daytime sleepiness. Venlafaxine, a reuptake inhibitor of both serotonin and norepinephrine, has also been reported to be effective treatment of cataplexy. All of these medications tend to suppress REM sleep, but the exact mechanism by which they suppress cataplexy is not clear. Recently, carbamazepine (Tegretol) was reported to decrease cataplexy in a patient who did not respond to the traditional medications. In that study, a dose of 200 mg twice daily was effective. The medications used to
286
treat cataplexy also suppress hypnagogic hallucinations and sleep paralysis; however, treatment of these two symptoms usually is not required. Abrupt withdrawal of medications used to treat cataplexy can result in an exacerbation of this symptom. A form of continuous cataplectic attacks (status cataplecticus) has been reported after abrupt cessation of treatment. The use of alpha-I adrenergic blockers (e.g., prazosin) also has been reported to worsen cataplexy. Therefore, these medications should be avoided in patients with narcolepsy. Guilleminault and coworkers recently reported that patients switched from amphetamines to modafinil sometimes had an increase in cataplexy. Evidently, amphetamines have some activity against cataplexy. The addition of venlafaxine to modafinil worked well in these patients. Gamma hydroxybutyrate (GHB), also know as sodium oxybate, has been shown to decrease cataplexy and increase sleep continuity in patients with narcolepsy. The drug does not acutely decrease daytime sleepiness. However, by improving nocturnal sleep, alertness may improve with chronic use of the medication. Unfortunately, the fact that this drug is abused (the "date-rape drug") has delayed approval for use in the United States. The drug has a short halflife and is usually taken on retiring and 2.5-4 hours later. Nightly total doses of 3, 6, and 9 grams were used in a large randomized trial. Nausea, headache, dizziness, and enuresis were the most common side effects. The abuse of GHB has been associated with a number of important CNS adverse clinical events, including seizure, respiratory depression, and profound decreases in level of consciousness, with instances of coma and death. Even at recommended doses, use has been associated with confusion. Orphan Medical has received U.S. FDA permission to market a liquid oral form of GHB (Xyrem). The drug is a Schedule III controlled substance. In addition, its distribution is governed by the FDA's subpart H regulations. To comply with these regulations, the company has developed a rigorous system that makes Xyrem available to patients from a single, specialty pharmacy. Both physicians and patients must receive an education program from the company before obtaining Xyrem. The company plans to release the medication in the last part of 2002. The indication will be treatment of cataplexy, but current studies are underway to evaluate the drug's long-term effects on daytime sleepiness. In the current patient, treatment was begun with f1uoxetine 20 mg daily. On this medication the frequency of cataplexy was significantly reduced. The patient tolerated the medication well and was satisfied with the treatment.
Clinical Pearls 1. Specific treatment for cataplexy may not be required in all patients with narcolepsy. 2. An increase in the frequency of cataplectic episodes can occur after withdrawal of medications treating this symptom or after initiation of treatment of other disorders with alpha-l adrenergic receptor antagonists (e.g., prazosin). 3. While the traditional treatment of cataplexy has been low doses of tricyclic antidepressants, treatment with serotonin reuptake inhibitors (fluoxetine) in the usual antidepressant dosage also has proven effective. 4. Carbamazepine can be efficacious when cataplexy does not respond to more conventional treatments. 5. Sodium oxybate may soon be released and will provide an alternative treatment for cataplexy with the additional benefits of improving nocturnal sleep.
REFERENCES Aldrich M, Rogers AE: Exacerbation of human cataplexy by prazosin. Sleep 1989; 12:254-256. Frey J. Darbonne C: Fluoxetine suppresses human cataplexy. Neurology 1994; 44:707-709. Guilleminault C, Gelb M: Clinical aspects and features of cataplexy. Adv Neurol 1995; 67:65-77. Vaughn BV, D'Cruz OF: Carbamazepine as a treatment for cataplexy. Sleep 1996; 19:101-103. Guilleminault C. Aftab FA, Karadeniz D, et al: Problems associated with switch to modafinil-A novel alerting agent in narcolepsy. Eur J Neurol 2000: 7:381-384. 6. U.S. Xyrem Multicenter Study Group: A randomized, double blind, placebo-controlled multicenter trail comparing the effects of three doses of orally-administered sodium oxybate with placebo for treatment of narcolepsy. Sleep 2002;25:42-49.
I. 2. 3. 4. 5.
287
PATIENT 89 A 24-year-old man with narcolepsy who was irritable and lost weight on methylphenidate A 24-year-old man was diagnosed as having narcolepsy on the basis of a sleep study showing no evidence of sleep apnea and an MSLT showing a short mean sleep latency (3.5 minutes) and three REM onsets in five naps. His original Epworth score was 18/24, which was reduced to 13/24 on methylphenidate 20 mg tid. Lower doses were not as effective. On this dose of medication he became quite irritable and had many fights with his wife. He also noted a dramatic decrease in his appetite and lost 15 pounds even though he was quite thin before starting medication.
Question:
288
What treatment would you recommend?
Answer:
A trial of modafinil.
Discussion: Methylphenidate and amphetamine medications are effective in decreasing daytime sleepiness to satisfactory levels in about 60-80% of patients with narcolepsy. However, some patients experience significant side effects, including nervousness, weight loss, or even sleep disturbance. Modafinil (Provigil) is a new alerting agent that is not a stimulant. Its mechanism of action is unknown. Double-blind placebo-controlled trials have shown that modafinil is effective at increasing objective and subjective measures of sleepiness in patients with narcolepsy. However, it has not been shown to be more effective than the stimulant medications such as methylphenidate. Modafinil has a number of advantages: It can be taken once daily (half life 9-14 hrs); it is not a schedule II medication (refills allowed); it does not disturb sleep if taken in the morning; and it is not associated with tolerance. Moreover, side effects are relatively few. The most common side effects are headache and nausea. Headache can be minimized by starting at a very low dose (100 mg) daily for a few days if necessary. Other side effects include nervousness and palpitations. The drug is metabolized in the liver, and there are a number of potential drug interactions. The most significant one is that modafinil may reduce the effectiveness of birth control medications. The usual starting dose of modafinil is 200 mg
once daily. If significant daytime sleepiness persists, a higher dose of 400 mg daily may be effective. While not studied systematically, some clinicians have also added small doses of methylphenidate to modafinil, if needed. One recent preliminary study suggested that if patients have breakthrough sleepiness in the afternoon, they can try splitting the dose of modafinil (modafinil 200 mg bid). Another alternative that can be tried in patients not tolerating stimulants is the irreversible MAO type B inhibitor selegiline. At doses of 10-20 mg/day, this drug has been shown to improve narcoleptic symptoms. Unfortunately, at doses over 20 mg/day it loses its MAO inhibitor selectivity, and even at lower doses a low tyramine diet is indicated to avoid the risk of hypertensive reactions. The drug also has anti-cataplectic activity in addition to its alerting ability. Patients who experience intolerable side effects with other agents may benefit from this medication as long as they are willing to adhere to a low tyramine diet. In the present case, the patient was started on modafinil 100 mg daily for I week. He did not feel as awake as he had on the methylphenidate, and the dose of modafinil was increased to 400 mg daily. On this dose he felt better, but still had problems near lunch time. Methylphenidate 10 mg was added at II AM. On this regimen he returned to his normal weight and noted less irritability,
Clinical Pearls I. Modafinil offers a useful treatment alternative and is the only FDA-approved medication for narcolepsy. 2. Modafinil has not been proven to be more effective than traditional stimulant medications for treating the daytime sleepiness of narcolepsy. 3. Modafinil has never been directly compared to methylphenidate with respect to side effects. However, modafinil did not impair sleep quality in placebo-controlled studies. Some patients may find modafinil more tolerable than stimulants. 4. Headache is the most common side effect of modafinil. Starting with 100 mg for a few days may minimize this side effect. 5. Modafinil has a number of potential drug interactions. However, the most significant is with hormonal birth control medications. 6. Selegiline, an MAO inhibitor, has both alerting and anti-cataplexic properties. It may be tried in patients intolerant of modafinil or stimulants. A low tyramine diet is required.
REFERENCES I. Mayer G, Ewert-Meier K, Hephata K: Selegeline hydrochloride treament in narcolepsy: A double-blind, placebo-controlled study. Clin Neuropharmcol 1995; 18:306-319. 2. U.S. Modafinil in Narcolepsy Study Group: Randomized trial of modafinil for the treatment of pathological somnolence in narcolepsy. Ann Neurol 1998; 43:88-97. 3. Moldofsky H, Broughton RJ, Hill JD: A randomized trial of the long-term, continued efficacy and safety of rnodafinil in narcolepsy. Sleep Med 2000; 1:109-116. 4. U.S. Modafinil in Narcolepsy Study Group: Randomized trial of rnodafinil as a treatment for the excessive daytime somnolence of narcolepsy. Neurology 2000; 53: 1166-1175.
289
PATIENT 90 A 35-year-old man with sleep apnea and a short REM latency A 35-year-old man complained of severe sleepiness of 5-year duration (Epworth Sleepiness Scale score 20/24). His wife reported that he snored heavily and had severe attacks of sleepiness in social situations and even at meals. However, she was unable to comment on the existence of periods of apnea because she slept in a separate bedroom. The patient had recently been fired for falling asleep on the job. He denied sleep paralysis, but reported feeling "funny" when angry. The sensation was more like being dizzy than weak. A multiple sleep latency test (MSLT) performed without nocturnal polysomnography at another hospital showed a mean sleep latency of 4 minutes (severe sleepiness) and two of five naps with REM sleep. The patient was diagnosed with narcolepsy, but treatment with stimulants was ineffective. Sleep Study Time in bed Total sleep time Sleep period time Sleep latency REM latency Arousal index
480 min (414-455) 350 min (400-443) 425 min (405-451) 10 min (2-20 min) 5 min (70-100) 65/hr
Sleep Stages
O/OSPT
Stage Wake Stage 1 Stage 2 Stages 3 and 4 Stage REM
18(0-3) 13 (2-9) 49 (50-64) 5 (7-18) 10 (20-27)
AHI PLM index
80/hr « 5) O/hr
( )= normal values for age, PLM = periodic leg movement
Questions:
290
What is your diagnosis? Should another MSLT be performed immediately?
Diagnosis: Obstructive sleep apnea. An MSLT would not be useful until after the sleep apnea is adequately treated. Discussion: Obstructive sleep apnea (OSA) can be associated with both a short sleep latency and two or more REM periods on an MSL T. In fact, one study of 1145 consecutive patients evaluated for suspected OSA found two or more sleep-onset REM periods in 4.7%. Thus, these MSLT findings cannot be used to support a diagnosis of narcolepsy in patients with significant sleep apnea. If narcolepsy is suspected, the approach is to first treat the sleep apnea, and then repeat the MSLT if clinically indicated. For example, treatment is begun with nasal CPAP. If daytime sleepiness completely resolves, then narcolepsy probably is not present. If some degree of sleepiness persists or there is a history of cataplexy, then further evaluation is indicated. After several weeks of treatment, another sleep study (on nasal CPAP) confirms adequate treatment and REM sleep, and a subsequent MSLT (also on CPAP) determines the severity of residual sleepiness as well as the presence of REM periods. A diagnosis of narcolepsy is supported when there is evidence of persistent, severe sleepiness (mean sleep latency < 5 minutes) and two or more of five naps with REM sleep-assuming that the nocturnal sleep study showed reasonable sleep quality (and no evidence of REM or slow wave sleep rebound). No further evaluation is needed when the MSLT is normal. However, if the MSLT shows significant sleepiness (sleep latency < 10 minutes) and no REM periods, then several possibilities must be considered, including: poor compliance with nasal CPAP, inadequate CPAP pressure, idiopathic hypersomnia, periodic leg movements, insufficient sleep, and narcolepsy. Remember, failure on an MSLT to show two or more REM periods in five naps does not rule out narcolepsy. When unequiv-
ocal cataplexy is present, a diagnosis of narcolepsy can be made on clinical grounds. Two studies have suggested that modafinil can improve sleepiness in patients with OSA still sleepy on positive airway pressure. Thus, a case can be made for adding this wake-promoting agent to positive airway pressure treatment even if a diagnosis of narcolepsy is not clearly documented. However, the addition should occur only after positive-pressure treatment is optimized and other sleep disorders eliminated, if possible. Note that while adequate positive pressure improves daytime sleepiness in OSA patients, it does not always return the MSLT mean sleep latency to a normal value (> 10 minutes). In the present patient, the polysomnogram revealed severe OSA and sleep fragmentation (high arousal index), with reduced amounts of slow wave and REM sleep. The REM latency was very short, suggesting narcolepsy - but this finding also can be seen in OSA. There was no history of unequivocal cataplexy, but daytime sleepiness can be present for several years before the onset of cataplexy. The patient underwent a nasal CPAP titration, and on 12 ern H20 the AHI was reduced to 5/hr. A large rebound in slow wave and REM sleep was noted. Treatment with nasal CPAP resulted in a complete resolution of symptoms: This fact alone made narcolepsy unlikely. However, because of the past diagnosis and the equivocal history of cataplexy, a repeat sleep study and MSLT (both on CPAP) were performed several weeks later. The nocturnal study showed a normal REM latency and adequate treatment of OSA. The MSLT showed a sleep latency of 12 minutes and an absence of REM sleep. These findings demonstrated that coexistent narcolepsy was unlikely.
Clinical Pearls 1. When significant sleep apnea is present on a nocturnal sleep study, testing for narcolepsy (MSLT) should be delayed until after the sleep apnea is adequately treated. 2. REM deprivation associated with OSA can result in both a short nocturnal REM latency and two REM periods during MSLT testing. 3. A nocturnal study documenting effective treatment of OSA (and a normal amount of REM sleep) coupled with a subsequent MSLT (on treatment) satisfying the diagnostic criteria for narcolepsy supports this additional diagnosis in a patient with OSA. 4. An MSLT without preceding nocturnal polysomnography can be misleading and is rarely indicated. 5. The addition of modafinil to positive-pressure treatment of patients with OSA can be considered if the patients are still sleepy on optimized positive-pressure treatment.
291
REFERENCES I. Walsh JK. Smitson SS. Kramer M: Sleep-onset REM sleep: Comparison of narcoleptic and sleep apnea patients. Clin Elec-
troencephalogr 1982: 13:57-60. 2. American Sleep Disorders Association: The clinical use of the multiple sleep latency test. Sleep 1992: 15:268-276. 3. Chervin RD, Aldrich MS: Sleep onset REM periods during multiple sleep latency tests in patients evaluated for sleep apnea. Am J Resp Crit Care Med 2000: 161:426--431. 4. Kingshott RN, Vennelle M, Coleman EL. et al: Randomized, double-blind, placebo-controlled crossover trial of modafinil in the treatment of residual excessive daytime sleepiness in the sleep apnea/hypopnea syndrome. Am J Respir Crit Care Med 200 I: 163:918-923. 5. Pack AI, Black JE. Schwartz JR. Matheson JK: Modafinil as adjunct therapy for daytime sleepiness in obstructive sleep apnea. Am J Respir Crit Care Med 2001: 164: 1675-1681.
292
PATIENT 91 A 40-year-old man with sleep apnea and persistent daytime sleepiness A 40-year-old African-American man with excessive daytime sleepiness since age 20 was diagnosed as having obstructive sleep apnea (AHI 80/hr) at another hospital. Nasal CPAP at 12 cm H 20 reduced the AHI to 3/hr. The patient was started on treatment, and he noted some improvement in his symptoms. However, significant daytime sleepiness persisted despite using CPAP for at least 6 hours a night. There was no history of cataplexy or sleep paralysis. Narcolepsy was considered, but the patient was HLA-DR 15 (a subtype of HLA-DR2) negative. He was referred for another opinion. Physical Examination: HEENT: dependent palate; 17-inch neck circumference. Chest: clear. Cardiac: normal. Extremities: no edema. Sleep Study (on nasal CPAP 12 em HP) Time in bed Total sleep time Sleep period time (SPT) WASO Sleep efficiency (0/0) Sleep latency REM latency
450 min (390-468) 395.5 min (343-436) 430 min (378--452) 34.5 min 88 (85-97) 10 min (2-18) 15 min (55-78)
( ) = normal values for age. AHI = apnea
Multiple Sleep Latency Test: five naps with REM sleep. Question:
+ hypopnea index. PLM
Sleep Stages
O/OSPT
Stage Awake Stage 1 Stage 2 Stages 3 and 4 Stage REM
8 (1-12) 10 (5-11) 52 (44-66) 10(2-15) 20 (19-27)
AHI « 5/hr) PLM index
3/hr IO/hr
= periodic limb movement
On nasal CPAP 12 cm H 20 : mean sleep latency 4 minutes; three of
What is causing the persistent sleepiness?
293
Diagnosis:
Narcolepsy.
Discussion: A combination of narcolepsy and obstructive sleep apnea (OS A) is not uncommon. Adequate treatment of both disorders is required for control of daytime sleepiness. If cataplexy is unequivocal, a diagnosis of narcolepsy can be made in patients with OSA on clinical grounds. However, cataplexy makes a delayed appearance in many patients with narcolepsy-sometimes years after sleep attacks begin-and is present in only about 70% of patients with narcolepsy. The multiple sleep latency test (MSLT) is used to support the diagnosis of narcolepsy in these patients with OSA and suspected narcolepsy without cataplexy. However, patients with untreated OSA can exhibit MSLT findings consistent with narcolepsy. Therefore, the first step in all of these cases is successful treatment ofthe GSA. Then a repeat sleep study (on treatment) is followed by an MSLT (also on treatment). The sleep study documents adequate treatment (and adequate sleep), and the MSLT provides objective evidence of continued daytime sleepiness (sleep latency < 5 min) and the presence of two or more REM periods. The differential of a patient with OSA still sleepy on CPAP includes: poor compliance, inadequate CPAP pressure, narcolepsy, periodic limb movements in sleep, idiopathic hypersomnia, insufficient sleep, and depression. "LA haplotyping has been used in evaluation of suspected narcolepsy since early studies showed that most patients with narcolepsy (with cataplexy) were HLA-DR2 positive. Obviously, many patients without narcolepsy are HLA-DR2 positive, so the
main utility of haplotyping is excluding the diagnosis in HLA-DR2 negative patients. The first reports were that most Japanese patients with narcolepsy were HLA-DR2 positive. Subsequent studies have found that DRI5 (a subtype of HLA-DR2) and DQ6 (particularly DQB I *0602) are present in 95-100% of Caucasian and Japanese patients with narcolepsy, and DQB I*0602 also is present in 95% of narcoleptic African-American patients. However, 40% of the latter are DR 15 negative. Therefore, DQBl *0602 appears to be the best marker across all races, but the utility of genetic testing is limited by the fact that 1-5% of all patients with narcolepsy are negative for DQB I *0602. Patients with narcolepsy without cataplexy are more likely to be DQB I *0602 negative. Of note, there appear to be factors other than genetic that determine the appearance of the syndrome. Cases of monozygotic twins have been reported where only one twin developed narcolepsy. In the present patient, a negative HLA-DR2 test did not rule out narcolepsy-the patient was, in fact, DQB I*0602 positive. The early age of symptom onset was consistent with narcolepsy. The sleep study on CPAP showed excellent treatment of his sleep apnea and sleep of fairly good quality (no evidence of REM rebound). The MSL T documented both severe daytime sleepiness and REM periods in three of five naps. The absence of other reasons to explain these MSLT findings makes narcolepsy highly likely. The patient was treated with methylphenidate 10 mg tid, with improvement in his symptoms of daytime sleepiness.
Clinical Pearls I. While most narcolepsy patients are DQB I*602 positive (all races), a negative result does not rule out narcolepsy. 2. When daytime sleepiness persists on nasal CPAP, consider the possibility of other sleep disorders as well as poor compliance or inadequate pressure. 3. An MSLT can provide objective evidence of persistent sleepiness on nasal CPAP and help support a diagnosis of narcolepsy. 4. If narcolepsy is suspected in a patient with significant OSA, first treat the OSA. Then, a sleep study and MSLT on treatment can be ordered to support a diagnosis of narcolepsy as well as OSA.
REFERENCES I. American Sleep Disorders Association: The clinical use of the multiple sleep latency test. Sleep 1992; 15:268-276. 2. Mignot E. Lin X. Arrigoni J. et al: DQB I*0602 and DQA I*0 10I are better markers than DR2 for narcolepsy in Caucasians and African-Americans. Sleep 1994; 17:60-67. 3. Bassetti C. Aldrich MS: Narcolepsy. Neurol Clin 1996; 14:545-569.
294
PATIENT 92 A 35-year-old man requesting stimulant medication A 35-year-old man was evaluated for complaints of excessive daytime sleepiness of 6-year duration. He had been diagnosed with idiopathic hypersomnia by another physician and had been receiving stimulant medications for more than 2 years. After having recently moved, he sought medical attention for medication refills. For the previous 2 months he had not taken stimulant medications, and at work he drank large amounts of coffee to combat sleepiness. His usual bedtime was 11:00 PM, and he awoke at 4:30 AM by alarm. The early awake time was necessary because of a lengthy commute to work. On the weekends, he slept to 9:00 AM and felt somewhat less sleepy. The patient denied a history of cataplexy, hypnagogic hallucinations, sleep paralysis, head trauma, or depression. There was no history of snoring. His previous evaluations included a normal nocturnal polysomnogram, and an MSLT showed a short sleep latency (8 minutes) with no episodes of REM sleep. The patient was asked to keep a sleep log and to obtain at least 7 hours of sleep nightly before a repeat polysomnogram and MSL T. Physical Examination: Normal. Laboratory Findings: Normal thyroid function. Sleep Study Time in bed Total sleep time Sleep period time (SPT) Sleep efficiency (0/0) Sleep latency REM latency Arousal index AHI AHI
= apnea + hypopnea index, MSLT:
440 min (414-455) 417 min (400-443) 430 min (405-451) 95 (95-99) 10 min (2-10 min) 110 min (70-100) 10/hr 2/hr « 5) PLM
Sleep Stages
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
3 (0-3) 13 (2-9) 49 (50-64) 15 (7-18) 20 (20-27)
PLM index PLM-arousal index
O/hr O/hr
= periodic leg movement. ( ) = normal
values for age
Mean sleep latency 13 minutes, no REM periods in five naps.
Question:
What is your diagnosis?
295
Diagnosis:
Insufficient sleep syndrome.
Discussion: In the insufficient sleep syndrome, an inadequate amount of time is allotted for sleep by the patient due to personal or societal (work) schedules. The amount of sleep required for normal function varies considerably between individuals, with a population mean around 7.5 hours. This sleep need is genetically determined. When less sleep is obtained, a sleep debt accumulates. Commonly, such patients sleep considerably more on weekends. A study of patients with the insufficient sleep syndrome found that this disparity between the amount of sleep obtained on weekday nights and on weekends was an important clinical clue. These patients had normal-to-high sleep efficiencies during nocturnal sleep testing, with greater total sleep times than reported for a typical night, and they showed moderate reductions in sleep latency without REM periods on MSLT. One study in normal subjects found that a reduction of the time in bed from 8 to 6 hours reduced the mean sleep latency from approximately 12.5 to 8.5 minutes. Thus, a mild reduction in nocturnal sleep can increase daytime sleepiness, although usually not to a severe degree (i.e., sleep latency < 5 minutes). Remember, though, that any reduction in nocturnal sleep magnifies the sleepiness associated with
other sleep disorders, such as narcolepsy or sleep apnea. The present patient's normal duration of sleep was, at most, 5.5 hours. Thus, the possibility of insufficient sleep was considered. This short sleep time would make interpretation of an MSLT difficult, which is why the patient was asked to sleep for at least 7 hours and keep a sleep log prior to testing. The nocturnal polysomnogram documented fairly normal sleep. The MSLT revealed a sleep latency in the "grey" zone: traditionally, a sleep latency> 15 minutes is considered normal, < 10 minutes abnormal, and 10-15 minutes could be either (mild sleepiness). Certainly a sleep latency of 13 minutes is inconsistent with the severe symptoms reported by this patient. When confronted with the results of his testing, the patient admitted that he thinks "sleep is a waste of time" and that he always tries to function on as little sleep as possible. Although he could not remember his sleep habits before the previous sleep testing, he believed he had allotted the usual short amount of time. While not entirely happy with the decision not to prescribe stimulants, the patient did understand that the test proved he would be less sleepy during the day if he had more nocturnal sleep.
Clinical Pearls 1. Proper interpretation of the MSLT depends on the patient having an adequate amount of sleep (ideally 7-7.5 hours a night) for at least 1 week before testing. 2. An accurate sleep log is an essential part of the evaluation of daytime sleepiness. It also is helpful in interpreting the results of both the nocturnal sleep study and the MSLT. 3. A modest shortening of nocturnal sleep (to about 6 hours) can shorten the mean sleep latency on the MSL T to < 10 minutes. 4. The insufficient sleep syndrome should be considered in the differential of excessive daytime sleepiness. It may also worsen the impact of other disorders such as narcolepsy and OSA.
REFERENCES l. Roehrs T. Zorick F. Sicklesteel J. et al: Excessive daytime sleepiness associated with insufficient sleep. Sleep 1983; 6:319-325. 2. American Sleep Disorders Association: The clinical use of the multiple sleep latency test. Sleep 1992; 15:268-276. 3. Rosenthal L. Roehrs TA. Rosen A. et al: Level of sleepiness and total sleep time following various time in bed conditions. Sleep 1993; 16:226-232. 4. Aldrich MS: The clinical spectrum of narcolepsy and idiopathic hypersomnia. Neurology 1996; 46:383-40 I.
296
PATIENT 93 A 64-year-old man with daytime sleepiness since age 21 A 64-year-old man was evaluated for the complaint of excessive daytime sleepiness present since age 21. He sometimes fell asleep while driving and in social situations. He denied a history of cataplexy, sleep paralysis, or hypnagogic hallucinations. There was a history of mild snoring. The patient retired nightly around 9:30 PM and reported falling asleep in less than 30 minutes. He usually arose at 6:30 AM (awakened by alarm clock). The patient commonly slept for up to 9 hours on the weekend, with no reduction in his symptoms of sleepiness. There was no history of head trauma nor symptoms to suggest depression. Physical Examination: Vital signs: normal. General: thin, in no distress. HEENT: normal. Chest: clear to auscultation and percussion. Cardiac: normal. Abdomen: normal. Extremities: normal. Neurologic: normal.
Sleep Study Time in bed Total sleep time Sleep period time (SPT) Sleep efficiency (%) Sleep latency REM latency Arousal index
490 min (414-489) 450 min (363-452) 470 min (404-479) 92 (83-97) 4.5 min (1-15 min) 100 min (65-103) lO/hr
( ) = normal values for age, AHI = apnea
MSLT:
Mean sleep latency
Question:
Sleep Stages
%SPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
10 (2-14) 10 (6-14) 55 (48-66) 7 (0-8) 18 (20-27)
AHI PLM index
O/hr « 5) O/hr
+ hypopnea index, PLM = periodic leg movement
= 6 minutes; no REM sleep in five naps.
What is the most likely cause of the patient's daytime sleepiness?
297
Diagnosis:
Idiopathic hypersomnia.
Discussion: The diagnosis of idiopathic hypersomnia (IHS) is made by documenting excessive daytime sleepiness (EDS) despite adequate sleep and excluding other disorders that cause daytime sleepiness, such as narcolepsy. Patients with IHS may complain of persistent daytime drowsiness or discrete sleep attacks. IHS, like narcolepsy, usually begins in adolescence or the early twenties. The syndrome accounts for 5-10% of patients seen in sleep clinics with complaints of EDS. The sleep period may be long (> 8 hours). Some patients are able to wake normally; others report difficulty waking and/or disorientation at awakening ("sleep drunkenness"). Unlike narcolepsy, naps are not refreshing. Some patients have the onset of symptoms after a viral illness such as hepatitis and mononucleosis. Rarely, familial cases occur and are associated with an increased incidence of HLA-Cw2. Some of this group have associated symptoms suggesting problems with the autonomic nervous system, including headache, syncope, orthostatic hypotension, and peripheral vascular complaints (Raynaud-type symptoms). Other patients with IHS have no history of viral illness or autonomic nervous system problems. Thus, patients with IHS are a heterogeneous group. The polysomnography of IHS patients shows a normal or increased quantity of sleep. Sleep quality usually is normal, and the amount of slow wave sleep may be increased. The REM latency is not decreased. The sleep latency usually is < 10 minutes. In contrast, the sleep of narcoleptics typically is shortened or fragmented, and the REM latency may be very short « 20 minutes). The multiple sleep latency test (MSLT) in patients with IHS documents EDS (sleep latency < 10 minutes) while showing no REM sleep episodes (rarely, one) in five naps. Some have suggested that 24-hour sleep recording may be useful in patients with IHS. Common results are long nocturnal sleep and long daytime naps, with
10-12 hrs of total sleep. Some patients with IHS report hypnagogic hallucinations and sleep paralysis. Thus, eliciting such symptoms does not necessarily differentiate IHS from narcolepsy. Before the diagnosis of IHS can be made with confidence, medical and psychiatric causes of EDS should be excluded. Chronic low-grade depression may be difficult to eliminate as a possibility. A moderately reduced nocturnal REM latency « 60 minutes) might be a clue that depression is present. Sleepiness also can be a symptom of progressive hydrocephalus. Recent onset, worsening of symptoms, or impairment of cognitive functioning suggests a need for neurologic evaluation and computed axial tomography or other studies to rule out this possibility. Posttraumatic hypersomnia is a syndrome in which symptoms and findings of hypersomnia develop 6-18 months after head trauma. Sedative/hypnotic abuse is another possible cause of daytime sleepiness. Urine or blood tests can screen for use of these agents. The insufficient sleep syndrome and the upper airway resistance syndrome (UARS) also should be excluded. The treatment of patients with IHS involves the same stimulant medications as used in narcolepsy, but patients with IHS do not always respond. Patients also are instructed to avoid reductions in sleep time or irregular sleep/wake schedules. The present patient snored lightly but aroused rarely, making UARS unlikely. The nocturnal sleep study did not show a decreased REM latency. There was no history of depression or head trauma. The MSLT documented moderate sleepiness (sleep latency = 6 min) despite fairly normal sleep, but no REM sleep was noted. The MSL T was not consistent with narcolepsy, and there was no history of cataplexy. However, neither of these facts absolutely excludes narcolepsy. Therefore, the diagnosis of IHS always is made with some uncertainty.
