Preliminary EEG and low resolution electromagnetic tomography correlates of migraine therapy

In this preliminary single case study resting-state EEG in a patient with migraine was recorded during a migraine attack with and without therapy and during a migraine-free day with no other complaints. Spectrotemporal dynamics were analyzed in sensor and source space to validate neurophysiologic changes during the different states. Delta, theta, alpha and beta power, hemispheric asymmetry and low resolution electromagnetic tomography (LORETA) analysis were calculated from artefact-free EEG. The data were analyzed with quantitative measures and LORETA compared to an age-adjusted normative database (n=625). EEG analyses revealed that neural activity in the theta band (4–7Hz) and alpha bands (8–12Hz) changes between the different states. During the migraine attack theta and alpha activity was significantly increased over all brain regions as compared to the migraine-free interval. LORETA localized increases of activity to the primary somatosensory cortex and the inferior parietal gyrus, bilaterally. Drug therapy of the migraine attack resulted in a global decrease in theta and alpha power. LORETA localized therapy-associated decreases in theta and alpha power to the bilateral operculoinsular, postcentral and superior temporal cortices. Thus, migraine therapy appears to reduce abnormal EEG activity in the theta and alpha bands. We conclude from this preliminary single case study that migraine attacks may be associated with abnormal increases in theta and alpha power. Drug therapy reduces these abnormal increases in neural activity. Our main finding in the present single case study was the increase in cortical central-posterior slow-wave activity during a migraine attack. This finding is in correspondence with imaging studies that found a posterior cortical hypoperfusion in migraine with and without aura. Changed activity patterns in cholinergic brainstem and thalamo-cortical connections during a migraine attack are likely. Moreover medication affects the EEG especially in the alpha activity band and reduced the theta- and alpha-increase in almost all electrodes.