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Rapid eye movement (REM) sleep behaviour disorder:
Rapid eye movement sleep behaviour disorder (RBD) is characterised by dream-enacting
behavior and a loss of normal muscle atonia during REM sleep - may result in
injury to the patient or the patient's bed partner
- RBD patients show electromyographic abnormalities during REM sleep
- exhibit a phenomenon called REM sleep without atonia - elevated muscle
tone during REM sleep
The majority of RBD cases occurring in older adults remain idiopathic, at least
initially, although a presumptive underlying cause of synucleinopathy neurodegeneration
and eventual emergence of overt parkinsonism, autonomic, or cognitive dysfunction
has been recognized, and RBD may also be seen in younger adults associated with
narcolepsy and antidepressant use (2).
- incidence is estimated at 0.5–1% of those
over 55 years), occurs in older people with a steady rise after 55
years and has a male preponderance in older patients (3)
- RBD usually recurs almost every
night (4)
- well recognised as the most robust prodromal, non-motor symptom
of a subsequent neurodegeneration, typically an alpha synucleinopathy (3)
- several cohorts under long term follow-up have
shown that 50% at five years and 91% at 15 years will have
developed another neurodegenerative problem
- often associated
with Parkinson’s disease (PD) (it is seen in up to 50% of PD
patients), Lewy body dementia (~70%), multiple system atrophy
(>90%) (3)
- RBD often precedes other symptoms of neurodegeneration
by several years (3)
The International Classification of Sleep Disorders states that for patients
who had typical episodes of dream-enacting behavior and showed complex motor
behaviors during polysomnography (PSG) but did not show sufficient REM sleep
without atonia, RBD may be provisionally diagnosed based on clinical judgment
- patients with RBD typically awaken quickly, become rapidly alert, and can
recall the contents of their dreams upon awakening, whereas patients showing
abnormal nocturnal behaviors related to other disorders, such as night delirium,
epilepsy, and hypoglycemia due to insulinoma, cannot awaken quickly or report
the contents of dreams
DSM-5 criteria for rapid eye movement sleep behavior disorder are as follows:
- recurrent episodes of arousal during sleep associated with vocalization
and/or complex motor behaviors that arise during rapid eye movement (REM)
sleep
- on waking from these episodes, the individual is not confused or disoriented
and is completely alert
- either of the following is present:
- REM sleep without atonia on polysomnographic recordings; or
- a history suggestive of REM sleep behavior disorder and an established
synucleinopathy diagnosis (e.g., Parkinson’s disease, multiple system
atrophy)
- the episodes cause significant distress or impairment in social, occupational
or other areas of functioning which may include serious injury to self or
the bed partner
- the disturbance cannot be explained by the effects of a drug of abuse or
medication
- the episodes cannot be attributed to another mental disorder or medical
condition
Diagnosis of parasomnias
- assessment of parasomnia may be possible with a detailed history
from patient or witness, but in general for adequate diagnosis,
referral to a specialist sleep centre for polysomnography
and video recording may be necessary especially for RBD
where loss of REM atonia is seen (3)
Clonazepam, a benzodiazepine, is the pharmacologic agent which has been the
most commonly used treatment for RBD (2). Melatonin has also been used in the
management of this condition (2).
Reference:
Last edited 05/2020 and last reviewed 08/2020
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