REM Sleep Behavior Disorder

Patients with rapid eye movement behavior disorder (RBD) act out dramatic and/or violent dreams during rapid eye movement (REM) stage sleep. Another feature of RBD is shouting and grunting. RBD seems similar to other sleep disorders that involve motor activity, like sleepwalking or periodic limb movement disorder. Unlike these conditions, RBD movements occur during REM sleep, which is usually characterized by a state of atonia, or sleep paralysis. Diagnosis and treatment involves polysomnography, drug therapy, and the exclusion of potentially serious neurological disorders.

RBD is usually seen in men 60 years old or older, but also occurs in younger people and in women. Incidents of REM behavior disorder are often described anecdotally to family members and not to physicians, so statistics of incidence are inexact.

Physiology and Causes

Rapid eye movement behavior disorder is an uncommon sleep disorder first described in 1986. There is no known cause for RBD. It is, however, known to occur during rapid eye movement sleep, which is characterized by brain activity patterns that resemble wakefulness and which has been documented with polysomnography and other sleep tests. Most dreaming occurs during REM sleep. Another characteristic of REM sleep is a general state of atonia, or muscle paralysis. So, while the brain is very active during REM sleep, the body is usually still.

Sleep Paralysis

The basic mechanism for REM sleep paralysis is found in the brainstem, the part of the brain that connects the spinal chord to the cerebral hemispheres and that consists of the pons, midbrain, and the medulla oblongata. Though physicians do not thoroughly understand the complex processes, it is known that the brainstem undergoes changes in REM sleep that result in paralysis of the body’s voluntary muscles. Certain neurotransmitters, like acetylcholine (Ach), become dormant and do not communicate motor activity. The absence of muscular contraction during REM can be seen with polysomnography. The electroencephalogram (EEG) shows elevated brain activity during REM.

Physicians and sleep technicians hypothesize that the brain naturally and purposely prevents motor activity during REM sleep to ensure restful, inactive sleep during the most electrically active stage of sleep. In this context, sleep paralysis describes a normal state of sleep, unlike sleep paralysis experienced in narcolepsy, which affects people while they are trying to stay awake.

Motor Activity and REM Sleep

In RBD, neurotransmitters are not blocked, and the voluntary muscles become tonic, or tensely contracted, allowing a sleeping person to move his or her muscles during REM. Rapid eye movement behavior disorder is characterized by significant submental (under the chin) and limb muscle tone. The combination of heightened cerebral activity and muscular tonicity results in physically acting out dreams that involve excited and sometimes violent movement.

The body can be rigid and extremely tense during episodes of RBD. For example, a person might straighten his or her leg, flexing it intensely for several seconds or a minute. Often, sleepers curl up slightly, while flexing their limbs and chin.

People with RBD typically remember little nothing of this activity, unless they fall out of bed, bump into the furniture, or injure themselves and wake up. But they can usually remember and tell the dreams they were having during an episode.

Dreams that involve physical or violent activity—such as fighting, dancing, running, chasing, attacking, being attacked, running from an assailant—are more likely to trigger RBD activity. Sleepers with RBD sometimes injure their bed partners. Some people have been known to leave the bed, run into a wall, run through a window, or run down the stairs. But RBD activity is usually confined to the bed and the surrounding area.

In addition to polysomnography, which records activity levels during REM sleep, diagnosis of RBD is based on sleep history, testimony of sleep partners, and one or several overnight video recordings of REM sleep activity. Video recordings present patients with an impressive and surprising revelation of their disorder.

Most cases of RBD are not associated with other disorders. It is, however, necessary to rule out myoclonic seizures, which are the product of neurological dysfunction and which may compromise health if not treated. Also, RBD symptoms have been described in cases of degenerative neurological disorder, like brainstem lesions. In cases of severe RBD and perhaps those that do not respond to treatment, diagnosis with magnetic resonance imaging (MRI) may help physicians exclude or detect other conditions, such as those listed below.

RBD and Parkinson’s Disease

There is some evidence to suggest that RBD precipitates Parkinson’s disease. Parkinson’s disease is caused by the continual death of dopamine-producing brain cells. Dopamine inhibits and regulates muscle control. Parkinson’s disease and RBD have been known to happen concurrently, but the relationship has not been proven. In one study, nearly 40% of men in their late 60s, who demonstrated RBD, later developed Parkinson’s disease. Parkinson’s disease affects as many women as it does men, but this isn't true of RBD.

Treatment

Clonazepam - Patients with RBD usually respond to treatment with clonazepam when taken nightly. Clonazepam is an antidepressant with anticonvulsant effects that has been shown to block neurotransmission in people with RBD, allowing them to achieve atonia and a state closer to REM paralysis. People with renal complications, pregnant women, and people who are taking other medications may not be good candidates for treatment with clonazepam.

Safety - People with RBD risk injuring themselves and their sleep partners. The frequency and intensity of RBD episodes are sometimes too much for a sleep partner to endure. This is often hard for those who suffer from RBD to understand, because they usually don't remember the episode because they sleep through it. Sleeping in a big bed can minimize the chance a sleep partner will be injured, but sleep partners often end up sleeping in different beds or even in different rooms.

A ground floor bedroom is recommended, especially for people who actually leave the bed during an episode. Placing heavy drapes over the windows to make going through them difficult, removing sharp objects from the room, padding the bed and nearby furniture, and clearing the floor around of furniture are all steps that can be taken to prevent injury.

Withdrawal from certain medications (e.g., tricyclics, monoamine oxidase inhibitors), alcohol, caffeine, and illicit drugs can cause acute episodes of RBD. Sudden discontinuation of controlled medication should be avoided under all circumstances.

Taken from: http://sleepdisorderchannel.com/rem/

Average: 5 (2 votes)