Migraine Associated With Incomplete Brain Artery Structure

A network of arteries in the brain called "the circle of Willis" is more likely to be incomplete in Migraine patients than in non-Migraineurs, according to a study by researchers at the University of Pennsylvania.

Researchers used imaging to examine the brain structures in three groups: a Migraine-free control group, a Migraine with Aura group, and a Migraine without Aura group. Although incomplete circle of Willis, a structure that protects the supply of blood from arteries to the brain, is actually quite common, it was more frequently observed in study subjects with Migraine with Aura and Migraine without Aura than in the Migraine-free control group.

The research team also measured changes in cerebral blood flow to learn more about the possible association between the circle of Willis structural abnormality and cerebral blood flow. Based on their analysis, there is diminished cerebral blood flow in areas supplied by the circle of Willis.

Blood vessels have been thought to play a role in the Migraine process for many years. But as we've learned more about Migraine, specific beliefs about that role have changed.

Migraine used to be considered a vascular disorder. Dilation of blood vessels in the head was believed to be responsible for a Migraine attack. It's now a widely accepted view that the Migraine process is instead initiated by neurons and a cascade of events in the brain. But the changes in cerebral blood flow observed in this study suggest blood vessels are also involved in Migraine in some way we don't yet understand.

These researchers hypothesize that cerebral blood flow impairment may allow development of a lack of oxygen (ischemia) relative to the excitement of neurons, trigger cortical spreading depression and predispose Migraineurs to stroke and lesions.

Unfortunately, the study had a very small sample size, which significantly limited the research team's ability to draw many conclusions about circle of Willis and cerebral blood flow. Future research that builds on these findings may give us more information and confirm the hypothesis about the role of cerebral blood flow changes.

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