A migraine headache is a form of vascular headache. Migraine headache is caused by vasodilatation (enlargement of blood vessels) that causes the release of chemicals from nerve fibers that coil around the large arteries of the brain. Enlargement of these blood vessels stretches the nerves that coil around them and causes the nerves to release chemicals. The chemicals cause inflammation, pain, and further enlargement of the artery. The increasing enlargement of the arteries magnifies the pain.
Migraine attacks commonly activate the sympathetic nervous system in the body. The sympathetic nervous system is often thought of as the part of the nervous system that controls primitive responses to stress and pain, the so-called "fight or flight" response, and this activation causes many of the symptoms associated with migraine attacks; for example, the increased sympathetic nervous activity in the intestine causes nausea, vomiting, and diarrhea.
- Sympathetic activity also delays emptying of the stomach into the small intestine and thereby prevents oral medications from entering the intestine and being absorbed.
- The impaired absorption of oral medications is a common reason for the ineffectiveness of medications taken to treat migraine headaches.
- The increased sympathetic activity also decreases the circulation of blood, and this leads to pallor of the skin as well as cold hands and feet.
- The increased sympathetic activity also contributes to the sensitivity to light and sound sensitivity as well as blurred vision.
Migraine afflicts 28 million Americans, with females suffering more frequently (17%) than males (6%). Missed work and lost productivity from migraine create a significant public burden. Nevertheless, migraine still remains largely underdiagnosed and undertreated. Less than half of individuals with migraine are diagnosed by their doctors.
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