Pattern and flash evoked responses in disseminated and selective optic pathway damage.

In multiple sclerosis (MS), an increase in delay in visual evoked responses (VER) may be important, but an earlier change is the behaviour of the wave-shape; amplitude is always lower even in MS patients without subjective visual symptoms, provided not only flash but also pattern stimulation is used. Normal amplitude with pattern stimulation does not necessarily mean normal amplitude with flash stimulation. Combining both stimulation methods, we found lowering of amplitude and change of wave-shape in 100 per cent of cases while latency was increased in only 77 per cent. Flash and pattern VER might be even more pathognomonic in MS than oligoclonal gammaglobulin fractionation on agar, which is positive in 75 per cent of cases. We recommend that subclinical cases of MS should be submitted to full electro-oculographic investigation. Patients with sectoral ischaemic neuropathy and open angle glaucoma (OAG) show the same findings; this emphasizes that the method is not specific for demyelinating diseases, nor selective for papillo-macular bundle involvement, but that VER, considering only its first components, reflects axonal damage somewhere in the visual pathway.