Comparison of Narcolepsy and Idiopathic Hypersomnia NARCOLEPSY
IHS
Symptoms
Cataplexy in 70% Hypnagogic hallucinations Sleep paralysis
No cataplexy Hypnagogic hallucinations Sleep paralysis
Nocturnal sleep
Fragmented sleep Short sleep latency Short REM latency Refreshing naps
Normal to long total sleep time Normal sleep architecture REM latency not decreased Non-refreshing naps
MSLT
Mean sleep latency < 5 min 2: 2 REM onsets in 5 naps
Mean sleep latency < 10 min < 2 REM onsets
298
Clinical Pearls I. The diagnosis of idiopathic hypersomnia depends on exclusion of other disorders causing excessive daytime sleepiness, including sleep apnea (and the upper airway resistance syndrome), periodic limb movements in sleep, narcolepsy, affective disorders, stimulant withdrawal, and insufficient sleep. 2. History of recent head trauma suggests the posttraumatic hypersomnia syndrome. 3. When polysomnography fails to explain the recent onset of hypersomnia in an older patient, exclude neurologic disease (e.g., brain tumors, hydrocephalus), medical illness, medication side effects, and depression. 4. Patients with idiopathic hypersomnia have a mean sleep latency < 10 minutes, but less than two REM onsets in fi ve naps on an MSL T.
REFERENCES I. Guilleminault C. van den Hoed J. Miles L: Posttraumatic excessive daytime sleepiness. Neurology 1983; 33: 1584-1589. 2. Baker TL. Guilleminault C. Nino-Murcia G. Dement We: Comparative polysomnographic study of narcolepsy and idiopathic central nervous system hypersomnia. Sleep 1986; 9:232-242. 3. Aldrich MS: The clinical spectrum of narcolepsy and idiopathic hypersomnia. Neurology 1996; 46:383-40 I. 4. Billiard M: Idiopathic hypersomnia. Neurol Clin 1996; 14:573-582.
299
FUNDAMENTALS OF SLEEP MEDICINE 19
PARASOMNIAS
Determining a cause for abnormal movements or behavior during sleep is often a challenging problem for sleep physicians. A parasomnia is a motor, verbal, or experential phenomenon that occurs during sleep and is often undesirable. Evaluation of these nocturnal "spells" begins with a detailed history of the nature, age of onset, and time of night of the episodes. Also explore factors (sleep deprivation) and medications that may have affected the behaviors. Simultaneous video and sleep monitoring can be of great value in evaluating parasomnias. Today most digital polysomnography equipment manufacturers offer digital video recording or a method of time stamping or synchronizing analog video recording. Additional electrodes are needed to evaluate the possibility of seizure activity (see Fundamentals 20). For the REM behavior disorder, monitoring of hand muscle EMG (flexor digitorum) is often performed in addition to right and left tibialis anterior (leg) EMGs. One problem in monitoring parasomnias is that they typically do not occur every night. Multiple nights of study may be needed.
Differential Diagnosis of Unusual Behavior Associated With Sleep DIAGNOSIS
USUAL SLEEP STAGE
Normal Sleep Phenomena Sleep starts (hypnic jerks) Sleep onset Nightmares (REM anxiety attacks) REM» NREM Parasomnias Sleep walking (somnabulism) NREM Sleep terrors NREM Confusional arousal NREM Sleep talking (somniloquy) NREM and REM REM behavior disorder REM Parasomnia overlap disorder NREM and REM Bruxism NREM (stage 2) Enureis NREM and REM (random) Psychiatric Disorders NREM (transition stage 2 to stage 3) Panic attacks Posttraumatic stress syndrome REM and NREM Seizure Disorders Nocturnal seizures NREM > Wake >REM Possible Seizure Disorders Nocturnal paroxysmal dystonia Episodic nocturnal wandering
Hypnicjerks (sleep starts) are brief, total-body jerks that occur at sleep onset. These are entirely normal. Nightmares (REM anxiety attacks) are unpleasant dreams that can awaken the individual. Both of these phenomena are present in most normal individuals. Sleep walking, sleep terrors, and confusional arousals occur out of NREM sleep (see Patients 94 and 95), are more common in childhood, frequently have a family history, and often decrease in frequency with increasing age. The REM behavior disorder 300
(see Patient 96), in contrast, is more more common in men in their 50s. Loss of muscle hypotonia during REM sleep enables the patient to act out his or her dreams. In the parasomnia overlap disorder, patients present with elements of both night terrors/sleep walking out of NREM sleep and the REM behavior disorder out of REM sleep. Bruxism, grinding and gnashing of teeth during sleep (see Patient 97), is most common in stage 2 NREM sleep. Enuresis (bed wetting) can occur in any stage of sleep. Sleep talking (somniloquy) is the utterance of speech or sounds during sleep without simultaneous, subjective, and detailed awareness of the event. Sleep talking can occur out of any stage of sleep. Patients with sleep terrors often talk out of slow wave sleep. The REM behavior disorder can be associated with talking as well as violent utterances. Sleep talking can also occur in the obstructive sleep apnea syndrome during arousals from sleep. Nocturnal paroxysmal dsytonia is a syndrome characterized by coarse movements associated with tonic spasms that often occur multiple times per night. The episodes can be violent or associated with vocalization. There is now evidence that this syndrome may in fact be a seizure disorder. Carbamazepine (400-600 mg) at bedtime is an effective treatment for the disorder. Episodic nocturnal wanderings may present with symptoms similar to sleep walking and sleep terrors. Patients may wander, vocalize, and show violent behavior during sleep. These patients respond to antiseizure medications, and this syndrome may represent automatisms secondary to an epileptic disorder. Among psychiatric disorders, panic attacks can present as nocturnal spells. While nocturnal panic attacks usually occur in patients with known daytime attacks, a few patients may have panic attacks only at night. Post-traumatic stress disorder patients also may complain of terrifying dreams and may awaken with episodes similar to night terrors. They usually are not confused on awakening and may have vivid dream recall.
Common Features Associated with Parasomnias SLEEP TERROR
CONFUSIONAL AROUSAL
SLEEP WALKING
NIGHTMARES
RBD
SEIZURE
Time of night Sleep stage at start Screams
Early SWS
Early SWS
Early SWS
Late REM
Yes
No
No
Rare
Autonomic activation Walking Confusion after episode Age Episodes also in Wake CNS lesion
Extreme
Minimal
Minimal
Mild
Any NREM > REM Rare (talking Rare or yelling) Mild Mild
No Usual
No Usual
Yes Usual
No Rare
Rare Rare
Common Usual
Child No
Child No
Child No
Child!Adult No
Adult No
Adult Usual
No
No
No
No
Can occur
Common
Late REM
RBD = REM behavior disorder. SWS = slow wave sleep (stages 3 and 4). > = more likely than Adapted from Broughton RJ: NREM arousal parasomnias. In Kryger MH. Roth T, Dement WH (eds): Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, WB Saunders. 2000. pp693-706. Not every patient with a parasomnia requires a sleep study; there are important factors to consider in the decision. Moreover, the type of monitoring will depend on the clinician's impression of the most likely diagnosis as well as the local resources.
Indications for Sleep Monitoring in Possible Parasomnias Very frequent events Unusual age of onset Injury has occurred to patient or bedpartner Associated with daytime sleepiness Medical/legal issues
301
REFERENCES I. Broughton RJ: NREM arousal parasomnias. ln Kryger MH. Roth T. Dement WH (eds): Principles and Practice of Sleep Medicine. 3rd ed. Philadelphia, WB Saunders. 2000. pp 693-706. 2. Mahowald MW. Schenck CH: REM sleep parasornnias. In Kryger MH. Roth T, Dement WH (eds): Principles and Practice of Sleep Medicine. Philadelphia. WB Saunders, 2000. pp 724-741. 3. Foldvary N: Video-encephalography/polysomnography for monitoring nocturnal events. In Lee-Chiong TL. Sateia MJ, Carsakadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002, pp 681-688.
302
PATIENT 94 A 20-year-old man with severe "nightmares" A 20-year-old man was evaluated for complaints of awakening with screaming and severe sweating once or twice a week, usually before 3 AM in the morning. According to his roommate, the patient was diaphoretic and difficult to communicate with during these episodes. Total amnesia for the events was reported. The patient admitted that he had severe nightmares as a child, but that they were infrequent until recently. The events typically occurred after he had missed his normal amount of sleep the night before because of social events or studying for tests. Physical Examination: Normal.
Question:
Are these episodes really nightmares? What is the correct diagnosis?
303
Diagnosis: Sleep terrors (pavor nocturnus). Discussion: Sleep terrors, also called night terrors or pavor nocturnus, consist of sudden arousal, usually from stage 3 or 4 sleep, accompanied by a scream or cry and manifestations of severe fear (behavioral and autonomic). The affected individual typically is confused, diaphoretic, and tachycardic, and he or she frequently sits up in bed. It is difficult or impossible to communicate with a person having a night terror, and total amnesia for the event is usual. Night terrors typically occur in prepubertal children (up to 3%) and subside by adolescence; they are uncommon in adults. Some studies have suggested that the presence of night terrors in adulthood indicates psychopathology. However, other authorities disagree with this conclusion. Patients may sleepwalk during episodes of night terrors. Thus, many consider sleepwalking and night terrors to be one syndrome with a spectrum of manifestations. Both are considered disorders of arousal. In adults, night terrors/sleep walking can occur out of stage 2 NREM sleep and during the second part of the night. Stress, febrile illness, sleep deprivation, and heavy caffeine intake have been identified as inciting agents for night terrors. Slow wave sleep rebound, such as occurs with nasal CPAP treatment of GSA, also has been associated with episodes of night terrors. Confusional arousals are also somewhat similar to night terrors. They also tend to occur out of stages 3 and 4 sleep. Individuals are very confused following spontaneous or forced arousals from sleep. In contrast to night terrors, there is no autonomic hyperactivity, signs of fear, or blood-curdling screams. The differential diagnosis of night terrors includes nightmares, nocturnal seizure activity, the
REM behavior disorder (RBD), and the posttraumatic stress syndrome. Nightmares (dream anxiety attacks) and RBD occur within REM sleep and are more common in the second part of the night. RBD usually does not begin until after age 40. Differentiation from partial complex seizures is difficult without complete EEG monitoring. Seizures tend to be more stereotypic and may occur during the day. Patients with nightmares, the posttraumatic stress syndrome, and RBD typically can relate complex dream mentation that promoted the event. Polysomnography usually is not required to evaluate night terrors unless the episodes are frequent, violent, or have the potential to result in self-injury. When polysomnography is performed, inclusion of video monitoring (synchronized if possible) is ideal. If seizures are suspected, then a complete clinical EEG montage is needed. When a night terror is captured, it appears as a sudden arousal from slow wave sleep. The EMG amplitude is greatly increased, and alpha waves are present; however, persistent slow wave activity also is noted. If the episodes of night terrors are infrequent, treatment beyond simple environmental precautions is unnecessary. Several medications, including benzodiazepines, tricyclic antidepressants, and selective serotonin reuptake inhibitors, have been used with some success. Avoidance of inciting agents is recommended. The present patient seemed emotionally welladjusted. He was told that irregular sleep patterns were probably responsible for the reappearance of the episodes. As he wanted to avoid medication at all costs, the patient diligently maintained good sleep habits and reported only one minor episode every 2-3 months.
Clinical Pearls I. Night terrors usually occur from slow wave sleep and are more common in the first part of the night in children. 2. In adults, night terrors can occur from stage 2 sleep and in the second half of the night. 3. The persistence of night terrors into adulthood or onset in adulthood is not necessarily evidence that psychopathology is present. 4. Unlike nightmares and RBD, patients with night terrors cannot relate dream mentation associated with the event. 5. Night terrors have been described in adults during nasal CPAP treatment of GSA.
304
REFERENCES I. Pressman MR, Meyer TJ .. Kendrick-Mohamed J, et al: Night terrors in an adult precipitated by sleep apnea. Sleep I'!'!J: 18:773-775. 2. Guilleminault C, Moscovithc A, et al: Forensic sleep medicine: Nocturnal wanderings and violence. Sleep 19'15: 18:740-748. 3. Crisp AH: The sleepwalking/nightterrors syndrome in adults. Postgrad Med J 1996; 72:599-604. 4. Mahowald MW, Schenck CH: NREM sleep parasomnias. Neurol Clin 1996: 14:675-696. 5. Broughton RJ: NREM arousal parasornnias. In Kryger MH, Roth T, Dement WH (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders, 2000, pp 693-706.
305
PATIENT 95 A 25-year-old woman walking in her sleep A 25-year-old woman was referred for evaluation of sleepwalking. She had a history of sleepwalking beginning at age 10, at which time she had about five episodes a month. These gradually decreased until they were uncommon (one or two a year) from age 13 on. However, recently the episodes had been occurring weekly. During this time she had been sleeping poorly because of stress related to college. She sometimes got as little as 3 hours of sleep because of studying for examinations. The patient sought evaluation because she had read that persistence of sleepwalking into adulthood implied psychiatric problems. She denied symptoms of depression and anxiety and did not abuse alcohol or stimulant medications. Physical Examination: Normal. Figure: The tracings below occurred when the patient was noted to sit up in bed and pick at the sheets. When the technician entered the room and tried to talk to the patient, she did not respond.
Question:
Should the patient be referred for psychiatric evaluation?
ROC-A 1 LaC - A 2
chin EMG
306
I
50 uv
Answer: No. Sleepwalking in adults is often not associated with psychopathology. Referral is indicated only if the history suggests an emotional problem. Discussion: Sleepwalking (somnambulism) is defined as a series of complex behaviors that are initiated during slow wave sleep and result in ambulation during sleep. Activity can vary from simply sitting up in bed to walking. Patients usually are difficult to awaken during these episodes, and if awakened, are confused. Talking during sleep (somniloquy) can occur simultaneously. In children, sleepwalking usually occurs during the first third of the night, when slow wave sleep is present. However, recent studies in adults have recorded episodes beginning in stage 2 NREM sleep and frequently in the second half of the night. Episodes in children are rarely violent, and movements often are slow, but episodes in adults can be frenzied and violent. Sleepwalking may be terminated by the patient returning to bed or by the patient simply lying down and continuing sleep out of bed. Typically, there is total amnesia for the episodes. Sleepwalking can occur as soon as children can walk, but peaks between the ages of 4 and 8. The onset of sleepwalking can occur in adulthood; however, most adult sleepwalkers had episodes during childhood. Sleepwalking usually disappears in adolescence. Fever, sleep deprivation, and certain medications (e.g., phenothiazines, tricyclic antidepressants, lithium) can precipitate the events. Sleepwalking during slow wave sleep rebound has been reported in a patient with obstructive sleep apnea (OSA) treated with nasal CPAP. While it was once thought that persistence of sleepwalking into adulthood was a manifestation of underlying psychopathology, several studies have found that at least 50% of adult sleepwalkers have no psychopathology. Sleepwalking is considered a disorder of arousal. Because there is some overlap with night terrors, some refer to the syndrome as sleepwalking/night terrors. Although polysomnography rarely is performed to evaluate cases of sleepwalking, the classic finding is a sudden arousal occurring in slow wave sleep. During the prolonged arousal, there usually is tachycardia and persistence of slow wave EEG activity-despite the presence of high-frequency EEG activity and an increase in EMG amplitude. Evaluation of parasomnias in the sleep laboratory is best performed with simultaneous video recording to document body movements. Sleep monitoring is indicated when sleepwalking has resulted in bodily injury or has failed to respond to simple measures. The differential diagnosis of sleepwalking includes the REM behavior disorder, seizure disorders (such as temporal lobe seizures), and dissocia-
tive states. The walking associated with the REM behavior disorder occurs during REM sleep usually in the later part of the night. When awakened, subjects generally are not confused and may relate a dream in which they were moving. Patients with nocturnal seizures also may have seizures during wakefulness. However, if seizure activity only occurs during sleep, this diagnosis is more difficult. Diagnosis of temporal lobe seizures may not be possible with conventional scalp electrodes. In one study of 100 adults referred for evaluation of sleep-related injury, 54 had night terrors/sleepwalking, 36 had the REM behavior disorder, and two had nocturnal seizures. Interestingly, 33% of the group with sleepwalking had an age of onset after age 16, and 70% had episodes arising from both stages I and 2 as well as slow wave sleep. The sleepwalking behaviors were variable in duration and intensity. Psychological evaluation identified 50% with psychiatric disorders (e.g., depression, substance abuse, dysthymia). However, 50% of the group had no identifiable psychopathology. The main complications of sleepwalking are social embarrassment and danger of self-injury. Violent behavior (homicide) has been reported. The treatment of sleepwalking includes environmental precautions (e.g., closed doors and windows, sleeping on the first level, avoidance of precipitating causes such as sleep deprivation) and reassurance. If the episodes seem to require medication, then benzodiazepines or tricyclic antidepressants may be tried. Clonazepam 0.5-2 mg qhs or temazepam 30 mg qhs is commonly prescribed. Medications should be given early enough before bedtime so that sleepwalking in the first slow wave cycle is prevented. Selective serotonin reuptake inhibitors also have been reported to work. In the present case, the irregular sleep schedule and sleep deprivation were the most likely causes of the return of sleepwalking. The sample sleep tracing shows evidence of arousal from slow wave sleep. Note that some slow wave activity still is present, despite the large amount of high-frequency EEG activity. As the history did not suggest psychopathology, referral for psychological evaluation was not deemed necessary. The patient was instructed to keep a regular sleep schedule and to take environmental precautions. She was reassured that the return of her sleepwalking did not necessarily imply that she had emotional problems. After she began following instructions, the sleepwalking episodes decreased to less than one every 2-3 months.
307
Clinical Pearls I. Not all adults with sleepwalking had episodes as children. 2. Sleepwalking classically occurs during slow wave sleep in the first part of the night (especially in children). However, in some adults onset can occur in stage 2 sleep and in the second half of the night. 3. The persistence of sleepwalking into adulthood does not necessarily imply underlying psychopathology. 4. Prior sleep deprivation with resulting slow wave sleep rebound (as with nasal CPAP treatment for OSA) can trigger episodes of sleepwalking.
REFERENCES I. Schenck CH, Milner DM, Hurwitz TD, et al: A polysomnographic and clinical report of sleep related injury in 100 adult patients. Am J Psych 1989; 146: 1166-1 172. 2. Kavey NB. Whyte J. Resor SA, et al: Somnabulism in adults. Neurology 1990; 40:749-752. 3. Millman RF. Kipp GJ. Carskadon MA: Sleepwalking precipitated by treatment of sleep apnea with nasal CPAP. Chest 1991; 99:750-751. 4. Mahowald MW, Schenck CH: NREM sleep parasomnias. Neural Clin 1996; 14:675-696.
308
PATIENT 96 A 55-year-old man with violent dreams A 55-year-old man complained of violent movements during sleep. The problem had begun 14 months ago. His movements tended to occur during the last half of the night and varied from simply moving his arms to hitting his wife. On some occasions, the patient got up from the bed. When awakened he was not confused, but only rarely remembered dream content. During some of the episodes, the patient also screamed or talked about harming someone. The episodes seemed to be worse after periods of interrupted sleep or a change in sleep schedule. There was no history of head trauma or change in intellectual functioning, motor strength, sensation, or coordination. There was no history of sleepwalking (somnambulism) during childhood. Physical Examination: Normal. Sleep Study: The following tracing was noted.
Question:
What is your diagnosis?
patient yelling
C4-Al C3-A2 02-Al ROC-Al LOC-A2 EKG chinEMG Leg EMG
FIGURE
I
309
Diagnosis:
REM sleep behavior disorder.
Discussion: The REM behavior disorder (RBD) is characterized by a loss of the normal muscle hypotonia associated with REM sleep or an overactivation of phasic REM phenomenon; thus, dreams can be "acted out." Limb and body movements often are violent (e.g., hitting a wall, kicking) and may be associated with emotionally charged utterances. The movements can be related to dream content ("kicking an attacker"), but the patient may not remember associated dream material when awakened during an episode. Serious injury to the patient or the bed partner can result from these episodes, which typically occur one to four times a week. The median age of onset is about 50 years, and a milder prodrome of sleeptalking, simple limbjerking, or vividly violent dreams may precede the full blown syndrome. Because the episodes occur during REM sleep, they are most common during the early morning hours (the second half of the night). The differential diagnosis of abnormal movement and behavior arising from sleep includes sleeprelated seizure activity, periodic limb movements in sleep, sleepwalking, night terrors, nocturnal panic attacks, nightmares, and the posttraumatic stress disorder. In contrast to RBD, sleepwalking (and variants) classically occurs during slow wave sleep (stages 3 and 4) and, hence, is most common in the early portion of the night. Unlike RBD, most adults with sleepwalking had episodes during childhood. When patients are awakened during sleepwalking or night terror episodes, they are quite confused and tend to have no memory of dream content. If content is remembered, usually it is not as complex as a typical dream. However, note that recent studies of sleepwalking and night terrors in adults have shown that episodes can begin in stage 2 sleep and during the second part of the night. In addition, the separation between sleepwalking/night terrors and RBD is not absolute-some patients have violent behavioral episodes occurring in both NREM and REM sleep (mixed disorder, or parasomnia overlap disorder). Although both nightmares and the posttraumatic stress syndrome can be associated with violent or terrifying dream content and arousal from sleep, complex body movements are uncommon. Nocturnal seizure activity usually occurs in NREM sleep, and behaviors typically are more stereotyped and less complex than in RBD. A few patients with abnormal EEG activity and complex and violent behavior have been described. These patients responded to anti-seizure medication. In animal experiments, lesions in the pons can result in body movements during REM sleep. Thus,
310
degeneration of the brainstem is believed to be one possible cause of RBD in humans. However, even with extensive evaluation, about 60% of cases are idiopathic. Others are associated with multiple sclerosis, subarachnoid hemorrhage, dementia, ischemic cerebrovascular disease, and brain stem neoplasm. In one study, almost 40% of patients with idiopathic RBD later developed Parkinson's syndrome. An acute form of RBD can occur after withdrawal from REM suppressants, such as ethanol. Drug-induced cases also have been reported, with the use of tricyclic antidepressants or selective serotonin reuptake inhibitors (SSRIs; e.g., fluoxetine). Polysomnography mayor may not reveal an episode, as most patients do not have nightly attacks. Some sleep centers routinely perform at least three serial sleep studies. Simultaneous video and sleep recording (including both leg and arm EMG) is recommended. An episode is evidenced by bursts of limb movement or persistent augmented chin and/or leg EMG activity during REM sleep. At first glance, the episode may appear as stage Wake (eye movements and elevated chin EMG; Fig. I). Clues to the fact that abnormal REM sleep is present include phasic EMG bursts in the limbs and alterations in airflow associated with bursts of eye movements. The heart rate also may remain constant despite the sudden appearance of increased EMG tone (as opposed to an awakening). In other episodes of RBD the chin tone may remain fairly normal, but large increases in the phasic activity of the limbs are seen. In Figure 2, the chin EMG is reduced, allowing easy recognition of REM sleep. However, the leg EMG activity is greatly increased. It differs from PLM activity because it is prolonged. Also note the many fine spikes in the leg EMG, characteristic of phasic activity in REM sleep. You would not make the diagnosis ofRBD solely from a tracing such as this one, which can occur during REM rebound with nasal CPAP treatment. An associated clinical picture must be present. A detailed neurologic evaluation of patients suspected of having RBD is indicated and should include MRI of the brain, a full clinical EEG, and a thorough neurologic examination. Successful treatment of RBD has been achieved with clonazepam 0.5-2.0 mg in approximately 90% of patients. Clonazepam dramatically reduces episode frequency. However, occasional breakthrough attacks can occur, and environmental precautions (e.g., bed mate sleeping in a separate bed, closed windows and doors) are essential. Successful treatment of RBD has also been reported with carbamazepine.
lowing awakening (typical of RBD). The present patient responded well to clonazepam, and his episodes of violent movement during sleep became infrequent, occurring only once every 2 months and at much milder intensity. The patient's wife began sleeping in a separate bed as a precaution.
In the present case, the patient was noted to awaken yelling from REM sleep (Fig. I). Shortly before this episode, the chin EMG and leg EMG showed increased phasic activity during REM sleep. Note the fine spikes in the EMG of both legs and chin. Also note that tachycardia is not present fol-
C4-Al 02-Al ROC-Al LOC-A2 EKG chin EMG
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Clinical Pearls I. Episodes of violent limb or body movements during sleep starting in adulthood suggest the REM behavior disorder (RBD). 2. Although most RBD is idiopathic, episodes can occur with tricyclic antidepressants or SSRIs. 3. A detailed neurologic examination is essential to rule out an associated neurologic problem. Some patients with idiopathic RBD later develop Parkinson's disease. 4. Polysomnography with video recording can help confirm the diagnosis. If seizures are suspected, a full clinical EEG montage should be monitored. 5. Treatment with clonazepam usually is successful, although breakthrough episodes can occur. Environmental precautions are essential. 6. An overlap parasomnia disorder that involves both NREM and REM sleep has been described. Manifestations of both sleep terrors/sleep walking and RBD are present.
REFERENCES I. Schenck CH, Bundlie SR, Patterson AL, et al: Rapid eye movement sleep behavior disorder: A treatable parasomnia affecting older males. JAMA 1987; 257:1786-1789. 2. Schenck CH, Mahowald MW: A polysomnographic, neurologic, psychiatric and clinical outcome report on 70 consecutive cases with REM sleep behavior disorder: Sustained clonazepam efficacy in 89.5% of 57 treated patients. Clev Clin J Med 1990; 57(Suppl); 10-24. 3. Bamford CR: Carbamazepine in REM sleep behavior disorder. Sleep 1993; 16:33-34. 4. Schenck CH, Bundlie SR, Mahowald MW: Delayed emergence of a parkinsonian disorder in 38% of 29 older men initially diagnosed with idiopathic rapid eye movement sleep disorder. Neurology 1996; 46:388-393. 5. Schenck CH, Boyd JL, Mahowald MW: A parasomnia overlap disorder involving sleep walking, sleep terrors, and REM sleep behavior disorder in 33 polysomnographically confirmed cases. Sleep 1997; 20:972-981.
311
PATIENT 97 A 50-year-old man with an interesting chin EMG A 50-year-old man underwent sleep monitoring because of a history of heavy snoring. The patient had originally seen a dentist for complaints of soreness of his teeth and temporomandibular joint in the morning. His wife reported that he snored, snorted, and stopped breathing at night. The patient denied recent increased stress in his life or any change in medication. He had gained about 20 pounds over the last 2 years and also noted some increase in daytime sleepiness (Epworth Sleepiness Scale score l4124-mild sleepiness). There was no history of sleep walking or episodes of acting out dreams. Sleep Study: The study showed heavy snoring. The tracing below shows 30 seconds of recording. In the prior epoch, some snoring was noted in stage 2 sleep. Although not shown, the heart rate did not change during this episode.
Question:
What is causing the rhythmic pattern noted on the tracing?
FIGURE I
312
Answer:
Bruxism.
