Rapid eye movement sleep behavior disorder (RBD) is a sleep disorder (more specifically a parasomnia) that involves abnormal behavior during the sleep phase with rapid eye movement (REM) sleep. RBD is a very strong predictor of progression to a synucleinopathy (for example, the Lewy body dementias).
The major feature of RBD is loss of muscle atonia (i.e., the loss of paralysis) during otherwise intact REM sleep (during which paralysis is not only normal but necessary). REM sleep is the stage of sleep in which most vivid dreaming occurs. The loss of motor inhibition leads to a wide spectrum of behavioral release during sleep. This extends from simple limb twitches to more complex integrated movement, in which people act out their dreams. These behaviors can be violent in nature and in some cases will result in injury to either the individual or their bed partner.
Melatonin is useful in the treatment of RBD. RBD was first described in 1986.
Video Rapid eye movement sleep behavior disorder
Symptoms
RBD is characterized by the dreamer acting out his or her dreams, with complex behaviors. These dreams often involve screaming, shouting, laughing, crying, arm flailing, kicking, punching, choking, and even jumping out of bed. The actions in an episode can result in injuries to oneself or one's bed partner. The sleeping person may be unaware of these movements. Dreams often involve violent or aggressive actions, and an attack theme like being chased by people or animals. Because violence in dreams is more likely to be recalled, this could be an artifact of recall bias or selection bias.
In a normal sleep cycle, REM sleep may be experienced at intervals of between 90 minutes and two hours every night, which means RBD episodes may occur up to four times a night. In a rare case, they may only happen once a week or once a month. Episodes occur more towards the morning hours because that is when REM sleep is more frequent. When awakened, people can usually recall the dream they were having, which will match the actions they were performing.
As the first indication of an underlying neurodegenerative disorder, symptoms of RBD may begin years or decades before other the onset of another condition.
Maps Rapid eye movement sleep behavior disorder
Causes
Rapid eye movement behavior disorder occurs when there is a loss of normal voluntary muscle atonia during REM sleep resulting in motor behavior in response to dream content. It can be caused by adverse reactions to certain drugs or during drug withdrawal; however, it is most often associated with the elderly and in those with neurodegenerative disorders such as Parkinson disease and other neurodegenerative diseases, for example multiple system atrophy and the Lewy body dementias.
The underlying cause of RBD is not well understood, but it is likely that RBD is an early symptom of synucleinopathy rather than a separate disorder. Brainstem circuits that control atonia during REM sleep may be damaged. REM sleep circuits are located in caudal brainstem structures--the same structures that are known to lead to be implicated in the synucleinopathies. Motor deficits like those seen in RBD are known to result from lesions in those circuits.
RBD is categorized as either idiopathic or symptomatic.
Idiopathic
Idiopathic RBD is when the individual's sleep structure seems to be normal but there is a significant increase in the density of REM sleep as well as the percentage of slow wave sleep. This category of RBD is more strongly linked to having a genetic component, as seen throughout familial gene patterns.
Symptomatic
Symptomatic RBD is the more characteristically seen disorder. This category of RBD is strongly associated with neurodegenerative diseases, "especially synucleinopathies such as Parkinson disease, dementia with Lewy bodies, and multiple system atrophy". Almost half of those with Parkinson's, at least 88% of those with multiple system atrophy, and about 80% of people with Lewy body dementia have RBD. RBD is a very strong predictor of progression to a synucleinopathy (for example, the Lewy body dementias). On autopsy, up to 98% of individuals with polysomnography-confirmed RBD are found to have a synucleinopathy.
Diagnosis
There are two ways to diagnose RBD: by documenting a history of complex, dream-enactment sleep behaviors, or by polysomnography recording of these behaviors along with REM sleep atonia loss.
