Sleep History

The sleep history is provided by the patient, parent, or guardian. It is crucial to the planning of appropriate diagnostic procedures and arriving at a specific diagnosis. Questions relevant to infants and preschool-age children include:

the sleeping environment (e.g., crib, bassinet, parent’s bed)

the sleeping position (e.g., prone or supine, semi-upright)

habitual need for sleep aids (e.g., pacifier, rocking, patting)

the time of going to bed, sleep onset, and the final morning awakening (on school nights and during weekends and holidays)

sensation of restlessness in the legs before sleep onset, intrusive thoughts or worries that might interfere with sleep onset

presence of habitual snoring, mouth breathing, observed apnea, restless sleep, sweating, gastroesophageal reflux, and abnormal behavior at night suggestive of seizures or parasomnias

behavior during the daytime (irritability, inattentiveness, hyperactivity, sleepiness)

number of daytime naps and their duration

medications that may affect sleep–wake function (e.g., sedatives, stimulants)

interventions that the parents have used to improve the child’s sleep.

In adolescents, one should also inquire about activities that might interfere with going to bed at a reasonable hour, such as after-school employment, and resorting to vigorous exercise, heavy meals, caffeine, cell phones, computers, television, nicotine, and illicit substances in the late evening or at bedtime. Patients with restless legs syndrome may experience an urge to move their limbs, a feeling of “bugs or spiders crawling on their legs” in the evening hours, exacerbation of this discomfort when the limbs are kept immobile, and relief with movement. Daytime sleepiness assessment should include questions about taking involuntary naps in the classroom, automatic behavior, and the impact of sleepiness on driving, cataplexy, hypnagogic hallucinations, medications used to promote alertness, academic function, behavioral and mood problems, and the number of school days missed because of sleepiness.

The Pediatric Daytime Sleepiness Scale (PDSS) is a simple, validated questionnaire that can be administered to children in the 11–14-year age group [Drake et al., 2003]. It has eight items, each rated on a 0–4 scale. It provides a numerical score for sleepiness; the 50th percentile score on the PDSS is 16, the 75th percentile is 20, and the 90th percentile is 23. Participants who reported low school achievement, high absenteeism, low school enjoyment, low total sleep time and frequent illnesses all had higher levels of sleepiness as measured by this scale [Drake et al., 2003]. Another survey tool that is commonly used in clinical practice is the Children’s Sleep Habits Questionnaire. It is a 45-item, validated questionnaire that is completed by parents of 4–11-year-olds [Owens et al., 2000]. The questions pertain to sleep–wake function in the preceding 2 weeks, such as “the child sleeps too little” or “the child suddenly falls asleep in the middle of active behavior.” The items represent several domains that present as sleep complaints, such as bedtime resistance, sleep-onset delay, sleep duration, sleep anxiety, night awakenings, parasomnias, breathing disturbance, and daytime sleepiness. Responses are rated as rarely (occurring 0–1 time/week; 1 point), sometimes (occurring 2–4 nights/week; 2 points), or usually (occurring 5–7 nights/week; 3 points). Scores of 41 or greater correlate with presence of a sleep disorder. The internal consistency estimate for this questionnaire in a community (nonclinic sample) of 4–10-year-olds is 0.36–0.70. The test-retest reliability over a 2-week period is 0.62–0.79.

Sleep-Related Examination

Height, weight, and body mass index are recorded because obstructive sleep apnea may be associated with poor weight gain during infancy, and with obesity during adolesence [Arens et al., 2010]. The blood pressure should be measured because long-standing and severe obstructive sleep apnea (OSA) can be associated with hypertension. OSA patients may exhibit craniofacial abnormalities such as micrognathia, dental malocclusion, macroglossia, myopathic face and midface hypoplasia, deviated nasal septum, swollen inferior turbinates, tonsillar hypertrophy and mouth breathing [Brooks, 2002; Hoban and Chervin, 2007]. Consultation with a pediatric otolaryngologist may be required to exclude adenoidal hypertrophy. Inattentiveness, irritability, and mood swings may be clues to daytime sleepiness. Obstructive sleep apnea related to brainstem abnormalities like the Chiari type I or II malformations [Gosalakkal, 2008] can lead to hoarseness of voice, decreased gag reflex, and changes in the amplitude of the jaw jerk relative to that of other tendon reflexes. Neuromuscular disorders, like myotonic dystrophy, may be associated with chronic obstructive hypoventilation from a combination of palatal muscle weakness, high-arched palate, and diminished chest wall–abdominal excursion [Givan, 2002; Misuri et al., 2000]. The parent–child interaction should be observed not only for clues indicating parental anxiety and reluctance to set limits on inappropriate behaviors that perpetuate insomnia in toddlers, but also for subtle clues indicating a child maltreatment syndrome. Home videos, if available, may be invaluable in the assessment of restless legs syndrome, parasomnias, and nocturnal seizures.

