Abnormal Ocular Movement in the Early Stage of Multiple-System Atrophy With Predominant Parkinsonism Distinct From Parkinson's Disease

Background and Purpose The eye-movement examination can be applied as a noninvasive method to identify multiple-system atrophy (MSA). Few studies have investigated eye move-ments during the early stage of MSA with predominant parkinsonism (MSA-P). We aimed to determine the characteristic oculomotor changes in the early stage of MSA-P.Methods We retrospectively selected 17 patients with MSA-P and 40 with Parkinson's disease (PD) with disease durations of less than 2 years, and 40 age-matched healthy controls (HCs). Oculomotor performance in the horizontal direction was measured in detail using videonys-tagmography.Results We found that the proportions of patients with MSA-P and PD exhibiting abnormal eye movements were 82.4% and 77.5%, respectively, which were significantly higher than that in the HCs (47.5%, p<0.05). Compared with HCs, patients with MSA-P presented significantly higher abnormal proportions of fixation and gaze-holding (17.6% vs. 0%), without-fixation (47.1% vs. 0%), prolonged latency in reflexive saccades (29.4% vs. 5.0%), memory-guided sac-cades (93.3% vs. 10.0%), and catch-up saccades in smooth-pursuit movement (SPM, 41.2% vs. 0) (all p<0.05). Compared with those with PD, patients with MSA-P presented a signifi-cantly higher proportion of catch-up saccades in SPM (41.2% vs. 2.5%, p<0.001).Conclusions MSA-P presented the characteristic of catch-up saccades in SPM in the early stage, which may provide some value in differentiating MSA-P from PD.