A migraine is more than just a headache; it is intensely painful and has distinct phases. The disorder used to be considered vascular, but recent research has revealed it to be neurological in origin, related to a wave of nerve cell activity that sweeps across the brain.
At the moment, only a few drugs can prevent migraines, all of them developed for other diseases such as hypertension, depression and epilepsy. But they work in only 50 percent of patients, and even then, only 50 percent of the time, and can also induce a range of potentially serious side effects.
Scientific American July 2008