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  • Updated 11.24.2023
  • Released 08.22.2010
  • Expires For CME 11.24.2026

Parasomnia overlap disorder and status dissociatus



In this article, the author reviews parasomnia overlap disorder and status dissociatus. Clinicians are occasionally faced with patients who have clinical features of both nonrapid eye movement (NREM) parasomnias and REM sleep behavior disorder (RBD), making management difficult. The epidemiology, etiology, investigation, and management of this condition are summarized. In addition, there is a detailed review of status dissociatus, a severe motor parasomnia in which features of wake and sleep states coexist. Importantly, status dissociatus is occasionally caused by voltage-gated potassium channel antibody syndromes and is treatable with immunomodulating therapy.

Key points

• Parasomnia overlap disorder occurs when patients demonstrate features of both nonrapid eye movement parasomnias (sleepwalking, sleep terrors, confusional arousals, sleep-related eating disorder, sexsomnia) and REM sleep behavior disorder. It is relatively common in the parasomnia population.

• NREM parasomnias emerging with parasomnia overlap disorder can include aggressive and violent behaviors as well as appetitive behaviors (feeding, sex).

• Some reported patients with parasomnia overlap disorder have six total parasomnias, including five NREM parasomnias and RBD. In addition, there can be comorbid obstructive sleep apnea in some reported patients with parasomnia overlap disorder.

• Patients with parasomnia overlap disorder are predominantly male and present younger than most idiopathic cases of REM sleep behavior disorder.

• Clinical history alone is insufficient to properly diagnose parasomnia overlap disorder, as cryptic confusional arousals and sleepwalking can occur together with RBD. Conversely, subtle (or more prominent) dream-enactment behavior is common among adult patients with NREM parasomnias as well as in the general population.

• Polysomnography in parasomnia overlap disorder typically demonstrates NREM sleep instability, at times with disordered arousals from deep NREM sleep with confused behaviors, sleep terrors, incipient sleepwalking, sexual behaviors, and eating behaviors, in combination with a lack of REM sleep atonia (at times with dream-enactment behaviors during REM sleep).

• Treatment of parasomnia overlap disorder should first be focused on resolving comorbid conditions that fragment sleep, such as sleep-disordered breathing and periodic limb movements with arousals, and the elimination of suspected precipitating pharmacology. Clonazepam is often effective, particularly for patients with violent dream-enactment behavior. For medication-resistant patients, a customized bed alarm may help prevent sleep-related injury.

• Status dissociatus is an extreme form of parasomnia overlap wherein features of NREM sleep, REM sleep, and wakefulness coexist or rapidly oscillate. This breakdown in wake-sleep state boundaries appears to be caused by pathologies involving GABAergic circuits in the thalamus, including fatal familial insomnia, delirium tremens, Morvan syndrome (and other related anti-potassium channel antibody disorders), and anti-NMDA receptor encephalitis. Status dissociatus may also represent the final, fulminant manifestation of multiple system atrophy and dementia with Lewy bodies (04).

Historical note and terminology

Early reports of sleepwalking date to the writings of Hippocrates and Galen. In 1968, sleepwalking was identified as a disorder of arousal emanating from deep NREM sleep (09). In 1986, a series of five patients with violent and complex dream-enactment behavior with a paucity of REM sleep atonia was reported (55), and the condition was named in 1987 "rapid eye movement sleep behavior disorder" with an expanded series of 10 patients (56). Subsequently, in 1997 a series of 33 cases with combined NREM parasomnias and RBD was reported, named "parasomnia overlap disorder" (54).

In 1991, status dissociatus was reported in six patients with neurodegeneration (olivopontocerebellar atrophy), anoxic injury, narcolepsy with cataplexy (and obstructive sleep apnea), or severe ethanol withdrawal (40). Later, etiologies included prion disease, other forms of neurodegeneration, autoimmune disease, and various toxic etiologies (04).

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