Scientists say they might have located the source of migraine headaches, a finding that suggests a new target for drugs to stop the attacks that strike some 16 million or more Americans.
Brain scans of nine migraine patients, studied within six hours of the start of migraine attacks, showed persistent overactivity in a structure called the brain stem at the base of the brain, researchers report.The scans revealed a possible migraine "generator" at the point where the brainstem joins the midbrain, said Dr. Hans Christoph Diener.
Attacks might result from the generator's losing normal control over brain stem centers that regulate perception of pain and the expanding and contracting of blood vessels, he said.
Overactivity in those centers might in turn lead to migraine symptoms, said Diener, chairman of the neurology department at the University of Essen in Germany.
The generator "continues firing even when the headache is gone," he said. That fits in with what many patients say, that even after the pain is gone they still feel tired and "they somehow know that the attack is not over," he said.
The work suggests looking for new anti-migraine drugs that not only relieve the pain but also suppress the generator to cut off migraine attacks at the root, he said in a telephone interview.
The brain-scanning results might be the first direct look at this migraine generator in humans, Diener and colleagues report in the July issue of Nature Medicine.
The scanning results showed overactivity in several brain centers before the patients received an injection of the anti-migraine medicine sumatriptan, which is marketed under the name Imitrex. Once the drug relieved symptoms, only the brain stem overactivity continued, researchers said.
Dr. Seymour Diamond, director of the Diamond Headache Clinic in Chicago, said this lingering activity may explain why headaches return some four to six hours after a single shot of sumatriptan in some patients. That happens in about 20 percent to 30 percent of migraine patients, he said.
Sumatriptan cannot reach the brain stem. It eases pain by acting outside the brain.
Diamond said drug companies are working on longer-lasting medications that might be able to suppress pain until the brain stem overactivity stops.