Discussion: Bruxism, defined as clinching or grinding of the teeth, is a common parasomnia. The phenomenon is caused by contractions of the masseter and temporalis muscles. Bruxism is common in young children before the adult teeth erupt, but also is quite common in adults. Prevalence in children ranges from 20% to 88% and declines over time to 3% in adults over age 60. Smokers are said to be more likely to brux than non-smokers. In the average patient there are about eight episodes of bruxing per night. Typically, the bedpartner reports the sound of teeth grinding. Patients often complain of soreness in the teeth, jaw, or temporomandibular joint as well as headache or pain in the neck muscles in the morning. Rarely are they aware that they brux. Patients may be identified by their dentist, who notes abnormal tooth wear or peridontal disease. The cause of bruxism is not known, but the disorder has been associated with stress, malocclusion, and certain medications (serotonin reuptake inhibitors. levodopa). Polysomnography shows a rhythmic increase (about 1 per second) in EMG tone associated with unusual EEG and EOG activity resulting from muscle artifact, or shows transmission of very high EMG activity to the EEG and eye leads. If EMG electrodes are placed over the masseter muscles instead of the lower chin, the EMG activity may be even more prominent. Bruxism may occur in any sleep stage, but is most common in stage 2 NREM sleep or in tonic REM sleep. One study reported that bruxism was common in patients with sleepdisordered breathing, but that episodes of bruxism were not necessarily occuring at apnea termination. Figure 2 (from another patient) shows an episode of bruxism without the characteristic EMG pattern at
the end of a period of snoring. The technician heard loud teeth grinding at this time and made a comment. Rhythmic changes in the EEG and eye leads are seen. No completely satisfactory treatment for bruxism exists. First, assess the degree of damage, perhaps with the help of a dentist. A mouth-guard protector or bite-splints can be used to prevent tooth damage. Correcting malocclusion may help in some cases. Medications that have been used include benzodiazepines, muscle-relaxers, levodopa, and botulinum toxin. Psychotherapy (stress reduction), relaxation therapy, biofeedback, and hypnosis have all been tried. No treatment has been demonstrated to be effective in a controlled trial. In the present patient, the tracing shows a rhythmic increase in EMG activity with rhythmic muscle artifact in the EEG and eye movements. The tracing has a "checkerboard pattern" that is said to be typical of bruxism. The episode did not occur out of REM sleep and was not associated with violent behavior. Therefore, the REM behavior disorder was not present. The episodes was not associated with screaming or body movements and autonomic hyperactivity. Thus, the illustrated episode is not a night terror. No spike and wave activity was found in the EEG during the night. The sleep technologist clearly heard the sound of grinding teeth during the episode. The patient was found to have snoring and positional sleep apnea with an overall AHI of 25/hr. He underwent treatment with nasal CPAP with resolution of snoring and daytime sleepiness. His dentist constructed a bite splint for tooth protection. The patient's wife reports that he still has some episodes, but the patient reported less mouth discomfort in the morning.
C4-Al C3-A2 02-Al ROC-A1 LOC-A2 EKG chin
snore
nasal pressure
FIGURE 2
313
Clinical Pearls I. Bruxism is a common parasomnia in both adults and children. 2. Polysomnographic features include a rhythmic increase (about I per second) in EMG activity, which can be transmitted in the EEG and EGG leads. 3. No treatment of bruxism has been documented to be effective in controlled trials. 4. Sleep technologist observations, such as hearing "teeth grinding," are very helpful in identifying abnormal EEG-EMG activity as bruxism.
REFERENCES I. SjoholmTT, Lowe AA, MiyamotoK, et al: Sleep bruxism in patients with sleep-disordered breathing. Arch Oral BioI 2000; 45:889-896. 2. Eng-King T, Jankovic J: Treating severe bruxism with botulinum toxin. JADA 2000; 131 :211-216. 3. Lavigne GJ, Manzini C: Bruxism. In Kryger M, Roth T, Dement W (eds): Principles and Practice of Sleep Medicine, 3'" ed. Philadelphia, WB Saunders Co, 2000.
314
FUNDAMENTALS OF SLEEP MEDICINE 20
Monitoring for Nocturnal Seizures
The international 10-20 system for electrode placement is illustrated in Figure I. Each electrode is represented by a letter that indicates the underlying region of the brain (Fp = frontopolar, F = frontal, P = parietal, 0 = occipital, T = temporal) and by numerical subscripts indicating position. The odd subscripts are on the left and the even on the right. Note that the new terminology, in which T7, T8, P7, and P8 replace T3, T4, T5, and T6, is illustrated. In the new terminology, all electrodes in a given sagittal plane have the same subscript (F7, T7, P7), and most electrodes in the same coronal plane have the same letter (P7, P3, Pz, P4, P8). old 10-20
new 10-20
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A derivation is the voltage difference between electrodes. For example Fpl - F3 is the voltage difference between electrodes Fpl and F3. By convention, if Fpl is more negative than F3, the deflection is up. A set of derivations is called a montage. Montages are designed for a particular purpose in mind. Standard montages to detect respiratory events and stage sleep have already been illustrated (see Fundamentals 2). Bipolar montages compare two standard electrodes sequentially, covering the head in an AP or transverse direction (see table). Different labs display the electrodes in different sequences. In the referential scheme, each electrode is referenced to the ipsilateral mastoid electrode. In modern digital EEG recording, usually
315
all electrodes are recorded against a common reference. Then any two electrodes may be compared by subtracting the signals (F7-ref)-(P7-ref) = F7-P7. Digital recording also allows one to visualize multiple time scales. The usual polysomnography paper speed is 10 mm/sec or a 30-second page. In contrast, EEG for seizure evaluation is usually 30 mm/sec or a lO-second page. The latter allows detection of brief, sharply contoured waveforms that may signify seizure activity. Standard EEG Montages
AP BIPOLAR ("DOUBLE BANANA")
TRANSVERSE BIPOLAR
REFERENTIAL
Fpl-F7 F7-T7 T7-P7 P7-01
F7-F3 F3-Fz Fz-F4 F4-F8
FPI-AI F7-AI T7-AI P7-AI
Fp2-F8 F8-T8 T8-P8 P8-02
Ff9-T7 T7-C3 C3-Cz Cz-C4 C4-T8 T8-Ff10
FP2-A2 F8-A2 T8-A2 P8-A2
Fpl-F3 F3-C3 C3-P3 P3-01 Fp2-F4 F4-C4 C4-P4 P4-02 Fz-Cz Cz-Pz
P7-P3 P3-Pz pz-P4 P4-P8 FPI-Ff9 FP2-FfIO Ol-Ff9 02-Ff10
Fpl-AI F3-AI C3-AI P3-AI Fp2-A2 F4-A2 C4-A2 P4-A2 Fz-A2 Cz-A2
If the capacity to add a few electrodes to traditional sleep monitoring exists, the ability to detect interictal epileptiform activity is increased. For example, four electrodes (F3, F4, T7, T8) could be added. The derivations F3-T7, T7-0 I, F4-T8, and T8-02 would add coverage over much of the frontal and temporal areas. These areas are the predominant foci of seizures occurring mainly during sleep. The terminology and identification of epileptic seizures and interictal activity is challenging for physicians without extensive training in EEG. A spike is defined as a transient (any isolated wave or complex that stands out compared to background activity), with a pointed peak and a duration of 20-70 milliseconds (Fig. 2). At polysomnography paper speed, or on a 30-second page, spikes look like a single vertical line. A sharp wave is a transient with a pointed peak and a deflection of 70-200 millseconds. Interictal activity (or interictal discharge) is defined as abnormal EEG activity that occurs between seizures. Because seizures do not always appear during recording, the physician reading an EEG searches for the "interictal footprint" of epilepsy - the epileptiform spike. Spikes represent abnormal brain activity that is seen as an area of negativity at the scalp. Spikes can be localized (negativity at the scalp over one area of the brain) or appear diffusely. Focal seizures usually, though not invariably, begin at the same location as the interictal spikes. The usual spike is followed by a slow wave. However, spikes should not be thought of as pre-seizure activity, because they more commonly follow than precede seizures. Localized spikes will show phase-reversal if the bipolar chains cross the area of the seizure focus. This may help differentiate them from artifact. For example, in Figure 3 negative spike activity is seen under electrode T7 (s = spike, w = wave). This results in downgoing deflections in F7-T7 as T7 is more negative than F7. This pattern reverses for T7-P7. If the spike focus is between two monitoring electrodes (F8 and T8; Fig. 4), the derivation connecting them may show little or no activity (F8-T8), and the derivations on either side will show phase reversal ([Fp2-F8] to [T8-P8]). If you notice interictal activity in the usual polysomnography display (C4-Al, etc.), remember that 316
10 sec page (30 rnrrvsec) EEG speed
30 sec page (10 rnrrvsec) PSG speed
sharp waves
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the mastoid electrodes are not neutral. For example, a left temporal seizure focus may be picked up in A I. Thus C4-A I may actually show more activity from a left temporal focus than C3-A2. Also, at the usual polysomnographic time base (paper speed), you might miss spikes. If you are using digital equipment, a switch from a 30-second to a lO-second page view is indicated to scrutinize any suspicious paroxysmal activity. Seizure activity may be manifested by rhythmic activity of many types. While the spike and wave activity is the most familiar, the pattern of repetitive sharp waves of various frequencies is also common. On traditional sleep monitoring montages, ictal activity can even be mistaken for alpha or faster activity or artifact. In Figure 5, a portion of a IO-second page shows a spike and wave complex (SW) followed by rhythmic activity (RA) of 8-9 Hz. At point A, oral autornatisms were noted. The rhythmic activity is differentiated from normal alpha rhythm by being more prominent in the eye leads than occipital leads. This is in fact a portion of a frontal seizure manifested by oral automatisms and loss of responsi veness. You
nasion
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317
nasion Fp2 - F8
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might suspect the frontal nature, as the activity is higher amplitude in the eye leads (near the frontal lobes). A complete EEG montage documented a right frontal location (in Figure 5, note the slightly higher amplitude in ROC-A 1 than LOC-A2).
SW
RA
A
LOC-A2 ROC-Al C3-A2 C4-Al 01-A2 02-Al (
)
1 second FIGURE 5
REFERENCES I. Fisch BJ: Spehlrnans EEG Primer. New York, Elsevier, 1991. 2. American Electrophysiological Society: Guideline Thirteen: Guidelines for standard electrode position nomenclature, J Clin Neuorphysiol1994: 11:111-113. 3. Chesson AL. DellaBadia J: Seizure disorders and sleep. In Lee-Chiong TL, Sateia MJ, Carsakadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002, pp 521-531. 4. Foldvary N: Video.encephalography/polysomnography for monitoring nocturnal events. In pp 681-688.
318
PATIENT 98 A 55-year-old man with unusual movements during sleep A 55-year-old man was evaluated for arm movements and confusion during sleep. The episodes, which occurred once or twice weekly, had begun 1 year previously. During an episode the patient did not get out of bed, but was unresponsive. Afterwards, he was groggy. There was no history of daytime sleepiness or insomnia. The patient had no recall of the events in the morning. Physical Examination: Unremarkable. Sleep Study: No overt body movements or periodic limb movements (PLM) were noted. Figure: The following was noted on a tracing when the patient had just fallen asleep.
Question:
What is causing the body movements during sleep?
C3-A2
01 - A2 ROC-A 1
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319
Diagnosis:
Seizure activity.
Discussion: Seizure disorders are part of the differential diagnosis of "nocturnal spells" -episodes of abnormal motor activity during sleep. Depending on the type of patients studied, as many as 10-40% of seizures occur exclusively or mainly during sleep. The incidence of nocturnal seizures has two peaks: one about 2 hours after bedtime and another between 4 and 5 am. Daytime seizures are most prevalent in the first hour after awakening. In general, all manifestations of nocturnal seizure disorders are much more common in NREM than REM sleep. Prior sleep deprivation activates seizures (see table below); therefore, patients often undergo clinical EEG monitoring in a sleep-deprived state to increase the likelihood of recording seizure activity. Seizures are classified as partial (focal) onset, arising from a localized area of the brain (with or without subsequent generalization), and generalized onset, arising from both hemispheres simultaneously. Partial seizures can become generalized and result in generalized tonic-clonic seizures. Focal seizure disorders are sometimes called sleeping epilepsies because they frequently are associated with interictal discharges or seizure activity in NREM sleep. Simple partial seizures result in focal motor, sensory, autonomic, or psychophysiologic manifestations without a change of consciousness. Complex partial seizures usually arise from the mesial or lateral part of the temporal lobe or adjacent parts of the frontal lobe. The symptoms consist of changes in the content of consciousness that reduce the patient's ability to interact with his or her surroundings. They can occur with only a change in conciousness or can include automatisms (repetitive movements which may be purposeful, but serve no obvious purpose in the actual situation). For example, lip smacking is a common
automatism. Patients with complex partial seizures may have no recollection of the events or only partial memory. Patients may remember an aura, a subjective sensation such as a visual or olfactory disturbance that precedes the start of the event. Primary generalized epilepsies include idiopathic Generalized tonic-clonic (GTC) seizures, absence seizures (petit mal), and juvenile myoclonic seizures. GTC seizures consist of a sudden loss of conciousness, a tonic phase of intense muscle contraction, and then a clonic phasic consisting of bilaterally synchronous jerking of the entire body. After the seizure, there is a post-ictal period of disorientation lasting a variable amount of time. Absence seizures are manifested as a blank stare during which the patient is unresponsive. The characteristic waking EEG pattern is a 3-Hz spike and wave pattern. Absence seizures start in childhood and rarely persist into adulthood. Juvenile myoclonic epilepsy is a genetically determined condition involving myoclonic jerks in the arms shortly after awakening. Primary generalized seizures are sometimes are called awakening epilepsies because they commonly occur when the patient is in a drowsy state upon awakening from sleep. Patients with both absence and juvenile myoclonic disorders also can have GTC seizures. GTC seizures associated with these disorders usually occur on awakening. Seizure activity comprises interictal and ictal phases (see table at right, top). Interictal refers to transient focal or generalized discharges between seizure events. Ictal discharge refers to the event itself, which, depending on the type of seizure, may be manifested by partial motor activity (limb jerking and twitching), a GTC seizure, myoclonic jerking, an absence seizure, or complex motor behavior. When these symptoms occur during sleep, they may not be recognized.
Seizure Disorders Affected By Sleep PARTIAL EPILEPSY* • Frontal lobe epilepsy (FLE) Nocturnal frontal lobe epilespy Autosomal dominant FLE • Temporal lobe epilespy 'Can secondarily generalize
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PRIMARY GENERALIZED EPILEPSY • Generalized tonic clonic seizures on awakening • Absence epilepsy (petit mal) • Juvenile myoclonic epilepsy
Typical Seizure Occurrence ICTAL DISCHARGE
INTERICTAL DISCHARGE SEIZURE TYPE
NREM
REM
NREM
REM
AFfER NREM*
Primary generalized Focal
Common Common
Rare Rare
Rare Common
Rare Rare
Common Possible
*After awakening from NREM sleep
Temporal and frontal lobe epilepsies are often mislabeled as other sleep-related conditions (e.g., PLMS, bruxism, sleepwalking). EEG-video monitoring during sleep can be useful in making the correct diagnosis. Of focal seizure disorders, approximately 20% have onset from the frontal lobes. The clinical manifestations of frontal lobe seizures may vary depending on localization of the epileptic focus. Typically, patients with electrographic onset from the midline regions will have supplementary motor cortex involvement, eliciting complex motor manifestations such as dystonic posturing, vocalizations, or speech arrest, with variable loss of consciousness and minimal post-ictal confusion. A classic manifestation is the ''fencing posture" with the head turned toward an outstretched arm. Seizures arising from the supplemental motor area may involve thrashing with maintenance of consciousness, and often are misdiagnosed as psychogenic seizures. Seizures originating from the orbitofrontal areas and the cingulate gyrus often resemble those originating from the temporal lobes, with staring, nonresponsiveness, and automatisms. Thus, the differentiation of frontal lobe and temporal lobe seizures (see table below) is not absolute. In addition, seizures originating from the cingulate gyrus may also have autonomic features such
as tachycardia, tachypnea, pallor, and sweating. Seizures originating from the dorsolateral frontal lobes may have minimal symptoms or have motor manifestations depending on the extend of spread of the seizure activity. On the contrary, seizure onset in the posterior frontal lobes from the primary motor cortex may have discrete motor manifestation that have a jacksonian march (begins in the distal muscles of an extremity and moves up the extremity). Unfortunately, patients with frontal lobe seizures frequently do not exhibit interictal EEG activity. Temporal lobe seizures begin focally and impair consciousness. Staring, orofacial or limb automatisms, and head and body movements frequently occur. Temporal lobe seizures are more common in NREM sleep, but also occur at the transition from NREM to REM sleep. Interictal activity can often be seen even using traditional sleep EEG monitoring as the mastoid electrodes are near the temporal lobes. Of note, no abnormal EEG activity may be observed in some patients with temporal lobe epilepsy using scalp electrodes. Partial seizures with complex automatisms have been described in a few patients; unusual sleepwalking episodes, vocalization, and violent behavior were noted. These patients responded to anti-epileptic medications.
Comparison of Frontal and Temporal Lobe Epilepsy* OCCUR ONLY DURING SLEEP
MAINTENANCE OF CONCIOUSNESS
Frontal Lobe
Usually
Usually
Temporal Lobe
Often
Conciousness impaired
BODY MOVEMENTS Tonic posturing ("fencing posture") Automatisms (lip-smacking)
POST-ICTAL CONFUSION Minimal Sometimes
*Note that these differences arenotabsolute-see text.
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Diagnosis of nocturnal seizures requires a full EEG montage and, ideally, simultaneous synchronized video recording. Temporal lobe epilepsy is especially difficult to document and often requires intracranial electrodes. Sometimes a diagnosis is elusive, and an empiric trial of anti-epileptic medications is needed. In routine clinical EEG monitoring, the paper speed is faster (30 mm/sec) and the EEG amplitude is less sensitive than in sleep monitoring. Therefore, on routine sleep monitoring interictal activity appears sharper and often with a higher amplitude. Unlike usual sleep patterns, interictal activity often manifests as repetitive occurrences of nearly identical patterns. If a computerized system is used to record sleep, the tracing can be reviewed at a simulated clinical EEG paper speed (30 mm/sec or lO-second page). The differential of nocturnal seizures includes bruxism, PLMS, night terrors, sleepwalking, and REM behavior disorder. General motor activity arising
from seizures is simpler and more stereotypic than motor activity associated with sleepwalking, night terrors, and REM behavior disorder. In the present case, a routine sleep study was initially performed (see Figure). This showed no PLMS, but frequent spike and wave complexes (5) occurred during NREM sleep. Note that the activity does not coincide with the EKG complexes. The complexes were not the usual vertex sharp waves, which are upgoing and sporadic. The spike and wave complexes in the tracing occurred in derivations with A2 (near the right temporal lobe). The patient was referred to a neurologist, and a full clinical EEG confirmed the presence of interictal activity in the right temporal area. The patient was treated with carbamazepine, with resolution of the episodes. An MRI of the brain showed increased size of the temporal horn of the right lateral ventricle, as well as scarring. The damage to the temporal lobe was felt to have developed from repeated seizure activity.
Clinical Pearls I. Seizures are part of the differential diagnosis of abnormal motor behavior occurring during sleep. 2. Optimal diagnosis of nocturnal seizures requires a full EEG montage, with simultaneous video recording if possible. 3. Episodes of repetitive, high-amplitude, sharp EEG activity during a routine sleep study could represent interictal seizure activity. 4. Identification of interictal activity on a polysomnogram should prompt a more extensive evaluation for epilepsy even if a frank seizure is not recorded. 5. Frontal lobe and temporal lobe epilepsies are often called sleeping epilepsies because they may occur more frequently or only at night. 6. Complex partial seizures are associated with a change in the content of conciousness as well as localized motor or sensory manifestations.
REFERENCES l. Guilleminault C. Moscovithc A. et al: Forensic sleep medicine: Nocturnal wanderings and violence. Sleep 1995; 18:740-748. 2. Malow BA: Sleep and epilepsy. Neural Clin 1996; 14:765-789. 3. Shouse MN, Martins da Silva A, Sarnmaritano M: Circadian rhythm, sleep, and epilepsy. J Clin Neurophysiol 1996; 13:32-50.
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PATIENT 99 A 60-year-old man with a rhythmic EEG pattern during a CPAP titration A 60-year-old man was evaluated for snoring, daytime sleepiness, and awakening with body jerks during sleep. Obstructive sleep apnea was noted during the initial portion of the sleep study, and a CPAP titration was initiated. During the titration, paroxysmal rhythmic activity lasting 15-30 seconds was noted. Physical Examination: Normal. Sleep Study: The 30-second tracing shown below was noted during stage 1 sleep. The second figure shows a lO-second segment of the same epoch. No unusual body movements occurred during this activity.
Question:
What is your diagnosis?
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323
Answer:
Seizures (spike and wave activity).
Discussion: Spike and wave activity is a common form of ictal discharge. Spikes are transient waves that are 20-70 milliseconds in duration. At conventional polysomnography paper speed of 10 mm/sec (30-second page), spikes appear as nearly vertical lines or may be difficult to separate from adjoining slow wave activity. They are usually surfacenegative (usually upward deflections) in central or eye leads. Spikes are frequently followed by slow waves. Isolated spike discharges are often seen in patients with seizures (interictal activity), but may occasionally be seen in patients with a family history of seizures who never have clinical seizures. About 10-40% of seizure activity occurs exclusively during sleep. Seizure thresholds are highest during REM sleep, followed by wakefulness, and then NREM sleep. Thus, the likelihood of seizure activity is NREM > Wake> REM. Generalized tonic clonic (GTC) seizures are most common soon after awakening in many patients. Nocturnal seizures present in many ways (see Table), including unusual behaviors or multiple arousals leading to complaints of insomnia or daytime sleepiness. Seizure-associated behaviors are often recurrent, stereotypic, and/or inappropriate. The patient usually has no recall of the events. Seizures can also result in automatisms and may include nocturnal wandering or other behavior that mimics sleepwalking, sleep terrors, or REM behavior disorder. Screaming, vocalizations, and violent autisms with the possibility of injury may also be seen. Seizures may also present as a recurrent nightmare or as isolated symptoms such as choking or laryngospasm. However, nocturnal seizures can also be entirely asymptomatic. Presentations of Nocturnal Seizures Frequent arousals Daytime sleepiness Complaints of insomnia Nocturnal "spells" -parasomnia Asymptomatic The non-neurologist may not be familiar with the elements of a clinical history that are important for differentiating seizures from other parasomnias. Abnormal focal movements, auras (a subjective sensation such as a smell or visual disturbance that precedes attacks), exact description of the attack, non-responsiveness during the episode, and the presence and absence of post-ictal confusion are all important historical elements. Unfortunately, if seizures occur only at night, the patient may not be observed doing anything unless 324
body movements or sounds awaken the bedrnate. Partial complex seizures can result in wanderings. However, patients are poorly responsive during the attacks and usually do not report complex dreams on awakening as in REM behavior disorder. Nocturnal seizures are also more likely to occur out of NREM than during REM sleep. Distinguishing seizure activity from artifact on a polysomnogram can be difficult for the non-neurologist. The ability to view the tracing at a faster paper speed (IO-second page) is very helpful in determining the morphology and frequency of the activity. This is an advantage of digital recording systems. If a spike and wave pattern is seen during the rhythmic activity in question, this is virtually diagnostic for seizure activity. Bursts of delta or theta activity can look somewhat similar, but do not have spikes. They also are rarely as regular as seizure activity. Electrode popping can give high-amplitude sharp waves, but often involves a bad electrode and has a slower periodicity. Of note, seizure activity sometimes is not seen on surface EEG recording (temporal or frontal lobe epilepsy). In such cases, video recording and technologist observation are essential in establishing the presence of subtle abnormal automatisms such as lip smacking or mouth movement. These can be important clues that a seizure is occurring. If no seizure activity can be documented despite extensive monitoring with additional leads, MR imaging can show a focal abnormality in the temporal or frontal lobe areas. Even if seizure activity is seen during traditional polysomnography, identification of a focal onset or localization may be difficult using the typical polysomnography EEG montage. Of note,frontal activity is often seen in the eye leads (ROC. LaC), and temporal activity is often noted in the mastoid electrodes (AI.A2). Some focal seizures generalize extremely rapidly and may appear to be generalized seizures at first glance. While frontal lobe seizures classically present as tonic posturing and temporal lobe seizures as partial complex seizures with automatisms or behavioral arrest, manifestations alone may not allow localization. For example, seizures originating from the orbitofrontal areas and the cingulate gyrus of the frontal lobes often resemble those originating from the temporal lobes-with staring, nonresponsiveness, and automatisms. In the present patient, nocturnal seizures were unrecognized by the patient's wife or the sleep lab technologist because the seizures had no motor manifestations. The patient had many 15- to 20-second bursts of seizure activity during sleep. At the usual sleep study page length (30-second page), the
abrupt onset of rhythmic activity is noted. However, changing the page duration from 30 seconds to 10 seconds allowed identification of a clear-cut spike and wave activity with a frequency of about 4 Hz. Of note, the activity was generalized (involved left and right sides of the brain). A subsequent full EEG montage study during the day also showed episodes of similar activity. The EEG technologist was able to document that the patient had a brief period of unresponsiveness during the episodes. The seizure activity appeared to have a generalized onset, and a diagnosis of generalized seizure disorder of the absence type (no motor manifestations) was made. Initiation of primary generalized seizures (without focal onset) in adulthood is distinctly rare. On the other hand, secondary generalization of initially
focal seizures is very common in adults. While classic petit-mal epilepsy is characterized by spike and wave of 3 Hz, the frequency can be faster in adults. It is always possible that this disorder was present from childhood, but went unrecognized. Although such a scenario is unlikely, neither the patient nor his wife were aware of the episodes. An alternate view is that the epilepsy was in fact a focal seizure with very rapid generalization. This possibility is suggested by the slightly earlier appearance of rhythmic activity in LaC (near the left frontal brain area). However, an MRI was within normal limits. The patient was treated with topiramate, an anti-epileptic medication that would be active against both focal and generalized seizures, and nasal CPAP.
Clinical Pearls I. Rhythmic activity during sleep should be examined at a faster rate or virtual paper speed to look for spike and wave activity. The traditional EEG paper speed is equivalent to a lO-second page on digital monitoring. 2. Spike and wave activity can be isolated (interictal) or occur in bursts (ictal or seizure activity). Recognition of the characteristic shape can differentiate a burst of seizure activity from artifact or EEG changes that mimic seizure activity. 3. About 10-40% percent of seizures occur primarily or only during sleep. 4. If seizures occur only or mostly during sleep and do not cause abnormal motor activity, they are frequently unrecognized. 5. Use of a complete seizure montage and video recording can assist in the diagnosis of seizures. 6. Nocturnal seizures can present with complaints of excessive daytime sleepiness or insomnia secondary to arousals during seizure activity.
REFERENCES I. Aldrich MS. Jahnke B: Diagnostic value of video-EEG polysomnography. Neurology 1991; 41: 1060-1066. 2. Malow B. Fromes A. Gail A. et al: Usefulness of polysomnography in epilepsy patients. Neurology 1997; 48: 1389-1394. 3. Chesson AL. DellaBadia J: Seizure disorders and sleep. In Lee-Chiong TL, Sateia MJ. Carsakadon MA (eds): Sleep Medicine. Philadelphia, Hanley & Belfus, 2002. pp 521-531.
325
PATIENT 100 A 30e:year-old man who got out of bed during sleep A 30-year-old man was evaluated for abnormal behavior during sleep, which had been ongoing for about 2 years. Sometimes he would awaken and was noted by his wife to be confused. Other times he would awaken in another room in his house and not remember how he got there. The awakenings could occur during any part of the night. The patient never exhibited any violent behavior during sleep or had any recall for the episodes. He had not recently begun any new medications and had no history of head trauma or sleepwalking as a child. His wife did not notice any mouth movements or talking during sleep. Physical Examination: Normal neurological examination Sleep Study: Included video monitoring. Initially, the tracings shown in Figure I were noted. Later in the night the patient awoke. A "strange artifact" was noted just before the awakening (Fig. 2; tracing at polysomnography/30-second page paper speed [left] and EEG/IO-second page paper speed [right]). The patient was observed by the technician to move his mouth in an odd manner.
Question:
What is causing the unusual behavior?
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)
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326
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)
5 seconds of 10 second page (EEG speed)
FiGURE 2
Diagnosis: Temporal lobe epilepsy. Discussion: Temporal lobe epilepsy can present with seizures that occur only at night. The seizures are typically complex partial seizures and may be manifested by lip smacking, episodes of an altered state of consciousness, confused awakenings, and automatic behavior such as wandering through the house. Even with a full seizure montage, the temporal focus may not always be seen with surface electrodes. The appearance of interictal spike activity from the temporal lobe in the typical sleep montage can be misleading. Remember that the mastoid electrodes are quite close to the temporal lobes. Therefore bipolar derivations containing the mastoid on the same side as the temporal lobe may show prominent activity even if the other part of the derivation is on the other side of the brain. For example C4-AI might show prominent activity from a left temporal focus despite the fact that C4 is central in location and on the other side of the brain. In general, approximately 60-70% of patients with partial seizure disorders and 80-85% of patients with primary generalized seizure disorders have seizure remission with anti-epileptic medication (AED). Typically, a single AED is advocated to optimize treatment and minimize adverse effects, but some patients may require two or more AEDs. Avoid sedative hypnotic agents such as phenobarbital, primidone, and clonazepam in patients with suspected concurrent obstructive sleep apnea. In the present patient, the first tracing shows
prominent spikes (arrowheads) in derivations containing A2 (near the right temporal lobe). The deflections are downward as A2 is the second electrode in the derivation. Recall that by convention in the derivation (X-V), if X is negative with respect to Y, the deflection is upward. If Y is negative with respect to X, the deflection is downward. Spikes are surface negative, and here A2 is negative compared to the other electrodes. At the typical polysomnograph page size, the spikes appear as a straight line, but at a to-second page size the typical spike morphology is clear (Fig. I). A spike and wave morphology is shown most clearly in LOC-A2. What looks like artifact at a normal 30-second page size (IS-second portion) in Figure 2 is seen on a portion of a lO-second page size to be ictal (seizure) activity consisting of repetitive sharp waves. Note that the rhymic activity is more prominent in derivations containing A2. The patient underwent a full EEG monitoring montage on another night. Figure 3 shows a portion of a "double banana" bipolar montage. You can see that the rhythmic activity is present on the right side. There is phase reversal at the F8-T8 area, localizing the seizure to the right temporal area. An MRI showed a decrease in size of the hippocampal area of the right temporal lobe, which was thought to be secondary to chronic seizure activity. The patient was treated with carbamazepine, an anti-epileptic medication, with a good response. The episodic nocturnal wanderings ended.
