Objective: To investigate the value of oculomotor function assessment in differentiating Parkinson’s disease (PD) from multiple system atrophy with predominant parkinsonism (MSA-P).

Background: PD and MSA-P share overlapping motor phenotypes in the early and intermediate stages, making clinical differentiation challenging. The two disorders, however, involve distinct patterns of neurodegeneration affecting basal ganglia, cerebellar, and brainstem networks that are integral to oculomotor control. Detailed assessment of visual and vestibular oculomotor function may therefore reveal disease-specific abnormalities and aid differential diagnosis.

Method: Thirty-nine patients with PD and eleven patients with MSA-P were consecutively enrolled from Shaanxi Provincial People’s Hospital. All participants underwent vestibular and visual oculomotor examinations using video nystagmography, including spontaneous nystagmus testing, saccade testing (ST), and smooth pursuit testing (SPT). Oculomotor parameters were recorded and compared among PD patients, MSA-P patients, and healthy controls.

Results: No spontaneous nystagmus was observed in the PD group, whereas vertical downbeat nystagmus was detected in one patient with MSA-P. There were no significant differences in ST or SPT velocities among the PD, MSA-P, and control groups (P > 0.05). Compared with controls, both PD and MSA-P patients showed significantly prolonged ST latency, reduced ST accuracy, and decreased SPT gain (P < 0.05), while no significant differences were found between the PD and MSA-P groups for these parameters (P > 0.05). The proportion of abnormal SPT patterns was significantly higher in the MSA-P group than in the PD group (81.8% vs. 59.0%, P < 0.05). Further analysis revealed that abnormal SPT patterns in MSA-P patients predominantly manifested as catch-up saccades, whereas anticipatory saccades were more common in PD patients (P < 0.05).

Conclusion: Visual oculomotor function assessment, particularly analysis of SPT patterns, provides additional value in the differential diagnosis of PD and MSA-P and may serve as a useful auxiliary tool in clinical practice.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/differential-oculomotor-patterns-in-parkinsons-disease-and-multiple-system-atrophy-with-predominant-parkinsonism/