CEREBRAL OXYGEN EXTRACTION, OXYGEN-CONSUMPTION, AND REGIONAL CEREBRAL BLOOD-FLOW DURING THE AURA PHASE OF MIGRAINE

Background and Purpose The aura phase of migraine is associated with focal blood flow changes, but it has been largely unknown whether these changes are correlated to changes in the cerebral metabolism. Methods Eight patients required carotid angiography for evaluation of transient neurological attacks. Cerebral blood flow (CBF) results, angiography, and clinical observations subsequently suggested the diagnosis: migraine with aura and occasional aura attacks without headache. In the same setting the cerebral angiography was followed by four to six repeated recordings of regional CBF using the intra-arterial Xe-133 injection method. Blood samples were drawn from the carotid artery and the internal jugular vein to measure oxygen extraction fraction and cerebral metabolic rate for oxygen. Results The intracarotid regional CBF technique provoked aura symptoms and typical, migraine-related, posterior focal hypoperfusion in four patients, followed by typical unilateral headache in three patients. The remaining four patients had no symptoms or regional CBF changes during the examination. There was a significant increase (mean, 13%) of global oxygen extraction fraction in the four patients during aura symptoms, whereas no significant changes of oxygen extraction fraction were found in the nonsymptomatic group. The increase in global oxygen extraction fraction in the symptomatic group coincided with a drop of hemispheric CBF (mean, 12%). Cerebral metabolic oxygen rate remained essentially unchanged, as did Paco(2). Conclusions The data presented suggest that the focal flow reduction during the migraine-aura phase is not a secondary phenomenon of reduced cerebral metabolism. However, arteriolar vasoconstriction might offer a possible explanation for the regional CBF changes observed during the migraine aura.