ESTIMATION OF CEREBROVASCULAR REACTIVITY IN MIGRAINE WITHOUT AURA

Background and Purpose The nature and role of vascular abnormalities i n migraine are controversial. In this study we evaluated cerebrovascul ar reactivity to hypercapnia in patients suffering from migraine witho ut aura with unilateral headache. Methods Using bilateral transcranial Doppler ultrasound, we studied the changes of flow velocity after hyp ercapnia in the anterior, middle, and posterior cerebral arteries of 1 6 migraine patients and 16 healthy control subjects. All patients were studied during an attack-free interval and during a migraine attack. Cerebrovascular reactivity was evaluated with the breath-holding index , obtained by dividing the percent increase in mean flow velocity occu rring during breath-holding by the time (seconds) in which the subject s held their breath after a normal inspiration. Results The response t o breath-holding was similar for all arteries considered in both contr ol subjects and patients during the attack-free interval. During the m igraine attack, the breath-holding index in patients was significantly lower than the migraine-free interval in all arteries (P<.001). No si de-to-side difference in cerebrovascular reactivity was detected in mi graine patients either outside or during attacks. Conclusions These re sults suggest that a failure of cerebrovascular regulation occurs duri ng attacks of migraine without aura.