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.