Assessment of the movements in REM sleep behaviour disorder (RBD) patients during the rapid ocular movement in REM sleep

Abstract

REM sleep behaviour disorder is characterized by the intermittent loss of REM sleep atonia and by the appearance of motor activity associated with dream mentation. Although the characteristic RBD movements are well known there are few descriptions of the relationship between these movements and the typical rapid eye movements occurring during REM sleep. To assess the occurrence, frequency and characteristics of REM sleep movements in RBD patients and their association with rapid ocular movements. Eighteen consecutive patients with RBD underwent synchronized audiovisual polysomnography recording the mentalis muscle, bilateral biceps brachii and anterior tibialis. Eleven patients with sleep disordered breathing effectively treated with CPAP, matched for age and sex served as controls. We analyzed EMG activity associated to the movements or vocalization detected in the video and studied if they occurred simultaneously with the bursts of rapid ocular movements (RemB). Eighteen RBD patients, 16 with Parkinson disease and 2 with idiopathic RBD (16 men; mean age 71 years) were included. Mean percentage of REM sleep was 7.64% ± 4.3 in patients and 9.27 % ± 5 in controls. In RBD: for upper extremities the mean number of movements associated with RemB was 12.9 and 19.7 for those not associated with RemB (P: 0.2). For body jerking these values were 5.7 and 1.9 respectively (P: 0.1); for complex movements 4.9 and 2.7 (P: 0.4); for mouth movements 2.7 and 3.6 (P: 0.4), for neck myoclonus 1.05 and 1.0 (P: 0.65); and for vocalization 0.7 and 0.6 (P: 0.2). RBD patients had significantly more movements during REM than controls (P < 0.018). In all the muscle groups analyzed there were no significant differences between the number of movements associated with RemB and those occurring independent of RemB (P > 0.1). The frequency of the involuntary movements during REM sleep in RBD patients does not depend on the presence of rapid ocular movements of REM sleep. We thank Dr. Joan Santamaria for his scientific supervission.