Pattern Reversal and Appearance-Disappearance Responses in MS Patients

Abstract

The contrast reversal response seems to be related to the contrast decrease response (Estevez & Spekreijse 1974). Therefore, the response to the appearance and disappearance of a pattern, which consists of 4 identifiable components probably of different cortical origin, should be a better diagnostic tool for discriminiating patients with possible demyelinating diseases than the response evoked by pattern reversal. We have thus far examined 65 MS patients with both stimulus conditions. On the basis of a 3 SD criterion we tested the latency of the major positive peak of the reversal responses, and the latencies of CI, CII, CIII and the major positive peak of the disappearance component in the appearance-disappearance responses. The detection of an increased latency, particularly for the group diagnosed as definite MS (N = 41), was highest for the appearance-disappearance condition. In addition all patients having an increased latency for the reversal condition also showed an increased latency for the appearance-disappearance condition. The results suggest that the appearance-disappearance stimulus, being more effective in evoking a significant contrast response, should be preferred for clinical diagnosis.