1 sec FP1-F7 F7-T7
~
T7-P7 P7-01 FP2-F8 F8-T8 T8-P8 P8-02 FIGURE 3
327
Clinical Pearls I. Temporal lobe epilepsy manifested as complex partial seizures may present as a parasomnia. 2. If interictal activity such as spikes from the temporal lobe are seen in the usual sleep montage of central and occipital derivations with a mastoid reference, the spikes will often be most prominent in derivations containing the ipsilateral mastoid electrode (A I, A2). 3. Changing the page size from 30 seconds to 10 seconds may help distinguish ictal rhythmic activity from artifact.
REFERENCES I. Fisch B1: Spehlmari's EEG Primer. New York, Elsevier, 1991. 2. Malow BA: Sleep and epilepsy. Neurol Clin 1996; 14:765-789. 3. Shouse MN, Mahowald MW: Epilepsy and sleep disorders. In Kryger MH, Roth T, Dement WH (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders, 2000, pp 707-723.
328
FUNDAMENTALS OF SLEEP MEDICINE 21
Evaluation of Insomnia
Insomnia is a broad term denoting unsatisfactory sleep. It includes difficulty initiating sleep (sleeponset insomnia), difficulty maintaining sleep (sleep-maintenance insomnia), early morning awakening (short sleep period), and nonrestorative sleep. Most causes of insomnia are associated with problems both initiating and maintaining sleep. Some, like the delayed sleep-phase syndrome, are associated mainly with sleep-onset insomnia. Patients with depression tend to report early morning awakening. The causes of insomnia are many and diverse, complicating the evaluation of patients with this complaint (see table).
Common Causes of Insomnia PRIMARY INSOMNIA
Psychophysiological Acute (adjustment sleep disorder) Chronic Idiopathic Sleep state misperception
SECONDARY INSOMNIA*
Sleep disorders (sleep apnea, PLMD, RLS) Psychiatric disorder (depression, panic attacks) Inadequate sleep hygiene Environmental sleep disorder Drugs (nicotine, ethanol, caffeine) Medical conditions/medications Fibromyalgia and chronic pain syndromes COPD and other respiratory disorders Medications (beta blockers, theophylline) Circadian disorders Delayed sleep-phase syndrome Advanced sleep-phase syndrome Shift work or jet lag syndrome
*"Secondary" means another disorder can be diagnosed. PLM = periodic leg movement. COPD = chronic obstructive pulmonary disease
An exhaustive history and collection of a sleep diary are the key elements in making a diagnosis. Obtaining a good history from a patient with insomnia can be difficult because of the many factors to be addressed (see table next page).
329
Insomnia History Nature and duration of problem Sleep habits Time in bed, lights out, sleep onset, waketime Bedroom environment Timing and duration of naps Changes on weekends
Effects of a new sleep environment (vacations) Medication/beverage history Symptoms of depression History of leg jerks, restless leg syndrome, snoring, apnea
Another challenging problem is identifying a mood disorder (depression). Many patients focus on their sleep disturbance and ignore manifestations of depression such as failure to get pleasure out of life and feeling sad. Others blame fatigue on their sleep disturbance despite the fact that depression often is manifested by this symptom. Some patients have difficulty sleeping because of noise, excessive light, or an uncomfortable temperature (environmental sleep disorder). Others suffer from poor sleep hygiene such as irregular bedtime and wake time, long naps, and/or working in bed. Rather than relying on the patient's memory, a sleep log (diary) is an essential tool in the evaluation of insomnia. Most sleep centers have patients complete such a diary for 2 weeks prior to the initial evaluation. There are many types of sleep diaries. The example below shows sleep behavior Monday night through Tuesday morning. The patient got into bed at 10 PM (1 ), but did not try to fall asleep until 11 PM (X). The first sleep did not occur until around 1 AM and lasted until 3 AM. A prolonged awakening between 3 and 5 AM was noted. Another episode of sleep occurred from 5 to 7 AM. The patient got out of bed at 8 AM(i).
PM 6
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7 8 9 10 11 12 1
AM 2
3 4
5
6
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9 10 11 12 1 2
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PM 3 4
5 6
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Mon
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Tues
Tues
Wed
Wed
Thurs
Thu
Fri
Fri
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~ In bed
t
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Polysomnography has a minor role in evaluation of most types of insomnia. Conditions with specific polysomnographic findings are sleep apnea, periodic limb movements in sleep (PLMS), and alphadelta sleep. Although excessive daytime sleepiness usually is the major complaint of patients with obstructive sleep apnea, a few patients complain mainly of insomnia. Complaints of insomnia are more prominent in central sleep apnea. PLMD may result in complaints of both insomnia and excessive sleepiness, but a complaint of insomnia is more common. Alpha-delta sleep is a polysomnographic finding of alpha intrusion into slow wave sleep. It has many causes, such as fibromyalgia (see Patient 107). In most cases of insomnia, polysomnography is not indicated unless sleep apnea or PLMS is suspected. However, if insomnia is severe or does not respond to empiric treatment, then a sleep study may be warranted. This is especially true if a history of snoring is elicited. For cases of insomnia in which polysomnography is obtained, the study tends to simply confirm patient complaints of a prolonged sleep latency (> 30 minutes), frequent prolonged awakenings, frequent arousals, reduction in total sleep time, reduced sleep efficiency, and decreased amount of slow wave and REM sleep. A short REM latency or early morning awakening suggests the diagnosis of depression. In
330
sleep misperception, a fairly normal night of sleep is recorded, but the patient believes that good sleep was not obtained. In psychophysiologic insomnia, sometimes both the sleep study and the patient confirm a good night of sleep, suggesting that the home sleep environment is either suboptimal or has become a stimulus for anxiety regarding sleep.
REFERENCES I. Buysse OJ, Reynolds CF: Insomnia. In Thorpy MJ (ed): Handbook of Sleep Disorders. New York, Marcel Dekker, 1990, pp
375-433. 2. Kupfer OJ, Reynolds CF: Management of insomnia. N Engl J Med 1997; 336:341-346.
331
PATIENT 101 A 30-year-old woman having difficulty falling asleep A 30-year-old woman was referred for complaints of an inability to sleep (insomnia). This problem had been severe for more than 5 years. The patient usually retired at 10 PM each night, but did not fall asleep until I AM. Three to four awakenings occurred each night, with the final awakening at 6:30 AM (spontaneous). After each, the patient required at least 30 minutes to fall asleep. Self-medication with over-the-counter sleeping pills and alcohol sometimes was effective. The only good night of sleep occurred when the patient went on vacations. The sleep environment was reported to be quiet and dark. The patient did keep a lighted clock at bedside. During the day, fatigue but not definite sleepiness was noted. No naps were taken. There were no symptoms of depression and no history of marital conflicts. The patient's husband reported that his wife did not snore, kick, or jerk during sleep. Physical Examination: General: thin and nervous. Otherwise unremarkable.
Sleep Study Time in bed (monitoring time) Total sleep time Sleep period time (SPT) Wake after sleep onset Sleep efficiency (0/0) Sleep latency REM latency
( ) =
Sleep Stages
O/OSPT
Stage Wake Stage 1 Stage 2 Stages 3 and 4 Stage REM
5 (0-6) 11.8 (3-6) 45 (46-62) 18 (7-21) 20.2 (21-31)
AHI PLM index
O/hr O/hr
normal values for age, AHI = apnea + hypopnea index, PLM = periodic limb movement
Question:
332
460 min (425-462) 411 min (394-457) 432.5 min (414-453) 21.5 min 89 (90-100) 20 min (0-19) 85 min (69-88)
Why is the sleep study relatively normal?
Diagnosis:
Psychophysiologic insomnia.
Discussion: Psychophysiologic insomnia is defined as a disorder of sornatized tension and learned sleep-preventing associations. In most sleep disorder centers, up to 15% of insomniacs receive a diagnosis of psychophysiologic insomnia. These individuals tend to react to stress with increased tension. and there is a marked overconcern and frustration with an inability to sleep. The bedroom and lightsout time become stimuli for increased tension and anxiety. The insomnia usually is fairly fixed, although it may vary in severity. A precipitating event may have caused the problem's onset. but it now has taken on a life of its own. Patients with this disorder frequently have a history of being "light sleepers" for many years. Inadequate sleep hygiene also may be present, but even after correction the problem persists. This diagnosis is not made if the patient can be classified as having an anxiety disorder, obsessive-compulsive neurosis, or major depression. The diagnosis of adjustment sleep disorder (transient psychophysiologic insomnia) is made if the insomnia is transient (usually less than 6 months). clearly follows an acute stress or conflict, and is a change from the patient's norm. Environmental sleep disorder is the diagnosis when insomnia is clearly secondary to problems with the sleep environment, such as noise, bed-partner disturbance, or the necessity of remaining vigilant (e.g., sick children). Polysomnography is of limited utility in evaluating most cases of insomnia; therefore, it is not routinely recommended and often is not reimbursed by
health insurance plans. The results usually corroborate the patient's complaints (long sleep latency. low sleep efficiency, frequent arousals. prolonged awakenings) and seldom reveal a specific reason for the sleep disturbance. However, identification of periodic limb movement in sleep (PLMS), a shortened REM latency (possible depression), or, rarely, central or obstructive sleep apnea can provide clues to the cause of the insomnia. Sometimes polysomnography results in an evaluation of insomnia are amazingly normal. In such a case, if the patient believes it was a poor night of sleep, then the diagnosis is sleep state misperceplion. In this disorder, patients do not seem to recognize that they were asleep. Conversely, if the patient recognizes that sleep was fairly normal and, in fact, expected a good night of sleep, then either the home sleep environment is suboptimal or it has become a conditioned stimulus for sleep difficulty. This phenomenon is called the reverse first-night effect, as normal subjects tend to sleep poorly in a novel environment (sleep lab). The present patient complained of both sleeponset and sleep-maintenance insomnia. There was no historical information to suggest sleep apnea, PLMS, or depression. A sleep study was performed at the patient's insistence. The study showed a near normal night of sleep in the sleep laboratory and an absence of evidence for other etiologies, making psychophysiologic insomnia the most likely disorder. The patient was treated with improved sleep hygiene and stimulus control therapy (see Patient 102). Treatment resulted in better sleep latency and sleep continuity.
Clinical Pearls I. Diagnosis of the cause of insomnia usually is made on the basis of a careful history and review of a patient sleep diary (log). 2. Polysomnography generally is not indicated in evaluation of insomnia. Two exceptions are when there is a suspicion of PLMS or sleep apnea and when the insomnia is severe and does not respond to empiric therapy. 3. A better-than-normal night of sleep in the sleep laboratory (a reverse first-night effect) suggests that the home sleep environment is suboptimal or has become a conditioned stimulus for sleep difficulty. 4. In psychophysiologic insomnia, sleeping in a novel location may temporarily improve insomnia.
333
REFERENCES I. Reynolds CF. Taska LS, Sewitch DE, et al: Persistent psychophysiological insomnia: Preliminary diagnostic criteria and EEG sleep data. Am J Psych 1984; 141:804-805. 2. American Sleep Disorders Association: The International Classification of Sleep Disorders: Diagnostic and Coding Manual. Lawrence, Kansas, Allen Press, 1990, pp 28-32. 3. Reite M, Buysse D, Reynolds C, Mendelson W: The use of polysomnography in the evaluation of insomnia. Sleep 1995; 18: 58-70. 4. Thorpy M, et al: Standards of Practice Committee of the American Sleep Disorders Association: Practice parameters of the use of polysomnography in evaluation of insomnia. Sleep 1995; 18:55-57. 5. Chesson A Jr, et al: AASM Standards of Practice Committee. Practice parameters for the evaluation of chronic insomnia. An American Academy of Sleep Medicine report. Standards of Practice Committee of the American Academy of Sleep Medicine. Sleep 2000; 23:237-241.
334
PATIENT 102 A 30-year-old woman with insomnia A 30-year-old woman with complaints of insomnia was diagnosed with psychophysiologic insomnia after an evaluation that included a polysomnogram. She admitted that she was a tense person and had problems relaxing. When she had problems falling asleep, she became very anxious: "I look at the clock and am upset that the night is almost over and I haven't fallen asleep." The patient denied drinking coffee, but admitted that she drank wine at bedtime to help her fall asleep. She reported being less tense about falling asleep on the weekends because she could sleep later the next day. Interestingly, the patient reported sleeping better on vacations than in her own bedroom. There was no history of snoring or leg movements during sleep. Sleep Diary PM 6
7 8
Midnight 11 12 1
9 10
AM 2
3
4
5
Sun
!
Man
!,~
~
Tues
~
I.... I'
Wed
!
Thu
~
6
7 8
~~ .'lE
Noon 9 10 11 12
PM 1 2
3 4
5
~
Man
~~ ,
Tues
.~
Wed
,1
"
)i \/1
Fri
~)i
Sat W
I....
Thurs
fE- ~1
Fri Sat
,
I....
...
6
... If I'
Sun
=3 glasses of wine, X =lights out and trying to sleep, = asleep, ! = in bed, t = out of bed
~--+)
Question:
What treatment options, other than medication, would you recommend?
335
Answer:
Good sleep hygiene, stimulus control therapy, relaxation therapy.
Discussion: The treatment of insomnia must be individualized. The mainstay of any treatment is to optimize sleep hygiene by educating patients about habits that interfere with good sleep. Good sleep hygiene includes maintaining a favorable sleep environment (e.g., quiet, dark, comfortable), keeping a regular sleep routine (constant bedtime and waketime), avoiding stimulants such as caffeine and other medications that interrupt sleep (e.g., ethanol), and avoiding long naps. Note that caffeine can impair sleep up to /0 hours later, and some patients are quite sensitive to just a tiny amount. Therefore, patients with insomnia should be questioned carefully about their caffeine intake, including colas and tea. Ethanol frequently is used to help promote sleep onset; however, ethanol intake near bedtime can cause awakenings and fragmented sleep later in the night, even at low doses. Behavioral techniques, although widely recommended as treatment for insomnia, are applied less commonly than the pharmacologic approach. One reason is that they are time-intensive for both clinician and patient. Readily available educational materials and instruction by knowledgeable ancillary personnel may reduce clinician involvement and make these techniques more cost-effective. Relaxation therapy is a commonly used behavioral treatment. Many patients with insomnia rep0l1 physiologic (tension) and cognitive/emotional (racing thoughts and worrying) arousal at bedtime. Progressive muscle relaxation (originated by Jacobson) consists of first tensing then relaxing each muscle group in a systematic way. Patients receive instruction in this technique and then practice twice daily, with the last session at bedtime. Biofeedback treatment uses feedback from EMG monitoring of a muscle, such as the frontalis muscle, to teach the patient how to relax. Patients with cognitive arousal at bedtime may benefit from meditation or guidedimagery techniques (refocusing on a pleasant mental target). For some patients, regular exercise can improve sleep. Exercise should not be within 2 hours of bedtime as it raises the body temperature, making sleep onset more difficult. A second behavioral option is stimulus control therapy. This treatment recognizes that insomniacs typically associate the bedtime (temporal cue) or the bedroom (environmental cue) with difficulty falling asleep: they become anxious as they stay in bed and "watch the clock," and over several nights the bedroom itself becomes a stimulus for anxiety and insomnia. This association explains why some patients with insomnia sleep better in a new setting.
336
Stimulus control therapy, developed by Bootzin and Nicassio, seeks to create a conditioned association between the bedroom and sleep. Activities in the bedroom are restricted to sleep and sex. Patient do not get in bed unless sleepy and do not remain in bed unless drowsy or asleep. If they fail to fall asleep in a reasonable time, they are instructed to get out of bed until they feel sleepy. Regular bedtime and waketime as well as avoidance of naps are part of the instructions. A third option is called sleep restriction therapy. The clinician looks at the sleep diary and estimates the time spent in bed and the time asleep. The patient is then asked to restrict the time in bed to match the previous time spent asleep. This induces mild sleep deprivation and increases sleep efficiency. As the efficiency is improved the time allowed in bed is slowly increased. Paradoxical intention is a fourth treatment technique. Patients are encouraged to engage in the most feared activity ("staying awake"). The central idea is that performance anxiety over being able to fall asleep may prevent sleep onset. By concentrating on staying awake, natural sleep processes may be allowed to work. Cognitive-behavioral therapy consists of 810 weekly sessions that provide education about sleep hygiene, stimulus control, sleep restriction, and relaxation techniques. Cognitive therapy focuses on changing unrealistic beliefs and fears regarding the loss of sleep. One common fear is that a large amount of sleep is necessary, or illness will result. The last approach is combined behavioral and pharmacological treatments. Pharmacological treatments of insomnia are discussed in Patient 103. Some patients can temporarily be treated with hypnotics while behavioral techniques are mastered. Others can be treated on a chronic basis with behavioral techniques and pro hypnotics. For some patients, knowing an effective hypnotic rescue is available decreases their anxiety about falling asleep. The standard of practice committe of the American Academy of Sleep Medicine reviewed the evidence for non-pharmacological treatments of insomnia. They gave a standard recommendation for stimulus control therapy. Progressive muscle relaxation therapy, biofeedback, and paradoxical intention received a "guideline" recommendation, which means a moderate degree of clinical certainty exists. Sleep restriction was deemed optional (conflicting or inconclusive evidence). The levels of recommendation are based on exisiting clinical studies.
Behavioral Treatment of Insomnia Relaxation techniques (progressive muscle relaxation, biofeedback, guided imagery) Stimulus control Sleep restriction Paradoxical intention Cognitive-behavioral treatment Combined behavioral and pharmacological treatment
The present patient, when questioned in detail, reported consumption of at least ten caffeine-containing carbonated beverages a day. Her sleep diary shows a lights-out time of 11 PM during the week and a long sleep latency. The patient typically was in bed an hour before lights out, and she sometimes read work-related materials during this time. On the weekends, bedtime was delayed and ethanol was consumed, resulting in a shorter sleep latency. One or two awakenings most nights were recorded. The history of sleeping better on vacation suggested that the patient had an association between her bedroom and problems falling asleep. Treatment included instructions to switch to noncaffeinated drinks and avoid ethanol near bedtime.
The patient removed the clock from her bedroom and went to bed just before lights out. If unable to fall asleep within a reasonable time, she got out of bed and read (recreational reading) until she felt sleepy, and then she returned to bed. If she awakened during the night and was unable to return to sleep, she again got out of bed until sleepy (stimulus control). In addition, the patient was given tapes instructing her in relaxation techniques. She practiced relaxation rather than engaging in work-related activities near bedtime. Initially, despite this combined approach, the patient still had some difficulty falling asleep. However, within a few weeks she reported falling asleep within 20 minutes on most nights and having fewer awakenings.
Clinical Pearls I. Every patient with insomnia must be questioned in detail about sleep habits and intake of beverages that can disturb sleep. 2. Treatment of insomnia always should begin with establishment of good sleep hygiene. 3. Relaxation therapy may be especially helpful in patients with emotional or physical tension at bedtime. 4. Stimulus control treatment can break the association between the bedroom and poor sleep. 5. Sleep restriction therapy increases sleep efficiency by creating mild sleep deprivation. 6. Cognitive-behavioral treatment employs elements of other approaches (Pearls 3-6) and reverses unrealistic fears and beliefs about sleep.
REFERENCES 1. Buysse DJ, Reynolds CF: Insomnia. In Thorpy MJ (ed): Handbook of Sleep Disorders. New York. Marcel Dekker. 1990. pp
375-433. 2. Morin CM, Culbert JP, Schwartz SM: Nonpharrnacologic interventions for insomnia: A meta-analysis of treatment efficacy. Am J Psych 1994; 151:1172-1180. 3. Chesson AL Jr, et al: AASM Standards of Practice Committee. Practice parameters for the nonpharmacologic treatment of chronic insomnia. An American Academy of Sleep Medicine report. Sleep 1999; 22: 1128-33 4. Morin Clvl, Hauri PJ, Espie CA, et al: Nonpharmacologic treatment of chronic insomnia. An American Academy of Sleep Medicine review. Sleep 1999; 22: I 134-1156. 5. Stepanski EJ: Behavior therapy for insomnia. In Kryger M, Roth T, Dement W (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders 2000, pp 647-656.
337
PATIENT 103 A 40-year-old man with difficulty falling asleep after the death of his brother A 40-year-old man who previously had no sleep problems developed difficulty falling asleep and staying asleep after the death of his brother 3 months previously. He had tried improvement in sleep hygiene and did not remain in bed unless sleepy. However, he was still unable to sleep for at least I hour after retiring at his normal bedtime. He had seen a psychiatrist who had started him on amitriptyline, but this made the patient very groggy the next day. The patient's primary care physician had given him triazolam, which enabled him to fall asleep quickly, but he sometimes felt very anxious in the mornings. The patient's wife noted that his legs jerked on occasion when he was asleep. Sleep Study Time in bed (TIB) Total sleep time (TST) Sleep period time (SPT) Wake after sleep onset Sleep efficiency (%) Sleep latency REM latency
()=
normal values for age. AHI
Questions:
338
440 min (390-468) 314 min (343-436) 370 min (378-452) 55.5 min 71 (90-100) 50 min (2-18) 85 min (55-78)
= apnea +
hypopnea index. PLM
=
Sleep Stages
% SPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
15 (1-12) 20 (5-11) 45 (44-66) 5 (2-15) 15 (19-27)
AHI PLM index
3/hr 5/hr
periodic limb movement
What is your diagnosis? Which hypnotic would you suggest for this patient?
Diagnosis: tion.
Adjustment sleep disorder. Temporary use of a hypnotic is a reasonable treatment op-
Discussion: Adjustment sleep disorder (transient psychophysiologic insomnia) is defined as insomnia related to an acute stress, conflict, or environmental change. Rather than a true disorder, it is a normal reaction to one of life's many stresses. The course usually is brief, lasting only days: an acute state is less than I week; subacute is up to 3 months. However, insomnia can become chronic (duration longer than 3 months) following a precipitating event. It then might be classified as psychophysiologic insomnia if the initial stressor is no longer present or a major concern. An example of the adjustment sleep disorder is the difficulty many people have in sleeping in a novel environment, such as a sleep lab. This is called the first-night effect and usually is rather mild. Benzodiazepines (BZs) are the most widely used hypnotic medications (see table). They are relatively safe and well-tolerated. Generally, it is safer to start with a low dose and increase gradually. The lowest dose should be used in older patients who are susceptible to side effects. Agents with a long halflife tend to cause daytime grogginess (flurazepam, clonazepam), but they can be useful in anxious patients. Benzodiazepines with a short half-life may cause rebound irritability when stopped abruptly (triazolam). All benzodiazepines tend to increase the amount of stage 2 sleep (increased sleep spindles) and cause decreases in slow wave and, to a lesser extent, REM sleep. When ceasing treatment it is wise to slowly decrease the dose, weaning the patient to minimize any rebound effects secondary to withdrawal. The traditional BZs act non-selectively at BZl, BZ2, and BZ3 receptors on the GABA-BZ receptor complex. Binding to BZl is thought to mediate hypnotic effects by increasing the flow of chloride ions produced by action of GABA on the GAB A-A receptor. Action at BZ2 and BZ3 mediates the muscle relaxant, anti-anxiety, and antiseizure actions of BZs. The BZ hypnotics are termed nonselective BZ receptor agonists. The new non-benzodiazepine hypnotic agents zolpidem and zaleplon are termed selective BZ receptor agonists because they selectively bind to BZ I. They do not reduce stages 3, 4, and REM sleep. Sleep latency is decreased and sleep duration is unchanged or increased. These agents do not have muscle relaxant, anti-anxiety, or antiseizure activity. Zolpidem gives little warning of impending sleep and is relatively expensive. Additionally, behavior in some elderly patients is altered by this medication. The usual dose is 10 mg at bedtime (5
mg in older or small patients). Tolerance, rebound insomnia, and psychomotor impairment is usually not seen with Zolpidem. Zaleplon has an ultra-short half-life and is especially useful when a hypnotic must be taken in the middle of the night. It can then be used as a "rescue" medication without causing morning grogginess. Sedating antidepressants are widely used as hypnotics in non-depressed individuals (see table, page 341). Two important facts about this practice must be emphasized. First, sedating antidepressants have not been proved to be effective hypnotics in the non-depressed population. Second, when used as hypnotics these medications often are not given in sufficient doses to be effective as antidepressants. The optimum use of these medications for insomnia is probably in patients with depression. In such patients, the goal should be to reach an effective antidepressant dose (unless the medication is used as a supplement to another antidepressant simply to improve sleep). Again, sedating antidepressants are probably best used in patients with a component of depression as well as insomnia. The sedating antidepressants include certain tricyclic antidepressants, trazodone, nefazodone, and mirtazapine. The tricyclic medications with sedating properties include doxepin (Sinequan) and amitriptyline (Elavil). The tricyclic antidepressants have anticholinergic and cardiovascular side effects (e.g., widened QRS, arrhythmias). Of the tricyclics, doxepin is thought to have a relatively safe cardiovascular profile. Trazodone, a sedating nontricyclic antidepressant, also is used as a hypnotic when depression is present. However, trazodone and all tricyclic antidepressants can cause profound orthostatic hypotension in some patients. Trazodone also can cause intractable priapism, and patients should be cautioned to stop the medication immediately if this occurs. Nefazodone is a blocker of the 5HT2 serotonin receptor and is a mild serotonin reuptake inhibitor. It is sedating without the postural hypotension noted with trazodone. In depressed patients nefazodone actually increases the amount of REM sleep. Rare cases of life-threatening liver failure have been reported with nefazodone. Mirtazapine is an alpha 2 blocker (increases both serotonin and norepinephrine) as well as a 5HT2 and 5HT3 receptor blocker. The drug tends to increase the amount of slow wave sleep and is sedating. It may cause nausea and weight gain. Nefazodone and mirtazapine usually do not cause sexual dysfunction.
339
The following guidelines for hypnotic use are suggested: I. Limit to a course of 4 weeks if possible (unless treating depression with an antidepressant). 2. Use the lowest effective dose. 3. Use a low dose in elderly patients. 4. Monitor for side effects. 5. Avoid abrupt discontinuation of the medication (wean off over several days). In the present patient, the absence of prior sleep problems and the obvious association with the re-
cent death of a family member makes adjustment sleep disorder the likely diagnosis. The need for a sleep study in this case is debatable; it was ordered because of the history of leg kicks. However, the study showed no evidence of significant leg movement. It did document a long sleep latency (> 30 minutes) and a low sleep efficiency consistent with the patient's complaints. The amount of slow wave and REM sleep also was reduced. The patient was treated with zolpidem 10 mg qhs and bereavement counseling. On this therapy his sleep improved, and he was weaned off the zolpidem after 3 weeks.
Commonly Prescribed Hypnotics (SIZE AVAILABLE) DOSE*
HALF-LIFE
COMMENTS
Benzodiazepine F1urazepam (Dalmane)
(15,30 mg) IS-3D mg qhs use lower dose in elderly
Long
Daytime drowsiness common; rarely used today
Clonazepam (Klonopin)**
(0.5, I, 2 mg) 0.5-2 mg qhs
Long
Used for PLMD, REM behavior disorder; take I hour before bedtime
Temazepam (Restoril)
(15,30 mg) IS-3D mg qhs 7.5-15 mg qhs in elderly
Intermediate
Can cause morning drowsiness
Triazolam (Halcion)
(0.125,0.25 mg) 0.125 -0.25 mg qhs use lower dose in elderly
Short
Rebound insomnia may occur if discontinued abruptly
Zolipdem (Ambien)
(5, 10 mg) 10 mg qhs 5mg qhs in the elderly
Short
Does not decrease slow wave sleep
Zalepelon (Sonata)
5,10,20 mg 5-10 mg qhs 5 mg qhs in elderly
Very short
Useful for middle of the night dosing
Non-Benzodiazepines
*Use lower dose in elderly ""'Not FDA-approved as a hypnotic PLMD = periodic limb movement disorder
340
Some Sedating Antidepressants Commonly Used As Hypnotics
(AV AILABLE SIZE) ANTIDEPRESSANT DOSE
EFFECT ON NEUROTRANSMITTERS
(10,25,50,75,100, 150) 150-300 po qhs Start 25-75 mg po qhs (50, I00, 150,300) 50-100 mg bid to tid max 400 mg 50-100 mg qhs as hypnotic (50, 100,150,200, 250) 100-300 mg po bid Start 100 mg bid Start 50 mg bid in elderly (15,30,45) 15--45 mg qhs Start 15 mg qhs
Doxepin (Sinequan)
Trazodone
Nefazodone (Serzone)
Mirtazapine (Remeron)
SLEEP EFFECTS*
SIDE EFFECTS
Blocks 5HT, NE uptake
Increased RL, decreased REM sleep
Anticholinergic (dry mouth, constipation)
5HT2 blocker, alpha blocker
NC or increased RL, NC or decreased REM sleep
Priapism, postural hypotension
5HT blocker, weak 5HT reuptake inhibitor
NC or decreased RL, NC or increased REM sleep
Rare liver toxicity, drug interactions
Alpha 2 blocker; 5HT2,5HT3 blocker
NC or increased RL, normal or decreased REM sleep
Nausea, weight gain
5HT= serotonin. NC = no change. NE = norepinephrine. RL = REM latency *May vary between studies ofdepressed. normal, or insomnia patients
Clinical Pearls I. The "first-night effect" refers to the insomnia many people experience when sleeping in a novel environment. 2. Adjustment sleep disorder follows an obvious life event and usually is transient. 3. The selection of hypnotics depends on the desired duration of action, the patient's age, and the presence or absence of depression. Use the lowest dose in older patients. 4. When hypnotics are prescribed for treatment of insomnia, the goal should be a limited course with a taper of medication to minimize rebound insomnia. 5. When sedating antidepressants are used in depressed patients with insomnia, the dose should be increased as tolerated to an effective antidepressant dose. 6. Sedating antidepressants have not been proved to be effective as hypnotics in nondepressed patients. 7. The ultra short-acting hypnotic zalepelon may be used in the middle of the night with minimal sedation the following morning. 8. The selective benzodiazepine receptor agonists do not appear to be associated with tolerance, rebound insomnia, or decreased slow wave sleep.
