EEG and topographic frequency analysis in common and classic migraine.

Electroencephalographic (EEG) changes occurring in patients with migraine have received much attention. However, almost equal number of reports indicate the predominance of normal and abnormal findings. We studied the EEG in symptom-free, otherwise healthy, unmedicated 18-28 year-old patients: 22 with common migraine, 20 with classic migraine, and 20 age-matched controls. The routine EEG findings in the three groups revealed mild non-specific slowing in 2 (9%), 3 (15%) and 2 (10%), respectively. Simultaneously, topographic EEG mapping and frequency analysis were performed in 13 consecutive patients with common migraine, 10 patients with classic migraine and 11 age-matched controls. EEG mapping showed minimal regional differences with lower power in the alpha range in patients with eyes closed. The peak alpha power, as well as its reactivity, were lower among patients than controls. This difference reached statistical significance only for patients with classic migraine versus controls in the left occipital region. Patients also had slightly faster peak alpha frequency. No frank right-left asymmetry was observed in the peak alpha power, neither among the controls, nor the patients. All the findings were rather minor. They may suggest some difference in the posterior background activity in the EEG in migraine patients as compared to the controls, but are not useful in differentiating migraine from non-migraine patients.