Combined visual and motor evoked potentials predict multiple sclerosis disability after 20 years

Abstract

Background: The development of predictors of multiple sclerosis (MS) disability is difficult due to the complex interplay of pathophysiological and adaptive processes. Objective: The purpose of this study was to investigate whether combined evoked potential (EP)-measures allow prediction of MS disability after 20 years. Methods: We examined 28 patients with clinically definite MS according to Poser’s criteria with Expanded Disability Status Scale (EDSS) scores, combined visual and motor EPs at entry (T0), 6 (T1), 12 (T2) and 24 (T3) months, and a cranial magnetic resonance imaging (MRI) scan at T0 and T2. EDSS testing was repeated at year 14 (T4) and year 20 (T5). Spearman rank correlation was used. We performed a multivariable regression analysis to examine predictive relationships of the sum of z-transformed EP latencies ( s-EPT0) and other baseline variables with EDSST5. Results: We found that s-EPT0 correlated with EDSST5 (rho=0.72, p<0.0001) and ΔEDSST5-T0 (rho=0.50, p=0.006). Backward selection resulted in the prediction model: E (EDSST5)=3.91–2.22×therapy+0.079×age+0.057× s-EPT0 (Model 1, R2=0.58) with therapy as binary variable (1=any disease-modifying therapy between T3 and T5, 0=no therapy). Neither EDSST0 nor T2-lesion or gadolinium (Gd)-enhancing lesion quantities at T0 improved prediction of EDSST5. The area under the receiver operating characteristic (ROC) curve was 0.89 for model 1. Conclusions: These results further support a role for combined EP-measures as predictors of long-term disability in MS.