RBD may be established from clinical interview as well as several validated questionnaires, when sleep studies cannot be performed. Questionnaires such as the Rapid Eye Movement (REM) sleep Behavior Disorder Screening Questionnaire (RBDSQ), the REM Sleep Behavior Questionnaires - Hong-Kong (RBD-HK), the Mayo Sleep Questionnaire (MSQ) and the Innsbruck REM Sleep Behavior Disorder Inventory are well-validated.
Individuals with RBD may not be able to provide a history of dream enactment behavior, so bed partners are also consulted. The REM Sleep Behavior Disorder Single-Question Screen offers diagnostic sensitivity and specificity in the absence of polysomnography with one question:
"Have you ever been told, or suspected yourself, that you seem to 'act out your dreams' while asleep (for example, punching, flailing your arms in the air, making running movements, etc.)?"
Treatment
RBD is treatable (even when the underlying synucleinopathies are not). Melatonin and clonazepam are the most frequently used, and are comparably effective, but melatonin offers a safer alternative, because clonazepam can produce undesirable side effects. In addition, patients with neurodegenerative diseases such as Parkinson's disease reported more favorable outcomes with melatonin treatment. Other medications and treatments are available, but have only anecdotal evidence.
Medications that may worsen RBD and should be stopped if possible are tramadol, mirtazapine, antidepressants, and beta blockers.
In addition to medication, it is wise to secure the sleeper's environment in preparation for episodes by removing potentially dangerous objects from the bedroom and either place a cushion round the bed or move the mattress to the floor for added protection against injuries. Some extreme sufferers sleep in a sleeping bag zipped up to their neck, and wear mittens so they can't unzip it until they awake in the morning.
Patients are advised to maintain a normal sleep schedule, avoid sleep deprivation, and keep track of any sleepiness they may have. Treatment includes regulating neurologic symptoms and treating any other sleep disorders that might interfere with sleep. Sleep deprivation, alcohol, certain medications, and other sleep disorders can all increase RBD and should be avoided if possible.
Epidemiology
RBD prevalence as of 2017 is estimated to be 0.5-2% overall, and 5-13% of those aged 60 to 99. It is more common in males overall, but equally frequent among men and women below the age of 50. This may partially be due to a referral bias, as violent activity carried out by men is more likely to result in harm and injury and is more likely to be reported than injury to male bed partners by women, or it may reflect a true difference in prevalence as a result of genetic or androgenic factors. Typical onset is in the 50s or 60s
Other conditions are similar to RBD in that sufferers exhibit excessive sleep movement and potentially violent behavior. Such disorders include sleepwalking and sleep terrors, which are associated with other stages of sleep, nocturnal seizures and obstructive sleep apnea which can induce arousals from REM sleep associated with complex behaviors. Because of the similarities between the conditions, polysomnography plays an important role in confirming RBD diagnosis.
RBD appears in association with other conditions. Narcolepsy has been reported as a related disorder. Both RBD and narcolepsy involve dissociation of sleep states probably arising from a disruption of sleep control mechanisms. RBD has also been reported following cerebrovascular accident and neurinoma (tumor), indicating that damage to the brain stem area may precipitate RBD. RBD is usually chronic. However, it may be acute and sudden in onset if associated with drug treatment or withdrawal (particularly with alcohol withdrawal). 60% of RBD is idiopathic. This includes RBD that is found in association with conditions such as Parkinson's disease and dementia with Lewy bodies, where it is often seen to precede the onset of neurodegenerative disease. Monoamine oxidase inhibitors, tricyclic antidepressants, Selective serotonin reuptake inhibitors, and noradrenergic antagonists can induce or aggravate RBD symptoms and should be avoided in individuals with RBD.
History
In the 1960s and 1970s, Michel Jouvet described brain lesions in cats that led to loss of atonia in REM sleep. Carlos Schenck and Mark Mahowald and their team in Minnesota first described RBD in 1986.
In animals
RBD has also been diagnosed in animals; specifically dogs.
See also
- Sleepwalk with Me
References
Source of article : Wikipedia
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