Section 3 Sleep Evaluation
3.1 Sleep History and Examination
Obstructive sleep apnea
Abnormal skeletal anatomy
Crowding of oropharyngeal cavity
2 You wish to evaluate the patient’s sleepiness. What is the most commonly used subjective test for the assessment of symptoms related to sleep?
4 Visual inspection of his throat with tongue extended is shown in Figure 3.1–1. How would you categorize this exam?
A 4-year-old with Restless Sleep and Snoring
5 Which of the following statements about his tonsils most fits this picture and history? Figure 3.1–2 is a photo of his pharyngeal airway.
An 8-year-old with Attention-Deficit/Hyperactivity Disorder
10 In addition to the standard montage recorded in adult polysomnograms, what data might be useful in evaluating this patient?
13 On that first visit you have her fill out an Epworth Sleepiness Questionnaire; her most likely score is:
14 You ask her to keep a detailed sleep diary of times awake and sleeping, and she faxes it to you 2 weeks later. The diary shows average sleep time is 7 hours per night, with multiple, brief sleep periods during the day that she describes as “sudden, unavoidable naps”; many naps take place in class. At this point you should order:
15 PSG and MSLT are delayed because she is in school and doesn’t have the time; she decides to have the tests in late May when she is out of school. Two weeks later her mother calls you, frantic; she has just learned that her daughter had two falling episodes at college. The falls occurred when she was with friends, and she fell abruptly to the ground while laughing. She was not drinking alcohol, did not lose consciousness, and both times recovered within about a minute. After the second episode she was taken to the school infirmary, where the diagnosis was “exhaustion.” She was advised to get some rest and “see her physician.” The mother wants to know what to do next. You should recommend:
A 74-year-old man comes to the office with his wife. He has daytime sleepiness, with an Epworth score of 14/24. His BMI is 24.5. He does not snore, but his wife notes that he moves his legs a great deal at night. “He kicks off the covers all the time, and keeps jerking his legs,” she says. He has no trouble initiating sleep but frequently gets up to go the bathroom. Sometimes he awakens in the middle of the night when he doesn’t have to urinate, and just lies in bed for a few minutes until he falls asleep again. When he gets out of bed in the morning he doesn’t feel refreshed. He takes oral medication for type 2 diabetes.
19 You order an overnight PSG that returns the following information:
Breathing: Apnea–hypopnea index = 7.5 events per hour; low SaO2 = 88%; SaO2 <90% for 2% of sleep time
Sleep: EEG arousal index = 30 per hour; stage N1 = 6% of sleep time; stage N2 = 55% of sleep time; stage N3 = 15% of sleep time; stage R = 24% of sleep time
20 One month after treatment with a dopamine agonist he feels considerably improved. He is sleeping through the night and feels refreshed upon awakening in the morning. His wife, however, says he still moves his legs a lot at night; the covers are all disheveled in the morning just like before treatment began. At this point the best course of action is to:
1 D. Insomnia is by far the most common sleep complaint. Most patients with insomnia do not complain of abnormal sleepiness during the day but rather of fatigue. More people might snore, but snoring is not nearly so common a complaint as difficulty falling or staying asleep. Restless legs is an uncommon complaint compared to insomnia.
2 B. The Epworth Scale consists of eight situations in which the patient is asked to rate from 0 to 3 the chance of dozing off. A score of 6 is the population norm. A score of 10 or higher is considered abnormal. A score of 16 is commonly reported in narcoleptic patients. The Stanford Sleepiness Scale is an altogether different questionnaire, mainly used in research; it assesses the degree of sleepiness at a specific point in time, when the questionnaire is answered. The Beck Depression Inventory assesses patients for depression, which often interferes with sleep. The Berlin Apnea Questionnaire helps identify patients at risk for sleep apnea, and it does correlate with the PSG. All questionnaires filled out by patients are subjective and best used as screening devices, not for diagnosis.
3 C. A large neck circumference is a statistical predictor of obstructive sleep apnea, more so in men than women. Katz et al, 1990, reported that mean neck circumference was 43.7 cm (17.2 in.) in patients with obstructive sleep apnea syndrome (OSAS) and 39.6 cm (15.6 in.) in patients without OSAS.
