Revisiting the impact of REM sleep behavior disorder on motor progression in Parkinson's disease

Estimation of progression in Parkinson's disease (PD) is useful to guide clinical decisions and to enable patients to plan and manage their life with PD. Rapid eye movement (REM) sleep behavior disorder (RBD) and REM sleep without atonia (RWA) are recognized as early harbingers of neurodegeneration and may precede motor symptoms by years. However, their impact on motor progression remains elusive.

We retrospectively analyzed polysomnographic and clinical data of 59 PD patients, grouping them into patients with RBD (n = 15), RWA (n = 22) and those with normal muscle atonia (n = 22). We compared the three groups with regard to motor progression, defined as changes in Unified Parkinson's Disease Rating Scale (UPDRS) III values per year, and selected PD specific characteristics.

Motor disability at first visit and time interval between first and last visits were similar between groups. We observed a significantly faster motor progression in PD patients with RBD and RWA than in those with preserved REM sleep atonia.

Our findings suggest that impaired muscle atonia during REM sleep might represent a marker of faster motor progression in PD.