Abstract
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. The polysonographical hallmarks of RBD include tonic/phasic loss of the skeletal muscle atonia of REM sleep (REM sleep without atonia; RWA), and the International Classification of Sleep Disorders 2nd edition (ICSDF-2) requires this finding of polysomnography (PSG) in the diagnosis of RBD. However, a scoring rule for RWA is not well established. We describe our methods of a scoring rule for RWA and some unsolved issues for RWA scoring were discussed.
Methods: The subjects were 10,745 consecutive patients who presented with sleep and/or wake problems at our sleep center between April 1998 and March 2006. Diagnosis of RBD was made based on ICSD-2 criteria. Our original analysis for RWA was that each page of REM sleep is marked either tonic or atonic (tonic=50% of the page or more is occupied by EMG activity). In our new RWA scoring, increased EMG activity was counted separately according to EMG activity patterns; tonic EMG, phasic pattern, and combined EMG activities. Date of 13 patients who underwent PSG with the same digital polygraph among patients with RBD were used for analyze according to new scoring methods, and we also calculated %tonic REM and REM density in 13 patients.
Results: Sixty-seven patients (0.6%) were diagnosed as having RBD. There was a strong male predominancy (85.1%). In 13 of 67 patients, there were no differences between the original and the new methods in %REM and %RWA. Patients with Parkinson disease had increased tonic chin EMG activity during REM sleep (39.5±17.1% vs. 22.3±14.6%) and REM density (60.9±11.0% vs. 44.6±11.9%) compared to idiopathic RBD patients, however it was not statically significant.
Conclusions: The pathogenesis of RBD is still unclear; therefore, detailed analysis of RWA give hints for finding predictors for the development of neurodegerative disease and for establishing its diagnostic classification.