REFERENCES
I. Agnew H. Webb W. Williams RL: The first-night effect: An EEG study ofsleep. Psychophysiology 1966; 7:263-266. 2. Buysee OJ. Reynolds CF: Insomnia. InThorpy MJ (ed): Handbook of Sleep Disorders. New York, Marcel Dekker, 1990. pp 375-433. 3. Kupfer OJ. Reynolds CF: Management of insomnia. NEngl J Med 1997; 336:341-346. 4. Walsh JK. Pollak CPo Scharf MB. etal: Lack ofresidual sedation following middle ofthe night zaleplon administration in sleep maintenance insomnia. Clin Neuopharmacol 2000; 13: 17-21.
341
FUNDAMENTALS OF SLEEP MEDICINE 22
Circadian Sleep Disorders
Propensity for sleep and wakefulness, cognitive function, hormonal secretion, and many other physiologic functions cycle regularly across each day. The nadir in body temperature occurs about 1-2 hours after mid-sleep time if awakening is spontaneous (Fig. I; idealized plot of body temperature as a cosine curve). This is usually about 4-5 AM in normal individuals, but may vary considerably-especially in patients with circadian rhythm disorders. Sleep propensity varies during the 24-hour day, with the greatest propensity during periods of low body temperature (usually during the night). Sleep propensity also depends on homeostatic factors such as the amount of time since the previous sleep. Biological rhythms that are periodic are described by period (time between two peaks), amplitude (peak to trough magnitude), mesor (mean value), acrophase (peak), and nadir (minimal value or trough). The term phase is used to describe the temporal position relative to some external event such as the light-dark cycle.
Acrophase
I
37.2
U 0
37.4 ~
::J
37.2
Q
s E
37.0
~
36.8
~
36.6
mesor .....
co
V
36.4
12
14
16
18 20
22
24
2
4
6
8
10
12
time of day FIGURE I
These circadian Cabout a day") rhythms are generated by an internal pacemaker in the suprachiasmic nucleus (SCN) of the hypothalamus. The major afferents to the SCN are retinal neurons whose axons leave the optic chiasm and synapse on SCN cells (retinohypothalamic pathway). The afferents transmit nonvisua 1light information. The main role of the SCN is to synchronize bodily functions with the environmental light-dark cycle. Light is the most potent stimulus for shifting the phase of the circadian cycle. The amplitude and direction of the phase shifts vary with timing of the stimulus (phase response curve). The point at which light shifts from phase delay to advance occurs close to the time of body temperature nadir in humans. In fact, monitoring body temperature is one method of detecting shifts in phase of the internal cir342
cadian clock. Application of light at times earlier than the nadir in body temperature causes a phase delay, with the magnitude of shift decreasing as one moves to earlier times (Fig. 2, Light C). Application of light after the nadir in body temperature causes a phase advance, with the magnitude of shift decreasing as one moves to later times (Light B compared to Light A). The amount of shift also depends on the intensity of light (measured in lux) and the duration of exposure. Even dim light can cause some phase shift, but outdoor light or indoor bright light of 2500 lux or more is much more potent.
Phase response curve to Light Advance
I
Light A
I I I I
:t=
-&
ffi o s:
a. '0 +-
Light A - large phase advance
I
I
+.
1hr
light B - small phase advance
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light C - large phase delay
I
o
I-----==----j----------==--
c
5
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i
Light C
Delay
(
Corresponds to timing of body temperature minimum FIGURE 2
In summary, light exposure in the early-evening-to-bedtime period shifts the internal rhythm to a later time (phase delay) decreasing the propensity to sleep (Fig. 3). Light exposure in the early morning causes a phase advance. While the largest phase shifts are induced by very bright light (outdoor sunlight), regular indoor illumination also can have a small effect. Indoor sources of bright light (> 2500 lux) have been used clinically to effectively shift the circadian clock. Several brands of light boxes are available. Melatonin, a hormone secreted by the pineal gland only during darkness, appears to playa role in synchronizing the SCN to the environment. There are melatonin receptors on the SCN cells. Exogenous melatonin can produce phase-shifting effects, but the required timing of administration for a given direction of shift is opposite to bright light. A few hours before the traditional dark period, ingestion of melatonin induces phase advance, whereas bright light phase delays. Melatonin's phase-shifting effects are not as potent as light and may require several days of medication. Experiments in animals and humans show that there is a limitation to how much the internal cycle can be phase-shifted during anyone day. Measuring the amount of salivary melatonin in a dim-light environment is another way of monitoring the internal clock. In the delayed sleep phase syndrome, the circadian rhythms are shifted to a later than normal clock time. Patients are unable to fall asleep until later than normal (2-4 AM). In the advanced sleep phase syndrome, circadian rhythms are shifted to an earlier clock time. These patients fall asleep earlier than normal (7-9 PM) and awaken in the middle of the night. In time zone change (jet lag), the internal circadian rhythms are out of phase with clock time (light-dark phases) because of rapid travel across several time zones. In patients traveling eastward, they are phase-delayed relative to clock time. They have difficulty falling asleep and awakening at the usual wake time in the new time zone. In patients traveling westward, they are phase-advanced relative to clock time. They desire to fall asleep earlier and awaken earlier than appropriate for the new clock time. Because most individuals find it easier to phase delay than advance (easier to stay up than to fall asleep), eastward travel is the most difficult. In the irregular sleep wake pattern, there is temporal disorganization and episodes of sleeping and wake behavior. Diagnostic criteria include complaints of insomnia or excessive daytime sleepiness, and three or more sleep episodes in a 24 hour period. The pattern must have been present for 3 months. Usu-
343
.•• •. .••.
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......
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~
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12
16
20
24
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•
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•
•
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20
•4
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hme of day
Pre-Light Post-Light
~ ~
(j
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~ 36 12
16
20
24
•
12
12
time of day
•
16
•
20
•
24
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•8 •
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time ot day
Pre-Light Post-Light FIGURE
3
ally the total amount of sleep for 24 hours is normal. This pattern occurs in patients with brain dysfunction or who are removed from normal environmental clues. The non-24-hour sleep-wake disorder is characterized by a steady pattern consisting of progressive delays in sleep and wake times. Most of these individuals are blind, and the absence of light stimuli to the SeN results in a progressive delay in the circadian rhythms.
Sleep Disorders Associated with Alterations in Circadian Rhythm Delayed sleep phase syndrome Advanced sleep phase syndrome Time zone change (jet lag) syndrome Shift work sleep disorder Irregular sleep wake pattern Non-24-hour sleep-wake disorder
REFERENCES I. American Sleep Disorders Association: International Classification of Sleep Disorders. Rochester MN, American Sleep Disorders Association, 1997, pp 118-140. 2. Chesson AL, Jr.. Littner M, Davila D, et al: AASM Standards of Practice Committee. Practice parameters for the use of light therapy in the treatment of sleep disorders. Sleep 1999; 22:641-660. 3. Lewy AJ. Bauer VK, Ahmed S, et al: The human phase response curve (PRC) to melatonin is about 12 hours out of phase with the PRC to light. Chronobiol Int 1998; 15:71-83. 4. Sack RL, Hughes RJ, Edgar DM, Lewy AJ: Sleep-promoting effects of melatonin: At what dose, in whom, under what conditions, and by what mechanisms? Sleep 1997; 20:908-915.
344
PATIENT 104 A 40-year-old woman complaining of difficulty falling asleep A 40-year-old woman had been having trouble falling asleep for more than 10 years. She typically went to bed around II PM, did not fall asleep until 2-3 AM and awakened to the alarm clock at 6 AM. Thus, she obtained only 4 hours of sleep per night during the work week and felt tired throughout the day. On the weekends, she slept until 10-11 AM and awoke feeling refreshed. The patient rarely took naps during the day. There was no history of depression or recent stressful life events. The patient avoided caffeine intake completely. Because she rarely felt sleepy at II PM, she sometimes took either a drink of ethanol or an over-the-counter sleeping medication, both of which were only moderately successful at inducing sleep. Sleeping pills left her feeling groggy in the morning. Physical Examination: Normal Sleep Diary PM 6
Sun
7 8
Midnight 9 10 11 12 1
2
3
,rX
4
AM 5 6 7 8
~><
Tues
.. X
t t
Wed
,.><
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Thu
~
1 2
~
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6
Wed
Thurs Fri ~
~X
Sat
5
Tues
,~"
t<
3 4
Man
i ,.
Fri
Man
9 10 11 12
PM
T
Man
Sun
Noon
Sat
Sun
,IX X
,
Man
, I
Tues
x = lights out and trying to sleep, =asleep, ~ =in bed, t =out of bed
+---.+)
Question:
What is the reason for this patient's difficulty falling asleep?
345
Diagnosis:
Delayed sleep-phase syndrome.
Discussion: The delayed sleep-phase syndrome (DSPS) is classified as a circadian rhythm sleep disorder. "Circadian" means related to the daily time period (circa, about; dian, day). The physiology of many human processes, including body temperature and sleep onset, is related to the daily 24-hour clock. In DSPS, the timing of sleep onset is delayed relative to clock time. Attempts to start sleep by getting into bed at the usual time are unsuccessful at inducing sleep. Sleep-onset time tends to be regular, but delayed (2-6 AM). There usually is no problem maintaining sleep, and when sleep is undisturbed, the sleep period is of normal length. However, waking at a typical clock time to fulfill social obligations results in a short duration of sleep. The duration of DSPS varies from months to decades. Adolescence is the most common age of onset; onset after age 30 is rare. True DSPS must be differentiated from sleep-onset insomnia in individuals who delay sleep for social reasons and then experience difficulty falling asleep when they sporadically try to go to bed earlier. These individuals have a transient sleep-wake cycle disorder caused by a self-enforced phase shift. When they maintain a regular bedtime and waketime for several days, they quickly adjust to this schedule. Patients with bipolar affective disorder in the mania phase also may have sleep-onset insomnia. The sleep period is short in these patients, but they have no difficulty arising at a conventional time. The non-24-hour sleep-wake syndrome is characterized by a progressive, incremental phase delay in sleep onset and waketimes. Treatment of DSPS often is difficult. While hypnotics may be temporarily successful at inducing sleep at normal clock times, daytime grogginess typically results. Chronotherapy is the traditional therapy for this disorder. This therapy is based on the fact that it is easier to phase delay (delay the time of sleep onset) than phase advance. Bedtime is progressively delayed by several hours on successive days. The sleep period is allowed to run its course, with later and later waketimes. Thus, the sleep period moves around the clock until sleep onset occurs at normal societal times. However, this therapy requires that the patient be free from societal constraints (e.g., job, child care) for the duration of the treatment, and the bedroom must be dark and quiet. Obviously, many patients are unable to commit to chronotherapy. Recently, bright light has been shown to shift the phase of the internal clock if applied at appropriate times. Therapy with bright light in the early morning (end of dark phase) and light restriction af-
346
ter 4 PM may help phase advance patients with DSPS. Some have used 2500 lux for 3 hours of exposure; others recommend 10,000 lux for a shorter duration. The optimal intensity and duration of light exposure is unknown. Light treatment results in the patient feeling sleepy earlier in the evening (phase advance). The treatment must be continued for several days with hopefully progressively earlier sleep times. Of note, the timing of light can be problematic in some patients who are very phase delayed. For example, suppose a patient naturally falls asleep at 3 AM and would sleep to 10 AM if undisturbed. In such a patient the nadir in body temperature might be around 8 AM. If he or she is forced to wake at 6 AM and apply light, it is possible that this timing is on the phase delay side of the light phase response curve. On the other hand, applying light too late will result in a very small phase shift. It is often difficult to know the exact timing of a patient's nadir in body temperature. One approach would be to start at the habitual wake-up time. If no phase advance occurs, try application 30 minutes to 1 hour earlier. Once phase advancing begins, move the light application time earlier to coincide with an earlier wake-up time. In some patients with DSPS, the bright light can be discontinued after a reasonable sleep-onset time is reached. However, maintaining a fixed bedtime and waketime is essential. Staying up late for any reason tends to reshift the internal clock. Bright light should be avoided near bedtime, as it can induce a phase delay. Commercial bright light units are available for use in the winter months. Another potential treatment of DSPS is the ingestion of melatonin in the evening. This hormone is manufactured in the pineal gland during the dark phase. When given at the end of the day, it can induce a phase advance (opposite timing from bright light). In supraphysiologic doses (> 0.5 mg), it also may have direct, mild, sleep-inducing effects. In one study, 5 mg was given at 2200 hours (5 hours before usual sleep-onset time) for 4 weeks. A mean advance of 72 minutes in sleep-onset time was noted. There are no clinical trials showing longterm efficacy and safety of melatonin. In general, the phase-shifting effects of melatonin are weaker than bright light. In the present patient, the sleep diary shows mainly sleep-onset insomnia. Once asleep, there was little difficulty maintaining sleep. Due to societal constraints, the waketime was set at 6 AM. Thus, a delayed sleep onset resulted in a very reduced total sleep time. The patient underwent a regimen of fixed waketimes (6 AM) on all days and avoided naps. She was treated with bright light
(10,000 lux) at 6 AM for 30 minutes to I hour, but this did not improve her ability to fall asleep. Because her spontaneous waketime on weekends was 9-10 AM, it was decided that the timing of light was possibly on the wrong side of the phase response curve. Bright light timing was delayed to 9:30 AM. After a few days of minimal response, it was moved up to 8:30 AM. The patient then began to note the ability to fall asleep earlier. Over the next few days,
the timing of light was moved earlier to correspond to her naturally earlier waketimes. This approach slowly improved her ability to fall asleep. After several weeks of treatment, sleep onset occurred by 12-12:30 on most nights. She maintained this response by sleeping no later than 6:30 AM on any day, including weekends and by continuing early morning outdoor light for 30 minutes to I hour or bright indoor light for at least ~ hour.
Clinical Pearls 1. Insomnia primarily of the sleep-onset type suggests the possibility of the delayed sleep-phase syndrome. 2. A sleep log is helpful in documenting a pattern of delayed sleep onset but relatively normal sleep maintenance. 3. Chronotherapy (progressive phase delay) is the traditional treatment for this problem. 4. Bright light therapy in the morning (to induce a phase advance) is an important new treatment for this disorder. 5. The ideal timing of bright light in this syndrome is soon after the nadir in body temperature. The nadir in body temperature is usually about 1-2 hours after spontaneous midsleep time, but may vary in individual patients. If a patient does not respond to light therapy, try adjusting the timing. 6. Melatonin administered 5-7 hours before habitual sleep time (not bed time) may help phase advance sleep.
REFERENCES I. Czeisler CA, Richardson GS, Coleman RM, et al: Chronotherapy: Resetting the circadian clocks of patients with delayed sleep phase insomnia. Sleep 1981; 4: 1-21. 2. Weitzman ED, Czeisler CA, Coleman RM, et al: Delayed sleep-phase syndrome: A chronobiological disorder with sleep-onset insomnia. Arch Gen Psych 1981; 38:737-746. 3. Rosenthal NE, Joseph- Vanderpool JR, Levendosky AA, et al: Phase-shifting effects of bright morning light as treatment for delayed sleep-phase syndrome. Sleep 1990; 13:354-361. 4. Dahlitz M, Alvarez B. Vignau J: Delayed sleep-phase syndrome response to melatonin. Lancet 1991; 337: 112-104. 5. Chesson AL Jr. Littner M, Davila D. et al: AASM Standards of Practice Committee. Practice parameters for the use of light therapy in the treatment of sleep disorders. Sleep 1999;22:641-660. 6. Terman M, Terman JS: Light therapy. In Kryger M, Roth T, Dement WC (eds): Principles and Practice of Sleep Medicine, 3rd ed. Philadelphia, WB Saunders, 2000, pp 1258-1274.
347
PATIENT 105 A 70-year-old man with early morning awakening A 70-year-old man was seen for complaints of early morning awakening. This problem had worsened since his retirement 5 years ago. His typical bedtime was 9 PM; he fell asleep within 5 minutes, and staying up later was difficult for him. During the night, the patient awakened twice with nocturia, usually at midnight and 2 AM, but returned quickly to sleep. He then awoke spontaneously between 4 and 5 AM and typically was unable to fall back asleep, but remained in bed until 6:30 AM. The patient's futile efforts to return to sleep caused him considerably distress. During the day, he was able to stay awake without difficulty. He normally took aI-I Y2 hour nap at I PM. He denied feeling sad or depressed. He had many hobbies and a good relationship with his wife. The patient took a diuretic for hypertension and denied taking any hypnotic medication. Physical Examination: Normal.
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348
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Diagnosis:
Advanced sleep-phase syndrome.
Discussion: The advanced sleep-phase syndrome (ASPS) is characterized by an early sleep onset (6-9 PM) and an early waketime (3-4 AM) relative to clock time. There usually is no difficulty initiating sleep or maintaining sleep until early spontaneous awakening. Delaying bedtime past 9 PM is difficult. While some patients complain of an inability to maintain wakefulness for evening social functions, the main presenting complaint is early morning awakening. The early awakening produces anxiety in patients who feel they are not getting a full night of sleep. However, as long as the total amount and quality of sleep is adequate, the early morning awakening causes no physiologic problems. ASPS is exacerbated by naps during the day (they reduce total nocturnal sleep need) and early morning walks in the sunshine- both of which are common habits in the elderly. The exposure to bright light in the early morning hours results in a phase advance. In contrast, exposure to bright light near bedtime results in a phase delay and is a possible treatment for this syndrome. Typical indoor light is not strong enough to reset the circadian phase; therefore, outside daylight or special indoor lighting (> 2500 lux) is required. Avoiding naps and enforcing a delayed bedtime, perhaps by engaging in physical activity in a brightly lit setting, may help. In addition, education can reduce the anxiety and frustration. Severe forms of ASPS (intractable sleepiness before 8 PM) are rare. A tendency for mild phase ad-
vancement is common in elderly persons and may be one cause of sleep maintenance problems in these patients. In one study, bright light in the evening induced a phase delay in the nadir of body temperature and improved sleep maintenance. However, this treatment may not be practical on a long-term basis. Depression is the other major cause of early morning awakening. Carefully check for symptoms of depression in older patients (e.g., loss of appetite, weight loss). Evaluation of a patient with suspected ASPS should include a daily sleep log to document the pattern of sleep. A sleep study probably is not useful, unless sleep apnea or periodic leg movement is suspected. If a sleep study is performed, the lights out and on time must be changed from the routine laboratory times. The present patient complained mainly of an early waketime. Daily sleep was reported to be approximately 7 hours at night plus a I-I ~ hour daytime nap. Thus, total sleep time was adequate. Symptoms of depression can be subtle in elderly patients. However, the patient denied any symptoms of depression and reported an active lifestyle. The most likely diagnosis was a mild form of ASPS. The patient was instructed to avoid naps and take his daily walk in the evening (and to avoid early morning light). These changes enabled him to delay his sleep onset to 10 PM and sleep until 5-5:30 AM. Upon awakening, the patient got out of bed and worked on one of his hobbies until breakfast. He seemed satisfied with his new schedule.
Clinical Pearls I. A mild form of advanced sleep-phase syndrome (ASPS) is common in elderly patients; severe forms are rare. 2. An early waketime is the main complaint in ASPS. 3. Exposure to bright light (outside sunshine) in the early morning advances the sleep phase and should be avoided in patients with ASPS. 4. The main differential of ASPS (early morning awakening) is depression.
REFERENCES I. American Sleep Disorders Association: International Classification of Sleep Disorders: Diagnostic and Coding Manual. Lawrence, Kansas, Allen Press. 1990. pp 133-136. 2. Campbell SS. Dawson D. Anderson MW: Alleviation of sleep-maintenance insomnia with timed exposure to bright light. J Am Geriatr Soc 1993; 41 :829-836. 3. Ando K, Kripke DP, Ancoli-Israel S: Estimated prevalence of delayed and advanced sleep-phase syndrome. Sleep Research 1995; 14:509.
349
PATIENT 106 A 44-year-old man with jet lag A 44-year-old business executive was referred for complaints of increasing difficulty adjusting to business trips from the West to the East Coast. He found it extremely difficulty to fall asleep at an East Coast bedtime and wake up for his early morning business appointments. If he did make it to the meetings, he was drowsy and found it hard to stay awake. These problems had seemed to worsen over the last 3 years. His normal bedtime was II PM and normal waketime was 6 AM. At home he awakened refreshed and had no problems with daytime sleepiness. There was no history of snoring. The patient had tried triazolam for the first night on the East Coast - he was able to fall asleep and sleep better, but still had problems maintaining alertness in the morning. Physical Examination: Normal.
Question:
350
What treatments would you advise?
Answer:
Phase advancing with early-morning, bright light exposure.
Discussion: Time zone change (jet lag) syndrome describes the condition arising from asynchrony between a patient's internal circadian pacemaker and external clock time secondary to rapid travel across several time zones. Symptoms include problems with sleep onset or maintenance and/or decreased alertness and performance in the new time zone. Traveling eastward is the more difficult direction, as patients find it easier to phase delay than phase advance. For example, West to East Coast travel results in a patient retiring at a clock time of 11 PM but an internal circadian time of 8 PM. Sleep onset is delayed, and sleep is easily disturbed. At 7 AM clock time, the circadian time is 4 AM, and the patient finds it difficult to awaken and achieve normal alertness. It appears that adjusting to jet lag is more difficult with increasing age. A number of maneuvers have been tried to minimize the difficulties of jet lag. Short-acting hypnotics, such as triazolam, improve the continuity of sleep but do not shift the circadian clock. Therefore, awakening and resuming full alertness is still a problem because the internal circadian clock is not truly shifted. Bright light exposure in the morning in the advanced time zone may assist in phase advancing the internal circadian clock, but this is not always practical. Melatonin (0.5-0.3 mg) has been reported to both consolidate sleep and shift the circadian clock. For example, taken in the evening it can help phase advance an eastward traveler. However, the effectiveness and safety of melatonin is
not well documented, and the FDA has not approved melatonin for any indication. Traditional stimulants, such as caffeine, are widely used to assist in maintaining alertness. Another approach is to prepare for the eastward trip by going to bed progressively earlier and arising earlier for I week before the trip. This slowly shifts the circadian clock prior to travel. Despite these maneuvers, most individuals still do not feel truly alert in the morning for several days. Scheduling meetings in the afternoon in the East Coast time zone or arriving several days prior to an important meeting are helpful approaches. Of note, the above recommendations for the timing of light exposure change if the patient travels across more than six time zones. For example, if a patient travels eastward for more than six time zones, it is then possible that early morning light falls on the phase-delay side of the individual phase response curve. In this case, early morning light would not assist with adapation to the new time zone. The present patient tried phase advancing himself before his eastward trips by getting bright light exposure in the morning, avoiding light in the evenings, and going to bed earlier for I week prior to his trips. When possible, he attempted to arrive a day or two earlier than his scheduled meetings. While on the East Coast, he tried to get as much early-morning, bright light exposure as possible. These procedures improved but did not eliminate his symptoms.
Clinical Pearls I. The jet lag syndrome can be treated with behavioral and scheduling changes, timed daylight exposure, short-acting hypnotics, and, possibly, melatonin. 2. The jet lag syndrome worsens with increasing age.
REFERENCES I. Moline ML, Pollack CP, Monk TH. et al: Age-related differences in recovery from simulated jet lag. Sleep 1991; 14:42-48. 2. Sack RL, Lewy AJ, Hughes RJ: Use of melatonin for sleep and circadian rhythm disorders. Ann Med 1998;30: 115-12l. 3. Sack RL. Shift work and jet lag. In Lee-Chiong TL, Sateia MJ, Caraskadon MA (eds): Sleep Medicine. Philadelphia, Hanley and Belfus, 2002, pp 255-263.
351
PATIENT 107 A 40-year-old woman with fibromyalgia A 40-year-old woman was referred for complaints of nonrestorative sleep. She had a history of generalized pain and chronic fatigue of I-year duration. She retired every night at 10 PM and usually took about 1 hour to fall asleep. During the night, she was awakened by discomfort three to four times. She had taken medications, including narcotics, that relieved the pain, but she often felt groggy the next day. There was no history of the restless leg syndrome. The patient's bed partner had not noted snoring or leg kicks. Physical Examination: Blood pressure 120176, pulse 80, temperature normal. Chest: clear to auscultation and percussion. Extremities: pressure on several points over the shoulders and back caused excruciating pain. Neurologic: normal. Laboratory Findings: Complete blood cell count, thyroid studies: normal. Figure: Below is a tracing obtained during a sleep study.
Question:
What is your diagnosis?
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352
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Diagnosis:
Fibromyalgia manifested as alpha-delta sleep.
Discussion: Intrusion of alpha waves into slow wave sleep (alpha-delta sleep) was originally described in psychiatric patients, but the most wellknown association is with fibrositis. Alpha-delta sleep is a nonspecific polysomnographic finding. It has been associated with rheumatoid arthritis, posttraumatic stress syndrome, chronic fatigue syndrome, and chronic pain syndromes. Other medical illnesses that disturb sleep can cause alpha-delta sleep, as well. Patients with alpha-delta sleep typically complain of nonrestorative sleep and fatigue, although frank, excessive daytime sleepiness usually is not prominent. The amount of alpha-delta sleep can vary considerably, and the amount of slow wave sleep often is decreased. Generally, no evidence of respiratory effort-related arousals or changes in the chin EMG is noted. Widespread alpha intrusion has been reported in some patients taking sedative-hypnotics. Therefore, diagnosis of alpha-delta sleep requires that the use of these medications be excluded. Fibromyalgia is a syndrome usually affecting women that is associated with generalized musculoskeletal pain, chronic fatigue (without another explanation), widespread but localized tender points, and complaints of nonrestorative sleep. Despite these complaints, few objective findings are noted
except for the tender points. The American College of Rheumatology has published specific criteria for fibrornyalgia, and these include tender points of a specificed number and location (II of 18 locations, with at least nine bilateral). Patients with fibromyalgia commonly show reductions in slow wave and REM sleep. However, in one study only 30% showed alpha-delta sleep. The usual treatment for sleep disturbance associated with fibromyalgia is amitriptyline (Elavil) 25-50 mg qhs. Amitriptyline may improve daytime symptoms as well as patient assessment of sleep quality, although alpha-delta sleep may persist. Complaints related to alpha-delta sleep and associated with other diseases, such as rheumatoid arthritis, also have been treated successfully with this medication. A recent study found that fIuoxetine 20 mg qam or a combination of amitriptyline and f1uoxetine was effective in treating patients with fibromyalgia. In the present patient, monitoring showed alpha intrusion into slow wave sleep (see figure) consistent with alpha-delta sleep. This was not surprising given the history and physical findings. Treatment was begun with amitriptyline 25 mg qhs. The patient reported an improvement in perceived sleep quality and reduced musculoskeletal pain and fatigue.
Clinical Pearls I. Alpha-delta sleep is a polysomnographic finding that can be associated with psychiatric disease, fibromyalgia, rheumatoid arthritis, and chronic pain syndromes. 2. Alpha-delta sleep may be associated with complaints of nonrestorative sleep. 3. In fibromyalgia and other conditions associated with chronic pain, low doses of amitriptyline at bedtime or f1uoxetine in the morning may improve sleep and daytime symptoms of pain.
REFERENCES I. Hauri P, Hawkins DR: Alpha-delta sleep. Electroencephalogr Clin Neurophysiol 1973; 34:233-237. 2. Whittig RM, Zorick Fl, Blumer 0, et al: Disturbed sleep in patients complaining of chronic pain. 1 Nerv Ment Dis 1982; 170:429-431. 3. Moldosky H, Lue FA, Smythe HA: Alpha EEG sleep and morning symptoms in rheumatoid arthritis. 1 Rheumatol 1983; 10:373-379. 4. Wolfe E, Smythe HA, Yunus MB, et al: The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia: Report of multi-center criteria committee. Arthritis Rheum 1990; 33: 160-172. 5. Goldenberg D. Mayskiy M, Mossey C, er al: A randomized, double-blind trial of ftuoxetine and amitriptyline in the treatment of fibromyalgia. Arthritis Rheum 1996; 39: 1852-1859.
