The occipital alpha rhythm related to the "migraine cycle" and headache burden: a blinded, controlled longitudinal study.

OBJECTIVE: Neurophysiological studies have shown a fluctuating neural dysfunction in migraine. This pathophysiological feature has not previously been investigated by quantitative electroencephalography (QEEG). The alpha rhythm is especially interesting, because it is influenced by ischemia and neuronal dysfunction within the posterior circulation area.
METHODS: We investigated alpha peak frequency, variability, peak power and asymmetry in 41 migraineurs and 32 controls. Electroencephalography (EEG) was recorded on three random days and retrospectively classified as preattack, attack, postattack or interictal, based on the patient's headache diaries. We also searched for correlations between alpha rhythm parameters and disease duration, attack duration, attack frequency, pain intensity and photophobia.
RESULTS: Peak frequency reduction correlated with increasing disease- and attack duration. Frequency variability increased before the attack, while peak power increased during the attack. Alpha peak width, peak frequency and peak power were similar for migraineurs and controls in the interictal period.
CONCLUSION: The accumulated burden of migraine caused slight alterations in the physiology of the visual cortex. Small alpha rhythm changes were observed along the migraine cycle. SIGNIFICANCE: This is a longitudinal, controlled study. It is the first to report changes in alpha rhythm with increased migraine load, even when the QEEG is not influenced by recent or imminent attacks.