Cerebrovascular reactivity in migraine during headache-free intervals.

Alterations of intracranial vessel tone have been implicated in the pathophysiology of migraine. The cerebrovascular reactivity was measured by means of transcranial Doppler in 60 migraine patients with (n = 30) or without aura (n = 30) during the headache-free interval and in 30 healthy controls. The vasomotor response was evaluated during hypercapnia induced by inhalation of a mixture of CO2 5% and O2 95% and during hypocapnia obtained after voluntary hyperventilation. To improve the power of the study in detecting possible abnormalities of cerebrovascular reactivity, two different measures were performed at 1 week intervals in migraine patients and controls. Reactivity index values during CO2 inhalation were significantly different (p = 0.01) among the three groups during the first and second measurements; in particular, lower values were found in patients suffering from migraine without aura with respect to controls (p < 0.05, Scheffé's test). Values of reactivity index obtained following induction of hypocapnia did not differ between migraine patients and controls (all p values > 0.05). Our data suggest a reduced vasodilatory response to hypercapnia of cerebral arterioles in patients suffering from migraine without aura with respect to controls that might be related to baseline arteriolar vasodilation.