Parasomnias
Carlos H. Schenck
Mark W. Mahowald
In all of us, even in good men, there is a lawless, wild-beast nature which peers out in sleep. -Plato, The Republic
Relevance of parasomnias to psychiatrists
Parasomnias are defined as undesirable physical and/or experiential phenomena accompanying sleep that involve skeletal muscle activity (movements, behaviours), autonomic nervous system changes, and/or emotional-perceptual events.(1) Parasomnias can emerge during entry into sleep, within sleep, or during arousals from any stage of sleep; therefore, all of sleep carries a vulnerability for parasomnias.(1) Parasomnias can be objectively diagnosed by means of polysomnography (i.e. the physiologic monitoring of sleep—figures 4.14.4.1, 4.14.4.2), and can be successfully treated in the majority of cases.(2, 3, 4 and 5) Understanding of the parasomnias, based on polysomnographic documentation, has expanded greatly over the past two decades, as new disorders have been identified, and as known disorders have been recognized to occur more frequently, across a broader age group, and with more serious consequences than previously understood.(1, 2, 3, 4, 5, 6, 7, 8, 9 and 10) Parasomnias demonstrate how our instinctual behaviours, such as locomotion, feeding, sex, and aggression, can be released during sleep, itself a basic instinct. There are at least eight reasons why parasomnias should be of interest and importance to psychiatrists:
 Fig. 4.14.4.1 Polysomnogram of a disordered arousal, with the persistence of sleep, in a 23-year-old man with a history of sleepwalking and sleep terrors. After a behavioural arousal from slow-wave sleep (with arm lifted up and then down), the EEG shows irregular delta and theta activity and superimposed faster frequencies. Immediately preceding the arousal, there is a cluster of three high-amplitude delta waves (channel 3). Electro-occulogram, channels 1. 2; EEG, channels 3, 10-17; EMG, electromyogram. (Reproduced from C.H. Schenck et al. Analysis of polysomnographic events surrounding 252 slow-wave sleep arousals in thirty-eight adults with injurious sleepwalking and sleep terrors. Journal of Clinical Neurophysiology, 15, 159-66, copyright 1998, American Clinical Neurophysiology Society) |
 Fig. 4.14.4.2 Polysomnogram of disordered rapid eye movement (REM) sleep in a man with REM sleep behaviour disorder who eventually developed Parkinson’s disease. There is complete loss of ‘REM-atonia’, as the submental electromyogram (EMG) shows continuous muscle tone (channel 7). The appearance of a rapid eye movement (channels 1, 2) signals the onset of excessive muscle twitching in the upper/lower extremity EMGs (channels 8-15). The EEG (channels 3-6) shows the typical low-voltage fast-frequency desynchronized activity of REM sleep. ECG rate (channel 16) remains constant despite generalized muscle twitching, which is a common finding in REM sleep behaviour disorder. Elecro-oculogram: channels 1,2. |
1 Parasomnias can be misdiagnosed and inappropriately treated as a psychiatric disorder.
2 Parasomnias can be a direct manifestation of a psychiatric disorder, e.g. dissociative disorder, nocturnal bulimia nervosa.
3 The emergence and/or recurrence of a parasomnia can be triggered by stress.
4 Psychotropic medications can induce the initial emergence of a parasomnia, or aggravate a preexisting parasomnia.
5 Parasomnias can cause psychological distress or can induce or reactivate a psychiatric disorder in the patient or bed partner on account of repeated loss of self-control during sleep and sleep-related injuries.
6 Familiarity with the parasomnias will allow psychiatrists to be more fully aware of the various medical and neurological disorders, and their therapies, that can be associated with disturbed (sleep-related) behaviour and disturbed dreaming.
7 Parasomnias present a special opportunity for interlinking animal basic science research (including parasomnia animal models) with human (sleep) behavioural disorders.
8 Parasomnias carry forensic implications, as exemplified by the newly-recognized entity of ‘Parasomnia Pseudo-suicide.’ Also, psychiatrists are often asked to render an expert opinion in medicolegal cases pertaining to sleep-related violence.
Classification of parasomnias
Parasomnias can be classified according to whether the signs or symptoms are primary phenomena of sleep itself, or whether they are secondary phenomena derived from various underlying disorders, with sleep facilitating the nocturnal manifestation of these disorders.(6) Table 4.14.4.1 contains such a classification, and provides a context (along with other current sources(1,11)) for the parasomnias to be discussed in this chapter. Parasomnias demonstrate how sleep and wakefulness are not mutually exclusive states. Features of rapid eye movement (REM) sleep, non-REM sleep and wakefulness can occur simultaneously, and with rapid oscillations.(12) Status dissociatus represents the most extreme form of state dissociation.(13)
Clinical evaluation of parasomnias
The evaluation of complex and violent nocturnal behaviours at our centre (Minnesota Regional Sleep Disorders Center) includes the following:(2,14)
1 Clinical sleep-wake interview, with review of medical records, and review of a patient questionnaire that covers sleep-wake, medical, psychiatric and alcohol/chemical use and abuse history, review of systems, family history, and past or current physical, sexual, and emotional abuse.
2 Psychiatric and neurologic interviews and examinations, including psychometric testing.
Table 4.14.4.1 Classification of parasomnias: primary and secondary sleep phenomena
Primary sleep phenomena
Non-REM sleep
Disorders of arousal: sleepwalking/sleep terrors/confusional arousal
REM sleep
REM sleep behaviour disorder (RBD)
Dream anxiety attacks (nightmares)
Miscellaneous (including mixed non-REM/REM sleep)
Parasomnia overlap disorder (sleepwalking/sleep terrors/RBD)
Sleep related eating disorder
Restless legs syndrome/periodic limb movements in sleep
Obstructive sleep apnoea-related parasomnias
Rhythmic movement disorders
Status dissociatus
Bruxism
Secondary sleep phenomena
Central nervous system
Seizures (conventional, unconventional)
Headaches
Psychiatric
Nocturnal dissociative disorders
Nocturnal panic attacks
Nocturnal bulimia nervosa
Post-traumatic stress disorder
Cardiopulmonary (arrhythmias, asthma, etc.)
