Visual contrast processing in migraine

Some migraine sufferers report certain visual patterns can reliably trigger a migraine attack, such as high contrast striped patterns or flickering li ghts. Differences between people with and without migraine on tasks that in volve these patterns have been attributed to abnormal cortical processing i n migraine, although the locus and extent of the abnormality remains unclea r, as is any relationship between impairment on various visual tasks. In th is study 58 migraine sufferers and 61 control subjects participated in thre e visual tasks involving striped patterns. One assessed pattern sensitivity with high contrast patterns, the second detection thresholds for low contr ast patterns and the third supra-threshold contrast scaling. With each meas ure, the performance of migraine sufferers as a group differed to the perfo rmance of non-migraine control subjects. There were no significant differen ces between the migraine subgroups when classified according to the presenc e or absence of aura. Cross-correlating the results from the three tasks, h owever, revealed consistent associations: impaired or extreme responses on one task were associated with impaired or extreme responses on the others. There were no overall effects due to migraine duration, the frequency of mi graine attacks or the time since the last attack. These results are discuss ed in the context of visually induced migraine, proposed causes of abnormal cortical function in migraine and the prospects for developing clinically useful tests of visual function.