The relation between abnormal behaviors and REM sleep microstructure in patients with REM sleep behavior disorder

Objective: To investigate the temporal relation between rapid eye movement (REM) sleep microstructure (REMs, EMG activity) and motor events in REM sleep behavior disorder (RBD). Methods: Polysomnographic records of eight patients with RBD were analyzed and compared with those of eight sex- and age-matched controls. We examined sleep microstructure for REM sleep with and without REMs and phasic chin EMG activity and their temporal relation to motor events on video. Results: All types of motor events were either more frequent in RBD patients than in controls (P <= 0.007) or present solely in RBD patients. In RBD, major motor events were significantly more frequent during REM sleep with REMs than during REM sleep without REMs (violent, 84.0% vs. 16.0%, P < 0.001 complex/scenic behavior, 78.1% vs. 23.2%, P < 0.001; major jerks, 77.5% vs. 20.3%, P < 0.001), whereas minor motor activity was evenly distributed (54.1%, vs. 45.9%, P = 0.889). Controls showed predominantly minor motor activity with rare myoclonic body jerks. The distribution of motor events did not differ between REM sleep with and without REMs (40.9% vs. 59.1%, P = 0.262). Conclusions: In RBD, major motor activity is closely associated with REM sleep with REMs, whereas minor jerks occur throughout REM sleep. This finding further Supports the concept of a dual nature of REM sleep with REMs and REM sleep without REMs and implies a potential gate control mechanism of REM sleep with REMs for the manifestation of elaborate or violent behaviors in RBD. (c) 2008 Elsevier B.V. All rights reserved.