A survey of the pattern reversal visual evoked response (PRVER) in 1428 consecutive patients referred to a clinical neurophysiology department.

The records of 1428 neurological patients referred to a department of Clinical Neurophysiology for PRVER testing have been reviewed. Half field studies with multichannel recordings were carried out in the majority. 1186 of these patients had a provisional diagnosis of MS; 42% had abnormal PRVERs compared with 25% for those patients who did not have MS. Symmetrical latency increases from stimulation of either eye, interocular latency abnormalities and amplitude abnormalities were as frequent in the non-MS patients as the group with a provisional diagnosis of MS. A small proportion of patients had neurophysiological evidence of field defects; homonymous hemianopias occurred as frequently as "central" defects in the MS group. The PRVER abnormalities are considered in relation to the current models of conduction in demyelinated fibres.