Clinical, Radiological, and Prognostic Features of Pediatric Clinically Isolated Syndrome and Risk of Conversion to Multiple Sclerosis: A Single-center Cohort Study

Abstract Pediatric clinically isolated syndrome (CIS) is the first inflammatory demyelinating event of the central nervous system and may progress to multiple sclerosis (MS). Data on relapse patterns and predictors of MS conversion in children remain limited. To evaluate the clinical, radiological, and immunological characteristics of pediatric CIS and to identify factors associated with relapse and final diagnosis. In this retrospective cohort study, pediatric patients (3–18 years) presenting with a first demyelinating event between 2011 and 2021 were included if follow-up was ≥6 months. Clinical, MRI, laboratory, and immunological data were reviewed. Group comparisons were performed using non-parametric tests. Relapse predictors were explored using penalized logistic regression. A total of 26 patients were included (mean age 13.2 ± 3.2 years; 14 male). Optic neuritis was the most common presentation (57.7%). During a mean follow-up of 1.28 ± 1.31 years, 30.8% were diagnosed with MS. Relapse occurred in 42% of patients and differed significantly across diagnostic groups (p < 0.001). EDSS scores improved significantly at 3 months (mean reduction 1.79 ± 0.92; p < 0.001). NMO/MOG seropositivity was associated with final diagnosis (p = 0.015). Oligoclonal band positivity showed an increased odds ratio for relapse (OR 7.22) but was not statistically significant. No independent relapse predictors were identified. Approximately one-third of pediatric CIS patients converted to MS. Relapse patterns differed across diagnostic groups. Although immunological markers may indicate increased relapse risk, larger prospective studies are required to define independent predictors of MS conversion.