Thirty eight patients with a history of diet-induced migraine were studied with recording of clinical responses, electro-encephalography in resting state, in response to photic stimulation, and to hyperventilation and visual evoked potentials. Tests were carried out on an initial baseline day and on a second day, after challenge with chocolate, red wine, cheese, and fasting.

Lateralized headache occurred in sixteen subjects (42%), four with scintillating scotomata. Electroencephalograms were abnormal on Day I and/or Day 2 in twelve subjects (32%), most abnormalities being non-specific slow waves. In three cases there were paroxysmal features.

Electroencephalographic response to hyperventilation was calibrated and was found to be exaggerated in eight subjects (21%) on either Day 1 or Day 2; such response was not related to the occurrence of a headache. Photic simulation showed high frequency driving response (so called “H” response) in all 16 individuals who developed headache but in only 14 out of 22 (64%) who did not (p<0.01). Pattern reversal visual evoked responses were normal and failed to show any difference in latency or amplitude between headache responders and non-responders.