Asymmetric cerebral blood flow patterns in migraine.

Although asymmetric EEG abnormalities have been reported during the headache-free period in migraineurs, asymmetries of regional cerebral blood flow (rCBF) have not been studied. Headache-free rCBF values measured by 133Xe inhalation were lower in migraineurs than in controls. Interhemispheric CBF and regional (anterior versus posterior) CBF did not differ between the groups. When a novel scoring system was used to obtain a mean asymmetry index (MAI), the MAI of the classic/complicated group was significantly higher than that of the controls but not significantly different from that of the common migraine group. These data suggest that in the headache-free interval rCBF asymmetries, variable in location, exist in classic/complicated migraineurs. These rCBF changes may be related to the cause or the effect of the focal neurologic dysfunction that occurs during an attack in these patients.