Spectrum of rapid eye movement sleep behavior disorder (overlap between rapid eye movement sleep behavior disorder and other parasomnias)

Abstract

Parasomnia Overlap Disorder (POD) was described and named in 1997 with a series of 33 cases of rapid eye movement (REM) sleep behavior disorder (RBD) combined with a disorder of arousal from non-rapid eye movement (NREM) sleep (sleepwalking, sleep terrors) that emerged idiopathically or symptomatically with neurological and other disorders. POD is a subtype of RBD in the International Classification of Sleep Disorders Diagnostic and Coding Manual, second edition (ICSD-2). An updated classification of POD also includes subclinical RBD-NREM parasomnia, RBD-sleep-related eating disorder, RBD-sexsomnia, RBD-rhythmic movement disorder, and status dissociatus (SD), which is another subtype of RBD in the ICSD-2. Similar to POD, a core feature of SD is sleep motor-behavioral dyscontrol, with release of dream-related behaviors suggestive of RBD, but with nearly continuous ambiguous polygraphic sleep precluding the identification of NREM/REM sleep states. SD exemplifies extreme state dissociation. SD is always a symptomatic disorder, and is causally associated with a broad range of neurologic disorders, often with thalamic, limbic, striatal, and pontine involvement. The parasomnia behaviors associated with POD and SD -typical RBD behaviors -can often be controlled with bedtime clonazepam therapy, including the abnormal dreaming.

From state dissociation to status dissociatus

“…5,42,43 This condition is male predominant. POD patients have an earlier age at onset (childhood or adolescence) than patients with RBD alone, and in most of them the disorder of arousal precedes RBD.…”

“…However, only few studies report details on neurophysiological investigations. 43 POD pathophysiology is unknown. Similarly to RBD and SD, in POD there is a motor/behavioral disorder occurring during sleep along with the presence of excessive phasic EMG twitching.…”

“…features (electro-oculogram with REMs, EMG phasic twitches) and complex behaviors as described in neurodegenerative diseases or transiently before the development of the full-blown SD, 40,41 -Parasomnia overlap disorder (POD). 5,42,43 …”

Rapid eye movement sleep behavior disorder in adults younger than 50 years of age

“…Additional unusual case reports of POD, including a 37 year old man with RBD, sleepwalking, and sexsomnia [32], and two Parkinson disease-related RBD patients (age 28 and 37) with SRED [33], suggest some subtypes of POD may occur more frequently in early-onset RBD than others. Idiopathic POD and POD variants—including SRED, sexsomnia, rhythmic movement disorder, status dissociatus, or those symptomatic of central nervous system lesions, were recently reviewed, along with an additional discussion of cumulative literature on POD and RBD in younger adults [34]. Due to the limited number of reported cases thus far, further study is necessary to determine whether age affects the variant of POD that may manifest in an individual.…”

Sleeping in fits and starts: a practical guide to distinguishing nocturnal epilepsy from sleep disorders

“…Some people have parasomnias with features of RBD and NREM arousal parasomnias 29. This is best considered a subgroup of RBD, and probably has similar implications in terms of its relationship with degenerative disorders.…”