Nocturnal Polysomnography

This procedure involves the monitoring of multiple physiologic parameters in sleep. It is useful in the evaluation of intrinsic sleep disorders, such as narcolepsy, obstructive sleep apnea, nocturnal spells, and periodic limb movement disorder. It may not be indicated for diagnosing obstructive sleep apnea secondary to severe adenotonsillar enlargement, which can be easily recognized on the basis of clinical findings combined with severe oxygen desaturation on simple overnight oximetry in the home environment. The nocturnal polysomnogram usually consists of simultaneous monitoring of 2–4 channels of the EEG, eye movements, chin and leg electromyogram, nasal pressure, thoracic and abdominal respiratory effort, electrocardiogram, and oxygen saturation [Kotagal and Goulding, 1996; Kotagal and Herold, 2002; Sheldon, 2007]. Patients with Down syndrome, neuromuscular disorders, and obesity may exhibit hypoventilation that is characterized by shallow chest and abdominal wall movement, with resultant CO₂ retention. It is therefore important to measure end-tidal CO₂ levels concurrently in these patients. Esophageal pH can be monitored simultaneously when there is a suspicion of gastroesophageal reflux. Criteria for the scoring of sleep and sleep-related events such as apnea, arousals, and periodic limb movements have been recently revised [Iber et al., 2007].

In patients with obvious upper airway obstruction secondary to obesity or neuromuscular disorders like myotonic dystrophy, a therapeutic trial of positive pressure airway breathing can be attempted midway during the course of the sleep recording. A full 16- to 20-channel EEG montage is recommended when parasomnias and seizures are both in the differential diagnosis. Simultaneous video monitoring is standard for all nocturnal polysomnograms. Normative data for common physiologic variables are listed in Table 66-1 [Marcus and Loughlin, 1996]. There is insufficient evidence regarding the utility of ambulatory, in-home polysomnograms, especially in the preschool age group; thus, traditional sleep laboratory monitoring remains the gold standard in pediatric sleep medicine.

Table 66-1 Normal Polysomnographic Values in Children

REM, rapid eye movement; TST, total sleep time.

(From Montgomery-Downs HE et al. Polysomnographic characteristics in normal preschool and early school aged children. Pediatrics 2006;117:741.)

Multiple Sleep Latency Test

The Multiple Sleep Latency Test (MSLT) assesses how quickly one is able to fall asleep during the daytime and whether transition from wakefulness is into NREM sleep or into REM sleep. The MSLT can reliably detect sleepiness under clinical and experimental conditions [Littner et al., 2005]. The lower age limit at which one can utilize this test is about 6–7 years. Application of the MSLT to children younger than 6 years is unhelpful because healthy pre-school age children tend to take physiologic daytime naps. In order to be able to derive valid conclusions, the MSLT must be preceded the night before by a polysomnogram in which the total sleep time approximates physiologic sleep. The MSLT consists of the provision of four or five daytime nap opportunities at 2-hour intervals: e.g., at 10:00, 12:00, 14:00, and 16:00 hours. The EEG, chin electromyogram, and eye movements are monitored during each nap opportunity. The patient should be dressed in street clothes. The attending parent or guardian should be available to prevent the child from dozing off involuntarily in between the scheduled nap times. At each planned nap opportunity, the lights are turned off and the patient is asked to try to sleep. The time from “lights out” to sleep onset is measured, and represents the sleep latency. A mean sleep latency is also derived for the four naps. Normative values for the mean sleep latency have been established. The nap opportunity is terminated either 15 minutes after sleep onset, or if the patient does not fall asleep, at 20 minutes after “lights out.” The mean sleep latency decreases inversely with an increase in the Tanner stage of sexual development, and ranges between 12 and 18 minutes [Carskadon, 1982]. A mean sleep latency of less than 5 minutes indicates severe daytime sleepiness; a value between 5 and 10 minutes indicates moderate daytime sleepiness. A urine drug screen is obtained in between the naps if illicit drug-seeking behavior is suspected. The occurrence of REM sleep within 15 minutes of sleep onset constitutes a sleep-onset rapid eye movement period (SOREMP). The presence of SOREMPs on two more MSLT nap opportunities in conjunction with a shortened mean sleep latency of less than 5 minutes is highly suggestive of narcolepsy.

