Def: parasomnia with abnormal behaviors arising during REM sleep
Two forms: idiopathic (primary) and symptomatic (secondary)
Idiopathic RBD may be the first sign of a neurodegenerative d/o
Secondary RBD: assoc with PD, DLB, MSA or narcolepsy
Male predominance, women may be underrecognized
Clinical features
Vigorous movements, unpleasant or violent dreams, loss of REM atonia
Behaviors and vocalizations match dream content (dream enactment)
Movements range from simple limb jerks to elaborate purposeful behavior
Often self-defense: punching, kicking, hitting nightstand, falling out of bed
Injuries to pt or bed partner: bites, bruises, dislocations, fractures
Non-aggressive behaviors also: reaching, eating, clapping
Vocalizations: talking, swearing, screaming, crying, laughing, whistling, singing
Dreams vivid and intense, threatening content, most pts recall them
Common themes: defending against attack by unknown person, animals, sports
Eyes closed during episodes
More common in last part of the night (REM-rich)
Presentation
Many pts unaware of the problem
Often 10-20 yrs delay before seeking care, often at partner’s insistence
Bed partner hx key for description, onset and frequency
Dx criteria (ICSD-3, A-D required)
A. Repeated sleep-related vocalization and/or complex motor behaviors
B. Documented on vPSG during REM, or presumed REM based on hx of dream enactment
C. PSG shows REM sleep without atonia (RWA)
D. Not better explained by another sleep or mental d/o, meds or substance use
Isolated (Idiopathic) RBD
High proportion develop neurodegenerative dz over time
Conversion risk 33% at 5 yrs, 76% at 10 yrs, 91% at 14 yrs
Overall conversion ~6.3%/yr
Latent period from RBD onset to parkinsonism or dementia up to 50 yrs
Alpha-synuclein seed amplification assay (CSF, skin biopsy) emerging as a biomarker
Prodromal signs
- Hyposmia
- Autonomic dysfunction
- Cognitive changes: visuospatial, executive, memory
- Subtle motor sx: hypomimia, hypophonia, reduced arm swing
Risk factors for conversion
- Older age
- Hyposmia
- Impaired color vision
- Abnormal DaT-SPECT ± substantia nigra hyperechogenicity
- EEG slowing
Secondary RBD
Due to neuro condition or med/substance
Neurodegenerative:
RBD in ~25-58% of PD, 70-80% of DLB, 90-100% of MSA
Bradykinesia disappears during RBD episodes, suggests basal ganglia bypass
Other causes:
a. Narcolepsy, mainly NT1: seen in younger pts
b. Autoimmune: anti-LGI1, anti-NMDA encephalitis
c. Brainstem lesions: stroke, MS
d. Meds: TCAs, SSRIs, SNRIs, beta blockers (bisoprolol)
Treatment
Safety measures
Move bedside table away from bed
Pad furniture corners
Consider bed rails
Mattress on floor next to bed, or place mattress directly on floor
Remove firearms and sharp objects from the bedroom
Medical tx
Start if injury risk, bothersome dreams or disturbed bed partner
Clonazepam and melatonin most used, limited evidence
Both reduce frequency and intensity in small trials and case series
Clonazepam 0.25-2 mg usually sufficient
Melatonin 3-12 mg, may be equally effective and better tolerated
AASM 2023: conditional recs for clonazepam, IR melatonin, pramipexole and transdermal rivastigmine
Review meds that may cause or worsen RBD: antidepressants, beta blockers
- Oxford Handbook of Sleep Medicine 2022