Reduced breath holding index in patients with chronic migraine.

Migraine is a neurovascular disorder characterized by autonomic nervous system dysfunction and severe headache attacks. Studies have shown that changes in the intracranial vessels during migraine have an important role in the pathophysiology. Many studies have been conducted on the increased risk of stroke in patients with migraine, but insufficient data are available on the mechanism underlying the increase. This study aimed to evaluate basal cerebral blood flow velocity and vasomotor reactivity in patients with chronic migraine. We evaluated 38 patients with chronic migraine. Three of them were excluded because they had auras and four of them were excluded because of their use of medication that can affect cerebral blood flow velocity and breath holding index (beta or calcium channel blockers). Our study population consisted of 31 patients with chronic migraine without aura and 29 age- and gender-matched healthy individuals who were not taking any medication. The mean blood flow velocity and breath holding index were measured on both sides from the middle cerebral artery and posterior cerebral artery, with temporal window insonation. The breath holding index for middle cerebral artery and posterior cerebral artery was significantly lower in the migraine group compared to that of the control group (p < 0.05).The vasomotor reactivity indicates the dilatation potential of a vessel, and it is closely related to autoregulation. According to our results, the vasodilator response of cerebral arterioles to hypercapnia was lower in patients with chronic migraine. These findings showed the existence of impairments in the harmonic cerebral hemodynamic mechanisms in patients with chronic migraine. This finding also supports the existing idea of an increased risk of stroke in patients with chronic migraine due to impaired vasomotor reactivity.