M-H-074 TONIC AND PHASIC MUSCLE ACTIVITY IN REM SLEEP BEHAVIOR DISORDER

Abstract

Introduction and Objectives: REM sleep behavior disorder (RBD) is characterized by the loss of the normal REM sleep skeletal muscle atonia, resulting in complex motor behaviors associated with dream mentation. The polysomnographical hallmarks of RBD include tonic/phasic loss of the muscle atonia of REM sleep (REM sleep without atonia; RWA). However, scoring RWA is not well established. We will describe our methods of scoring RWA and will discuss some unsolved issues of RWA scoring. Materials and Methods: The diagnosis of RBD was made based on the International Classification of Sleep Disorders 2nd criteria. The subjects were 20 consecutive patients (19 male and 1 female, mean age: 67.9±7.8 years) who underwent full PSG. In our RWA scoring based on “The AASM Manual for Scoring 2007”, increased EMG activity was counted separately according to the EMG activity patterns; tonic EMG, phasic pattern, and combined EMG activities. If chin EMG activity was present for more than 50% of each 30-second epoch, that epoch was scored as tonic. Phasic EMG density was scored from the chin EMG and represented the percentage of 3 second mini-epochs containing EMG activity lasting 0.1 to 5 seconds. We calculated the percentage of RWA, tonic REM, phasic and REM density. Results: The mean values of the proportions of REM and RWA as a percentage of total sleep time were 19.7±6.3% and 7.2±4.6%. The mean values of tonic REM percentage and phasic EMG activity during REM sleep were 26.0±19.8% and 18.7±7.9%. Conclusion: Some groups have reported cut off or mean values of RWA to diagnose RBD or to identify a predictor for the development of neurodegenerative diseases. Compared to this data, our tonic REM percentage and phasic activity was low. The causes of differences were unclear. Further investigation including a large scale study population will be necessary to clarify the adequate values.