Migraine headaches affect about 6 out of 100 people. They are a common type of chronic headache . They most commonly occur in women and usually begin between the ages of 10 and 46. They appear to run in the families in some cases.
Common migraine accounts for almost all migraine headaches.
Migraines occur when blood vessels of the head and neck spasm or constrict, which decreases blood flow to the brain. Multiple mechanisms trigger the spasm and subsequent blood vessel dilation. There is an increase in many of the substances produced by the body that can cause blood vessels to constrict or dilate. Inflammation around the blood vessels also occurs in some cases. The occurrence of common migraine may be reduced in high-risk people who avoid factors that have been associated with previous migraine .