Rapid Eye Movement Sleep Behavior Disorder

Abstract: Rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by loss of normal voluntary muscle atonia during REM sleep, and is associated with excessive motor activity related to dreaming. The movements are often potentially harmful and may lead to repeated injuries to the patients and/or their bedpartners.
RBD is more common in the elderly and affects predominantly males. A recent survey reported an estimated prevalence of RBD of 0.38% in the elderly and 0.5% in the general population. Because the treatment of RBD is effective and safe in most cases, awareness and diagnosis of RBD is critical. Overnight polysomnography is required to differentiate accurately between RBD and other sleep disorders, even though the patients have been clinically diagnosed as RBD according to the minimal criteria of the International Classification of Sleep Disorders. Muscle tone persists during REM sleep in RBD patients, and may be frequently augmented for prolonged periods of time. The density of REMs or phasic muscle activity occurring during REM sleep significantly increases in these patients, although their overall sleep architecture is usually normal, with the expected cycles of non-REM and REM sleep.
RBD occurs in both acute and chronic form. Acute cases are associated with intoxication and withdrawal. Chronic cases are most often either idiopathic or associated with neurological disorders—especially neurodegenerative diseases. The etiology of idiopathic RBD is still unknown, but a recent study has shown an association between some cases of idiopathic RBD and neurodegenerative disorders with parkinsonism such as Parkinson's disease, multiple system atrophy, and diffuse Lewy body disease. RBD patients thus need to be carefully followed up in terms of neurological evaluation.