Migraine Headache

A migraine headache is a common form of headache that is believed to occur as a result of complex interactions between the nervous system and the vascular system as well as alterations in brain chemicals. It was formerly believed that migraine headache was simply caused by vasodilatation (enlargement of blood vessels) that caused the release of chemicals from nerve fibers that coil around the large arteries of the brain. While these blood vessels do indeed enlarge, advanced imaging studies of blood flow in the brain have shown that changes in blood flow cannot be solely responsible for all features of migraine. Instead, complex processes within the nervous system are believed to initiate the development of migraine headache. For example, it is known that certain neurological pathways become sensitized and are stimulated more easily during a migraine headache, and chemicals that promote inflammation are secreted by nerves around the blood vessels.

During migraine headaches the sympathetic nervous system in the body is stimulated. 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 stimulation. This 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 nervous system 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 oral 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 as well as blurred vision.

Migraine headaches afflict over 30 million Americans, with women suffering more frequently than men. (About 75% of migraine sufferers are women.). Missed work and lost productivity from migraine headaches 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.

Source: MedicineNet.com
http://www.medicinenet.com/migraine_headache/article.htm