4 D. This is a Mallampati class 3 airway. Figure 3.1–5 shows a drawing of normal throat opening, and Figure 3.1–6 represents the range of Mallampati scores. The Mallampati classification was first described in the mid 1980s as a method for anesthesiologists to predict difficult tracheal intubation. Later it was found to correlate with likelihood of obstructive sleep apnea. Mallampati score is determined by looking at the oral cavity with the mouth wide open and tongue extended, without a tongue depressor. Mallampati et al, 1985; Nuckton et al, 2009
FIGURE 3.1–5 Answer 4.
(Adapted from Netter F: Atlas of human anatomy, ed 5, St Louis, 2001, Saunders. 2011, plate 51).
5 D. This is an example of tonsillar hypertrophy in a 4-year-old child with a diagnosis of obstructive sleep apnea by nocturnal polysomnogram; the apnea–hypopnea index was 6.5 events per hour. In the majority of children with sleep-disordered breathing, the upper airway is obstructed at the level of the enlarged adenoids and tonsils. The cross-sectional area of the narrowest segment is significantly smaller in children with sleep-disordered breathing than it is in normal children. Tonsil size is graded on scale from 0 (absent tonsils) to 4 (“kissing tonsils” that touch at midline). Atlas, 11.2-25
6 C. This is an example of retrognathia; the lower jaw is too far back (Figs 3.1-13, 3.1-14, 3.1-15). On lateral inspection, note the relative position of the nasion, anterior nasal spine, and mental protuberance. Sleep breathing disorders can occur with both retrognathia (an underdeveloped lower mandible, also called type 2 malocclusion) or prognathia, which usually occurs with an underdeveloped maxilla.
7 B. This is an example of grade 3 tonsils. In Grade 0 tonsils are absent (see Fig 3.1–7). Grade 1 tonsils are hidden behind tonsillar pillars (see right tonsil in Fig. 3.1–8). Grade 2 tonsils extend to the pillars (see left tonsil in Fig. 3.1-8). Grade 3 tonsils are visible beyond the pillars (see Fig 3.1-9). Grade 4 tonsils are enlarged to midline (see Figs 3.1-10, 3.1-11, 3.1-12).
8 B. Examination of the alignment of the lower teeth would confirm the suspected anatomic abnormality. Nasopharyngoscopy is not indicated at this stage of evaluation. BMI and neck collar size would not be particularly helpful in this case (Fig. 3.1–16). In this patient one would expect to find crowding of the lower teeth and an overbite (or overjet), as shown in Figure 3.1–16. There are three types of malocclusion:
Type 2 (see Fig. 3.1–16): Upper jaw and teeth overlap the lower jaw and teeth. This malocclusion is called retrognathia, overbite, or overjet.
9 D. Although he likely has obstructive sleep apnea, before tonsillectomy that condition should be documented with an overnight polysomnogram.
10 C. In pediatric polysomnograms, measurement of either end-tidal or transcutaneous PCO2 is recommended; this measurement is an “option” in adult PSGs. Rule 5A for pediatric patients states: “Score the presence of sleep-related hypoventilation when >25% of the total sleep time as measured by either transcutaneous PCO2 and/or end-tidal CO2 sensor(s) is spent with a CO2 >50 mm Hg.” Note that there is no “end tidal PO2” in polysomnography. AASM, 2007
11 B. In children, movement or autonomic arousals are more common than cortical (EEG) arousals. The other statements are true. ICSD2, p 56
12 B. There are no hard and fast criteria for diagnosing OSA in children, in part because the range in size from infant to adolescent is so great. One publication (Lipton and Gozal, 2003) interprets pediatric PSGs as follows:
“Apnea–hypopnea index (AHI) from less than 1 to 4, without a drop in SaO2: mild OSA. Treat if there are daytime sequelae, such as excessive daytime sleepiness.
AHI greater than 10 with SaO2 less than 85% and clinical sequelae: severe OSA. Treatment is strongly recommended.”
There are very few normative data for hypopneas. This patient qualifies for treatment (tonsillectomy) because his AHI is elevated at 2.1 events per hour and he has clinical sequelae: restless sleep, attention-deficit/hyperactivity disorder (likely from OSA), and need for medication (which only worsened his sleep). Note that he does not meet criteria for diagnosing hypoventilation because his PCO2 was not elevated more than 25% of the total sleep time.
13 C. The Epworth Sleepiness Scale is a subjective measure of daytime sleepiness (assuming sleep normally takes place at night). The possible range of scores is from 0 (no sleepiness) to 24 (extremely sleepy). Given this history, you would expect her score to be between 10 and 24, and only C fits in this range.
