The prevalence of epileptic seizures in multiple sclerosis in a large tertiary hospital in Australia

RATIONALE: To determine the prevalence of epileptic seizures in multiple sclerosis (MS) at an Australian tertiary hospital and to define their clinical features. METHODS: We retrospectively analysed adult patients at the Royal Melbourne Hospital electronically identified to have ICD codes for MS and seizures and/or epilepsy between 1996 to 2019, utilising paper and electronic-based records. RESULTS: Of the 2,125 MS patients identified, 16 (0.75%) experienced epileptic seizures during a mean follow-up period of 12.9 years. Median age of MS diagnosis (SD) was 38 (9.3) years. Four patients had relapsing remitting MS (25%), 10 secondary progressive MS (63.5%), and 2 primary progressive MS (12.5%). More than two-thirds of patients had seizure onset following the diagnosis of MS, and the majority of these had advanced disease (approximate EDSS >6) at the time of seizure onset. Focal onset-seizures occurred in 87.5% of patients with seizures. CONCLUSION: The estimated prevalence of seizures in our cohort was lower than in previous studies (0.75 vs 2–4%). In most cases, seizures occurred after the diagnosis of MS in the context of advanced disease. Further studies are required to determine if MS disease modifying treatments reduce the risk of seizures in this cohort.