Gastrointestinal (gastro-oesophageal reflux etc)
Malingering
Modified from Mahowald and Ettinger.(7)
3 Extensive overnight polysomnographic monitoring at a hospital sleep laboratory, with continuous audio-visual recording. Figures 4.14.4.1, 4.14.4.2 depict the polysomnographic montage that includes the electro-oculogram, EEG, chin and four-limb electromyograms, ECG, and nasal-oral airflow (with full respiratory monitoring whenever indicated). Polysomnographic recording speeds of 15 to 30 mm/s are employed in order to detect epileptiform activity. Urine toxicology screening is performed whenever indicated.
4 Daytime multiple sleep latency testing, if there is a complaint or suspicion of excessive daytime sleepiness or fatigue (methods discussed in Narcolepsy chapter).
Causes of sleep related injury
A report on a series of 100 consecutive adults presenting to a multidisciplinary sleep disorders centre on account of sleep-related injury identified five causes:(2)
1 Sleepwalking/sleep terrors (M:F 3:2; mean age of onset, 5 years);
2 REM sleep behaviour disorder (predominantly male; mean age of onset, 57 years)
3 Dissociative disorders (Mostly female mean age of onset, 21 years)
4 Nocturnal seizures (uncommon)
5 Obstructive sleep apnoea/periodic limb movements (uncommon).
The sleep-related injuries included ecchymoses, lacerations, and fractures in 95 per cent, 30 per cent, and 9 per cent of patients respectively.
Non-REM sleep parasomnias: sleepwalking and sleep terrors
The polysomnographic correlates of sleepwalking and sleep terrors were first identified in the 1960s and 1970s by Gastaut and Broughton,(15, 16) Kales et al.,(17) and Fisher et al.(18) from France, Canada, and the United States. Sleepwalking and sleep terrors are classified as ‘disorders of arousal,’ and typically arise from delta non-REM (slow wave) sleep and usually affect children, but adults can also be afflicted, and suffer from sleep-related injuries and adverse social consequences.(2,9,10,19, 20, 21, 22, 23 and 24)
Clinical findings
Sleepwalking (SW) is characterized by complex, automatic behaviours, such as aimlessly wandering about, nonsensically carrying objects from one place to another, rearranging furniture, eating inappropriately, urinating in cupboards, going outdoors, and on rare occasion, driving a car.(1,25,26) The eyes are usually wide open and have a glassy stare, and there may be some mumbling. However, communication with a sleepwalker is usually poor or impossible. Frenzied or aggressive behaviour, the wielding of weapons (knives, guns), or the calm suspension of judgement (e.g. leaving via a bedroom window, wandering far outdoors) can result in inadvertent injury or death to self or others. Homicidal sleepwalking can occur.(25)
Sleepwalking episodes usually emerge 15-120 minutes after sleep onset, but can occur throughout the entire sleep period in adults. The duration of each episode can vary widely. The following is a wife’s description.(2)
‘He seems to have the strength of 10 men and shoots straight up from bed onto his feet in one motion. He’s landed clear across the room on many occasions and has pulled down curtains (bending the rods), upset lamps, and so forth. He’s grabbed me and pulled on me, hurting my arms, because he’s usually dreaming that he’s getting me out of danger … He’s landed on the floor so hard that he’s injured his own body … There are low windows right beside our bed and I’m afraid he’ll go through them some night.’
Sleep terrors (ST) are characterized by sudden, loud, terrified screaming and prominent autonomic nervous system activation (tachycardia, tachypnea, diaphoresis, mydriasis) that usually appears early in the sleep period, although episodes in adults can occur at any time of the night. The individual may sit up rapidly while screaming, and engage in frenzied activity, such as bolting out of bed, and becoming injured.
Childhood sleepwalking and sleep terrors are characterized by complete amnesia for the events. In adult SW and ST, there can be subsequent recall of the behavioural episode, and also recall of dream-like mentation that usually involves being threatened by imminent danger.(2,27) The distinction between ST and agitated SW in adults is often blurred, with both states being admixed in response to a perceived threat.(24)
The prevalence of SW has been estimated to be as high as 17 per cent in childhood (peaking at age 4-8), and recent data indicate a higher prevalence in adults (4 per cent) than previously recognized.(28, 29 and 30) The prevalence of ST in children can be greater than 6 per cent and greater than 2 per cent in adults.(1) A familialgenetic basis for SW and ST has been well-established.(30,31) Non-injurious SW does not have a gender preference,(1) although injurious SW appears to be more male-predominant.(2) Sleep terrors do not have a gender preference.(1) ‘Confusional arousals’ comprise another category of ‘disorder of arousal,’ and represent partial manifestations of sleepwalking and sleep terrors in which aggression and sexual impulses can be released.(1,10)
Polysomnographic findings
Sleepwalking/sleep terrors episodes arise abruptly during arousals from delta non-REM sleep.(1,15, 16, 17 and 18) In a systematic study of 38 adults with injurious SW/ST,(24) three postarousal EEG patterns were detected: diffuse, rhythmic delta activity; diffuse delta and theta activity intermixed with alpha and beta activity; and prominent alpha and beta activity. Thus, the postarousal EEG can show the complete persistence of sleep, the admixture of sleep and wakefulness, or complete wakefulness. Figure 4.14.4.1 shows the polysomnogram of a disordered arousal from slow-wave sleep.
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