Migraines... A migraine is a splitting headache that just seems to set in apparently due to no reason at all. The reasons for a migraine are mainly vascular. That means that certain changes in the blood vessels that supply blood to the brain trigger of the pain. Of course, the causes for thechanges in the blood vessels may vary from person to person but this is generally how it starts. Migraines are easily the most common headache syndrome. It affects 10 to 15 percent of the global popul.