Raman Malhotra, MD, on REM Sleep Behavior Disorder
Between 50 and 70 million US adults have a sleep disorder, according to the Institute of Medicine.1 A less common, but very important, sleep disorder is REM sleep behavior disorder (RBD). People with RBD physically act out their dreams by moving their limbs or even perform activities associated with waking.
Raman Malhotra, MD, who is associate professor of neurology at the Washington University Sleep Medicine Center in St. Louis, Missouri, recently spoke at the Sleep Medicine Trends 2019 annual meeting about RBD and what sleep medicine specialists can expect on the horizon.
NEUROLOGY CONSULTANT: How common is RBD in the context of sleep disorders?
Raman Malhotra: RBD is not common in the general population, thought to affect roughly 0.5% to 1% of the population. It is more common in older populations, and it is likely that we are underestimating prevalence, as many patients may not come to clinical attention due to not being aware they are having abnormal movements (ie, dream enactment) during sleep, especially if the movements do not result in injuries, or the patient does not have a bed partner to report them. The majority of cases of RBD go unrecognized, and most of the patients eventually diagnosed with RBD are usually referred to a sleep center for a different sleep complaint.
NEURO CON: What is new in the realm of evaluating RBD?
RM: In order to diagnose RBD, a patient must have a clinical history of dream enactment as well as a sleep study demonstrating REM sleep without atonia (RSWA). RSWA is a sleep study finding of abnormally increased chin or limb muscle tone noted during REM sleep (when we would normally expect muscle tone to be absent). Since this finding of RSWA is not always noted on one night of study, new research is exploring improved methods for detection of RBD. One such method is adding upper extremity sensors to sleep studies in patients that are being evaluated for abnormal movements during sleep. Standard polysomnography only include lower extremity sensors, and by adding more sensors to capture upper extremity movements, studies have been able to pick up more RSWA.
Other researchers are looking at methods of detecting RBD at home using actigraphy (accelerometers worn on the extremities) or other home monitors. Though studies with these new devices have been promising, more data is required before home devices can be used to help in the diagnosis of RBD due to multiple confounders and other causes of movements during sleep that look similar (ie, sleep apnea, restless legs).
NEURO CON: Are symptoms different in men vs women? Does age play a role in severity of RBD?
RM: The symptoms of REM sleep behavior disorder are related to the motor activity that mimics the dream content of the person. Up until recently, there was thought to be a higher prevalence of RBD in men compared with women, but more recent studies are finding that there are just as many women as men with the condition. The reason for this discrepancy may be that women do not present to clinical attention due to fewer violent dreams and motor activities as compared with men, or due to other factors (less likely to have bed partner, male bed partner may not report motor activity).
Age does play a role in not only the onset but also the severity of RBD, as many neurodegenerative conditions, such as Parkinson disease, are associated with RBD with up to a half having RBD. In addition, as the underlying neurological disorder progresses, the RBD motor activity tends to become more frequent and disruptive.
NEURO CON: What are the treatment options for RBD? What treatments are on the horizon for 2019?
RM: Treatment options start with educating the patient and his/her bed partner about safety precautions:
- Remove furniture with sharp edges or other sharp objects from the bedroom.
- Remove weapons from the bedroom.
- Move bed away from any windows.
- Use heavy curtains or drapes.
- Consider placing the mattress on the floor.
- Provide cushions or soft padding to any hard surfaces close to the bed.
- Consider sleeping in separate beds to avoid injury.
- Possibly add a bed alarm to awaken the patient or partner, or to pacify the patient.
Treating any underlying primary sleep disorders, such as restless legs syndrome or sleep-disordered breathing, should also be emphasized in order to prevent arousals that could precipitate an RBD event. If pharmacological treatment is necessary to reduce the risk of injury, either melatonin or clonazepam are used to decrease the frequency and severity of motor activity during sleep. Melatonin is typically preferred due to a better safety profile than clonazepam. The main concern regarding clonazepam is worsening balance (ie, fall risk) or cognition, especially since many patients with RBD are older and may have conditions such as Parkinson disease or dementia.
Pramipexole and rivastigmine have also been shown in small trials to be helpful in treating RBD.
NEURO CON: What else should sleep medicine specialists know about evaluation and treatment of RBD?
RM: One of the other important things to consider when managing a patient with RBD, is informing the patient about the very high risk of future development of neurodegenerative conditions such as Parkinson disease and other synucleinopathies (dementia with Lewy bodies). RBD may predate the onset of other clinical symptoms of these diseases by years or even decades. Studies following patients with idiopathic RBD have demonstrated high rates of conversion to Parkinson disease and other synucleinopathies: 45% conversion rate at 5 years, 76% at 10 years, and more than 90% at 14 years. These rates have been found to be even higher in RBD patients with orthostatic hypotension, constipation, hyposmia, or impaired color vision. Though the high risk of conversion to future neurodegenerative disorders is known, there is no proven neuroprotective therapy to delay or prevent onset or progression of these neurodegenerative diseases at this time. Follow up typically involves a regular, detailed neurologic history and examination to look for early signs of disease. One option to offer patients with idiopathic RBD is an opportunity to join a registry or other research team that is working on ways to delay the onset of synucleinopathies.
Reference:
- Institute of Medicine Committee on Sleep Medicine and Research. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington, DC: National Academies Press; 2006.