Migraine with and without aura: electrophysiological and functional neuroimaging evidence

The neuropathological processes believed to underlie migraine with and without aura are still widely debated in the literature. In order to arrive at a more detailed and comprehensive picture of the altered processes present in migraineurs, electrophysiological data obtained through transcranial magnetic stimulation (TMS) and electroencephalography (EEG) were combined with haemodynamic data obtained through functional magnetic resonance imaging (fMRI). Ten subjects affected by migraine (with or without aura) underwent TMS and EEG investigation prior to a visual stimulation task, studied in fMRI. Our preliminary results showed a reduced cortical silent period especially in subjects affected by migraine with aura. The fMRI BOLD response was found to be weaker in occipital areas proportionally to the frequency and severity of migraine attacks. The data obtained from our study seem to support the theory of cortical spreading depression recently observed in human subjects. Moreover, the electrophysiological data were also correlated to migraine attack frequency, thus pointing to elevated cortical excitability between attacks. Better understanding of the neuropathological processes that trigger migraine attacks will help in the selection of more adequate prophylactic therapies. The results of this preliminary study need to be confirmed in a a large sample of subjects.