Quantitative EEG power and asymmetry increase 36 h before a migraine attack.

The aim was to estimate ictal, pre- and postictal brain function changes in migraine in a blinded paired quantitative EEG (QEEG) study. EEG recordings (n = 119) from 40 migraineurs were retrospectively classified as ictal, interictal, preictal or postictal. delta, theta, alpha and beta power, and hemispheric asymmetry in frontocentral, temporal and occipitoparietal regions were calculated from artefact-free EEG. Power and power asymmetry were calculated for two time-windows, 36 and 72 h before/after the attack, and compared with the interictal values. Frontocentral delta power increased (P = 0.03), whereas frontocentral theta and alpha power tended to increase (P < 0.09) within 36 h before the next attack compared with the interictal period. Occipitoparietal (alpha and theta) and temporal (alpha) power were more asymmetric before the attack compared with the interictal baseline (P < 0.04). Ictal posterior alpha power increased slightly (P = 0.01). Postictal power and power asymmetry were not significantly different from interictal baseline. EEG activity seems to change shortly before the attack. This suggests that migraineurs are most susceptible to attack when anterior QEEG delta power and posterior alpha and theta asymmetry values are high. Changed activity patterns in cholinergic brainstem or basal forebrain nuclei and thalamo-cortical connections before the migraine attack are hypothesized.