353
PATIENT 108 A 40-year-old woman with fatigue and disturbed sleep A 40-year-old woman was evaluated for fatigue and disturbed sleep of 6-month duration. The patient went to bed at II PM and fell asleep in from 15-45 minutes. She reported about three awakenings nightly and an earlier-than-normal waketime (5:00 AM). During the day she felt very fatigued. There was no of history of cataplexy or sleep paralysis. The patient's husband reported that she frequently snored, but never kicked or moved her legs during sleep. She denied feeling depressed, but did admit to being under a lot of stress after a recent promotion and worrying that she was not spending enough time with her husband. There was no history of prior treatment for depression or episodes of mania. Physical Examination: Unremarkable. Figure: The 30-second tracing below was noted 40 minutes after sleep onset. Sleep Study (Lights out 11:00 PM, lights on 7:00 AM, final awakening 5: 10 AM) Time in bed Total sleep time Sleep period time (SPT) Sleep efficiency (0/0) Sleep latency REM latency Arousal index Respiratory arousal index
Question:
420 min (419-464) 302 min (402-449) 355 min (408-456) 72 (94-98) 15 min (2-14) 40 min (65-99) 10/hr 5/hr
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Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
15 (0-11) 13 (3-7) 49(51-64) 2 (5-17) 21 (19-25)
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What is causing the fatigue and sleep disturbance?
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Diagnosis:
Major affective disorder-depression. A high REM density is noted during early REM.
Discussion: Approximately 90% of patients with major depression complain of sleep disturbance. If the patient reports feelings of sadness and despair, the diagnosis is obvious. However, a patient may emphasize loss of energy and decreased appetite. Therefore, depression should be considered in anyone complaining of sleep disturbance and fatigue. A medical evaluation is essential to rule out anemia, hypothyroidism, and other causes of fatigue. Fifty percent of sleep studies performed in patients suffering from depression show objective abnormalities (see Table). Common findings include a reduced REM latency, normal or increased amounts of REM sleep, and decreased stages 3 and 4 NREM sleep. The REM latency typically is 40-60 minutes, but occasionally is in the range suggestive of narcolepsy (10-20 min). In addition, the first REM episode is longer (20-25 minutes instead of the usual 10-15 minutes) and has a higher REM density (number of rapid eye movements per time) than normal. These alterations in REM sleep may persist even after successful treatment ofdepression or between depressive episodes. A short REM latency may be seen with other psychiatric disorders, including schizophrenia and borderline personality. In patients with unipolar depression, insomnia with early-morning awakening usually is the major sleep complaint. Sleep complaints tend to be more pronounced in older patients. Typical sleep study findings are: increased sleep latency, decreased sleep efficiency, increased stage Wake and stage I, decreased stages 3 and 4 sleep, reduced total sleep, and early-morning awakening. The sleep of older patients with depression tends to be more disturbed than that of younger patients. In the depressive phase of bipolar disorder, seasonal affective disorder, and atypical depression, hypersomnia typically is the major complaint, with a prolonged total sleep time and daytime sleepiness. The REM latency is
typically normal in depression that is secondary to another disorder. If the diagnosis of depression is obvious, a sleep study is not indicated unless another sleep disorder is suspected. The finding of a short REM latency by itself is not specific for depression, but in the absence of other pathology, it is suggestive. Sometimes it is difficult to determine if the major patient complaint is fatigue or daytime sleepiness. In addition, as stated above. some patients with depression complain of hypersomnia rather than sleep disturbance. Thus, the major utility of a sleep study is to rule out other sleep disorders. Psychological questionnaires also may help uncover suspected depression. In the present case, a sleep study was ordered because of the history of snoring, to rule out obstructive sleep apnea and upper airway resistance syndrome (UARS). The study revealed a modestly shortened nocturnal REM latency, early-morning awakening, and an absence of evidence for sleep apnea and periodic limb movements. UARS remained a possibility, but the arousal index was not very high. Interestingly, the first REM period was quite long (25 minutes) and the REM density (number of eye movements/time) was unusually high during this initial episode of REM. During initial REM sleep, only one or two bursts of eye movements are normally seen per epoch. These findings suggested the presence of depression. Subsequently, symptoms of depression were explored in more detail when the sleep study results were discussed with the patient. At that time, she admitted that she felt torn between her responsibilities to her employer and to her husband and was overwhelmed at times. The patient was referred to a psychiatrist with whom she could explore these issues. Treatment with counseling and fluoxetine 20 mg qd improved her symptoms and early-morning awakening.
Findings ill Mood Disorders COMPLAINTS
SLEEP STUDY
Depression
Insomnia Frequent awakening Early morning awakening Fatigue
Increased sleep latency Decreased REM latency Increased REM density/long first REM period Normal or increased amount of REM sleep Decreased slow wave sleep
Depressive phase of bipolar disorder Seasonal affective disorder Atypical depression
Hypersomnia
Decreased REM latency Increased total sleep time
355
Clinical Pearls I. A moderately short REM latency and a prolonged initial REM period with an increase in REM density is characteristic of depression. These findings may persist after successful treatment, or may be present between depressive episodes. 2. Depression can present with complaints of disturbed sleep and early-morning awakening (unipolar depression) or hypersomnia (bipolar depression). 3. Depression always should be considered when evaluating insomnia or excessive daytime sleepiness. 4. Consider depression when patients complain of fatigue and disturbed sleep.
REFERENCES I. Rush AJ. Erman MK. Giles DE. et al: Polysomnographic findings in recently drug-free and clinically remitted depressed patients. Arch Gen Psychiatry 1986; 43:878-884. 2. Benca RM, Obermeyer WH, Thisted RA, et al: Sleep and psychiatric disorders: A meta-analysis. Arch Gen Psychiatry 1992;
49:651-668.
356
PATIENT 109 A 45-year-old man with persistent insomnia while on treatment for depression A 45-year-old man was referred by his psychiatrist for evaluation and treatment of insomnia. The patient had a long history of major depressive episodes. which generally responded to treatment with tricyclic antidepressants. However, he had difficulty with the side effects of the medication. The current episode was under treatment with fluoxetine 60 mg daily, and although the patient's energy level and feelings of sadness were much improved, he continued to have difficulty initiating and maintaining sleep. Frequent awakenings during the night were a major problem. The patient felt tired in the morning. There was no history of snoring, and the patient's wife reported an absence of leg kicks and apnea. Physical Examination: Height 6 feet, weight 200 pounds. Vital signs: normal. Neck: l6-inch circumference. Chest: clear. Cardiac: normal. Extremities: no edema.
Question:
What evaluation and treatment do you recommend?
357
Diagnosis:
Treatment of insomnia secondary to antidepressant therapy.
Discussion: Insomnia is a common complaint of patients with depression. In patients with known depression, a sleep study adds little to the evaluation unless periodic limb movement in sleep or sleep apnea is suspected. Today, most patients with mildto-moderate depression are started on selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine, paroxetine, sertaline, citaloprarn, and tluvoxamine. Venlafaxine, an inhibitor of serotonin and norepinephrine uptake, and bupropion (increases dopamine and serotonin) are also widely used. These agents have fewer side effects than the traditional tricyclic antidepressants (TCAs). Unfortunately, insomnia is a common side effect of these medications. All of the previously listed medications (except bupropion) increase the REM latency and decrease the amount of REM sleep. Bupropion can actually increase REM sleep. The MAO inhibitors are sometimes used for refractory depression. They are the most potent inhibitors of REM sleep. Behavior techniques plus improved sleep hygiene should be the first treatment of SSRI-induced insomnia. However, many patients may not respond. In these situations, low doses of trazodone (50-100 mg) at bedtime can be a useful adjunct to SSRI treatment. This medication is sedating, but has fewer anticholinergic side effects than the sedating TCAs. Trazodone has no consistent effect on the amount of REM sleep and either increases or has no effect on the REM latency. Men must be counseled about the side effect of priapism (persistent and painful erections). If a priapism occurs, surgery may be needed, as permanent impotence can result. Trazodone also can cause severe postural hypotension. An alternative is the addition of a benzodiazepine hypnotic or the nonbenzodiazepine hypnotics (zolpidem and zaleplon). A third option in treating severe insomnia in a depressed patient is to switch to a different type of antidepressant. Nefazodone is a mildly sedating antidepressant that is a useful treatment alternative in
depressed patients with prominent insomnia. In one study comparing nefazodone and fluoxetine, both were effective antidepressants, but only nefazodone improved objective sleep quality. Interestingly, the fluoxetine group also reported subjective improvements in sleep quality. Thus, the traditional SSRIs may actually improve a patient's perception of sleep by improving mood. Nefazodone is a postsynaptic serotonin type 2 receptor (5HT2) blocker and it also weakly inhibits the reuptake of serotonin. It must be administered twice daily, and the most common side effect is dizziness. Nefazodone inhibits the cytochrome P450 system and has important potential drug interactions (e.g., increases the risk of myopathy with anticholesterol statins). Unlike most other antidepressants, it may increase the amount of REM sleep and does not increase the REM latency. Bupropion is the only other available antidepressant that increases REM sleep. Mirtazapine is another sedating antidepressant that can be tried if patients have severe insomnia on other agents. This medication increases both serotonin and norepinephrine via alpha 2 receptor blockade rather than reuptake inhibition. Like nefazodone, mirtazapine also blocks 5HT2 receptors, and this may ehance sleep quality. Mirtazapine also blocks 5HT3 receptors and histamine type I receptors. The latter effects may cause sedation and weight gain. Neither nefazodone nor mirtazapine cause sexual dysfunction or postural hypotension. (See Patient 103, dosage table. Also see reference 4 for discussion of pharmacology and use of newer antidepressants. ) In the current case, since the patient's depression had responded so well to fluoxetine, trazodone 50 mg at bedtime was added to the fluoxetine regimen. The patient reported slight improvement, and the dose was increased to 100 mg at bedtime. On this combination of medications he reported improved sleep quality and felt rested on awakening in the morning.
Clinical Pearls I. Insomnia is a frequent complaint of patients with depression. 2. Insomnia in depressed patients may be exacerbated by treatment with reuptake inhibitors of serotonin. 3. The addition of a low dose of trazodone (50-100 mg) or hypnotics at bedtime may improve sleep in patients having persistent/worsened sleep difficulty on serotonin reuptake inhibitor treatment. 4. Switching from an SSRI to nefazodone or mirtazapine may improve sleep quality in patients with depression and persistent insomnia.
358
REFERENCES I. Nierenberg AA. Adler LA. Peselow E. et al: Trazodone for antidepressant-associated insomnia. Am J Psychiatry 1994; 151: 1069. 2. Neylan TC: Treatment of sleep disturbance in depressed patients. J Clin Psychiatry 1995; 56(suppl 2):56-61. 3. Gillin JC. Rapaport M. Erman MK. et al: A comparison of nefazodone and fluoxetine on mood and on objective, subject, and clinician-rated measures of sleep in depressed patients. J Clin Psychiatry 1997; 58: 186-192. 4. Kent JM: SNaRls. NaSSAs. and NaRis: New agents for the treatment of depression. Lancet 2000;355:911-918.
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PATIENT 110 A 45-year-old man with hyperphagia and hypersomnia A 45-year-old man was evaluated for a 6-month history of daytime sleepiness (Epworth Sleepiness Scale score 16/24). During this time he had developed a tremendous appetite and had gained 20 pounds. He also had increased difficulty dealing with the stresses of his job. His wife reported that he was hypersensitive to criticism and seemed to believe she did not love him anymore. The patient usually retired at 10 PM and slept until the alarm clock awakened him at 6:30 AM. He had tremendous difficulty getting out of bed and was late to work on several occasions. On the weekends he sometimes slept from I I PM until 10-11 AM. The patient was reported to snore, but his wife had not noticed any pauses in breathing. Physical Examination: Height 5 feet II inches, weight 210 pounds. HEENT: slightly edematous uvula; 16-inch neck circumference. Chest: clear. Cardiac: normal. Extremities: no edema. Sleep Study (Lights out 10:30 PM, lights on 6:00 AM) Time in bed Total sleep time Sleep period time (SPT) WASO Sleep efficiency (%) Sleep latency REM latency Respiratory arousal index
450 min (390-468) 391.5 min (343-436) 435 min (378-452) 43.5 min 87 (85-97) 15 min (2-18) 35 min (55-78) 5/hr
Sleep Stages
%SPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
10(1-12) 6 (5-11) 60 (44-66) 4 (2-15) 20 (19-27)
AHI PLM index
O/hr
( ) = normal values for age. AHI = apnea + hypopnea index, PLM = periodic limb movement Question:
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What is causing this patient's hypersomnia?
l/hr
Diagnosis: Atypical depression. Discussion: A majority of patients with major depression present with complaints of disturbed sleep. In most cases, insomnia and fatigue are the major complaints, rather than daytime sleepiness. However, hypersomnia is commonly noted in patients experiencing the depressive phase of bipolar disorder, seasonal affective disorder (SAD; winter depression), or atypical depression. Atypical depression is characterized by weight gain (hyperphagia), rejection hypersensitivity, hypersomnia, and leaden paralysis (heavy feeling in the extremities). Treatment of depressed patients with hypersomnia typically involves selective serotonin reuptake inhibitors (fluoxetine, in particular) because these drugs are not sedating. Patients not responding to SSRIs have been treated with MAO inhibitors, but these drugs have the potential for serious drug and food interactions. In bipolar patients, adjunctive treatment with mood stabilizers is indicated to avoid inducing a manic episode. SAD is characterized by a regular temporal relationship between the onset of depression (fall or winter). Remission of depression occurs at a regular time (spring). Patients often complain of sleeping late and feeling tired all the time. SAD often responds to light therapy (usually in the early morning hours). For example, one method of light treatment is to use an intensity of 10,000 lux for a duration of 30 minutes with the daily treatments starting about 3 hours after the midpoint of spontaneous sleep. The differential diagnosis of hypersomnia with depression includes recurrent hypersomnia, sleep
apnea, and PLMD. Recurrent hypersomnia (KleineLevin syndrome) is characterized by episodes (at least once or twice yearly) lasting 3-21 days and featuring voracious eating, hypersexuality, and disinhibited behavior (e.g., irritability, aggression). Monosymptomatic forms (hypersomnolence only) also exist. This disorder typically affects males and starts in adolescence. Onset in adulthood and occurrence in women have been described. During intervals between periods of somnolence, individuals appear normal. In the present case, the history of snoring and weight gain prompted a sleep study to rule out obstructive sleep apnea (OSA). The study showed minimal amounts of apnea. The upper airway resistance syndrome also was considered, but the arousal index was low. While personality change can be noted with OSA, the rapidity of onset made this seem less likely. The REM latency was moderately short-a characteristic of a variety of disorders, including sleep apnea, narcolepsy, and depression. However, there was no history consistent with narcolepsy. Onset of recurrent hypersomnia is unlikely at age 45. Given the weight gain, hypersomnia, and recent onset of problems dealing with criticism and rejection, the diagnosis of atypical depression was considered a likely possibility, and the patient was referred to a psychiatrist for evaluation. Treatment with fluoxetine produced considerable improvement within 4 weeks, and the patient lost about 10 pounds. The symptoms of daytime sleepiness resolved.
Clinical Pearls I. The depressive phase of bipolar disorder, atypical depression, and seasonal affective disorder (winter depression) can present with symptoms of hypersomnia. 2. Patients with atypical depression may gain weight (hyperphagia), and this may trigger a suspicion of sleep apnea. 3. Seasonal affective disorder (SAD) can be treated effectively with early morning light. 4. Atypical depression is characterized by hypersomnia, hyperphagia/weight gain, and leaden paralysis (heavy feeling in the extremities).
REFERENCES I. Billard M. Dolenc L. Aldaz C. et al: Hypersomnia associated with mood disorders: A new perspective. J Psychosom Res 1994; 38(suppll):4I--47. 2. Benca RM: Sleep in psychiatric disorders. Neurol Clin 1996; 14:740-748. 3. Pande AC. Birkett M. Fechner-Bates S. et al: Fluoxetine versus phenelzine in atypical depression. Bioi Psychiatry 1996; 40:1017-1020. 4. Chesson AL, Jr.• Littner M. Davila D. et al: AASM Standards of Practice Committee. Practice parameters for the use of light therapy in the treatment of sleep disorders. Sleep 1999; 22:641---660. 5. Terman JS, Terman M. Lo E. Cooper TB: Circadian time of morning light administration and therapeutic response in winter depression. Arch Gen Psychiatry 2001; 58:69-73.
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PATIENT 111 A 50-year-old veteran of the Vietnam War with upsetting dreams A 50-year-old man was evaluated for recurrent awakenings with frightening dreams at night. These awakenings had been a frequent problem since his service in the Vietnam War. The dreams often were related to memories of combat, and when they occurred he could not go back to sleep. The patient reported difficulty falling asleep on some nights, and he generally felt unrefreshed in the morning. His wife reported that he frequently thrashed about during the night while asleep. There was no history of snoring. Previous treatment with benzodiazepines had not improved his symptoms. Physical Examination: Unremarkable. Sleep Study Time in bed Total sleep time Sleep period time (SPT) WASO Sleep efficiency (0/0) Sleep latency REM latency Arousal index ( ) =
Sleep Stages
O/OSPT
Stage Wake Stage I Stage 2 Stages 3 and 4 Stage REM
15 (2-7) 14 (4-12) 51 (51-72) 0(0-13) 20 (17-25)
AHI PLM index
4/hr 5/hr
normal values for age, AHI = apnea + hypopnea index, PLM = periodic limb movement
Question:
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470 min (378-468) 365.5 min (340-439) 430 min (361-453) 64.5 min 78 (88-96) 30 min (1-22) 70 min (65-104) 30/hr
What is causing the patient's sleep disturbance?
Diagnosis:
Post-traumatic stress disorder.
Discussion: The post-traumatic stress disorder (PTSD) occurs in individuals who have experienced a traumatic event in their life, such as combat, physical attack, natural disaster, or traumatic injury. The disorder is characterized by reexperiencing the events in flashbacks, intrusive recollections, or recurrent dreams. While it once was thought that complex dreaming is confined to REM sleep, recent studies suggest dreams may occur in both REM and NREM sleep. Symptoms of PTSD can begin immediately after the event or have a delayed onset (up to years later). Patients with PTSD also report a heightened startle response. Given a common exposure to a traumatic event, PTSD appears to occur more frequently in women than men. Patients with PTSD also may have depression and may abuse ethanol or other substances. The differential of awakening with anxiety includes sleep panic disorder, REM behavior disorder, and night terrors. Unlike patients with panic attacks during sleep, patients with PTSD can recount a dream of a specific traumatic event. In contrast to night terrors, patients become alert quickly after awakening. Sleep studies in patients with PTSD have produced conflicting results. The duration of REM latency and the amount of REM sleep have varied among studies. This may be a reflection of the fact that some patients with PTSD also are suffering from depression. Several studies have found an increase in REM density in patients with PTSD (as in depression), an increase in body movements during sleep, and the presence of periodic limb movements in sleep (PLMS). The treatment of PTSD includes counseling and medication. Although many patients with PTSD have anxiety, benzodiazepines have not been effective, and withdrawal of these medications may produce a flair of symptoms. Any REM-suppressing medication might decrease the incidence of nightmares. However, medications without REM suppression also have been effective (nefazodone). Treatment with tricyclic antidepressants, MAO inhibitors, and selective serotonin reuptake inhibitors has been effective in selected patient groups. Sertaline, an
SSRI, was effective in a double-blind placebocontrolled study and is the only antidepressant that has an FDA indication for PTSD treatment. Several open-label studies found that fluoxetine, paroxetine, and nefazodone were also effective. A few studies showed low doses of anticonvulsant medications (e.g., carbmazepine, valproate) to be helpful in some patients. Anticonvulsants do not decrease the amount of REM sleep. Patients with PTSD are a heterogeneous group, and if one medication does not work, others should be tried. For example, fluoxetine is activating and may increase anxiety or sleep disturbance. Nefazodone is mildly sedating, causes less sexual dysfunction, and may be better tolerated in anxious patients. The main side effect of this medication is dizziness, and severe drug interactions can occur as nefazodone inhibits the cytochrome P450 system. The drug should not be used with with the statin cholesterol medications. Rare instances of hepatic failure have been noted. Clonidine and propanolol also have been used for severe anxiety symptoms. Abrupt withdrawal of any of the aforementioned medications can induce a rebound in symptom severity. When starting a new medication, it is wise to start with a low dose and titrate upward slowly. In the present patient, a sleep study was ordered to rule out OSA and PLMS (history of thrashing around in bed). However, no significant amount of PLMS was noted. The sleep study showed a reduced sleep efficiency with increased waketime during the night, and stages 3 and 4 were absent. The patient was started on low-dose amitriptyline (50 mg qhs), resulting in improved sleep and fewer nightmares; however, he felt groggy the next day. This symptom usually resolves after 2 weeks of treatment, but it did not resolve in this patient. Medication was switched to fluoxetine, and nightmares were reduced. However, the patient reported continued frequent awakenings on this medication and increased anxiety during the day. Nefazodone was started at 100 mg po bid, and the patient reported improved sleep and a decrease in nightmares. His wife also noted less thrashing around in bed.
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Clinical Pearls 1. Sleep disturbance and awakenings with frightening dreams are common manifestations of post-traumatic stress disorder (PTSD). 2. Patients with PTSD have increased REM density but variable amounts of REM sleep. 3. Increased body movements and PLM during sleep also have been reported in PTSD. 4. A wide variety of medications are successful in different patient groups. Treatment must be individualized. 5. While anxiety is a major problem for many patients with PTSD. antidepressants are usually more effective than benzodiazepines
REFERENCES I. Ross RJ. Ball WA. Dinges DR. et at: Rapid eye movement sleep disturbance in posttraumatic stress disorder. Bioi Psychiatry 1994; 35: 195-202. 2. Brown TM. Boudewyns PA: Periodic limb movements of sleep in combat veterans with posttraumatic stress disorder. J Trauma Stress 1996; 9: 129-136. 3. Davidson JR: Biological therapies for posttraumatic stress disorder: An overview. J Clin Psychiatry 1997; 58(SuppI9):29-32. 4. Mellman TA, Nolan B, Hedding J, et al: A polysomnographic comparison of veterans with combat-related PTSD. depressed men, and non-ill controls. Sleep 1997; 20:46-51. 5. Davis LL, English BA, Ambrose SM, et al: Pharmacotherapy for post-traumatic stress disorder: A comprehensive review. Expert Opin Pharmacother 200 I; 2: 1583-1595. 6. Davidson JR, Rothbaum BO, van der Kolk BA, et al: Multicenter. double-blind comparison of sertraline and placebo in the treatment of posttraumatic stress disorder. Arch Gen Psychiatry 200 I; 58:485-492.
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PATIENT 112 A 40-year-old woman with terrifying awakenings A 40-year-old woman was evaluated for episodes of awakening from sleep with intense anxiety and fear. These awakenings were first noted at age 38. Similar attacks sometimes occurred during wakefulness, but they did not seem as intense. The patient experienced shortness of breath, palpitations, diaphoresis, and chest pain during these episodes, which usually occurred within 1-2 hours of bedtime. During one of the episodes she had been admitted to a hospital to rule out myocardial infarction. A subsequent evaluation for cardiac disease was negative. The patient denied having frightening dreams preceding the attacks and was able to remember the episodes the following morning. Previously, the patient was under the care of a psychiatrist for phobias related to elevators. Physical Examination: Unremarkable.
Question:
What is your diagnosis?
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Diagnosis:
Sleep panic attack.
Discussion: Panic attacks are repeated occurrences of extreme anxiety accompanied by at least four of the associated symptoms: shortness of breath, choking, palpitations, chest pain, sweating, dizziness, nausea, paresthesia, fear of dying, flushing, and chills. Although panic attacks usually take place while the patient is awake, up to 65% of patients with panic disorder report nocturnal panic attacks as well. The duration of the attacks is usually less than 10 minutes. The symptom of dyspnea appears to be more common in nocturnal panic attacks. The attacks occur from NREM sleep, commonly at the transition from stage 2 to stage 3 sleep. In most patients, sleep architecture is normal (normal REM latency and sleep efficiency). However, some patients may develop sleep phobia, and this can be associated with findings consistent with insomnia. The differential of panic attacks includes night terrors, nightmares, post-traumatic stress disorder, and REM behavior disorder. Night terrors usually begin in childhood, and the affected individual is not well aware of his or her surroundings and does not remember the episodes in the morning. In panic attacks, the patient is awake and aware of his or her surroundings. In nightmares, the patient usually is aware of a frightening dream. In contrast, patients with panic attacks remember the episode, but typically do not report a terrifying dream.
The treatment of panic attacks includes behavioral psychotherapy or relaxation techniques and pharmacotherapy. Although benzodiazepines (e.g., alprazolam, clonazepam) were the classic treatments for panic disorder, many psychiatrists prefer a trial of selective serotonin reuptake inhibitors (SSRIs) or tricyclic antidepressants (TCAs). Both SSRIs (e.g., paroxetine, sertaline) and TCAs (e.g., imipramine) must be started at very low doses, or panic attacks initially may be exacerbated. For example, paroxetine is started at 10 mg daily or imipramine at 10-25 mg daily. The doses are slowly increased to 20-40 mg for paroxetine or 100-200 mg for imipramine, as tolerated. As improvements may take 4-6 weeks or longer, many physicians add benzodiazepines during the early course of therapy. Many of the traditional TCAs are effective (desipramine, nortriptyline, amitryptiline, and doxepin). The antidepressants trazodone, protriptyiine, and bupropion have not been effective in this disorder. In the present case, the patient was referred for psychiatric treatment. She was started on c10nazepam I mg and imipramine 10 mg at bedtime. Over the next 2 months, the imipramine was slowly increased to 100 mg daily, and clonazepam was discontinued. The patient noted almost complete resolution of the nocturnal attacks.
Clinical Pearls 1. Patients with sleep panic attacks usually have similar episodes when awake. 2. Nocturnal panic attacks occur most commonly during the transition from stage 2 to stage 3 sleep. 3. Unlike sleep terrors, the patient is awake and alert immediately after the attack begins. 4. Treatment with benzodiazepines, serotonin reuptake inhibitors, or tricyclic antidepressants usually is effective. The usual recommendation is to begin antidepressants at low doses-otherwise the panic attacks may exhibit an initial exacerbation. Concurrent use of a benzodiazepine at the start of treatment may also be needed.
REFERENCES I. Mellman TA. Ude TW: Patients with frequent sleep panic: Clinical findings and response to medication treatment. J Clin Psychiatry 1990; 51:513-516. 2. Benca RM: Sleep in psychiatric disorders. Neurol Clin 1996; 14:750-751. 3. Hahn RK. Albers LJ. Reist C: Psychiatry-Current Clinical Strategies. Laguna Hills. CA. Current Clinical Strategies Publishing. 1997. pp 46-48. 4. Moroze G. Rosenbaum JF: Efficacy. safety. and gradual discontinuation of clonazepam in panic disorder: A placebo-controlled. multicenter study using optimized doses. J Clin Psychiatry 1999; 60:604-612.
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APPENDIX I
Sleep Disorders Classification Sleep disorders comprise a diverse set of syndromes. The Diagnostic Classification of Sleep and Arousal Disorders (published in 1979) divided sleep disorders on the basis of the presenting complaint. The major categories included: disorders of initiating and maintaining sleep (DIMS), disorders of excessive sleepiness (DOES), parasornnias, and disorders of the sleep-wake schedule. Some disorders appeared in more than one category. Subsequently. the International Classification of Sleep Disorders (lCSD; published in 1990) used a different approach. Sleep disorders directly affecting sleep (dyssomnias) were classified on the basis of whether they developed from internal, external, or circadian rhythm causes. The 1997 revised classification outline appears below. The reader is referred to the valuable text by the American Academy of Sleep Medicine (formerly the American Sleep Disorders Association) from which it comes.' 1. DYSSOMNIAS
A. Intrinsic Sleep Disorders I. Psychophysiologic Insomnia 2. Sleep State Misperception 3. Idiopathic Insomnia 4. Narcolepsy 5. Recurrent Hypersomnia 6. Idiopathic Hypersomnia 7. Post-traumatic Hypersomnia 8. Obstructive Sleep Apnea Syndrome 9. Central Sleep Apnea Syndrome 10. Central Alveolar Hypoventilation Syndrome II. Periodic Limb Movement Disorder 12. Restless Legs Syndrome 13. Intrinsic Sleep Disorder Not Otherwise Specified (NOS) B. Extrinsic Sleep Disorders I. Inadequate Sleep Hygiene 2. Environmental Sleep Disorder 3. Altitude Insomnia 4. Adjustment Sleep Disorder 5. Insufficient Sleep Syndrome 6. Limit-setting Sleep Disorder 7. Sleep-onset Association Disorder 8. Food Allergy Insomnia 9. Nocturnal Eating (Drinking) Syndrome 10. Hypnotic-Dependent Sleep Disorder II. Stimulant-Dependent Sleep Disorder 12. Alcohol-Dependent Sleep Disorder 13. Toxin-Induced Sleep Disorder 14. Extrinsic Sleep Disorder NOS C. Circadian-Rhythm Sleep Disorders I. Time Zone Change (Jet Lag) Syndrome 2. Shift Work Sleep Disorder 3. Irregular Sleep-Wake Pattern 4. Delayed Sleep-Phase Syndrome 5. Advanced Sleep-Phase Syndrome 6. Non-24-Hour Sleep-Wake Disorder 7. Circadian Rhythm Sleep Disorder NOS 2. PARASOMNIAS A. Arousal Disorders
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I. Confusional Arousals 2. Sleepwalking 3. Sleep Terrors B. Sleep-Wake Transition Disorders I. Rhythmic Movement Disorder 2. Sleep Starts 3. Sleep Talking 4. Nocturnal Leg Cramps C. Parasomnias Usually Associated with REM Sleep l. Nightmares . 2. Sleep Paralysis 3. Impaired Sleep-Related Penile Erections 4. Sleep-Related Painful Erections 5. REM Sleep-Related Sinus Arrest 6. REM Sleep Behavior Disorder D. Other Parasomnias I. Sleep Bruxism 2. Sleep Enuresis 3. Sleep-Related Abnormal Swallowing Syndrome 4. Nocturnal Paroxysmal Dystonia 5. Sudden Unexplained Nocturnal Death Syndrome 6. Primary Snoring 7. Infant Sleep Apnea 8. Congenital Central Hypoventilation Syndrome 9. Sudden Infant Death Syndrome 10. Benign Neonatal Sleep Myoclonus II. Other Parasomnia NOS 3. SLEEP DISORDERS ASSOCIATED WITH MENTAL, NEUROLOGIC, OR OTHER MEDICAL DISORDERS A. Associated with Mental Disorders I. Psychoses 2. Mood Disorders 3. Anxiety Disorders 4. Panic Disorders 5. Alcoholism B. Associated with Neurologic Disorders I. Cerebral Degenerative Disorders 2. Dementia 3. Parkinsonism 4. Fatal Familial Insomnia 5. Sleep-Related Epilepsy 6. Electrical Status Epilepticus of Sleep 7. Sleep-Related Headaches C. Associated with Other Medical Disorders l. Sleeping Sickness 2. Nocturnal Cardiac Ischemia 3. Chronic Obstructive Pulmonary Disease 4. Sleep-Related Asthma 5. Sleep-Related Gastroesophageal Reflux 6. Peptic Ulcer Disease 7. Fibromyalgia 4. PROPOSED SLEEP DISORDERS I. Short Sleeper 2. Long Sleeper 3. Subwakefulness Syndrome 4. Fragmentary Myoclonus 5. Sleep Hyperhidrosis 6. Menstrual-Associated Sleep Disorder 7. Pregnancy-Associated Sleep Disorder 8. Terrifying Hypnagogic Hallucinations 9. Sleep-Related Neurogenic Tachypnea 10. Sleep-Related Laryngospasm II. Sleep Choking Syndrome "Reprinted from American Sleep Disorders Association: International Classification of Sleep Disorders. Rochester, Minnesota, ASDA, 1997; with permission.