14 B. Overnight polysomnogram (PSG) followed by a multiple sleep latency test (MSLT) is the standard workup for narcolepsy, which you strongly suspect. A PSG without MSLT is not useful to diagnose narcolepsy. Modafinil is not indicated until there is a confirmed diagnosis to explain her problem. Approximately 40% of narcoleptic patients are HLA DQB1*0602 positive. However, because 12% to 38% of controls are also positive for this antigen, HLA typing is never used to diagnose narcolepsy without cataplexy. Another biological marker for narcolepsy, the CSF hypocretin-1 level, is sometimes used to confirm difficult-to-diagnose cases of narcolepsy, but it is not done routinely. ICSD2, p 88
15 D. The patient’s mother is describing classic cataplexy: sudden bilateral loss of muscle tone triggered by emotion, with a duration of less than 2 minutes. Sodium oxybate is the active ingredient in Xyrem, an FDA-approved drug for the treatment of cataplexy associated with narcolepsy. For patients with daytime sleepiness and no cataplexy, an MSLT (after a normal overnight PSG) is needed to help confirm the diagnosis of narcolepsy. A confirmatory MSLT shows mean sleep latency of 8 minutes or less and two or more early-onset REM periods. In patients with definite cataplexy, the diagnosis of narcolepsy can be made on clinical grounds alone, because there is almost no other disease that causes this symptom (rarely, some brain tumors may cause cataplexy). Note, however, that often the attacks of sudden weakness are not clearly cataplexy and might suggest syncope or even a seizure. When in doubt, the patient should have PSG followed by MSLT. In this case, given the patient’s age, daytime sleepiness, and recent symptoms as related by the mother, cataplexy seems likely, and a confirmatory MSLT is not considered mandatory. Treatment should be started as soon as feasible. Whoever prescribes sodium oxybate must be familiar with the compound and review how it is to be used and what to expect. ICSD2, pp 81-86
16 D. Narcolepsy may be associated with other signs and symptoms, including those listed in the answer to question 14; however, they are nonspecific and therefore not diagnostic. Cataplexy is the only symptom considered specific for narcolepsy.
17 A. RLS is a diagnosis made by history; it is not a PSG diagnosis. PLMS is a PSG diagnosis that requires four EMG-detected limb movements in a specified time period (no closer than 5 seconds and no more than 90 seconds between movements). RLS diagnosis is made by history of abnormal limb sensations (which may include pain) at bedtime, urge to move the legs, and relief by movement. The symptoms are circadian. They tend to manifest around bedtime and therefore commonly interfere with sleep. A PSG is not indicated in the workup of RLS. Although up to 80% of patients with RLS do manifest PLMS on PSG, PLMS commonly occurs in adults without RLS. Two dopamine agonists, ropinirole and pramipexole, are FDA approved for treatment of RLS but not for PLMS. Many patients with RLS have low iron stores documented by serum ferritin level, but this test is not always diagnostic.
18 A. Diagnoses B, C, and D are made on the basis of a PSG. Restless legs syndrome is a diagnosis based on history and is usually manifest as abnormal sensation in the legs at bedtime, urge to move them, and relief with movement. RLS also affects sleep onset and can lead to insomnia. The brief history in this case indicates a limb movement disorder during sleep, not RLS.
19 B. This is a case of interrupted sleep from PLMS. He has an increased EEG arousal index, most of which is from PLMS-associated arousals. Although leg movements during sleep can be associated with sleep apnea events, he has only a mild OSA with minimal oxygen desaturation, so this is likely not the cause of the increased PLMS index. Neuropathy is a clinical diagnosis and not based on PSG. Though diabetics can develop peripheral neuropathy, there is nothing in the history to suggest that diagnosis. Currently there is no FDA-approved drug for PLMS, but clinicians sometimes use dopamine agonists or clonazepam.
20 D. PLMS is usually a benign and incidental finding on PSG; most patients with RLS don’t have interrupted sleep that results in daytime sleepiness. Only when there is interrupted sleep causing daytime sleepiness is treatment usually considered. If the patient is now without symptoms, there is no need to pursue further diagnosis. Because there is no history of dangerous behavior (to the patient or spouse), REM sleep behavior disorder seems unlikely. Many people twist and turn (or kick legs) during sleep, and simply waking up with bedcovers in disarray is not a disorder that needs further evaluation or treatment.
