Being aware of potentially serious and long-term implications of patients with SWS and arousal disorders can help physicians provide effective treatment.
By Stephen J. Sharp, MD
Sleep walking or somnambulism, sleep terrors, and confusional arousals are arousal disorders, which are the most frequent and clinically impressive of the NREM parasomnias. Parasomnias are sleep phenomena characterized by undesirable autonomic or physical events associated with varying degrees of arousal. The parasomnias are classified as primary, those resulting from disturbances in the sleep cycle or sleep-wake transitions, and secondary, those resulting from disorders of other organ systems. The primary parasomnias are further categorized as those occurring in REM sleep or NREM sleep, and miscellaneous disorders that do not derive from any specific sleep state. Disorders of arousal typically have abrupt onset and cessation, occur early in the night, are of relatively brief duration, and are associated with veiled levels of consciousness and with poor recall in the morning.
Traditionally, parasomnias were not thought to represent pathologic cerebral functioning, but rather a response to central nervous system activation resulting in sleep-wake or REM-NREM state confusion or overlap. Recent studies, however, have demonstrated differences in sleep patterns and neuronal sleep control mechanisms in individuals with parasomnias compared with controls.
Normal sleep involves a rhythmic cycling between wakefulness, NREM, and REM sleep with each cycle averaging approximately 50 minutes for a newborn and increasing to approximately 90 minutes (range 60 to 110 minutes) by adolescence. Slow wave sleep (SWS) normally occurs in the first two sleep cycles, with younger children having an additional block of SWS toward the end of the sleep period. Children often enter their deepest period of SWS quickly after sleep onset, often within 15 minutes. This initial SWS period is also typically the longest, lasting up to 45 to 75 minutes. The end of the SWS is marked by a transition to light NREM sleep, REM sleep, or brief wakefulness. Partial arousals may occur at this point, and parasomnias occur when the child or, less commonly, adult is caught in the transition between SWS and full arousal.1-3
Sleepwalkers appear to have an abnormality of neural control mechanisms regulating SWS. Spectral analysis of sleep EEG using a fast Fournier transform has demonstrated differences in delta power. SWS has more arousals and lower levels of slow-wave activity (SWA) during the first sleep cycle. Additionally, patients have less decline in SWA through the night and have relative increases in SWA just before a parasomnia episode. Sleep spindle frequency is similar throughout the night instead of the normal increases seen later in the sleep period.4-6
Single photon emission computed tomography scan suggests a dissociation of mind sleep and body sleep with activation of thalamocingulate pathways and persisting deactivation of other thalamocortical arousal systems.7
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Children and SWS Disorders
SWS and arousal disorders have largely been considered disorders of childhood with up to 17% of children reporting at least one episode. The frequency in adults is not insignificant, however. In a survey of adults in the United Kingdom, 2.0% reported SWS, 2.2% night terrors, and 4.2% confusional arousals.8 In children, 2.5% reported a frequency of once a month, with peak age prevalence at 11 to 12 years. In another study, episodes of one to four times per week were reported in 1% to 6% of children, with up to 30% of children having some type of sleep problem. Episodes were most common between the ages of 4 and 12 years.9 No sex or racial differences have been found in children. Of interest is a reported increased frequency in “good, compliant children who do not show their emotions.” These children do not have increased overall anxiety, but show greater use of psychological defense mechanisms to inhibit their anxiety and aggression.8
The Finnish Twin Cohort study showed an increased concordance rate for monozygotic twins and a 10 times increased risk in those with a first-degree relative with SWS. In the same study, 24.6% of boys and 18.3% of girls with SWS went on to have symptoms as adults, and in adults with SWS, 88% of men and 84% of women had SWS as children.10
An increased frequency of DQB1*04 and *05 alleles is present in SWS with 35% of patients demonstrating positivity versus 13.5% in controls. An increased rate has also been seen in familial SWS cases. The DQB1 genes have been implicated in narcolepsy and other disorders of motor control during sleep.11
Clinically and prognostically, the typical SWS episodes in children now appear to be different than those occurring in adolescents and adults. Episodes range from quiet walking about the room to agitated running or attempts to “escape.” Typically, the eyes are open with a glassy, staring appearance as the child quietly roams the house. Movements appear somewhat uncoordinated and illogical (urinating in places outside the toilet). On questioning, responses are slow or absent. If returned to bed without awakening, the child usually does not remember the event. In older children and adolescents, who may awaken easier at the end of an event, the behavior is often embarrassing.
