Motor-Behavioral Episodes in REM Sleep Behavior Disorder and Phasic Events During REM Sleep

STUDY OBJECTIVES: To investigate if sudden-onset motor-behavioral episodes in REM sleep behavior disorder (RBD) are associated with phasic events of REM sleep, and to explore the potential meaning of such an association. DESIGN: Observational review analysis. SETTING: Tertiary sleep center. PATIENTS: Twelve individuals (11 males; mean age 67.6 +/- 7.4 years) affected by idiopathic RBD, displaying a total of 978 motor-behavioral episodes during nocturnal in-laboratory video-PSG. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: The motor activity displayed was primitive in 69.1% and purposeful/semi-purposeful in 30.9% of the motor-behavioral episodes recorded. Sleeptalking was significantly more associated with purposeful/semi-purposeful motor activity than crying and/or incomprehensible muttering (71.0% versus 21.4%, P<0.005). In 58.2% of the motor-behavioral episodes, phasic EEG-EOG events (rapid eye movements REMs, alpha bursts, or sawtooth waves STWs) occurred simultaneously. Each variable (REMs, STWs, alpha bursts) was associated more with purposefullsemi-purposeful than with primitive movements (P<0.05). CONCLUSIONS: Motor-behavioral episodes in RBD were significantly more likely to occur in association with phasic than with tonic periods of REM sleep. The presence of REMs, alpha bursts and STWs was found to be more frequent in more complex episodes. We hypothesize that motor-behavioral episodes in RBD are likely to occur when the brain, during REM sleep, is in a state of increased instability (presence of alpha bursts) and experiencing stronger stimulation of visual areas (REMs).