DETECTING INTERNUCLEAR OPHTHALMOPLEGIA IN MULTIPLE SCLEROSIS: PREVALENCE IN A POPULATION-BASED COHORT

Background and Aims: Internuclear ophthalmoplegia (INO) is a common eye movement disorder in multiple sclerosis (MS). INO can be detected more reliably by infrared oculography than by physical examination. Methods for diagnosing INO with infrared oculography in patients with MS and the association between INO and MS characteristics still need confirmation. Methods: We investigated INO prevalence in a cross-sectional population-based cohort of MS patients with the same birth year (Project Y). Thresholds for the versional dysconjugacy index (VDI), assessed by infrared oculography, were used to detect INO. Clinical characteristics, visual functioning and visual complaints were compared between MS patients with and without INO. Results: Two-hundred-twenty MS patients and 110 healthy controls were included. INO was detected in 53 (24%) of the MS patients. Nineteen (15%) healthy controls showed VDI values surpassing the threshold for INO. INO was associated with male sex (43% versus 22%, p = .002), greater disability (expanded disability status scale score 4.0 versus 3.5, p = .044), worse cognition (symbol digit modalities test score 49 versus 53, p = .046) and worse arm function (nine hole peg test time 22.20 versus 21.41 sec; p = .015) in MS patients. INO was not associated with disease duration, visual function or visual complaints. Conclusions: INO is prevalent among MS patients and related to the clinical characteristics of MS. This highlights the relevance of assessing INO in MS using quantitative oculography. Validation of INO detection with oculography across MS patients with varying demographic characteristics is needed