REM sleep behavior disorder in Parkinson disease: Association with abnormal ocular motor findings

Background: The anatomical substrates associated with generalized muscle atonia during REM sleep are located on the pontine tegmentum and medial medulla oblongata. We examined whether patients with REM sleep behavior disorder (RBD) have abnormal ocular movements suggesting brainstem or cerebellar dysfunction in Parkinson's disease (PD). Methods: Cross-sectional survey for the existence of RBD and abnormal ocular movements. Ocular movements were examined by video-oculography (VOG). Results: A total of 202 patients were included in this study. One hundred and sixteen (57.4%) of the 202 patients have clinically probable RBD, and 28 (24.1%) of the 116 with clinically probable RBD patients had abnormal VOG findings suggesting brainstem or cerebellar dysfunction; whereas 86 of the 202 patients did not have clinically probable RBD, and only 7 (8.1%) of the 86 patients had abnormal VOG findings suggesting brainstem or cerebellar dysfunction (P= 0.001). Conclusion: This study suggests that the presence of RBD is associated with more severe or extensive brainstem pathology or different distribution of pathology in PD.