“Understanding the Pathophysiology of Migraine Pain”
Migraine is the most common headache disorder, prevalent in 18% of females and 6% of males. Emergency room visits, physician consults, hospitalizations, medications, and indirect costs such as lost work days and decreased productivity place the global economic burden of migraines at over 20 billion dollars. It is prevalent in 28 million people in the US alone. Symptoms include unilateral, throbbing, debilitating headache pain accompanied by nausea, vomiting, photophobia, and phonophobia. Upwards of 75% of migraine patients have reduced functionability, have lost time at work, and 1/3 of patients require bed rest to manage the symptoms. The health-related impact on quality of life was comparable with that experienced by patients with congestive heart failure, hypertension, or diabetes. While the burden of migraines on our society is clear, the pathophysiology of migraines remains largely unknown. The trigeminovascular system, including the external and internal carotid arteries and their associated sensory fibers which subserve the head have long been implicated in the pain and cutaneous allodynia experienced by migraine patients. Wolff in 1953, was the first to posit that migraine headache pain is the caused by dilation or circumferential expansion of the extracranial carotid artery. He demonstrated that migraineurs had twice the pulse amplitude in their external carotid arteries compared to control subjects and these changes were directly correlated to migraine symptoms. In a 2008 study, randomized migraineurs received nitroglycerin via peripheral IV or placebo for 20 minutes prior to obtaining magnetic resonance angiography (MRA). Nitroglycerin, a potent dilator of blood vessels, reliably induced migraine-like pain in up to 80% of patients, and transient dilation of vessels of up to nearly 40%, mostly in the extracranial vessels. Sumatriptan's efficacy in migraine relief provides further evidence for this theory, as it is a selective extracranial vessel constrictor which does not cross the blood brain barrier. The goal of this current work is to utilize the direct, real-time angiography, which provides a high resolution map of vasculature, and demonstrate changes in vessel flow in patients who have migraine headache attacks. This information may guide therapeutic interventions in the future in order to better treat these migraine patients.
Intra-arterial adminstration to dilate external carotid artery branches to replicate migraine pain
Understanding the Role of the External Carotid Artery in the Pathophysiology of Migraine Pain