DISCRIMINATIVE POWER OF VISUAL-EVOKED POTENTIAL CHARACTERISTICS IN MULTIPLE-SCLEROSIS

To investigate the discriminative power of pattern-reversal visual evo ked potential characteristics (peak latencies and amplitude) and to te st whether the addition of visual evoked potential amplitude can incre ase the power of the visual evoked potential in the diagnosis of multi ple sclerosis, we retrospectively studied visual evoked potentials in 59 patients with definite multiple sclerosis and 126 control subjects. Two check sizes (17' and 10') were used. Females had significantly hi gher amplitudes and shorter latencies than males. N80 latency showed a gradual increase and P100 amplitude a decrease with age. P100 latency was stable between the ages of 20 and 55 years but was increased in c hildhood and the elderly. The significance of visual evoked potential peak latencies and amplitude in separating the two groups was investig ated by means of a (multivariate) discriminant analysis. The visual ev oked potential with a pattern of 10' could be measured in 58% of patie nts with multiple sclerosis. The exclusive use of the P100 amplitude i n the discriminant analysis resulted in a percentage of correctly clas sified cases of 84%, whereas for P100 and N80 latency it was 85% and 9 0%, respectively. With the 17' pattern, the N80 latency yielded also a higher correct percentage than did the P100 latency. Although N80 lat ency is, to a greater extent than P100 latency, influenced by age, sex and size of stimulus pattern, when these influences are accounted for , the N80 latency is st more sensitive measure than P100 latency in th e classification of multiple sclerosis. Combined use of latency and am plitude for discriminant analysis yielded no significant improvement o f the percentage of correctly classified cases.