Quantitative assessment of oculomotor function by videonystagmography in multiple system atrophy

•Extremely high incidence of oculomotor impairments observed using videonystagmography.•Comprehensive oculomotor examination aids in the diagnosis of multiple system atrophy.•Abnormal eye movements detected in the early stages of multiple system atrophy. To quantitatively assess oculomotor impairments in multiple system atrophy (MSA) and to explore their correlation with clinical characteristics. We recruited 45 patients with MSA, including 21 with dominant ataxia (MSA-C), 24 with dominant parkinsonism (MSA-P), and 40 age-matched healthy controls. Detailed oculomotor performance in the horizontal direction was measured using videonystagmography (VNG). We found that the proportion of abnormal eye movements in patients with MSA was 93.3% (37.7%, 51.1%, 73.3%, 71.1%, and 37.8% on fixation and gaze-holding, without fixation, saccade, smooth pursuit, and optokinetic nystagmus tests, respectively). Patients with MSA-C showed significantly lower gains in smooth pursuit test and optokinetic nystagmus test, and a higher incidence of hypermetria in the saccade test than patients with MSA-P (all P