Rapid Eye Movement (REM) Sleep Behavior Disorder: A Sleep Disturbance Affecting Mainly Older Men
Oksenberg, Arie, Radwan, Hendryk, Arons, Elena, Hoffenbach, Dalia, Behroozi, Bezalel, The Israel Journal of Psychiatry and Related Sciences
Abstract: Rapid Eye Movement (REM) sleep behavior disorder is characterized by the intermittent loss of REM-related muscle atonia and the appearance of elaborated motor behaviors (sometimes violent behavior) and vocalizations associated with dream mentation. Nine patients were diagnosed in our Sleep Disorders Unit with this syndrome during the period August 1997-April 2000. All were male, average age 67.9+/-6.9 years. The complaint of all our patients was the occurrence of violent or injurious sleep behavior mainly during the dream stage. Jumping or falling out of bed and slapping or beating their wives were more common. None had history or showed signs of dementia, Parkinson or other neurodegenerative diseases. A relative high amount of SWS (20.9%) was found. Seven showed an intermittent increase in chin EMG tonus while the other two had an almost continuous high chin EMG tonus during REM sleep. We did not observe any violent motor behavior during the polysomnographic recordings. Phasic activities during REM sleep were high but density quantification was not performed. Six patients had also Periodic Limb Movement (PLM) Disorders, four had also Obstructive Sleep Apnea (OS A) Syndrome. The treatment recommended to all patients was Clonazepam beginning with a 0.5-mg dose. Four patients reported a decrease or disappearance of sleep agitation and nightmares and were very happy with the treatment and without side effects. The others decided not to try Clonazepam or stopped after a few days of using it. RBD appears to be a sleep disturbance affecting mainly aged men. Its violent expression may frighten the patients and their bed-partners and may cause injury to both. In some cases this sleep disorder seems to be an early manifestation of a neurodegenerative disorder while in others it may represent only an idiopathic form. Clonazepam at lower doses is a good agent for the treatment of this condition.
One of the main distinctive features that characterize Rapid Eye Movement (REM) sleep is the generalized atonia of antigravity muscles. This atonia is a consequence of an active inhibitory mechanism of motor activity by pontine areas located in the peri-locus coeruleus region. This area exerts an excitatory influence on the nucleus reticularis magnocellularis of the medulla via the lateral tegmentoreticular tract, and the nucleus reticularis magnocellularis, in turn, hyperpolarizes spinal motoneurons postsynaptic membrane via the ventrolateral reticulospinal tract (1). Normally, this atonia of REM sleep is interrupted by fast excitatory inputs producing muscle jerks and twitches which together with the rapid eye movements represent the main phasic components of this sleep stage in humans (2).
Bilateral lesions in the pontine tegmentum in the cat result in a persistent absence of this REM sleep atonia and prominent motor activity during REM sleep (3). Loss of REM sleep atonia has been shown to be necessary but not sufficient for the expression of complex behavior during REM sleep. The site of the lesion will define whether the cat will show only the absence of REM atonia or will also present a range of complex behaviors during REM sleep (4).
Rapid Eye Movement sleep behavior disorder (RBD) is characterized by the intermittent loss of electromyographic (EMG) atonia and by the appearance of elaborate motor activity associated with dream mentation. This disorder was first formally described in 1986 by Schenck et al. (5), although ten years earlier Japanese researchers, describing a disorder with similar characteristics associated with alcohol withdrawal, used the term "stage 1 - REM with tonic EMG" (6). This represents the acute form of the disorder and has been also documented in association with the use of several medications (7). The chronic form of this disorder is either idiopathic or associated with neurological disorders. The idiophatic category is observed in those patients whose RBD is not associated with psycho-- pathological or detectable neuro-- pathological disorder. …