Migraine
Migraine, severe headache that occurs periodically and is sometimes confined to only one side of the head. A migraine is characterized by intense, throbbing, often blinding pain, and one or more of the following symptoms: sensitivity to light, nausea, vomiting, chills, facial swelling, tenderness of the scalp, sweating, frequent urination, irritability, visual hallucinations, and malaise. The headache may be preceded by a warning sensation, known as an aura, that may include flashes or patterns before the eyes, illusory tastes or odors, dizziness, tingling, or numbness. At the onset of a migraine headache, blood vessels within the head constrict, causing a decrease in blood flow to the surface of the brain. Swelling of blood vessels in the head and scalp then sets off a chain of reactions that result in the headache. Among the biochemical changes associated with migraines are a reduced level of the neurotransmitter serotonin as well as an insufficient supply of enkephalins, the brain