A new study done by researchers at the Perelman School of Medicine at the University of Pennsylvania has found that the net of arteries supplying blood to the brain is more likely to be incomplete in people who have migraines. Say what? That is what I said. Essentially, “Variations in arterial anatomy lead to asymmetries in cerebral blood flow that might contribute to the process triggering migraines.”
“The arterial supply of blood to the brain is protected by a series of connections between the major arteries, termed the “circle of Willis” after the English physician who first described it in the 17th century. People with migraine, particularly migraine with aura, are more likely to be missing components of the circle of Willis.”
There was once the theory we are all familiar with that migraines were caused by dilation of blood vessels in the head… but more recent studies have shown it is attributed to abnormal neuronal signals. Now this study, which appears in PLOS ONE, suggests blood vessels have a different role in the game… these structural alterations of the blood supply to the brain itself may increase “susceptibility to changes in cerebral blood flow, contributing to the abnormal neuronal activity that starts migraine.”
“People with migraine actually have differences in the structure of their blood vessels – this is something you are born with,” said the study’s lead author, Brett Cucchiara, MD, Associate Professor of Neurology. “These differences seem to be associated with changes in blood flow in the brain, and it’s possible that these changes may trigger migraine, which may explain why some people, for instance, notice that dehydration triggers their headaches.”
The study involved 170 people divided into three groups: a control group with no headaches, those with migraine with aura and those with migraine without aura. The researchers found that an incomplete Willis was more common in the group with migraine with aura (73%) and the migraine without aura (67%) compared to the control group (51%). They used magnetic resonance angiography to determine blood vessel stricture and a noninvasive magnetic resonance imaging method called Arterial spin labelling (ASL) developed at the University of Pennsylvania to measure changes in the cerebral blood flow.
“Abnormalities in both the circle of Willis and blood flow were most prominent in the back of the brain, where the visual cortex is located. This may help explain why the most common migraine auras consist of visual symptoms such as seeing distortions, spots, or wavy lines,” said the study’s senior author, John Detre, MD, Professor of Neurology and Radiology.
That is intriguing to me. The visual cortex is also where Visual Snow comes from and maybe these structural abnormalities lead to higher comorbidity in that as well. Either way, there has been a lot of research coming out that shows people with migraines have different brains, migraines or not, and can have in-between migraine events that clearly demonstrate this is a disease.