Changes in cerebral blood flow velocity after treatment with sumatriptan or placebo and implications for the pathophysiology of migraine.

Whether the primary mechanisms of migraine are vascular or neurogenic is, as yet, unresolved. In humans it is still unclear whether sumatriptan acts via constriction of dilated arteries or through other mechanisms. Doppler sonography is a non-invasive method for measuring blood flow velocities (BFV), an indirect marker of vessel diameter. This double-blind crossover placebo-controlled trial investigated changes in BFV in extra- and intracranial arteries in 132 migraine attacks (66 patients) before and after treatment with either 6 mg sumatriptan s.c. or placebo. Significant increases in BFV were observed only in the middle cerebral artery (MCA) and the basilar artery (BA) after administration of sumatriptan. However, the majority of the patients showed no change in BFV following sumatriptan. No difference in BFV could be detected between headache and non-headache side or between migraine and headache free periods. Despite a slight increase in BFV in intracerebral arteries, this study does not support the concept that vasoconstriction is sumatriptan's principal mechanism in pain relief.