Do multimodal evoked potentials add information to MRI in clinically isolated syndromes?

ABSTRACT

The role of multimodal evoked potentials (MMEPs) in establishing multiple sclerosis (MS) diagnosis and prognosis has diminished nowadays. The objective of this article is to evaluate whether MMEPs add information to MRI in identifying patients with higher risk of relapse or development of disability after a clinically isolated syndrome (CIS). Patients who underwent visual, somato-sensory and brainstem auditory evoked potentials (EPs) were identified from a cohort of consecutive CIS. Patients also underwent brain MRI within 3 months of first attack. We analysed time to second attack and to Expanded Disability Status Scale (EDSS) score of 3.0 according to number of Barkhof criteria and number of abnormal MMEPs. A complete study was performed in 245 patients who were followed for a mean of 76.4 months (interquartile range 61 to 96). Seventy-one patients (29%) had the three EPs normal, 115 patients (47%) had one abnormal EP; 40 patients (16%) had two; and 19 patients (8%) had three abnormal EPs. Baseline MRI determined the risk for converting to clinically definite MS and correlated with disability according to previous studies. EPs individually did not modify the risk of conversion or disability. However, the presence of three abnormal EPs increased the risk of reaching moderate disability (hazard ratio 7.0; 1.4-34.9) independently of baseline MRI. In conclusion, in the presence of three abnormal EPs could help identify CIS patients with a higher risk of developing disability, independently of MRI findings. However, the utility of MMEPs is limited by the low percentage of CIS patients having the three abnormal at baseline.