16. Pattern reversal visual evoked responses – Stimulation patterns revisited

Abstract

To study large check central and peripheral hemisurround stimulus with the more commonly used full and half field stimulus, in the detection of abnormalities in optic neuritis in 21 subjects with multiple sclerosis, and in comparison with 35 control subjects. Black-and-white large (65’) checkerboard PRVEPs were recorded for full field, central field, half field and hemisurround stimulation. Of the 19 female and 16 male healthy participants studied, females had shorter P100 latencies and larger amplitudes than males. In 9 of the 18 patients with VER abnormalities, central fields showed more marked abnormalities than was recorded in the full field response. It was difficult to reliably elicit responses from hemisurround stimulus in patients. In optic neuritis, large check central field stimulation can show a greater extent of abnormality than can be appreciated in full field stimulation alone. Previously reported sex differences with smaller check size were also noted with this method. Our findings show that central fields, even with large check sizes, are a useful adjunct to stimulation protocols in the investigation of optic neuritis and that it is best to use separate normative values for males and females.