Video Head Impulse Testing in Relapsing Remitting Multiple Sclerosis: Evaluation of Canal Gains, Asymmetry, and Corrective Saccades with Cerebellar Lesions

This study aimed to compare video head impulse test (vHIT) metrics in relapsing–remitting multiple sclerosis (RRMS) versus controls, test differences by cerebellar MRI status within RRMS, and explore clinical/MRI correlates of corrective saccades.

Single-center prospective study including 35 adults with RRMS and 35 age-/sex-matched controls. Disability was quantified by EDSS; a blinded neuroradiologist classified cerebellar involvement. The MS cohort was categorized into two subgroups according to the occurrence of cerebellar lesions. Each group participated in a vHIT to assess VOR gain.

RRMS participants had low disability (mean EDSS 0.95). Compared with controls, RRMS showed lower VOR gain in the right anterior/posterior, left posterior, and left lateral canals and higher asymmetry across RALP, LARP, and lateral planes (p=0.012, 0.024, <0.001). Corrective saccades differed between groups only in the left anterior canal (p=0.025). Within RRMS, cerebellar-positive versus cerebellar-negative subgroups did not differ for gain or asymmetry (all p>0.05); corrective-saccade prevalence was similar (33.3% vs 35.0%; chi-square p=0.918). In regression, cerebellar involvement, relapse count, EDSS, and disease duration were not associated with recurrent corrective saccades.

vHIT reveals canal-selective gain reductions and elevated asymmetry in patients with mildly disabled RRMS, but these abnormalities do not differ by cerebellar MRI status.