a migraine headache is a form of vascular headache. migraine headache is caused by vasodilation (enlargement of blood vessel)that causes the release of chemicals from nerves fibers that coil around the large arteries of the brain. Enlargement of these blood vessels stretches the 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 of flight" response,and thai activation causes many of the symptoms associates 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 prevent 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 decreaese the