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

Background and Purpose The aura phase of migraine is associated with f ocal 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 transie nt neurological attacks. Cerebral blood flow (CBF) results, angiograph y, and clinical observations subsequently suggested the diagnosis: mig raine with aura and occasional aura attacks without headache. In the s ame setting the cerebral angiography was followed by four to six repea ted recordings of regional CBF using the intra-arterial Xe-133 injecti on method. Blood samples were drawn from the carotid artery and the in ternal jugular vein to measure oxygen extraction fraction and cerebral metabolic rate for oxygen. Results The intracarotid regional CBF tech nique provoked aura symptoms and typical, migraine-related, posterior focal hypoperfusion in four patients, followed by typical unilateral h eadache in three patients. The remaining four patients had no symptoms or regional CBF changes during the examination. There was a significa nt increase (mean, 13%) of global oxygen extraction fraction in the fo ur patients during aura symptoms, whereas no significant changes of ox ygen extraction fraction were found in the nonsymptomatic group. The i ncrease in global oxygen extraction fraction in the symptomatic group coincided with a drop of hemispheric CBF (mean, 12%). Cerebral metabol ic oxygen rate remained essentially unchanged, as did Paco(2). Conclus ions The data presented suggest that the focal flow reduction during t he migraine-aura phase is not a secondary phenomenon of reduced cerebr al metabolism. However, arteriolar vasoconstriction might offer a poss ible explanation for the regional CBF changes observed during the migr aine aura.