REM Sleep Behaviour Disorder

It is not unknown for this practice to be contacted by a quite distressed spouse of a patient informing us they are concerned for their safety, as their usually docile partner has been “attacking” them in their sleep.   Thankfully they have found the courage to call us (and not the authorities) so they can be reassured that there is a probable medical explanation for this, namely REM Sleep Behaviour Disorder (usually seen in middle age and elderly people, most often men) and that something can be done to help.

Normal sleep consists of two distinct stages, one with four phases of non rapid eye movement (NREM) and one of rapid eye movement (REM) sleep. During REM sleep (which is about 25% of total sleep) rapid eye movements occur, breathing is irregular, blood pressure increases and there is loss of muscle tone.  The brain though is highly active and this is the time usually associated with dreaming.

In a person with REM Sleep Behaviour Disorder (RBD) the paralysis that normally occurs during REM sleep is incomplete or absent.  This allows the person to act out their often vivid, intense and violent dreams with potential to cause self injury or injury to the bed partner .Dream enacting behaviours may include punching, kicking, leaping or jumping from the bed while still asleep. The person may waken during the attack and vividly recall the dream that corresponds with the physical activity.

In the majority of people the cause is unknown but in some it may be associated with alcohol or sedative-hypnotic withdrawal, or use of certain antidepressants.

RBD may occur in association with various degenerative neurological conditions such as Parkinson’s disease and Lewy body dementia, often preceding the development of these diseases by several years.  The prevalence of RBD is increased in persons with Parkinson’s disease however not all persons with RBD develop Parkinson’s disease.

Neurologic examination is often normal but signs and symptoms of Parkinson’s disease may suggest an underlying cause. Monitoring of the patient in a Sleep Centre is the most significant diagnostic test.  A polysomnogram will show an increase in muscle tone in the EEG pattern of REM sleep (where normally there would be an absence of muscle tone) and video recording will show body movements coinciding with this. Imaging studies are usually indicated only if some abnormality is detected during neurological examination or in maybe younger patients where there is no identifiable cause.

Clonazepam has been found to be 90% effective in relieving symptoms and tricyclic antidepressants may be effective in some patients (though precipitate RBD in others).