Critical frequency of photic driving in the diagnosis of multiple sclerosis. A comparison to pattern evoked responses.

Patients with known or suspected multiple sclerosis (MS) were tested for abnormalities in visual evoked potentials. We compared the critical frequency of photic driving (CFPD) with pattern reversal visual evoked potentials (PVER). We found the CFPD to be somewhat more sensitive than PVER for detecting abnormalities in the visual pathways of patients with MS. When used together, the two were complementary, each fining abnormalities that the other missed. When evaluating patients with MS with evoked potentials, both PVER and CFPD should be tested.