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APPENDIX I
APPENDIX II
Sleep Stage Characteristics
Characteristics
Stage EEG
EOG
EMG
Wake (eyes open)
Low voltage, high frequency Attenuated alpha activity
Eye blinks, REMs
Relatively high
Wake (eyes closed)
Low voltage, high frequency > 50% alpha activity
Slow rolling eye movements
Relatively high
Stage I
Low amplitude, mixed Slow rolling eye movements frequency < 50% alpha activity No sleep spindles, no K complexes Sharp waves near transition to stage 2
May be lower than in stage Wake
Stage 2
At least one sleep spindle or K complex < 20% slow wave activity
May be lower than in stage Wake
Stage 3
20-50% slow wave activity
Usually low
Stage 4
> 50% slow wave activity
Usually low
Stage REM
Low voltage, mixed frequency Saw tooth waves may be present
Episodic REMs
Relatively reduced (equal or lower than the lowest in NREM)
Notes: Required characteristics for the determination of each stage are in boldface. Slow wave activity has a frequency < 2 Hz and a peak to peak amplitude> 75 microvolts. Percentages refer to amount of time during each epoch. EEG = electroencephalogram, EOG = electro-oculogram, EMG = electromyogram, REM = rapid eye movements, NREM = nonrapid eye movement sleep.
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APPENDIX III
Disorders Causing Excessive Daytime Sleepiness Sleep apnea syndromes Upper airway resistance syndrome Narcolepsy Depression Periodic limb movement disorder Idiopathic hypersomnia Withdrawal from stimulants Inadequate sleep Sedatives/medications Post-traumatic hypersomnia
Common Causes of Insomnia Primary Insomnia
Secondary' Insomnia
Psychophysiological Acute (adjustment sleep disorder) Chronic Idiopathic Sleep state misperception
Other sleep disorders (sleep apnea, PLMD) Psychiatric disorders (depression, panic attacks) Drugs (nicotine, ethanol, caffeine) Medical conditions/medications Fibromyalgia and chronic pain syndromes COPD and other respiratory disorders Medications for illness (theophylline, beta blockers) Circadian disorders Delayed sleep-phase syndrome Advanced sleep-phase syndrome Shift work or jet lag syndrome Inadequate sleep hygiene Environmental sleep disorder
'Secondary means another disorder can be diagnosed. PLMD = periodic limb movement disorder, COPD = chronic obstructive pulmonary disease
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GLOSSARY
AASM-American Academy of Sleep Medicine Advanced sleep-phase syndrome (ASPS)-characterized by early sleep onset and final wake time relative to societal (clock) norms in the external world Alpha activity-EEG activity at 8-13 Hz Alpha-delta sleep-prominent alpha activity occurring during slow wave sleep Alpha sleep-prominent alpha activity occurring during sleep Amplitude-the magnitude of deflection in a signal; units depend on calibration. For slow wave activity, refers to peak-to-peak deflection. Apnea - absence of airflow at the nose and mouth for 10 seconds or longer Apnea + hypopnea index (AHI)-the number of apneas and hypopneas per hour of sleep, expressed as total number/total sleep time in hours. Also called the respiratory disturbance index (RDI). Arousal-abrupt, possibly brief awakening from sleep. In NREM sleep, an abrupt shift in EEG frequency longer than 3 seconds; in REM sleep, the EMG also must show augmentation to qualify as an arousal (ASDA definition). ASDA-American Sleep Disorders Association, now called the American Academy of Sleep Medicine AutoCPAP-auto-adjusting or auto-titrating CPAP units that deliver the lowest required pressure at any time needed to maintain upper airway patency Automatisms-repetitive movements that may be purposeful, but are not of benefit Beta activity-EEG activity> 13 Hz Bilevel pressure-method of ventilation allowing separate pressure levels in inspiration (inspiratory positive airway pressure, IPAP) and expiration (expiratory positive airway pressure, EPAP). Biocalibration-the initial recording of maneuvers during wakefulness to determine if the corresponding deflections in EEG, EOG, chin EMG, leg EMG, and airflow channels are satisfactory and to adjust amplifier gains, if necessary Bruxism-clinching or grinding of the teeth C4 (C3)-central EEG electrode on the right (left) side of the head Calibration-adjustment of amplifier baseline and gain. In polysomnography, the settings of EEG,
EOG, and EMG amplifiers are adjusted so that a known reference square wave input voltage elicits the desired pen deflections (or tracing deflection on a digital system). The low and high filter settings at the time of calibration are documented, as these affect the amplitude and shape of the deflections for a given calibration voltage. Capnogram - tracing of exhaled CO 2, The plateau of the deflection from each exhalation is the endtidal PC0 2 (an estimate of the arterial PC0 2) . Cataplexy - sudden loss of muscle tone (especially antigravity muscles) at moments of high emotion (e.g., surprise, laughter, fear); characteristic of narcolepsy Central apnea-apnea associated with an absence of respiratory effort Cheyne-Stokes breathing-crescendo-decrescendo pattern of breathing with central apneas or hypopneas at the nadir Chronic obstructive pulmonary disease (COPD)chronic bronchitis, emphysema, or a mixture Confusional arousals-a parasomnia characterized by confusion following a spontaneous or forced arousal from sleep. Confusional arousals tend to occur out of stages 3 and 4 sleep. In contrast to night terrors, there is no autonomic hyperactivity, signs of fear, or blood-curdling scream. Continuous positive airway pressure (CPAP)maintenance of positive airway pressure during inspiration and expiration CPAP flow-the flow signal from the positivepressure device utilized in polysomnography Delayed sleep-phase syndrome (DSPS)-characterized by delayed sleep onset and final waketime relative to societal (clock) norms in the external world Delta activity-EEG activity at < 4 Hz. In human sleep staging, the slow wave activity used to determine the sleep stage is < 2 Hz (see Slow wave activity). Derivation - the choice of two electrodes providing input to a differential amplifier (e.g., C4-A I) Desaturation - fall in arterial oxygen saturation ;::: 4% from baseline Diurnal-pertaining to daytime Early-morning awakening - final awakening earlier than expected; characteristic of depression 373
Electroencephalogram (EEG)-recording of brain electrical activity Electromyogram (EMG)-recording of the electrical activity of a muscle. In routine sleep monitoring, surface electrodes monitor EMG activity in the chin area. Electro-oculogram (EOG) - recording of the electrical activity generated during eye movements EPAP-expiratory positive airway pressure Epoch-a period of time usually corresponding to 30 seconds (one page of recording at a paper speed of 10 mm/sec) Epworth Sleepiness Scale (ESS) - a score from 0 to 24 of the propensity to fall asleep in eight normal situations (see Fundamentals of Sleep Medicine II). Normal is:s: 10, and 24 is the maximal ESS score (the most sleepy). FEV,IFVC - ratio of the forced expiratory volume in l second to the forced vital capacity. Reduced in obstructive airway disease. In this text, normal is > 0.70 and 90% of predicted. Forced expiratory volume (FEV)- FEY I is the volume of air in liters exhaled in the first I second of a maximal forced vital capacity maneuver. In this text, normal is assumed to be 80-120% of predicted. Forced vital capacity (FVC)-volume of air in liters exhaled from maximal inhalation (total lung capacity) to residual volume (maximal exhalation) during a forced maneuver. In this text, normal is assumed to be 80-120% of predicted. Hypnagogic-an event occurring on transition from wake to sleep Hypnagogic hallucination-vivid imagery at sleep onset; a feature of narcolepsy in which REM periods occur at sleep onset Hypnic jerk (sleep start) - brief total-body jerk at sleep onset Hypnogram-a graphical overview of the cyclic nature of sleep (see Patient 9) Hypnopompic-an event occurring on transition from sleep to wakefulness Hypocretins-two peptides, Hcrt I and Hcrt 2 (also known as orexins A and B), that are secreted by hypothalamic neurons that project to specific areas of the brainstem and cortex. The peptides are thought to influence the sleep-wake cycle and alertness. A disruption of hypocretin neurotransmission may play a key role in the pathogenesis of canine and human narcolepsy. Hypopnea - reduction in airflow for 10 seconds or longer. Definitions vary (see text). ICSD- International Classification of Sleep Disorders Interictal-refers to transient focal or generalized discharges between seizure events K complex -large-amplitude biphasic deflection ofO.5-second or longer duration; a negative (up)
374
sharp wave followed by a positive (down) slow wave Laser-assisted uvuolopalatoplasty (LAUP)-palatoplasty performed with a laser Left outer canthus (LOC)-electrode placed lateral to the outer corner of the left eye Maintenance of wakefulness test (MWT)-test to determine the ability to stay awake Mean sleep latency-the mean of sleep latencies recorded during naps over the course of a multiple sleep latency test Mixed apnea-apnea composed of an initial central part followed by an obstructive component Montage-the particular arrangement of electrodes by which a number of derivations are displayed simultaneously in a polysomnogram Movement arousal-defined in the R&K scoring manual as an increase in the chin EMG accompanied by a change in pattern on any additional channel. For EEG channels, qualifying changes include a decrease in amplitude, paroxysmal high voltage activity, or an increase in alpha activity. Movement time (MT)-epochs in which the sleep stage is indeterminant due to movement artifact in the EEG Multiple sleep latency test (MSLT) - test to determine the mean sleep latency during daytime naps as an objective measure of daytime sleepiness. The presence/absence of REM sleep during the naps also is determined. Nasal pressure-used to detect airflow; see Fundamentals of Sleep Medicine 10 Non-REM (NREM) sleep-sleep stages I, 2, 3, and 4 02 (Ol)-occipital EEG electrode on the right (left) side of the head Obesity-hypoventilation syndrome (OHS)-daytime hypoventilation (hypercapnia) not secondary to lung disease in an obese patient, usually accompanied by severe obstructive sleep apnea Obstructive apnea-apnea with persistent respiratory effort Obstructive sleep apnea syndrome (OSAS)syndrome characterized by obstructive and mixed apnea and hypopneas, as well as excessive daytime sleepiness Overlap syndrome-obstructive sleep apnea plus chronic obstructive pulmonary disease (OSA + COPD) Parasomnia - a condition associated with or occurring from sleep. Disorders of arousal or partial arousal. Examples include sleepwalking, night terrors, and REM behavior disorder. Periodic leg (limb) movement(s) (PLM, PLMs)leg (arm) movements, such as foot flexion, big toe extension, and partial flexion at hip and knee, of about I-second duration that occur every 2060 seconds during sleep. To be considered a GLOSSARY
PLM, a leg movement must occur in a group (sequence) of four or more movements separated by > 5 seconds and < 90 seconds. Periodic leg (limb) movements in sleep (PLMS)the entity describing periodic leg movements during sleep, usually referring to an abnormal number of leg movements or a PLM index> 5/hr Periodic leg (limb) movement disorder (PLMO)a disorder of excessive daytime sleepiness or insomnia secondary to PLMS Periodic leg (limb) movement index (PLM index) - number of movements per hour of sleep Periodic leg (limb) movement-arousal index (PLM-arousal index)-number of PLMs associated with arousal per hour of sleep Phasic REM sleep - REM sleep in which rapid eye movements are present Phase response curve (PRC)-a curve characterizing the magnitude and direction of the shift of the internal clock (circadian rhythm) induced by light as a function of the timing of light relative to the baseline circadian rhythm (relative to the nadir in body temperature) Polysomnography - the detailed monitoring of sleep Popping artifact-high-voltage artifact caused by temporary disconnection of electrodes from the skin R&K - refers to the sleep staging criteria of Rechtschaffen and Kales, published in their book: A Manual of Standardized Terminology Techniques and Scoring System for Sleep Stages of Human Sleep. Los Angeles, Brain Information Service/ Brain Research Institute, UCLA, 1968. Rapid eye movement (REM)-a sharp (short duration) eye movement Rapid eye movement behavior disorder (RBO)a parasomnia occurring from REM sleep associated with body movement and violent behavior Rapid eye movement density-number of eye movements per time in REM sleep. Normally highest during the last REM periods of the night. Rapid eye movement sleep-a sleep stage characterized by a low-voltage, mixed-frequency EEG; episodic REMs; and a relatively lowamplitude EMG (:5 the lowest amplitude in NREM sleep) Recording time; time in bed (TIB)-total time of sleep monitoring from lights out to lights on REM latency - time from sleep onset to the start of stage REM Respiratory arousal index (RAI) - arousals secondary to an apnea or hypopnea, and, in many sleep laboratories, respiratory effort-related arousals per hour of sleep Respiratory disturbance index (ROI)-see Apnea + hypopneaindex Respiratory effort-related arousal (RERA)-an event characterized by an arousal following a peGLOSSARY
riod of increased respiratory effort that does not qualify as an obstructive apnea or hypopnea. Increased respiratory effort is usually detected by increased esophageal pressure deflections. Respiratory inductance plethysmography (RIP)a method of detecting chest and abdominal movement secondary to changes in the inductance (a component of impedance) of bands around those regions. See Fundamentals of Sleep Medicine 10. Restless legs syndrome (RLS)-syndrome marked by creeping sensation in the legs that can be temporarily relieved by movement Right outer canthus (ROC)-electrode placed lateral to the outer corner of the right eye Saw tooth waves-form of theta rhythm (jagged up and down) seen in stage REM Sharp wave (vertex sharp wave)-high-voltage, brief, negative (up) wave present in stage I near transition to stage 2. Sharp waves have a duration of 70-200 milliseconds. Sleep architecture-the relative amounts of the different sleep stages composing sleep and timing of sleep cycles. See Fundamentals of Sleep Medicine 7. Sleep efficiency - usually defined as total sleep time * 100/time in bed Sleep hygiene-conditions and practices that promote continuous and effective sleep Sleep latency-time from lights out (start ofmonitoring period) to the first epoch of any stage of sleep Sleep maintenance insomnia-difficulty maintaining sleep; frequent awakenings Sleep onset insomnia-difficulty falling asleep Sleep paralysis-inability to move while still awake at sleep onset (hypnagogic) or at the end of a sleep period (hypnopompic) Sleep period time (SPT)-time from sleep onset until the final awakening; total sleep time (TST) plus wake after sleep onset (WASO) Sleep spindle-EEG activity of 12-14 Hz occurring in bursts of O.5-second or longer duration; characteristic of stage 2 sleep but can be seen in stages 3 and 4 Sleep stages-also see Appendix II • Stage I-sleep characterized by a low-voltage, mixed-frequency EEG; an absence of sleep spindles and K complexes; and alpha activity present in < 50% of the epoch • Stage 2-sleep characterized by an EEG showing at least one sleep spindle or K complex (see Three-minute rule) and slow wave activity present in < 20% of the epoch • Stage 3-sleep with an EEG showing slow wave activity meeting the voltage criteria for 20-50% of the epoch • Stage 4-sleep with an EEG showing slow wave
375
activity meeting the voltage criteria for> 50% of the epoch • Stage REM-see Rapid eye movement sleep Sleep starts (hypnic jerk) - brief whole-body jerk at sleep onset Sleep state misperception - patients do not seem to recognize that they were asleep Sleep terrors-a parasomnia characterized by sudden awakening from NREM sleep (usually stages 3 and 4) with a cry or scream, confusion, and autonomic hyperactivity Sleep walking (somnambulism)-characterized by a partial awakening from NREM sleep (classically from stages 3 and 4) with complex movements including walking Slow rolling eye movement (or slow eye movements)-smooth, undulating eye movements occurring during drowsy wakefulness and stage I sleep Slow wave activity - by convention, oscillations slower than 2 Hz ( > 0.5 seconds in duration) with a minimal peak-to-peak amplitude of 75 microvolts. The amount of slow wave activity determines whether stage 2, 3, or 4 is present. Slow waves (delta waves)-EEG waves with a frequency of 1-4 Hz (see Slow wave activity) Spike-defined as an EEG transient with a pointed peak and a duration of 20-70 milliseconds Sweat artifact-slow undulations in EEG and EOG tracings secondary to sweat
376
Ten-twenty system-an international standard for the placement of EEG electrodes in which spacing of electrodes is 10% or 20% of the distance between landmarks on the head Theta activity - EEG acti vity at 4-7 Hz Three-minute rule-epochs of sleep between two spindles or K complexes that otherwise would be scored as stage 2 sleep are scored as stage I if the time between the spindles/K complexes is > 3 minutes and as stage 2 if the time is < 3 minutes. Time in bed (TIB); recording time-total monitoring time, from lights out to lights on Tonic REM sleep-REM sleep in which rapid eye movements are absent Total sleep time (TST)-total minutes of stages I, 2, 3, and 4, and REM sleep Upper airway resistance syndrome (UARS)syndrome characterized by daytime sleepiness secondary to frequent arousals related to increased respiratory effort during periods of high upper airway resistance (narrowing) without an abnormal amount of frank apnea or hypopnea. Some authorities believe it is simply a mild form ofOSA. Uvulopalatopharyngoplasty (UPPP)-an upper airway surgery for sleep apnea and snoring. The uvula, a portion of the soft palate, and excess pharyngeal tissues are removed. Wake after sleep onset (WASO)-wake before the final awakening
GLOSSARY
INDEX Abdominal movements, paradoxical, 92 during hypopnea, 84, 98 during obstructive sleep apnea, 91,92,93 Abdominal volume, in respiratory effort measurement,85-86 Acetazolamide, as idiopathic central sleep apnea treatment, 240 Adenoidectomy, 210-212 Adjustment sleep disorder, 333, 338-341, 343, 348-349 Age at onset, in sleep disorders, 100 Airflow monitoring in obstructive sleep apnea, 88-90 techniques in, 84-85 Airway obstruction. See also Upper airway obstruction periodic limb movements of sleep-related, 262264 Alcohol use as insomnia cause, 335, 336 sleep architecture effects of, 53 as snoring cause, 113-115,185,186 Alertness, maintenance of wakefulness test documentation of, 180-181 Alpha-delta sleep, 39 Alpha intrusion, 39 Ambient temperature, for prevention of sweat artifacts, 71 Amitriptyline as fibromyalgia treatment, 353 as insomnia treatment, 339 as post-traumatic stress disorder treatment, 363 Amphetamines, as narcolepsy treatment, 283 Anemia, iron-deficiency, as restless legs syndrome cause, 259-261 Anticonvulsants, as restless legs syndrome treatment, 267, 268, 270 Antidepressants, as insomnia treatment, 339 Anxiety panic attacks-related, 365-366 post-traumatic stress disorder-related, 363, 364 Apnea central, 233-252 Cheyne-Stokes breathing associated with, 243-245,246-247 congestive heart failure associated with, 234 definition of, 82, 233 idiopathic, 236-238, 239-240 oxygen therapy for, 239-240 definition of, 82
Apnea (Cont.) differentiated from hypopnea, 84-85 mixed Cheyne-Stokes breathing associated with, 242 definition of, 82 obstructive sleep apnea-associated, 94-95 obstructive. See Obstructive sleep apnea Apnea-hypopnea index in children, 212 effect of continuous positive airway pressure on, 128, 130, 131, 133 definition of, 82 in obstructive sleep apnea, 98, 103, 106, 116, 117,118,122 uvulopalatopharyngoplasty-related reduction of, 167 Apneic threshold, in central sleep apnea, 237 Arousal central sleep apnea-related, 238 Cheyne-Stokes breathing-related, 244 chin EMG evaluation of, 35-36, 38-39 confusional, 300-301,304 electrocortical, 36, 37 nocturnal seizure-related, 324 periodic limb movements of sleep-related, 257 in REM sleep, 43--44 respiratory, 108-118 respiratory effort-related, 108-112 upper respiratory resistance syndrome-related, III somnambulism-related, 307 Arousal index, in excessive daytime sleepiness, 36,37 Arrhythmias, obstructive sleep apnea-related, 194-196 Arterial oxygen desaturation in chronic obstructive pulmonary disease, 216218,219-221,222-223,227-229 in congestive heart failure, 242 definition of, 82 during initial continuous positive airway pressure use, 163-165 measurement of, 86 in obstructive sleep apnea, 116-118,205-206 severity of, 106, 107 during REM sleep, 31, 32, 116-118 Artifacts EKG, 62-63, 65 electrode popping, 72-73 377
Artifacts (Cont.) sixty-cycle, 64-66 sweat or respiratory, 70-71 Asthma, nocturnal, 230-232 Auditory monitoring, during polysomnography, 59 Augmentation effect, in levodopa/carbidopa therapy,270 Autoimmune disorders, as narcolepsy risk factor, 275 Automatisms, seizure-related, 321, 324 Automobile accidents, by obstructive sleep apnea patients, 182-183 Awakening. See also Arousal early-morning advanced sleep-phase syndrome-related, 349 depression-related, 354-356 terrifying, 365-366 Bed partners of excessive daytime sleepiness patients, 103 of periodic leg movements in sleep patients, 264,273 of REM sleep behavior disorder patients, 310 of restless leg syndrome patients, 259, 260 of untreated obstructive sleep apnea patients, 134-135 Bed wetting, 30 I Behavior problems, pediatric obstructive sleep apnea-related, 207-209, 210-212 Benzodiazepines as adjustment sleep disorder treatment, 339-340 use in chronic obstructive pulmonary disease patients, 225 obstructive sleep apnea-exacerbating effects of, 273 as panic attack treatment, 366 as restless legs syndrome treatment, 267, 268, 270 sleep architecture effects of, 3-5, 52-53 Beta-agonists, as nocturnal asthma treatment, 231, 232 Bilevel pressure, 157-159 as continuous positive airway pressure alternative, 152 as obesity hypoventilation syndrome treatment, 203,204 use in post-polio syndrome patients, 252 Biocalibrations definition of, 23 EEG during, 23
378
Biocalibrations (Cont.) for eye movement detection, 73 procedures for, 60-61 Bipolar disorder, 361 Birth control medications, interaction with modafinil, 289 "Blue bloater" variant, of chronic obstructive pulmonary disease, 227-229 Body temperature, nadir in, during sleep, 342, 347 Bradytachycardia, 195 Bright light, contraindication in advanced sleepphase syndrome, 349 Bright light therapy, for delayed sleep-phase syndrome, 346-347 Bronchodilator therapy for chronic obstructive pulmonary disease, 220, 225 for nocturnal asthma, 231, 232 Bruxism, 301, 312-314 Caffeine as insomnia cause, 3335, 336, 337 as restless leg syndrome cause, 260 Carbamazepine as cataplexy treatment, 286, 287 as REM sleep behavior disorder treatment, 310, 311 as restless legs syndrome treatment, 268 Carbidopa. See Levodopa/carbidopa Carbon dioxide. See also Partial pressure of carbon dioxide (PC0 2 ) exhaled as airflow measure, 85 apnea-related fluctuations in, 88-90 Carbon dioxide retention congenital central hypoventilation syndromerelated, 248-250 unexplained, obesity hypoventilation syndrome-related, 20 I Cardiovascular disease apnea-hypopneaindexin, 83 untreated obstructive sleep apnea-related, 134-135 Cataplexy, 100 drug therapy for, 285-287 narcolepsy-associated,276-278 Chest movements, paradoxical, 92 during hypopnea, 84, 98 during obstructive sleep apnea, 91, 92, 93 during respiratory effort measurement, 85-86 Cheyne-Stokes breathing adaptiveservo ventilation treatment for, 244
Cheyne-Stokes breathing (Cont.) central apnea associated with, 234 congestive heart failure-associated, 241-242, 243-245,247 obstructive sleep apnea-associated, 241-242, 2462-47 "Chicago criteria," for definition of hypopnea, 82-83 Children airflow measurement in, 85 congenital central hypoventilation syndrome in, 248-250 hypoventilation in, 85 night terrors in, 304 obstructive sleep apnea in as behavior problem cause, 207-209, 210-212 tonsillar enlargement-related, 208, 210-212 somnambulism in, 307, 308 Chronic obstructive pulmonary disease, 216218 arterial oxygen desaturation associated with, 219-221,222-223,227-229 "blue boater" variant of, 227-229 obstructive sleep apnea (overlap syndrome) associated with, 227-229 pedal edema associated with, 219-220, 222-223,227-229 "pink puffer" variant of, 224-225 Chronotherapy, 346, 347 Circadian rhythm sleep disorders, 342-351 Claustrophobia, in CPAP patients, 140, 145147 Clomipramine, as cataplexy treatment, 286 Clonazepam as insomnia treatment, 340 as panic attack treatment, 366 as REM sleep behavior disorder treatment, 310, 311 as restless legs syndrome treatment, 268 side effects of, 267, 268 as somnambulism treatment, 307 Clonidine, as post-traumatic stress disorder treatment,363 Cognitive-behavioral therapy, for insomnia, 336, 337 Congenital central hypoventilation syndrome, 248-250 Congestive heart failure central apnea associated with, 234 Cheyne-Stokes breathing associated with, 241-242,243-245
Continuous positive airway pressure (CPAP), 124-126, 139-201 alternatives to genioglossus advancement, 172-173, 174 hyoid myotomy, 172, 173 maxillary mandibular osteotomy, 173, 174 oral appliances, 175-177, 179 tracheostomy, 171-173 uvulopalatopharyngoplasty, 172-174 in asymptomatic patients, 136-138 auto-adjusted, 151-153 auto-titration, 160-162 chin strap use with, 149 in claustrophobic patients, 140, 145-147 for congestive heart failure-associated CheyneStokes breathing, 244-245, 246-247 decongestant use with, 155 discontinuation following weight loss, 121-123 esophageal pressure in, 128 full face mask (oronasal), 154-156 humidification use with, 149, 150, 155 as idiopathic central sleep apnea treatment, 239-240 initial use of, arterial oxygen desaturation during,163-165 inspiratory positive airway pressure, 157-159 mask interface problems in, 145-147 Medicare reimbursement for, 124, 137, 138 modafinil use with, 143 mouth leaks associated with, 140, 146, 149, 150, 158 nasal and mouth flow and leak recordings in, 125-126,131-133 nasal symptoms associated with, 140, 148-150, 154-156 a night terrors risk factor, 304 nocturnal seizures during, 323-325 as obesity hypoventilation syndrome treatment, 201,202-204 for obstructive sleep apnea diagnosis, 103 oral leaks associated with, 155 overtitration during, 130-133 with oxygen therapy, as overlap syndrome treatment, 228, 229 patients' acceptance/adherence to, 139 inadequate, 142-144 patients' intolerance of, 124, 154-156, 157-159,160-162,175-176 periodic leg movements in sleep associated with, 272-273 persistent daytime sleepiness on, 142-144 post-uvulopalatopharygoplasty use of, 179
379
Continuous positive airway pressure (CPAP) (Cont.)
