Researchers at the Perelman School of Medicine at the University of Pennsylvania discovered that variations in arterial anatomy of brain lead to the asymmetries in cerebral blood flow, which in turn contributes to process of triggering migraine.
The study conducted by the researchers found out that the networks of arteries which supply the blood flow to brain are incomplete in people suffering from migraines. It is important to note that the arterial supply of blood to brain receives protection from series of the connections between major arteries called circle of Willis. The circle of Willis is the term named after English physician, who described this first in the 17th century.
It was found by the researchers that people suffering from migraine and especially the migraine with aura, will mostly have missing circle of Willis. It was earlier believed that the root cause of migraine was dilation of blood vessels in head.
In the study, it was found that blood vessels have a different role to play, than suspected earlier. It was suggested in the study that the structural alterations of the blood supply to brain can increase the vulnerability to alterations in the cerebral blood flow, which in turn contributes to the abnormal neuronal activity starting migraine.
Lead author of the study, Brett Cucchiara, the Associate Professor of Neurology explained that people suffering from migraine have difference in the blood vessels’ structure. And, this is something that a person is born with. These differences attribute to changes in blood flow in brain. It is because of these changes that the migraine triggers. This also explains that some people also feel that dehydration is the cause of their severe headaches.
In the study, 170 people were studied. There were three groups- a group that had no headaches, a group that had migraine with aura and the third group, that had migraine without any aura. The team of researchers found out that there were incomplete circle of Willis mostly in the people who had migraine with aura (73 percent), followed by the migraine without aura (67 percent), followed by headache-free group (51 percent).
Magnetic Resonance Angiography was used by the team in order to examine the blood vessel structure. For measuring the changes in cerebral blood flow, noninvasive magnetic resonance imaging method pioneered at the University of Pennsylvania, called Arterial spin labelling (ASL) was used.
It was found that abnormalities in the blood flow as well as the circle of Willis were most commonly found at the rear of the brain, where visual cortex is situated. This explains why people suffering from migraines with aura have visual symptoms like seeing wavy lines, spots or distortions.