Assessing visual pathway function in multiple sclerosis patients with multifocal visual evoked potentials.

Multifocal visual evoked potentials provide a topographic measure of visual response amplitude and latency. The objective of this study was to evaluate the sensitivity and specificity of the multifocal visual evoked potential technique in detecting visual abnormalities in patients with multiple sclerosis. Multifocal visual evoked potentials were recorded from 74 patients with multiple sclerosis with history of optic neuritis (MS-ON, n = 74 eyes) or without (MS-no-ON, n = 71 eyes), and 50 normal subjects (controls, n = 100 eyes) using a 60-sector pattern reversal dartboard stimulus (VERIS). Amplitude and latency for each sector were compared with normative data and assigned probabilities. Size and location of clusters of adjacent abnormal sectors (p < 0.05) were examined. Mean response amplitudes were (+/- SE) 0.39 +/- 0.02, 0.53 +/- 0.02, and 0.60 +/- 0.01 for MS-ON, MS-no-ON, and control groups, respectively, with significant differences between all groups (p < 0.0001). Mean latencies (ms; +/-SE relative to normative data) were 12.7 +/- 1.3 (MS-ON), 4.3 +/- 1.1 (MS-no-ON), and 0.3 +/- 0.4 (controls); group differences again significant (p < 0.0001). Half the MS-ON eyes had clusters larger than five sectors compared with 13% in MS-no-ON and 2% in controls. Abnormal sectors were distributed diffusely, although the largest cluster was smaller than 15 sectors in two-thirds of MS-ON eyes. Cluster criteria combining amplitude and latency showed an area of 0.96 under the receiver operating characteristic curve, yielding a criterion with 91% sensitivity and 95% specificity. We conclude that the multifocal visual evoked potential provides high sensitivity and specificity in detecting abnormalities in visual function in multiple sclerosis patients.