Association between clinical conversion to multiple sclerosis in radiologically isolated syndrome and magnetic resonance imaging, cerebrospinal fluid, and visual evoked potential: follow-up of 70 patients.

BACKGROUND Subclinical demyelinating lesions may occur in the brains of asymptomatic individuals. OBJECTIVE To describe the clinical and magnetic resonance imaging (MRI) follow-up of patients with subclinical demyelinating lesions that fulfill the Barkhof/Tintoré criteria. DESIGN Prospective study. SETTING University-affiliated teaching hospitals. PATIENTS Fifty-three women and 17 men with subclinical demyelinating lesions (mean age, 35.63 years). MAIN OUTCOME MEASURES Cerebrospinal fluid, MRI, and visual evoked potential measurements. METHODS All patients underwent their first brain MRI for various medical problems that were not suggestive of multiple sclerosis (MS). The patients' physicians proposed that they undergo paraclinical studies (blood, cerebrospinal fluid, and visual evoked potential analysis) and follow-up with MRI. RESULTS Twenty-three patients (33%) had clinical conversion: 6 to optic neuritis, 6 to myelitis, 5 to brainstem symptoms, 4 to sensitive symptoms, 1 to cerebellar symptoms, and 1 to cognitive deterioration. The mean time between the first brain MRI and the first clinically isolated syndrome was 2.3 years (range, 0.8-5.0 years). Twelve patients had been treated with immunomodulators after a clinically isolated syndrome. Examination of pejorative markers for clinical conversion showed that sex, number of T2 lesions, presence of oligoclonal bands, and IgG index were not statistically different in patients with MS determined by MRI compared with clinically definite MS. Visual evoked potential abnormalities, young age, and gadolinium enhancement on follow-up MRI were more frequent in clinically definite MS than in MS determined by MRI. CONCLUSIONS In this cohort, we determined the rate of clinical conversion (33%) during a mean follow-up of 5.2 years. To our knowledge, this is the first clinically isolated syndrome cohort with preclinical follow-up. Early treatment of these patients with MS determined by MRI should be discussed.