REM sleep parasomnia characterized by loss of muscle atonia during REM sleep (known as REM sleep without atonia, or RSWA) and dream enactment during sleep.
REM sleep parasomnia characterized by loss of muscle atonia during REM sleep (known as REM sleep without atonia, or RSWA) and dream enactment during sleep.
Aetiology
Synucleinopathy associations:
RBD is frequently associated with clinically-diagnosed Parkinson’s disease, dementia with Lewy bodies, and multiple system atrophy.
Parkinson’s disease
Dementia with Lewy bodies
Multiple system atrophy
Schematic representation of the hypothesized progression in cognitive functioning with increasing age and disease severity in evolving Lewy body disease in the dementia with Lewy bodies (DLB)-predominant phenotype. The onset of RBD typically begins years or decades prior to the onset of cognitive decline and a diagnosis of mild cognitive impairment (MCI), with subtle and often asymptomatic motor signs (mild parkinsonian signs or MPS – represented by the area shaded in light yellow) evolving concurrently or after the onset of cognitive decline. More obvious features of parkinsonism (represented by the area shaded in dark yellow) evolves no earlier than 1 year prior to the onset of dementia to warrant the DLB diagnosis. Over time, dementia, parkinsonism, and problematic neuropsychiatric features such as visual hallucinations and delusions tend to progress. | Boeve B. F. (2010). REM sleep behavior disorder: Updated review of the core features, the REM sleep behavior disorder-neurodegenerative disease association, evolving concepts, controversies, and future directions. Annals of the New York Academy of Sciences, 1184, 15–54. https://doi.org/10.1111/j.1749-6632.2009.05115.x
Schematic representation of the hypothesized progression in motor functioning with increasing age and disease severity in evolving Lewy body disease in the Parkinson’s disease-predominant phenotype. The onset of RBD typically begins years or decades prior to the onset of subtle motor signs (mild parkinsonian signs or MPS); such motor signs may be asymptomatic and only detectable on clinical examination. Typical features of Parkinson’s disease (PD) evolves months or years later. Over time, PD with mild cognitive impairment (PD+MCI) evolves, followed some time thereafter by parkinsonism which is less levodopa-responsive, and a full dementia syndrome (PD with dementia or PDD) becomes manifest. | Boeve B. F. (2010). REM sleep behavior disorder: Updated review of the core features, the REM sleep behavior disorder-neurodegenerative disease association, evolving concepts, controversies, and future directions. Annals of the New York Academy of Sciences, 1184, 15–54. https://doi.org/10.1111/j.1749-6632.2009.05115.x
Pathophysiology
Most patients with REM behavior disorder will eventually manifest neurodegenerative diseases like parkinsonism, dementia with Lewy body, or multisystem atrophy.
Theoretical model of rapid eye movement sleep behavior disorder (RBD) and its relationship with different clinical manifestations of synucleinopathies. Idiopathic RBD may remain as an isolated syndrome with or without additional cognitive, autonomic, or motor “soft signs” that may or may not evolve toward more definitive, clinically overt, “full-blown” synucleinopathy subtypes of dementia with Lewy bodies (DLB), multiple system atrophy (MSA), Parkinson disease (PD), or PD with dementia (PDD). Patients with parkinsonism and dementia are considered to have PDD if cognitive decline occurs longer than 1 year after the emergence of parkinsonism and DLB if patients present with cognitive decline less than 1 year after the emergence of parkinsonism. Patients with PD and patients without RBD may represent different clinical phenotypes, given different and more severe motor signs, cognitive impairments, and autonomic signs in those with PD compared with those without PD. | MCI = mild cognitive impairment; PAF = pure automatic failure. | McCarter SJ, St Louis EK, Boeve BF. Is rapid eye movement sleep behavior disorder in Parkinson disease a specific disease subtype? Sleep Med. 2013;14(10):931–933.
Clinical features
Clinical features during sleep include abnormal vocalizations, abnormal motor behavior, and altered dream mentation. This enactment may be violent and can lead to injury to themselves or others without any conscious awareness. A patient can recall the contents of the dream upon awakening.
Diagnosis
International Classification of Sleep Disorders (ICSD-3):
Diagnosis of RBD requires all of the following
Repeated episodes of sleep-related vocalization and/or complex motor behaviors
Behaviors are documented by polysomnography to occur during REM sleep or, based on the clinical history of dream enactment, are presumed to occur during REM sleep
Presence of REM sleep without atonia (RSWA) on polysomnography
An absence of epileptiform activity during REM sleep, unless RBD can be clearly distinguished from any concurrent REM sleep-related seizure disorder
Sleep disturbance not better explained by another sleep disorder, medical or neurologic disorder, mental disorder, medication use, or substance use disorder
RBD is the only parasomnia which requires an in-facility polysomnogram for diagnosis.
Polysomnography:
REM sleep without atonia (RSWA) (CHARACTERISTIC): Elevation of motor tone during REM sleep as measured by electromyography (EMG) activity in the chin and/or limb leads
PSG recording of REM sleep: a) Polysomnography (PSG) recording from a control individual. b) PSG recording from a patient with rapid eye movement (REM) sleep behaviour disorder (RBD). Note the electromyogram (EMG) activity in the chin EMG and left arm EMG. The leg EMG recording was obtained from the left and right anterior tibialis muscles, and the arm EMG recording was obtained from the left and right flexor digitorum superficialis muscles. | EEG, electroencephalogram; EOG, electrooculogram | Dauvilliers, Y., Schenck, C.H., Postuma, R.B. et al. REM sleep behaviour disorder. Nat Rev Dis Primers 4, 19 (2018). https://doi.org/10.1038/s41572-018-0016-5
Differential Diagnosis
Differentials include other sleep enactment behaviors. The differences of these disorders can usually be identified with detailed history taking, but a video-monitored polysomnographic study is often warranted.
Obstructive sleep apnea
Seizures
Nocturnal panic attacks
Nightmares
Non-REM parasomnias: Night terrors, somnambulism, or confusional arousals
Management
Primary goal of treatment is to provide patients with a safe sleeping environment for them and their bed partners. Healthcare professionals can achieve this through non-pharmacologic approaches and pharmacotherapy if needed.
Pharmacological management:
Melatonin (first-line therapy): Augments REM atonia and improves RBD symptoms
Low-dose clonazepam (0.5-1 mg at bedtime): Suppress unpleasant dreams
Schematic framework of the natural history effects of neuroprotective therapies in iRBD: a) Many patients with idiopathic rapid eye movement
(REM) sleep behaviour disorder (iRBD) eventually develop a neurodegenerative disorder, of which α- synucleinopathy (including Parkinson disease, dementia with Lewy bodies and multiple system atrophy) is common. Before these patients develop overt synucleinopathy, they may have an intermediate stage (RBD+), in which mild cognitive impairment, mild parkinsonism signs and mild autonomic disturbances might occur.
b) Commencing neuroprotective therapy (when available) inindividuals with iRBD might delay conversion to α- synucleinopathy. | St Louis, E. K. & Boeve, B. F. REM sleep behavior disorder: diagnosis, clinical implications, and future directions. Mayo Clin. Proc. 92, 1723–1736 (2017).
Summary:
REM sleep behaviour disorder (RBD) is characterized by a loss of muscle atonia during REM sleep, leading to excess muscle tone and abnormal behaviours. | REM sleep behaviour disorder. Nat Rev Dis Primers 4, 20 (2018). https://doi.org/10.1038/s41572-018-0020-9
