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[Demographic characteristics of RBD patients at a sleep center--with special emphasis on neurodegenerative diseases as the background condition].

UNLABELLED
REM sleep behavior disorder (RBD) is characterized by loss of normal REM sleep skeletal muscle atonia, resulting in complex motor behaviors associated with dream mentation. Reports have been accumulated showing an association of RBD and neurodegenerative diseases. However, in Japan, no data has been available about demographic features of RBD in a large patient population. We describe demographic characteristics of RBD patients presenting to our sleep center with special emphasis on association of RBD and neurodegenerative diseases.


METHODS
The subjects were consecutive 10,745 patients who presented with sleep and/or wake problems at our sleep center from April 1998 to March 2006. Diagnosis of RBD was made based on ICSD-2 criteria. Medical and sleep histories with complementary information from family members, and findings of neurological examination were assessed retrospectively from the notes of RBD patients.


RESULTS
Sixty-seven patients (0.6%) were diagnosed as having RBD. There was strong male predominancy (85.1%). The onset of RBD symptoms was at 61.4+/-8.8 years of age. Neurological symptoms and signs were present in twelve (17.9 % of RBD patients) when they firstly came to our sleep center: 4 patients with Parkinson disease, 4 with multiple system atrophy and 1 with probable dementia with Lewy body. Thirteen patients (43.3%) were aware of olfactory impairment when inquired (out of 30 patients). Clonazepam was administered in 29 patients, and 21 (72.4%) responded well.


CONCLUSION
Our study showed the similar demographic characteristics of RBD to what was shown in the previous large case series. Although the association between RBD and neurodegenerative diseases was not so strong in our cases, it may be mainly because our sleep center was not run in the domain of neurology department and we could not vigorously detect the possible coexistence of neurodegenerative disease. The pathogenesis of RBD is still unclear; therefore, neurologists and sleep specialists need to collaborate in following up RBD patients to confirm whether they are at higher risk for developing a neurodegenerative disease.