In adults, a mean sleep latency of less than 5 minutes in association with two or more SOREMPs is 70 percent sensitive and 97 percent specific for the diagnosis of narcolepsy [Aldrich et al., 1997]. Comparable data on the sensitivity and specificity are not available for children and adolescents. A study by Gozal et al. [2001] suggests that, in prepubertal children, the normal mean sleep latency is 23.7 minutes, plus or minus 3.1 minutes. Palm et al. [1989] also found a mean sleep latency of 26.4 minutes plus or minus 2.8 minutes in 18 prepubertal children. These data suggest that the normal mean sleep latency in children may actually be higher than previously reported, and that normative data for the multiple sleep latency test in childhood might perhaps need revision. One of the merits of the multiple sleep latency test is that it provides reliable and quantitative information about the propensity for sleepiness. It has been validated as a measure of daytime sleepiness following episodes of sleep loss [Rosenthal et al., 1993], sleep disruption [Stepanski et al., 1987], and hypnotic drug and alcohol abuse [Billiard et al., 1987; Papineau et al., 1998]. The effects of treatment of daytime sleepiness with stimulants cannot be reliably measured, however. In addition, although one can control ambient noise and light that might affect sleep during the testing process, one cannot control for internal factors, like anxiety and apprehension, that also affect sleep propensity.

Maintenance of Wakefulness Test

The Maintenance of Wakefulness Test (MWT) is the mirror image opposite to the MSLT; one measures the ability to stay awake in a darkened, quiet environment during the daytime while the patient is seated in a semireclining position [Littner et al., 2005]. EEG, eye movements, and chin electromyography are monitored in a manner identical to that in the MSLT. The patient is provided four or five nap opportunities. The duration of each session is 40 minutes. The average mean sleep latency for normal adults is 35.2 minutes. Normative values have not been established for children. The test helps assess the effect of stimulant medication treatment on daytime sleepiness [Mitler et al., 2000].

Actigraphy

This technique involves the recording and storing of skeletal muscle activity continuously for 1–2 weeks in the home environment, generally from the nondominant forearm, using a wristwatch-shaped microcomputer device that measures linear acceleration and translates it into a numeric and graphic representation. This numeric representation is sampled frequently – that is, every 0.1 second – and aggregated at a constant interval or epoch length [Acebo and LeBourgeois, 2006]. The device captures signals during periods of muscle activity (generally correlating with wakefulness) and periods of no muscle activity (generally correlating with sleep; Figure 66-2). There is close correlation with polysomnographically determined total sleep time, sleep latency, and sleep efficiency [total sleep time or total time in bed ×100; Kothare and Kaleyias, 2008; van de Water et al., 2010]. Wrist actigraphy should be combined with 1–2 weeks of “sleep logs” that document specific wake-up and sleep-onset times, daytime naps, and so on. Wrist actigraphy is useful in the study of insomnia and circadian rhythm disorders like the delayed sleep phase syndrome [Kothare and Kaleyias, 2008]. In the latter instance, it will depict sleep onset late at night or in the early morning hours and uninterrupted sleep thereafter, with final awakening late in the morning or early afternoon (see Figure 66-1). In patients being evaluated for suspected narcolepsy, 2 weeks of actigraphy before nocturnal polysomnography and the MSLT help exclude the possibility of sleepiness resulting from a circadian rhythm disorder or insufficient sleep at night.

