High risk of early conversion to multiple sclerosis in clinically isolated syndromes with dissemination in space at baseline.

INTRODUCTION: Multiple sclerosis (MS) usually presents at onset with a clinically isolated syndrome (CIS). According to 2010 McDonald criteria, a diagnosis of MS can be made if CIS patients satisfy clinical/MRI criteria of both dissemination in time (DIT) and space (DIS). OBJECTIVE: The aim of this study was to analyze the follow-up data and possible prognostic factors of CIS patients satisfying DIS MRI criteria. PATIENTS AND METHODS: We performed a retrospective, multicenter study across 2 Italian centers. Clinical, MRI, and laboratory assessments were performed according to real-life clinical workup. RESULTS: Out of the 137 enrolled patients, during a median follow-up time of 3.1years, 116 (84.7%) converted to MS with the large majority (78.4%) of the converters developing MS within 1year. In multivariate analysis, baseline predictors of an earlier conversion were a cerebellar/brainstem CIS (HR 2.00, 95% CI: 1.3-3.0, p=0.001) and the presence of all the Barkhof-Tintore MRI criteria (HR 1.67, 95% CI: 1.1-2.6, p=0.028). CONCLUSIONS: Patients with CIS and DIS are at very high risk of an early conversion to MS. The onset with cerebellar/brainstem symptoms and the evidence of a higher MRI lesion load at baseline are the strongest independent predictors of an early conversion to MS.