A motor signature of REM sleep behavior disorder.

BACKGROUND

The purpose of this study was to determine if there was a common pattern in movements during REM sleep behavior disorder (RBD).

METHODS

We blindly compared video-monitored movements during RBD (n = 136 clips) and wakefulness/arousal (n = 53 clips) in patients with Parkinson's disease (n = 29) and without parkinsonism (idiopathic RBD, n = 31; narcolepsy, n = 5).

RESULTS

The scorers accurately guessed the sleep/wake stage of 94% of video clips. Compared with wake movements, RBD movements were faster and more often repeated, jerky, and pseudohallucinatory, not self-centered, never associated with tremor, and rarely involved the environment in an appropriate manner. A specific posture of the hand (limp wrist with flexed digits) during grasping movements was evidenced during RBD in 48% of patients, reminiscent of hand-babbling in babies.

CONCLUSIONS

These characteristics of movements were found in the 3 conditions (Parkinson's disease, idiopathic RBD, and primary narcolepsy), delineating a common motor signature of RBD.