What is Migraine?
Migraine Headache is a disease that affects 26 million Americans. It is the second leading cause of primary headaches, and often afflicts individuals between the ages of 25-45. It is a neurological illness with biological changes (see causes) that often start in childhood. The number and severity of attacks decline after age 45.
There are two types of migraines: migraine with aura (15%) and migraine without aura (85%). An aura is a warning sign (see symptoms) that often precedes the headache. In a small number of patients with this condition, the lower portion of the brain (brain stem) is involved (i.e., basilar migraine).

Symptoms
Prodromal symptoms (24-48 hours before the headache):
Mood swings (feeling depressed or unusually happy), weakness, fluid retention, craving certain foods
Symptoms once a Migraine Headache starts:
Severe pain over one side of head (both sides in 1/3 of the patients)
Sensitivity to light, Tenderness of the scalp, Sensitivity to sound and smells, Nausea or vomiting, Swelling or pain that overwhelms the face
Pain can be disabling, and last anywhere from 4-72 hours

Cause
An abnormality of the blood vessels and blood flow in the superficial layer of the brain (cerebral cortex). The blood vessels in the cortex first shrink (constrict), then swell (dilate), bringing about the pain.
Genetic factors -- seems to run in families (especially in identical twins)
Platelet disorders -- platelets are cell fragments that help to stop bleeding after an injury
Abnormal levels of brain chemicals (neurotransmitters) such as serotonin, enkephalins (natural painkillers), and chatecholamines. Certain migraines result from changes in female hormones (i.e., estrogen and Progesterone) during menstruation, menopause, and when birth control pills are used.