21 C. The patient’s wife is describing what is likely REM behavior disorder (RBD), a type of parasomnia. It occurs in middle age (average age 52 years) and has male predominance (87% of patients). It is basically motor movement manifesting during REM sleep, a stage in which the body is normally flaccid. Injuries to the patient and bed partner are common, and they are, in fact, the principal reason patients seek help; a secondary reason is for sleep disruption. Most patients with RBD also have hyposmia (impaired sense of smell). More ominously, in half or more of patients RBD is the first sign of an alpha synucleinopathy such as Parkinson’s disease or Lewy body dementia. (Synucleinopathies are neurodegenerative conditions characterized by intraneuronal inclusions containing the protein alpha-syncuclein.) RBD can be idiopathic or induced by medications.
22 B. In a significant percentage of patients (50% to 75%), RBD can be the first sign of a synucleinopathy such as Parkinson’s disease, Lewy body dementia, or multiple system atrophy. Although a synucleinopathy might not manifest for years after onset of RBD, it would be appropriate to evaluate this patient for Parkinson’s disease when RBD is first suspected. There is nothing in the history to indicate ALS, sleep apnea, or congestive heart failure.
23 B. Drugs most often associated with RBD have been tricyclic antidepressants, SSRIs, and SNRIs. Venlafaxine (Effexor) is an antidepressant of the serotonin-norepinephrine reuptake inhibitor (SNRI) class. It is indicated for treatment of major depressive disorder, generalized anxiety disorder, and anxiety disorders with depression. Venlafaxine is a widely used drug and probably the most commonly prescribed medication associated with RBD. It is unknown if these patients would have developed RBD anyway and the drug just hastens its manifestation.
24 C. PSG monitoring for RBD properly requires extra EMG leads (for upper and lower extremities) and time-synchronized video monitoring, techniques many community sleep labs are not equipped for. When there is strong clinical suspicion for drug side effect, as in this case, it is appropriate to have the patient stop the drug and see if symptoms improve. If not, an overnight PSG should be considered. Clonazepam has been used for treatment of RBD, although it is not FDA approved for this indication.
Summary
This topic, history and physical examination, will be addressed in about 12 questions on the examination but it covers a great deal of clinical knowledge. Some of the information reviewed here will also be covered when testing for knowledge about specific disorders described elsewhere in this book. The reader must know in detail all of the terms in the outline below because many will be used in clinical vignettes on the exam.
Cardinal Manifestations on History
Key Findings on Physical Examination
Sleep Breathing Disorders (Atlas ch 11.1)
Obstructive sleep apnea
Abnormal skeletal anatomy• Mandibular and maxillary structures
♦ Type 1. Upper and lower teeth aligned (bite is normal) but teeth are crowded or malpositioned; small dental arch
Crowding of oropharyngeal cavity• Tongue too large for oral cavity
♦ Documented by modified Mallampati score
• Class 4: Only hard palate or tongue visible
Box 3.1–1 About Mallampati Scores
There is confusion about how to document the Mallampati score: is it using a class or grade?
Mallampati in 1985 published classes 1 to 3 to describe the oral findings in an attempt to predict possible difficulty in intubation (Mallampati et al, 1985). What is used currently and called a Mallampati score is actually the original score modified by Friedman’s group, which described Grades 1 to 4 (Friedman et al, 1999).
Bruxism
Box 3.1–2 Don’t Forget
• Insomnia is by far the most common sleep complaint. Most patients with insomnia do not complain of abnormal sleepiness during the day but rather of fatigue.
• A widely used subjective scale for assessing daytime sleepiness is the Epworth Sleepiness Scale, which has a score ranging from 0 to 24. A score of 10 or higher is considered excessive daytime sleepiness.
• Correlated with likelihood of OSA are a large neck circumference (more than 17 inches in men, more than 15 inches in women) and a high Mallampati score (3 or 4).
• In contrast to adults, most children with clinically significant OSA have upper airway obstruction from enlarged tonsils and adenoids.
• There are 3 types of malocclusion. In type 1, upper and lower teeth are aligned (bite is normal) but teeth are crowded or malpositioned. In type 2, the upper jaw and teeth overlap the lower jaw and teeth; this is called retrognathia, overbite, or overjet. In type 3, the lower jaw protrudes and the lower teeth extend over the upper teeth; this is called prognathia or underbite.
