A network of arteries supplying blood flow to the brain is more likely to be incomplete in people who suffer migraines, according to a new study by researchers in the Perelman School of Medicine at the University of Pennsylvania. The study, published in the journal PLOS One, found that abnormal arteries triggered migraines in more than two out of three people who suffer from them.
“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, an associate professor of Neurology, University of Pennsylvania.
“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 split into three groups: those with no headaches, those who had migraine with aura, and those who had migraine without aura. An aura refers to symptoms such as blind spots and weakness that migraine sufferers experience before a headache.
Researchers found that people who had migraine with aura commonly had an incomplete “circle of Willis”. The term is named after the 17th century English physician who was the first to discover that the arterial supply of blood to the brain was protected by a series of connections between major arteries.
Researchers used magnetic resonance imaging (MRIs) to examine blood vessel structure and measure changes in blood flow. They found abnormalities in 73% of those who had migraine with aura, 67% who had migraine without aura, and in 51% of those in the control group without migraine.
“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,” said the study’s senior author, John Detre, MD, Professor of Neurology and Radiology.
“This may help explain why the most common migraine auras consist of visual symptoms such as seeing distortions, spots, or wavy lines.”
Researchers note that both migraine and incomplete circle of Willis are common, one of many factors that contribute to migraine.
Scientists say diagnostic tests of blood flow in the brain may help pinpoint the cause of migraine in individual patient s, leading to personalized treatment strategies.
About 28 million Americans suffer from migraines. They can last from hours to weeks and are debilitating enough to prevent people from working and lead to depression.
The exact mechanisms are not known, but are believed to be caused by a combination of environmental and genetic factors. People with migraines may inherit the tendency to be affected by migraine triggers, such as fatigue, bright lights, weather changes, and others.
For years, scientists believed that migraines were linked to expanding and constricting blood vessels on the brain’s surface. Now, research shows that they may be caused by inherited abnormalities in certain areas of the brain.