in pregnant patients, 198, 199 pressure intolerance associated with, 151-153 ramp mode of, 152 REM rebound in, 163-165 run time meter documentation of, 13 side effects of, 140 snoring during, 189 as somnambulism treatment, 307, 308 split-night studies with, 128, 129 suboptimal titration in, 160-162 in supine body position, 127-129 time at pressure documentation of, 143 Cor pulmonale chronic obstructive pulmonary disease-related,
227-229 neuromuscular disorders-related, 252 obesity hypoventilation syndrome-related, 20 I obstructive sleep apnea-related, 206 Corticosteroids, inhaled, as nocturnal asthma treatment, 231 Crescendo pattern, of respiratory effort, III Deep sleep, somnambulism during, 28-29 Deflections, K complexes as, 25-26 Delayed sleep-phase syndrome, 329, 343,
345-346 Delta sleep. See Slow wave sleep Depression as early-morning awakening cause, 349 as excessive daytime sleepiness cause, 40-41, 100 hypersomnia associated with, 298, 360-361 insomnia associated with, 329, 330, 339 REM latency in, 354-356 as weight loss cause, 360-361 Dextroamphetamine, as narcolepsy treatment,
283,284 Dopamine agonists, as restless legs syndrome treatment, 265-268 Doxepin, as insomnia treatment, 339, 340 Dreams. See also Nightmares recurrent, post-traumatic stress disorder-related,
362-364 violent, 309-311 Driving risk, posed by obstructive sleep apnea patients, 180-183 Drugs. See also specific drugs sleep architecture effects of, 53, 55-56 Dyspnea nocturnal, chronic obstructive pulmonary disease-related, 225
380
Dyspnea (Cont.) panic attacks-related, 366 Dystonia, nocturnal paroxysmal. 30 I Edema, pedal chronic obstructive pulmonary disease-related,
219-220,222-223,227-229 congestive heart failure-related, 241 EKG artifacts, 62-63, 65 Elderly patients advanced sleep-phase syndrome in, 349 periodic leg movements in sleep in, 262-264 Electrocardiography (EKG) artifacts, 62-63, 65 Electrode impedance, 65, 66 Electrode popping, 72-73 Electrodes, referential, 67-69 Electroencephalography (EEG) alpha activity of background, 39 in insomnia, 6-7 during sleep stage I, 24-25 electrode impedance in, 65, 66 electrode placement in, 315-316 electrode popping artifacts in, 72-73 filter settings in, 74-76 high-amplitude activity of, electro-oculographic detection of, 16-17 lead placement in, 8-11 in nocturnal seizures, 315-318 during continuous positive airway pressure titration, 323-325 spike and wave activity during, 323-325 temporal lobe epilepsy-related, 326-328 patterns of, 1-7 referential leads in, 67-69 saw-tooth patterns of, 31, 32 in REM sleep, 2, 43, 44 for seizure activity evaluation, 321, 322 in stage 2 sleep, 26-27 sweat artifacts in, 70-71 during wakefulness, 6-7 Electromyography (EMG) chin (submental), 18-41 for arousal evaluation, 35-37, 38-39 for bruxism evaluation, 312, 313, 314 for daytime sleepiness evaluation, 25 electrode popping artifacts in, 72-73 for excessive daytime sleepiness evaluation,
30-32,33-34,35-37,40-41,64-66 for insomnia evaluation, 20-21, 22-23, 26-27 muscle artifacts in, 20-21 polysomnographic applications of, 62-63,
64-66,67-69,70-71
Electromyography (EMG) (Cont.) during REM sleep. 18-19, 30-32. 34. 43 for REM sleep behavior disorder evaluation. 310,311 sixty-cycle artifacts in, 64-66 for snoring evaluation, 33-34, 70-71, 186 for somnambulism evaluation, 28-29 hand. for REM behavior disorder evaluation. 300 lead placement in, 12 leg, for periodic leg movements in sleep diagnosis. 256-258 referential leads in, 67-69 sixty-cycle artifacts in, 64-66 sweat artifacts in, 70-71 Electro-oculography (EOG), 12-13 electrode popping artifacts in, 72-73 high-amplitude electroencephalographic activity during, 16-17 lead placement in, 12 referential leads in, 67-69 sweat artifacts in, 70-71 "Elvis legs," 253 End-tidal PCO z monitoring, in pediatric obstructive sleep apnea, 211, 212 Enuresis, 301 Environmental sleep disorder, 333 Epilepsy juvenile myoclonic, 320 temporal lobe, 32\, 326-328 Epochs 70-75, scored as stage REM sleep, 42-43, 4549 definition of, 1 of sleep stage 4, in insomnia, 10-11 Epworth Sleepiness Scale, 99-100, 102, 105 Esophageal pressure, apnea-related increase in, 82 Esophageal pressure monitoring of hypopnea, 83 of respiratory effort, 92, 93 of respiratory effort-related arousals, 108 of snoring, 186 of upper respiratory pressure syndrome, 112 Excessive daytime sleepiness, 99-107 arousal index in, 36, 37 Cheyne-Stokes breathing-associated, 241-242 chin EMG evaluation of, 30-32, 33-34, 35-37, 40-41 congestive heart failure-related, 243-245 with CPAP therapy, 142-144 as depression cause, 40-41 EKG artifacts associated with, 62-63 history of, 99-100
Excessive daytome sleepiness (Cont.) idiopathic central sleep apnea associated with, 236-238 idiopathic hypersomnia-related, 297-299 insufficient sleep syndrome-related, 296 maintenance of wakefulness testing for, 78, 180-181 most common causes of, 99 multiple sleep latency testing for, 78, 80-81, 100 narcolepsy-related, 274, 276-278, 279-281, 283-284,293-294 obstructive hypopnea-related, 96-98 periodic leg movements in sleep-related, 273 polysomnographic evaluation of, 100 EEG filter settings in, 74-76 electrode popping artifacts in, 72-73 post-uvulopalapharyngolpasty, 178-179 Prader- Willi syndrome-related, 213-215 REM eye movements in, 16-17 Expiratory reserve volume (ERY), in obstructive sleep apnea, 106, 107 Eye movements. See also Electro-oculography biocalibrations for detection of, 73 patterns during sleep, 14-15 during REM sleep, 31, 32,43-44 effect of selective serotonin reuptake inhibitors on, 40-41 Fatigue alpha-delta sleep-related, 353 depression-related, 354-356 upper airway resistance syndrome-related, 110-112 "Fencing posture," 321 Fibromyalgia, as alpha-delta sleep cause, 330, 352-353 First-night effect, 23, 339, 341 reverse, 333 Flashbacks, 363 F1uoxetine as cataplexy treatment, 286, 287 as fibromyalgia treatment, 353 as hypersomnia treatment, 361 as post-traumatic stress disorder treatment, 363 sleep architecture effects of, 55-56 Flurazepam, as insomnia treatment, 340 Formoterol, as nocturnal asthma treatment, 231 Functional residual capacity, chronic obstructive pulmonary disease-related decrease in, 216-218 Gabapentin, as restless legs syndrome treatment, 268 381
Gamma hydroxybutyrate, as cataplexy treatment, 286 Gasping excessive daytime sleepiness-related, 100 obstructive sleep apnea-related, 103 Genioglossus advancement, 172-173, 174 Glossectomy, laser midline, 173 Grief, as insomnia cause, 338-340 Hallucinations, hypnagogic, 100, 277, 286 Head trauma, as hypersomnia cause, 298, 299 Heart rate variability, in obstructive sleep apnea patients, 195, 196 HLA haplotyping, for narcolepsy evaluation, 294 Homicide, somnambulism-related, 307 Hydrocephalus, progressive, 298 Hypercapnia during initial continuous positive airway pressure therapy, 164 obesity hypoventilation syndrome-related, 200-201 Hyperphagia depression-related, 360-361 Prader- Willi syndrome-related, 214 Hypersomnia depression-related, 355, 360-361 idiopathic, as excessive daytime sleepiness, 297-299 Hypertension, as obstructive sleep apnea risk factor, 103, 104, 191-193 Hypnic jerks (sleep starts), 300 Hypnogram, for somnambulism evaluation, 29 Hypnotics as adjustment sleep disorder treatment, 339-340,341 use in chronic obstructive pulmonary disease patients, 224, 225 as excessive daytime sleepiness cause, 298 as jet lag treatment, 351 Hypocretin, 274-275 Hypopnea central, 83, 233 airflow measurement in, 89 nasal pressure in, 84 in children, as behavior problem cause, 207-209 definition of, 82-82, 97 differentiated from apnea, 84-85 mixed, 83, 84 obstructive, 83-84, 96-98 nasal pressure during, 85 Hypothyroidism, as obstructive sleep apnea risk factor, 188-189
382
Hypotonia, REM sleep-associated skeletal muscle, 31-32 Hypoventilation bilevel pressure treatment for, 158 central sleep apnea-related, 233, 237 in children, 85 chronic obstructive pulmonary diseaserelated, 216-218 congenital central, 248-250 nonapneic, during initial continuous positive airway pressure therapy, 163-165 obstructive, in children, 208, 209 post-polio, 251-252 Prader- Willi syndrome-associated, 213-215 Hypoxemia, during initial continuous positive airway pressure therapy, 164 Hypoxic ventilatory response, in Prader- Willi syndrome, 214 Imipramine, as cataplexy treatment, 285, 286 Insomnia, 329-341 alcohol use-related, 335, 336 delayed sleep-phase syndrome-related, 345-347 depression-related, 355, 356, 357-358 EEG during, 22-23 muscle artifacts in, 20-21 patterns in, 6-7 sleep stage 4-related epochs, 10-11 evaluation of, 329-331 psychophysiologic, 331, 332-333 transient, 339 rebound, 339, 341 selective serotonin reuptake inhibitors-related, 357-358 sleep-onset, sleep latency in, 22-23 treatment of, 335-337 with relaxation therapy, 336, 337 with sleep hygiene therapy, 336, 337 Inspiratory effort, arousal-inducing effect of, 108 Inspiratory positive airway pressure, 157-159 Insufficient sleep syndrome, 295-296, 298 Ipratropium bromide as chronic obstructive pulmonary disease treatment, 224, 225 as nocturnal asthma treatment, 231 Irregular sleep wake patterns, 343-344 Jacksonian march, 321 Jet lag, 343,350-351 K complexes in sleep stage 1, 46 sleep staging between, 42, 46
K complexes (Cant.) in stage I sleep, 42 in stage 2 sleep, 42 Kleine-Levin syndrome, 361 Left ventricular hypertrophy, hypertensionrelated, 192 Leg jerks. See Periodic limb movements in sleep Levodopa/carbidopa, as restless legs syndrome treatment, 266 rebound effect in, 269-271 Light, effect on circadian cycle, 342 Lingualplasty, 173 Lip smacking, during seizures, 320 Locus ceruleus, in narcolepsy, 274 Lung disease. See also Chronic obstructive pulmonary disease arterial oxygen desaturation in, 31, 32 bilevel pressure treatment for, 158 Macroglossia, hypothyroidism-related, 189 Magnetic resonance imaging, for seizure evaluation, 324 Maintenance of wakefulness test (MWT) definition of, 78 use with drivers, 180-181 Major affective disorder, 354-355 Medicare, continuous positive airway pressure coverage by, 124, 137, 138 Medroxyprogesterone, as obesity hypoventilation syndrome treatment, 20 I Melatonin as circadian sleep disorder treatment, 343 as delayed sleep-phase syndrome treatment, 346 as jet lag treatment, 351 Methamphetamine, as narcolepsy treatment, 283, 284 Methylphenidate, as narcolepsy treatment, 283, 284,288-289 Microawakenings, 36 Mirtazapine as insomnia treatment, 339, 341 as selective serotonin reuptake inhibitor-related insomnia treatment, 358 Modafinil as narcolepsy treatment, 283, 284, 288-289 use with continuous positive airway pressure, 143 Mood disorders, 355 Movement time, 50 Multiple sleep latency test (MSLT), 77-81
Multiple sleep latency test (MSLT) (Cant.) comparison with maintenance of wakefulness test, 180-181 definition of, 77 for excessive daytime sleepiness, 78, 80-81 for insufficient sleep syndrome evaluation, 296 mean sleep latency in, 77, 78, 79, 296 for narcolepsy evaluation, 78,80-81,277-278, 279-281,290-291,294 Myoclonus, nocturnal. See Periodic limb movements in sleep Myotomy, hyoid, 172, 173 Nap monitoring, in multiple sleep latency testing, 77,79,80-81 Naps, advanced sleep-phase syndromeexacerbating effect of, 349 Narcolepsy, 274-284, 288-289, 293-294. See also Cataplexy age at onset of, 100 differentiated from idiopathic hypersomnia, 298 drug therapy for, 282-284, 288-289 during pregancy, 198 excessive daytime sleepiness associated with, 274,276-278,279-281,283-284, 293-294 multiple sleep latency test for, 78, 80-81, 277-278,279-281,290-291,294 obstructive sleep apnea associated with, 290-291,293-294 periodic limb movements associated with, 254 REM latency in, 56 secondary, 274 Narcotics, as restless legs syndrome treatment, 267 Nasal cannulas for airflow evaluation, 85, 89, 90 for continuous positive airway pressure administration, 146 Nasal congestion, continuous positive airway pressure-related, 148-150, 154-156 Nasal pressure monitoring, for airflow measurement, 84-85, 89, 90 in obstructive hypopnea, 97, 98 in respiratory effort-related respiratory arousal, 110,111,112 Nasopharyngeal inlet stenosis, postuvulopalatopharyngoplasty, 169-170 Neck circumference, as obstructive sleep apnea risk factor, 103, 104 Nefazodone as insomnia treatment, 339, 341 as post-traumatic stress disorder treatment, 363
383
Nefazodone (Cont.) as selective serotonin reuptake inhibitor-related insomnia treatment, 358 Nightmares definition of, 300 differentiated from night terrors, 303-304 differentiated from panic attacks, 366 Night terrors, 300-30 1,303-304 differential diagnoses of, 304 differentiated from nightmares, 303-304 differentiated from panic attacks, 366 differentiated from REM sleep behavior disorder, 310 REM sleep behavior disorder-associated, 311 somnambulism associated with, 307 Nocturnal spells, 320 Non-24-hour sleep-wake disorder, 344 NREM (nonrapid eye movement) sleep nocturnal seizures during, 324 seizures during, 320, 322 somnambulism during, 28-29, 304, 307 stages of, 1-6 Obese patients, polysomnographic studies in, 70-71 Obesity obstructive sleep apnea associated with, 103, 121-123 in Prader- Willi syndrome patients, 213, 214, 215 respiratory monitoring in, 91-93 Obesity hypoventilation syndrome, 200-201, 202-204 bilevel pressure treatment for, 158 oxygen therapy for, 205-206 Obstructive sleep apnea age at onset of, 100 arterial oxygen desaturation in, 106, 107, 116-118, 205-206 asthma-associated, 231, 232 asymptomatic, 136-138 "blue bloater" variant of, 227-229 Cheyne-Stokes breathing associated with, 246-247 in children as behavior problem cause, 207-209, 210-212 tonsillar enlargement-related, 208, 210-212 chronic obstructi ve pulmonary disease-related (overlap syndrome), 227-229 continuous positive airway pressure treatment for. See Continuous positive airway pressure (CPAP)
384
Obstructi ve sleep apnea (Cont.) in drivers, 180-183 heart rate variability in, 195, 196 hypertension associated with, 191-193 hypothyroidism associated with, 188-189 insomnia associated with, 330, 333 mild-to-moderate, treatment of, 120 mixed apnea associated with, 94-95 multiple sleep latency testing for, 78 narcolepsy associated with, 290-291 obesity hypoventilation syndrome-related, 201 oxygen therapy for, adverse effects of, 205206 paradoxical respiration in, 82 partial-night studies of, 147 periodic leg movements in sleep-related, 261, 262-264 positional, 122, 123 premature ventricular contractions associated with, 194-196 REM latency in, 290-291 REM sleep-specific, 116-118 respiratory effort detection during, 91-93 severity of assessment of, 105-107, 119, 145-147 post-uvulopalatopharyngoplasty, 169-170 snoring associated with, 188-189 split-night studies of, 146, 147 treatment of, 119-123 genioglossus advancement, 172-173, 174 with hyoid myotomy, 172, 173 with maxillary mandibular osteotomy, 173, 174 with tracheostomy, 172-174 with uvulopalatopharyngoplsaty, 166-168 untreated, as cardiovascular events risk factor, 134-135 Opiates, as restless legs syndrome treatment, 270 Oral appliances, as obstructive sleep apnea treatment, 175-177, 189 Overlap syndromes bilevel pressure treatment for, 158 hypercapnic respiratory failure associated with, 202-204 oxygen therapy for arterial oxygen desaturation in, 206 with continuous positive airway pressure, 228, 229 parasomnia, 301 Overtitration, in continuous positive airway pressure, 130-133 Oximetry, nocturnal, 86, 107,220
Oxygen therapy for chronic obstructive pulmonary disease, 220, 223,225 for idiopathic central sleep apnea, 240 for obesity hypoventilation syndrome, 205-206 for overlap syndromes, 206, 228, 229 Painful legs and moving toes syndrome, 260 Palatoplasty, laser-assisted, as snoring treatment, 167,168 Panic attacks, 365-366 Pa0 2 (partial pressure of oxygen), awake supine, in obstructive sleep apnea, 106 Paradoxical intention, for insomnia, 336 Paralysis, leaden, 361 Parasomnia overlap disorder, 30 I Parasomnias, 300-30 definition of, 300 Parkinson's disease, REM sleep disorder associated with, 310, 311 Partial pressure of carbon dioxide (PCO l ) as airflow measure, 85, 89 in Cheyne-Stokes breathing patients, 244 exhaled, as airflow measure, 85 in idiopathic central sleep apnea, 237 in mixed apnea, 95 Partial pressure of oxygen (Pa0 2) , awake supine, in obstructive sleep apnea, 106 Pavor nocturnus. See Night terrors Pe0 2. See Partial pressure of carbon dioxide (PC0 2) Pemoline, as narcolepsy treatment, 283, 284 use during pregnancy, 198 Pergolide, as restless leg syndrome treatment, 266 Periodic limb movement disorder, 255 Periodic limb movements, definition of, 253-254 Periodic limb movements in sleep, 100 asymptomatic, 264 causes and associations of, 254, 255 definition of, 254 insomnia associated with, 330, 333 obstructive sleep apnea-related, 262-264 pharmacologic treatment for, 265-268 restless leg syndrome associated with, 259 -261 unmasked by continuous positive airway pressure, 272-273 Piezo-electric sensors, for respiratory effort measurement, 85, 92, 98 "Pink puffer" variant, of chronic obstructive pulmonary disease, 224-225 Plethysmography, respiratory impedance, 89 inductance, 85-86
PLM arousal index, 257, 258, 273 PLM index,254,255,257,258 Pneumotachography, 84, 186, 187 Polysomnography, 58-76 for bruxism evaluation, 313, 314 calibration procedures for, 60-61 for central sleep apnea evaluation, 236, 237 definition of, 58 double referencing in, 63 EKG artifacts in, 62-63, 65 for excessive daytime sleepiness evaluation, 62-63 for insomnia evaluation, 330-331, 333 in multiple sleep latency testing, 77-78 for narcolepsy evaluation, 277, 280 for obstructive sleep apnea evaluation, 103, 104 sixty-cycle artifacts in, 64-66 visual and auditory monitoring in, 59 Popping artifacts, 72-73 Position therapy, for obstructive sleep apnea, 122, 123 Positive airway pressure. See Continuous positive airway pressure Positive airway pressure titration, 124-126. See also Bilevel pressure; Continuous positive airway pressure (CPAP) Post-polio syndrome, 251-252 Posttraumatic hypersomnia syndrome, 298, 299 Post-traumatic stress disorder, 301, 362-364 differentiated from night terrors, 304 differentiated from panic attacks, 366 differentiated from REM sleep behavior disorder, 310 Prader-Willi syndrome, 213-215 Prarnipexole, as restless legs syndrome treatment, 266-267,270 Pregnancy, snoring during, 197-199 Premature ventricular contractions, 194-196 Propranolol, as post-traumatic stress disorder treatment, 363 Protriptyline, as cataplexy treatment, 286 Prozac. See Fluoxetine Psychiatric disorders, somnambulism associated with, 306-308 Rapid eye movements. See REM eye movements Rebound effect, in restless legs syndrome treatment, 269-271 Rebound irritability, 339 Referential electrodes, 67-69 Relaxation therapy, for insomnia, 336, 337 REM efficiency, latency of, 50 REM eye movements, 14-15,31,32 385
REM eye movements (Cont.) in excessive daytime sleepiness, 16-17 REM latency benzodiazepines-related increase of, 52 definition of, 81 in depression, 41, 55-56, 354-356 in multiple sleep latency testing, 77 during naps, 80-81 in narcolepsy, 56, 277, 278 in obstructive sleep apnea, 278, 290-291 REM rebound, during continuous positive airway pressure therapy, 163-165 REM rules, 42 REM (rapid eye movement) sleep arterial oxygen desaturation in, 31, 32, 116-118 benzodiazepines-related decrease of, 52 chin EMG during, 30-32, 34 in chronic obstructive pulmonary disease, 225 depression-related decrease of, 41, 55-56 EEG patterns in, 2, 43 eye movements during, 14-15, 16-17,31,32 in post-traumatic stress disorder patients, 363, 364 scoring of, 42-44, 45-49 sleep-onset, 56 REM sleep behavior disorder, 30 I differentiated from night terrors, 304 differentiated from panic attacks, 366 somnambulism associated with, 307 violent dreams associated with, 309-311 Renal failure, restless leg syndrome associated with,254 Respiration monitoring, during sleep, 82-98 airflow or tidal volume measurement techniques in, 84-85 arterial oxygen saturation measurement in, 86 for central apnea evaluation, 91-93 for excessive daytime sleepiness evaluation, 96-98 respiratory effort measurement in, 85-86 for sleep apnea evaluation, 88-90 for snoring evaluation, 94-95 Respiratory arousal index, 108, 109 Respiratory artifacts, 71 Respiratory disturbance index. See Apneahypopneaindex Respiratory effort arousal associated with, 108-112 measurement of, 85-86 paradoxical, in obstructive sleep apnea, 82 Respiratory failure obesity hypoventilation syndrome-related, 202-204 post-polio, 251-252 386
Respiratory muscles, post-polio syndrome-related weakness in, 251,252 Restless leg syndrome, 253-254, 259-261 classification of, 255 definition of, 253 pharmacologic treatment for, 265-268 during pregnancy, 198 rebound effect in, 269-271 Reverse first-night effect, 333 RIPsum signal, 89, 92 Ropinirole, as restless leg syndrome treatment, 266,267,270 Salmeterol as chronic obstructive pulmonary disease treatment, 224, 225 as nocturnal asthma treatment, 231 Seasonal affective disorder, 355, 361 Sedatives, as excessive daytime sleepiness cause, 298 Seizures classification of, 320-321 nocturnal, 319-322 during continuous positive airway pressure titration, 323-325 differentiated from night terrors, 304 differentiated from REM sleep behavior disorder, 310, 311 electroencephalic monitoring of, 315-318 NREM sleep-related, 300 spike and wave activity during, 323-325 Selective serotonin reuptake inhibitors as cataplexy treatment, 285-287 effect on eye movements, 40-41 as hypersomnia treatment, 361 as insomnia cause, 357-358 as panic attack treatment, 366 as post-traumatic stress disorder treatment, 363 as REM sleep behavior cause, 310, 311 Selegiline, as narcolepsy treatment, 283, 284, 289 Sertraline, as post-traumatic stress disorder treatment, 363 Sixty-cycle artifacts, 64-66 Sleep alpha-delta, insomnia associated with, 330, 352-353 amount required for normal function, 296 nonrestorative, alpha-delta sleep as, 353 Sleep architecture, 50-57 definitions of, 50-51 effect of alcohol on, 53 effect of benzodiazepines on, 3-5, 52-53 Sleep attacks, 277
Sleep deprivation, as somnambulism treatment, 306-308 Sleep diary for advanced sleep-phase syndrome evaluation, 348 for delayed sleep phase syndrome evaluation, 345,346 for excessive daytime sleepiness evaluation, 296 for insomnia evaluation, 330, 333, 335 Sleep efficiency, 50 Sleep hygiene, as insomnia treatment, 336, 337 Sleep latency definition of, 81 multiple sleep latency testing of. See Multiple sleep latency testing during naps, 80-81 in narcolepsy, 277, 280, 281 Sleep log. See Sleep diary Sleep misperception, 330-3\ Sleep paralysis, narcolepsy-related, 100, 277 Sleep period time, 50 Sleep restriction therapy, for insomnia, 336, 337 Sleep spindles benzodiazepines-related increase in, 3-5 definition of, I incipient, 44 Sleep stages, 1-7 scoring of, 42-49 stage I definition of, I EEG alpha activity during, 24-25 K complexes of, 12 stage 2 definition of, I K complexes, 26-27, 42, 46 stage 3 benzodiazepine-related decrease of, 52, 53 definition of, I stage 4 benzodiazepine-related decrease of, 52, 53 definition of, I stage REM. See REM sleep Sleep state misperception, 333 Sleep talking, 30 I Sleep terrors. See Night terrors Sleepwalking. See Somnambulism Slow frequency artifacts, 70-71 Slow wave sleep in chronic obstructive pulmonary disease, 225 somnambulism during, 28-29 Snoring alcohol use-related, 113-115, 185, 186 in children, 210-212
Snoring (Cant.) chin EMG evaluation of, 33-34 excessi ve daytime sleepiness-related, 33-34 idiopathic central sleep apnea-related, 236, 237, 238 insomnia associated with, 330 mixed apnea-related, 94-95 obesity hypoventilation syndrome-related, 200-201 obstructive sleep apnea-related, 94-95, 102, 104, 127, 188-189 as obstructive sleep apnea risk factor, 103, 104 periodic leg movements in sleep-related, 256, 262-264 polysomnographic evaluation of, 67-69, 70-71 pregnancy-related, 197-199 simple, 185-187 sleep stage scoring in, 45-46 uvulopalatopharyngoplasty treatment for, 166-168, 169-170 Sodium oxybate, as cataplexy treatment, 287 Somnambulism, 300-301 in children, 307, 308 differentiated from REM sleep behavior disorder, 310 night terrors associated with, 304 psychiatric disorders associated with, 306-308 during REM sleep, 28-29 REM sleep behavior disorder-associated, 311 seizure-related, 321 Somniloquy, 30 I "Spousal arousal syndrome," 135 Stanford Sleepiness Scale, 99 Stimulants, as narcolepsy treatment, 283-284 Stimulus control therapy, for insomnia, 336, 337 Stress, as insomnia cause, 339 Sweat artifacts, 70-71 Temazepam as insomnia treatment, 340 as somnambulism treatment, 307 Theophylline as chronic obstructive pulmonary disease treatment, 224, 225 as nocturnal asthma treatment, 231 Thermistors, 84 in obstructive apnea evaluation, 89, 90 in snoring evaluation, 186 Thermocouples in obstructive apnea evaluation, 89, 90 in snoring evaluation, 186, 187 Three-minute rule, 42, 43, 46 Thyroid replacement therapy, 189 387
Tidal volume, measurement of, 85 with respiratory inductance plethysmography, 89 Time in bed (TIB) definition of, 50 in insufficient sleep syndrome patients, 296 Time zone change syndrome. See Jet lag Tonsillar enlargement, as pediatric obstructive sleep apnea cause, 208, 210-212 Tonsillectomy, with adenoidectomy, 210-212 Total sleep time (TST), 50 Tracheostomy as obesity hypoventilation syndrome treatment, 201,206 as obstructi ve sleep apnea treatment, 171-174 Trazodone as insomnia treatment, 339, 341 as panic attack treatment, 366 as selective serotonin reuptake inhibitorrelated insomnia treatment, 358 Triazolam use in chronic obstructive pulmonary disease patients, 225 as idiopathic central sleep apnea treatment, 240 as jet lag treatment, 351 sleep spindle effects of, 3-5 Tricyclic antidepressants as insomnia treatment, 339, 341 as panic attack treatment, 366 as post-traumatic stress disorder treatment, 363 as REM sleep behavior cause, 310, 311 Upper airway, size of, in obstructive sleep apnea, 122 Upper airway obstruction obstructive hypopnea-related, 83 as obstructive sleep apnea cause, 95 Upper airway resistance, in hypopnea, 83 Upper airway resistance syndrome, excessive daytime sleepiness associated with, 110-112, 298 Urine drug screens, 4, 5 Uvulopalatopharyngoplasty excessive daytime sleepiness following, 178-179 as nasopharyngeal inlet stenosis cause, 169-170 as snoring treatment, 166-168, 169-170 Uvulopalatoplasty, as snoring treatment, 167
388
Ventilation adaptiveservo, as Cheyne-Stokes breathing treatment, 244 positive-pressure. See also Continuous positive airway pressure as obesity hypoventilation syndrome treatment,203 positive-pressure volume-cycled, use in postpolio patients, 252 Ventilation-perfusion mismatch, chronic obstructive pulmonary disease-related, 216-218 Ventilatory drive, during REM sleep, 117 Video recording of parasomnias, 59, 300 of seizure activity, 59, 321,324,325 Vietnam War veterans, post-traumatic stress disorder in, 362-364 Violent behavior seizure-related, 321 somnambulism-related, 307 Violent dreams, 309-311 Visual monitoring, during polysomnography, 59 Vocalization, seizure-related, 321 Wake after sleep onset (WASO), 50 Wakefulness, EEG during eyes-closed, 6-7 eyes-open, 20-21 Wakefulness stimulus, 237 Walks, early-morning, advanced sleep-phase syndrome-exacerbating effect of, 349 Wanderings, episodic nocturnal, 301 Weight control, as Prader-Willi syndrome treatment, 214, 215 Weight gain depression-related, 360-361 in obstructive sleep apnea patients, 103 Weight loss, as obstructive sleep apnea treatment, 121-123, 179, 263 Winter depression. See Seasonal affective disorder Xyrern, as cataplexy treatment, 286 Zaleplon, as insomnia treatment, 339, 340, 341 Zolpidem as adjustment disorder treatment, 339, 340 as insomnia treatment, 339, 340