Fig. 66-2 Wrist actigraph demonstrating 2 weeks of sleep–wake recording in a teenager with delayed sleep phase syndrome, who presented with difficulty falling asleep.

The dark bars indicate presence of muscle activity, which correlates closely with wakefulness, and the clear areas indicate lack of muscle activity, which generally correlates with sleep. Notice sleep onset late in the early morning hours (down arrow) and awakening in the afternoon (up arrow).

Sleep-Related Breathing Disturbances

In increasing level of severity, the spectrum of sleep-disordered breathing in childhood ranges from snoring without sleep disruption (primary snoring) to the upper airway resistance syndrome (snoring that disrupts sleep continuity but without associated apnea or oxygen desaturation) to classic obstructive sleep apnea and, finally, obstructive hypoventilation (apnea, oxygen desaturation, plus hypercarbia). Between 10 and 12 percent of children snore on a habitual basis [Corbo et al., 2001; O’Brien et al., 2003]. The snoring sound is the result of vibration of the soft palate during inspiration due to narrowing of the oropharynx. Although some guidelines [American Academy of Pediatrics, 2002] suggest that primary snoring may be a “benign condition that does not warrant any specific therapy,” a study of 87 children of 5–7 years of age [O’Brien et al., 2004] found that, compared with age-matched nonsnoring children, those with primary snoring performed worse on neuropsychologic measures of attention and had more social problems and anxious or depressive symptoms. Community-based studies have determined the prevalence of childhood obstructive sleep apnea at 1.1–2.9 percent [Ali et al., 1993; Brunetti et al., 2001].

OSA is characterized by partial or complete upper airway occlusion, with impaired air exchange despite persistence of thoracic and abdominal respiratory effort. This generally occurs in association with increased resistance to inspiration and transient oxygen desaturation of 3–4 percent (Figure 66-3). In some instances, there is an additional component of hypoventilation due to shallow abdominal and chest wall motion, which leads to hypercarbia. The most common etiologic factors for childhood OSA are adenotonsillar hypertrophy, craniofacial anomalies like micrognathia or maxillary hypoplasia, neuromuscular disorders such as myotonic dystrophy or congenital nonprogressive myopathies, and obesity [Lumeng and Chervin, 2008]. Repetitive occlusion of the upper airway during sleep, with resultant oxygen desaturation, provokes cortical arousals and suppression of REM and N3 sleep. Nocturnal symptoms of childhood obstructive sleep apnea include habitual snoring, restless sleep with snort arousals, bed wetting, excessive sweating, mouth breathing, choking sounds, and parasomnias such as confusional arousals and sleepwalking. Parental reports of snoring that is interrupted by silent pauses, which then terminate with snorting sounds, are characteristic of OSA. A metabolic syndrome, characterized by insulin resistance, hyperglycemia, hypertension, dyslipidemia, abdominal obesity, and proinflammatory and prothrombotic states, may develop as a consequence of OSA [Arens et al., 2010]. Daytime symptoms of OSA include inattentiveness, impaired academic performance, hyperactivity, and sleepiness [Chervin et al., 2002; Gozal, 2008]. The upper airway resistance syndrome is a form of upper airway obstruction in which no frank apneas or oxygen desaturation are observed during sleep, but the airway narrowing leads to recurrent arousals, fragmented sleep, and daytime sleepiness [Guilleminault et al., 1996]. Some patients exhibit subtle posterior displacement of the tongue, narrow nostrils, or a high-arched palate, but others might not have any craniofacial anomalies. The nocturnal polysomnogram may appear superficially normal, with the exception of snoring and increased EEG arousals of 3 or more seconds (normally less than 10–12 per hour of sleep). Simultaneously obtained intraluminal pressures from an esophageal balloon demonstrate a marked increase in the intrathoracic negative pressure during the upper airway resistance syndrome episodes. Nocturnal polysomnography is not needed to confirm the diagnosis in patients who already manifest the classic symptoms of OSA with marked tonsillar hypertrophy; one night of oximetry in the home environment, which documents recurrent oxygen desaturation, is sufficient for establishing the diagnosis in these patients [Brouilette et al., 2000