By Amanda Gardner
Monday, November 19, 2007 12:00 AM
MONDAY, Nov. 19 (HealthDay News) -- People who suffer from repeated migraines have a thickening in an area of their brains that's involved in processing pain, researchers report.
But exactly what this means, or whether the migraines or the brain-thickening come first, is not yet clear.
"We don't know if it's a cause or a consequence" of migraines, said study senior author Dr. Nouchine Hadjikhani, an associate professor of radiology at the Martinos Center for Biomedical Imaging, affiliated with both the Massachusetts General Hospital and Harvard Medical School.
"What we need is more people and also more time points. If we could follow people over a few years of migraines and see if we can see changes going one direction or the other, that would be something in the direction of an answer," she said. "For the moment, we have one snapshot in time. We see a difference. We don't know why."
"The authors suggested that it may be that repeated attacks of migraine lead to the changes in the brain, although another possibility is that these alterations in the brain structure predispose to migraine," added Dr. Richard Lipton, director of the Montefiore Headache Clinic in New York City. "I have a bias in favor of the hypothesis they present -- that recurrent migraines alter the brain --- because I want to believe that if patients get treated with preventive medication and acute treatments, maybe this thickening could be prevented."
The study is published in the Nov. 20 issue ofNeurology.
Some 28 million Americans suffer from migraines, debilitating headaches that usually strike on one side of a person's head and can also involve nausea, vomiting and sensitivity to light. Some migraines are accompanied by "aura," or changes in vision.
Previous researchers have noted changes in the frontal and temporal cortices of the brain in individuals with chronic pain disorders, such as migraine and back pain.
Hadjikhani and her colleagues had previously found changes in the brain's white matter (which consists of nerve fibers) in people suffering from migraines.
"We found changes in migraineurs compared to controls in the white matter pathways that are important for the somatosensory processing of pain," she explained. "That's why we decided to look at cortical thickness, to see if white matter had any bearings on the gray matter [which consists of cell bodies]."
The somatosensory system includes sensations from the body -- including touch, pain and pressure -- that do not involve the organs devoted to sense, such as the eyes and ears.
The researchers used brain scanning to examine 24 people with migraine, 12 with aura and 12 without. They then compared those scans to scans of 12 people without migraine.
The cortical thickness of the somatosensory cortex area (SSC) of the brain was an average of 21 percent thicker in individuals with migraine, the team found.
It's not clear why this thickness varies in people with and without migraines.
"The brain is a plastic organ, and its structure can change depending on whether you're using it or not," Hadjikhani said. "Now, the question is, do we see the increase in thickness because we have repetitive attacks of migraine? That's our interpretation. The idea is, if you are stimulating this system three or four times a month since you were a teenager, maybe it makes it bigger."
And changes in the brain induced by repetitive migraine attacks may make sufferers more prone to suffering from other pain disorders, the researchers theorized. This would explain the high number of people with migraine who also suffer from such conditions as fibromyalgia and back pain.
There's more on migraine at the National Headache Foundation.
SOURCES: Nouchine Hadjikhani, M.D., associate professor, radiology, Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School; Richard B. Lipton, M.D., director, Montefiore Headache Center, New York City; Nov. 20, 2007,Neurology