By Amy Norton
TUESDAY, March 26 (HealthDay News) -- People who suffer migraines may have certain structural differences in pain-related areas of the brain, a new study suggests.
Using MRI scans, researchers found that in specific brain regions related to pain processing, migraine sufferers showed a thinner and smaller cortex compared to headache-free adults. The cortex refers to the outer layer of the brain.
It's not clear what it all means. But the researchers suspect that certain aspects of brain development may make some people more vulnerable to developing migraines -- and that migraine attacks create further changes in the brain.
The surface area of the brain "increases dramatically" during fetal development, while the thickness of the cortex changes throughout life, explained senior researcher Dr. Massimo Filippi.
"We speculate that migraine patients might have a sort of cortical 'signature' -- abnormal cortical surface area -- which could make them more susceptible to pain and abnormal processing of painful stimuli," said Filippi, a professor of neurology at the University Vita-Salute's San Raffaele Scientific Institute in Milan.
Once migraines develop, they may alter the thickness of the brain's cortex, Filippi explained.
A neurologist who was not involved in the study said it "adds to the growing body of knowledge that patients with migraine have brains that not only function differently, but may actually look different structurally as well."
That's important because it helps "legitimize" migraine as a neurological disorder associated with "real structural changes in the brain," said Dr. Matthew Robbins, of the Albert Einstein College of Medicine and Montefiore Headache Center, in New York City.
Worldwide, an estimated 11 percent of people have had a migraine in the past year. Migraines typically cause intense, throbbing pain on one side of the head, along with sensitivity to light and sound, and sometimes nausea and vomiting.
About 30 percent of people with recurrent migraines also have sensory disturbances right before their head pain hits. Those disturbances, known as "aura," are usually visual -- like seeing flashes of light or blind spots.
No one knows precisely what causes migraines, but they do seem to involve abnormal brain activity and -- like the new study suggests -- abnormal brain structure.
The findings, published online March 26 in Radiology, come from MRI scans of 63 adults with migraines, and 18 migraine-free men and women.
Filippi's team found that the migraine brain was complicated. In some areas, the cortex was thicker, but in others -- including pain-processing areas -- the cortex was thinner, versus migraine-free adults.
And there were also differences among migraine sufferers. The exact location of the cortex abnormalities tended to differ between the half of patients who had aura and the half who did not.
According to the researchers, those structural differences might help explain why the two forms of migraine manifest differently.
Filippi said it's important to understand the structural brain changes linked to migraines because that could give insight into the cause of people's pain and other symptoms.
But whether any of this will help in managing migraines remains to be seen. According to Filippi, it's possible that doctors could eventually monitor structural changes in the brain's cortex to gauge migraine patients' response to treatment, for example.
Robbins, of Montefiore Headache Center, said that right now, it's "very hard to say" whether that will happen.
He pointed out that the study participants had one MRI scan, so it's not known what happens later on. "It is unclear if these changes in the brain are dynamic -- meaning, do they change over time?" Robbins said.
Filippi said his team is now following these patients to see whether the structural patterns in their brains are "stable" or tend to shift. They are also doing a similar study of children with migraines.