Migraines are are due to a malfunction of the stellate ganglion at the base of the neck. When the ganglion is congested a malfunction can be brought about either by its stimulation or by increased congestion around it. Stimulation is caused by tiredness, anxiety (both stimulate the whole sympathetic chain), bright light (it has some control over the pupil of the eye) and indigestible or allergic food (resulting in the redirecting of blood to the stomach). Increased congestion is brought about when asleep at night (reduced muscle pump), by travel (the muscles have extra work maintaining the position of the head against the force of acceleration, braking, cornering etc. This increases the circulation to the muscles but with little increase in the muscle pump thus congesting the area), and by excessive exercise especially using the arms (increased circulation floods the area of the neck and shoulders some time later).
The warning symptoms of an attack are when the artery to the brain goes into a spasm. As the brain is deprived of blood it produces visual disturbances, numbness etc. The compensatory dilatation of the artery causes pressure in the skull resulting in the blinding headaches, nausea, vomiting etc.
Treatment would include Interx, Nutritional Advice, and EFT (tapping).