Serial recording of VEPs to different stimuli in multiple sclerosis patients.

VEPs to different spatial frequencies (1,2,4 cycles per degree) and different stimulus configurations (vertical, horizontal gratings and checkerboard) were recorded in 47 Multiple Sclerosis patients and a corresponding group of control subjects. Serial recordings were performed in periods of 1-6 years. We show that the highest diagnostic yield in MS is for VEPs of higher spatial frequency than 1 cpd, and that vertical gratings give reliable results when high spatial frequencies are used, whereas checkerboard stimuli elicit consistent VEPs only when the check size is 30'-15' of arc of visual angle. The use of fine vertical grating patterns dissipates controversies dependent on "W" shaped VEPs.