MIAMI BEACH — A patient with REM sleep behavior disorder has about a 50/50 chance for developing Parkinson's disease within 12 years, according to a recently published report.
REM sleep behavior disorder (RBD) “is a striking parasomnia very common in Parkinson's disease,” Dr. Ronald Postuma said. Also, because RBD often precedes the onset of symptoms of Parkinson's disease, patients with this sleep disorder should be closely followed and counseled about their increased risk, he said at the World Federation of Neurology World Congress on Parkinson's Disease and Related Disorders.
RBD is characterized by speech and body movement during the rapid eye movement phase of sleep. “Normally, we are paralyzed when we dream. You lose this in RBD,” he said. Other phases of sleep appear normal. Apnea, sleep walking, and sleep talking are part of the differential diagnosis, said Dr. Postuma, who is a member of the neurology faculty at McGill University, Montreal, and is a neurologist at Montreal General Hospital.
Dr. Postuma and his colleagues conducted follow-up with 93 patients who were diagnosed with RBD at the Hôpital du Sacré-Coeur in Montreal. During follow-up, 26 of these patients developed a neurodegenerative disease—14 developed Parkinson's disease; 7, Lewy body dementia; 4, dementia; and 1, multiple system atrophy (Neurology 2009;72:1296-300).
Based on these findings, the estimated 5-year risk of neurodegenerative disease was 18%, the estimated 10-year risk was 41%, and the estimated 12-year risk was 52%. A diagnosis of RBD, therefore, carries important counseling implications.
The consensus is that about 35% of patients with Parkinson's disease have RBD, Dr. Postuma said. Prevalence estimates are higher from polysomnography studies, with reports that 40%–60% of Parkinson's disease patients have signs.
“An important clinical question is: Do you need polysomnography to diagnose RBD?” he said. Proponents point out that mimics of RBD can have consequences and some are treatable, such as apnea. Opponents say that patient history is often reliable for diagnosis and polysomnography is expensive. Dr. Postuma's approach is a compromise of sorts: With the relatively rare RBD, “the stakes are high” and he always recommends polysomnography.
Medication may be worthwhile, he added, particularly if a patient has a history of being violent during episodes of RBD.
Disclosures: Dr. Postuma reported having no relevant financial ties.