Positional nystagmus in multiple sclerosis: a cross-sectional case–control study

Oculomotor dysfunction is common in multiple sclerosis (MS), yet central positional nystagmus (CPN) remains insufficiently characterised. As a manifestation of central vestibular pathway dysfunction, CPN may reflect subtle brainstem or cerebellar involvement. This study aimed to evaluate the occurrence and characteristics of CPN in MS using videonystagmography (VNG). In this observational cross-sectional study, 46 patients with definite MS (Expanded Disability Status Scale [EDSS] ≤ 6.5) and 46 age- and sex-matched healthy controls underwent standardised positional testing (Dix–Hallpike, Pagnini–McClure, and Yacovino manoeuvres) recorded with VNG. MS patients were stratified by EDSS severity. Positional nystagmus was assessed for occurrence, direction, temporal pattern, canal-plane concordance, latency, and slow-phase velocity. Group differences were analysed using multivariable logistic regression adjusted for age and sex. Positional nystagmus was identified in 24/46 MS patients (52%) compared with 5/46 controls (11%). MS patients had significantly higher odds of exhibiting positional nystagmus than controls (odds ratio 9.06, 95% confidence interval 3.22–30.2; p < 0.001). Increased occurrence was observed across all positional manoeuvres. No significant differences were detected across EDSS severity strata, and age and sex were not significant predictors. Compared with controls, positional nystagmus in MS showed greater heterogeneity, higher slow-phase velocity, broader directional patterns, frequent canal-plane non-concordance. CPN was commonly observed in this MS cohort. These findings support the feasibility of VNG-based positional testing in MS and suggest that CPN may reflect subtle infratentorial dysfunction, although its clinical relevance remains uncertain. Longitudinal studies integrating clinical and imaging data are warranted.