New aspects of migraine pathophysiology: lessons learned from positron emission tomography.

Recent positron emission tomography investigations found spreading oligemia in the early phases of a human migraine attack. During the headache phase, increased cerebral blood flow was found in cortical sensory association areas and unilaterally in the brainstem. The brainstem activation persisted after complete relief from headache, indicating that this area might reflect the 'migraine generator'.