Assessing the risk of early multiple sclerosis in patients with clinically isolated syndromes: the role of a follow up MRI.

OBJECTIVES With increasing evidence that permanent tissue damage occurs early in the course of multiple sclerosis, it is important that treatment trials include patients in the earliest stages of the disease. For many patients with multiple sclerosis the first presentation is a clinically isolated syndrome. Not all patients with a clinically isolated syndrome develop multiple sclerosis, however, and treatment of all such patients would be unwarranted. A single abnormal brain MRI identifies patients at a higher risk for the early development of multiple sclerosis, but current criteria are limited by either poor specificity (T2 lesions) or sensitivity (contrast enhancing lesions). The aim of the study was to assess the positive predictive value, sensitivity, and specificity of MRI indices for the development of multiple sclerosis after 1 year from two MRI examinations obtained 3 months apart. METHODS MRI examinations were performed in 68 patients with a clinically isolated syndrome, with a clinical assessment after 1 year. RESULTS Contrast enhancing lesions at both time points were the most predictive indices for developing multiple sclerosis (positive predictive value 70%) but had low sensitivity (39%). The combination of T2 lesions at baseline with new T2 lesions at follow up had the best overall positive predictive value (53%), sensitivity (83%), and specificity (76%). In patients with T2 lesions at baseline, the presence or absence of new T2 lesions at follow up significantly altered the risk of multiple sclerosis within 1 year (55% and 5% respectively, p<0.001). Multiple sclerosis also developed in 10% of patients with a normal baseline MRI. CONCLUSIONS Serial imaging in patients with clinically isolated syndromes improved the positive predictive value, sensitivity, and specificity of MRI for the development of early multiple sclerosis and also identified patients at a lower risk of early multiple sclerosis than would have been expected from their abnormal baseline MRI. Selection of patients with clinically isolated syndromes for therapeutic intervention or clinical trials may benefit from serial MRI, to target those at greatest risk of early development of multiple sclerosis.