Quantitative assessment of oculomotor function by videonystagmography in 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 < 0.05). No oculomotor deficits were correlated with age, age of onset, sex, disease duration, or Unified Multiple System Atrophy Rating Scale (USMARS) (all r < 0.25, P > 0.1).

An extremely high incidence of oculomotor impairments could be observed using VNG in both the MSA-C and MSA-P subtypes, although there were some differences between them.

A comprehensive oculomotor examination could serve as a valuable tool in the diagnostic workup of patients with MSA.