In addition to standard pattern-reversal VEPs, the motion-onset VEPs were examined in 50 patients with acute unilateral retrobulbar neuritis (RN) and in 187 patients with possible or definite multiple sclerosis (MS). In MS patients (without sign or history of RN), the results of both types of VEPs correlated only partially. 26.2% of them displayed changes only in the motion-onset VEPs having the pattern-reversal VEPs completely normal. That is why we suppose that the magnocellular system (tested by motion-onset VEPs) can be affected by demyelination separately. In 28 patients with "pure" RN (without any other sign indicating demyelination disease) the always abnormal pattern-reversal VEPs were accompanied by delayed motion-onset VEPs in only 28.6% of patients. In contrast, much higher rate--68.2%--of delayed motion-onset VEPs was found in the 22 RN patients simultaneously suspected of MS These results indicate that RN affects predominantly the parvocellular visual system (tested by reversal VEPs). Distinct latency changes of the motion-onset VEP's in RN patients seem to signal a linkage between RN and demyelination.

Department of Physiology Medical Faculty Charles University Hradec Králové