S26-3 Clinical application of PSG to REM sleep behavior disorder and periodic leg movements during sleep

Abstract

Periodic leg movements during sleep (PLMS) is frequently observed in rapid eye movement (REM) sleep behavior disorder (RBD) especially during REM sleep period. We made a series of studies for investigating the clinical significance and the underlying mechanism of PLMS in RBD. Consecutive 54 patients with idiopathic RBD without PLMS (iRBD w/o PLMS, 65.9±6.9 yrs), 27 patients with iRBD with PLMS (iRBD-PLMS, 67.7±7.1 yrs), and 31 patients with idiopathic PLMS (iPLMS, 63.5±5.9 yrs) were enrolled. Scores of Epworth Sleepiness Scale (ESS) were compared among the three patients groups. PLMS index, mean duration of PLMS, and inter-PLMS interval were calculated during both NREM sleep period and REM sleep period respectively, and compared among the three patient groups. Correlation analysis between ratio of PLMS related arousal index to PLMS index (PLMAI/PLMI) and proportion of REM sleep without atonia to total REM sleep (RWA/REM) were performed in the iRBD-PLMS group. The associated factor for the presence of PLMS during REM sleep period was also investigated in the subject iRBD group. In 15 out of iRBD-PLMS patients, effectiveness of the treatment with pramipexole, a dopamine agonst, was also evaluated. The iRBD-PLMS group showed significantly lower ESS score than the iPLMS w/o PLMS group did. PLMAI/PLMI was negatively correlated with RWA/REM. The iRBD-PLMS group showed significantly higher PLMS index, longer duration of PLMS, and shorter inter-PLMS interval than the iPLMS group did. RWA/REM appeared as a significantly associated factor for the presence of PLMS during REM sleep period among the iRBD patients. However, pramipexole treatment did not show a statistical decrease in the amount of PLMS. Conclusions: RWA could be associated with attenuation of arousal response to PLMS possibly leading to lower daytime sleepiness in iRBD. Our result impresses that PLMS during this sleep period could become an disease process marker of iRBD.