• Daytime sleepiness is a nonspecific and common symptom. Diagnosis of narcolepsy requires either a PSG followed by an abnormal MSLT, or a clear history of cataplexy, which is bilateral sudden loss of muscle tone (often leading to falling) without loss of consciousness.
• Restless legs syndrome (RLS) is a diagnosis made by history alone. Periodic limb movements of sleep (PLMS) is a diagnosis made by PSG alone. Patients with RLS often have PLMS, and vice versa. The FDA has approved dopamine agonists for treatment of RLS but not PLMS.
• REM sleep behavior disorder (RBD) can be idiopathic or drug induced. One of the most common drug causes of RBD is venlafaxine.
American Academy of Sleep Medicine. The AASM manual for the scoring of sleep and associated events: rules terminology and technical specifications. Darien, IL: American Academy of Sleep Medicine; 2007.
American Academy of Sleep Medicine. International classification of sleep disorders: diagnostic and coding manual. Westchester, IL: American Academy of Sleep Medicine; 2005.
Friedman M, Tanyeri H, La Rosa M, et al. Clinical predictors of obstructive sleep apnea. Laryngoscope. 1999;109:1901-1907.
Katz I, Stradling J, Slutsky AS, et al. Do patients with obstructive sleep apnea have thick necks? Am Rev Respir Dis. 1990;141(5 Pt 1):1228-1231.
Kryger MH. Atlas of clinical sleep medicine. Philadelphia: Saunders; 2010.
Lipton AJ, Gozal DG. Obstructive sleep apnea in children: do we really know how? Sleep Med Rev. 2003;7:61-80.
Mallampati SR, Gatt SP, Gugino LD, et al. A clinical sign to predict difficult tracheal intubation: a prospective study. Can Anaesth Soc J. 1985;32:429-434.
Nuckton TJ, Glidden DV, Browner WS, Claman DM. Physical examination: Mallampati score as an independent predictor of obstructive sleep apnea. Sleep. 2006;29:903-908.
3.2 Polysomnography: Methods, Rules, and Event Scoring
1 For the EEG lead placements you will use the 10-20 system. This means:
B The electrodes are placed either 10% or 20% of the distance between a given pair of skull landmarks.
2 After explaining the test to your patient, your first task is to place electrodes for the recommended EEG derivations. These are:
3 Next, to detect eye movements, you must place electrodes 1 cm below the left eye outer canthus (E1) and 1 cm above the right eye outer canthus (E2). This placement will give the recommended EOG (electro-oculogram) derivations, which are:
4 You understand that recording of eye movements is possible because:
C Gross eye movements generate electrical signals that differ slightly owing to the distance of each eye to the recording electrode.
5 You next attach leads for the EMG (electromyogram) that will be used for sleep staging purposes; these are attached to the:
6 Once the patient falls asleep you help monitor the channels. You enjoy figuring out the EEG patterns, knowing that they can be distinguished by all of the following except:
10 The term “relatively low voltage, mixed frequency pattern” for the EEG most closely describes which sleep stage?
11 Delta activity includes brain waves with a frequency less than 4 Hz. Within this group, slow waves are defined as:
12 The sleep-staging nomenclature in the AASM 2007 manual includes all of the following stages except:
16 Which of the following is true about the artifact shown in the PSG fragment in Figure 3.2–2?
A Can result from high electrode impedance, a poor electrical connection, or excessive current leakage from nearby electrical equipment (e.g., computers, televisions)
17 In polysomnography (PSG), most of the recorded signals are amplified by AC (alternating current) amplifiers. A few signals are amplified by DC (direct current) amplifiers. Which of the following is recorded by a DC amplifier in the PSG?
18 All of the following are true about the K complex except:
A It is defined as a well-delineated negative sharp wave immediately followed by a positive component standing out from the background, with total duration of 0.5 seconds or longer.
B For an arousal to be associated with a K complex, it must commence no more than 1 second after termination of the K complex.
19 Figure 3.2–3 is a portion of a 30-second epoch. The large waves seen in channel F4-M1 in the first 3 seconds of this epoch (from beginning to first solid vertical line) are:
20 Figure 3.2–4 is a portion of a 30-second epoch. The large waves seen in all three EEG channels (F4-M1, C4-M1, O2-M1) in the first 3 seconds of this epoch (from beginning to first solid vertical line) are:
22 The 2007 AASM manual states apnea duration should be measured:
C As the total period that the flow is 90% or more reduced from baseline plus the preceding and following breath