Adult Behavior
Adults have a higher incidence of complex behaviors and behaviors that seem purposeful or semipurposeful. These include high-risk, abusive behaviors resulting in injury or death to the patient or others. The majority of self-injuries (limb fractures, thoracic trauma, and abdominal trauma) have resulted from leaping through open or closed windows.12
Sexual behavior, seen with SWS and other arousal phenomena, has resulted in the coining of the term sexsomnia. In addition to the sexual behavior (reported as occurring with other adults and with children), there is increased autonomic arousal, relatively restricted motor activities, and often some associated dream mentation.13
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Legally and socially, these “non-insane automatisms” have stimulated increasing interest. The legal dilemma is demonstrated in recent murder cases, defended as due to SWS—declared as not guilty in a case in Canada, and guilty in a case in the United States.14,15 Also, suicide resulting from SWS has significantly different implications from religious, insurance, and social/cultural standpoints.16
In each of these cases, behaviors were provoked by high stress and by other high-risk behaviors such as alcoholism. Present legal thought suggests that if patients are aware of risk behaviors that provoke SWS, especially complex episodes, they become legally responsible for the consequences.14
A new overlap disorder in adults has been described consisting of injurious SWS, sleep terrors, and REM behavior disorder. While diagnosis is typically made in adults (a large majority, up to 70%, of all these bizarre SWS events being in males), onset of parasomnias is typically in childhood with a mean age of 15 to 16. A good response to therapy has been shown using clonazepam, alprazolam, or carbamazepine.17
Triggers of SWS
Common triggers for SWS and other parasomnias are listed in Tables 1 and 2. Additional factors associated with increased frequency of SWS in adults were age 15-24 years, a subjective sense of choking or blocked breathing at night, sleep talking, and a history of a road accident in the previous year.8
SDB and sleep apnea are increasingly recognized as triggers in children and adults. Increased SDB is seen in parasomniacs—increased arousals resulting in sleep fragmentation and consequent increase in rebound delta sleep as the suggested mechanism. Treatment of SDB is shown to decrease the incidence of SWS and other parasomnias. Family members of children with parasomnias also had a high frequency of SDB. Polysomnogram diagnoses may be difficult, as apneas may not be seen, especially in children. Other criteria such as nasal flow limitation, increased respiratory effort, and bursts of theta or slow alpha on EEG are indicators of SDB. At times esophageal manometry may be necessary for diagnosis.18,19
In children 6 to 8 years old, an association with hyperactivity has been described. Using a “Strength and Difficulties” questionnaire, a score consistent with hyperactivity and other behavior problems was higher than in controls.20
Diagnosing Arousal Disorders
The diagnoses of the arousal disorders are usually evident from history (see Table 1). Nocturnal frontal lobe epilepsy (NFLE) may be the most difficult alternative diagnosis to exclude. A history of onset in the second decade, frequent complex and repetitive behaviors of short duration, nocturnal agitation, and daytime complaints of fatigue or sleepiness is suggestive of NFLE in comparison to onset in early childhood, relatively infrequent episodes of longer duration, and absence of stereotype seen with parasomnias.21
While no specific laboratory studies are indicated in the work-up of routine parasomnias, if, after history, the diagnosis remains unclear, video-polysomnogram with or without multiple sleep latency testing remains the gold standard for diagnoses. The diagnosis is supported by polysomnogram findings of SWS arousals and lower SWA power. Sleep deprivation can be used in the laboratory to trigger parasomnic events and polysomnogram changes. Microarousals and sleep state disorganization are observed frequently and may be noted on nocturnal EEG alone.22
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Treatment Modalities
Reassurance remains the mainstay of treatment. The benign nature of the events and subsequent disappearance in most cases should be emphasized, especially in children. If environmental or predisposing factors are elicited by history, attempts should be make to eliminate them. Assure adequate sleep and regulation of the sleep cycle, avoid offending medications, be sensitive to stressful situations, and provide treatment of underlying medical conditions (gastroesophageal reflux, SDB, periodic leg movements, and seizures). A safe environment can be promoted by locking windows and doors, removing obstacles in the room, and adding alarms (if necessary) to decrease the likelihood of injury during an episode. Depending on the situation, comforting the patient and gently directing him back to bed may be appropriate.
Pharmacologic measures may be necessary if the possibility of injury to the patient or others is real, if continued behaviors are causing significant family disruption or excessive daytime sleepiness, or if nonpharmacological interventions have proven to be inadequate.
Benzodiazepines, tricyclic antidepressants, serotonin reuptake inhibitors, and carbamazepine have been shown to be effective with parasomnias. Clonazepam in low doses (.25 mg to .5 mg and increased by .25 mg every few nights as tolerated) before bedtime and continued for 3 to 6 weeks is usually effective. In adults, 86% had complete control with clonazepam and 14% improved. Safety and effectiveness have also been shown for those needing long-term treatment.23 Occasionally, frequency of episodes increases briefly after discontinuing the medication.
Nonpharmacologic treatments have included relaxation techniques, mental imagery, and anticipatory awakenings, which are preferred for long-term treatment. Guidance of an experienced behavior therapist or hypnotist is recommended for the first two techniques. Anticipatory awakenings consist of awakening the patient approximately 15 to 20 minutes before the usual time of the event and then keeping him awake during the time the episodes usually occur.
Arousal disorders in childhood are generally not associated with long-term sequelae. While frightening in the short term, the prognosis for resolution is excellent. Prolonged disturbances in sleep have been associated with school and behavioral issues. Persistence of SWS and sleep terrors into adolescence is indicative of a risk for psychiatric issues including overanxious disorder, panic disorder, neurotic traits, phobias, and suicidal thoughts.24 Similarly, these disorders in adults may be indicators of underlying mental disorders and have serious long-term consequences. Physicians providing care to individuals with SWS and arousal disorders, while providing reassurance and guidance for families of children with these disorders, need to be aware of the potentially serious and long-term implications in adolescents and adults.
Stephen J. Sharp, MD, is chief of the Department of Pediatric Neurology, Keesler Medical Center, Biloxi, Miss.
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