Migraine headaches result from a combination of blood vessel enlargement and the release of chemicals from nerve fibers that coil around these blood vessels.[3] Some people who suffer from migraines can clearly identify triggers or factors that cause the headaches.[2]A migraine headache causes the sympathetic nervous system to respond with feelings of nausea, diarrhea, and vomiting.[3] Migraines may be caused by changes in the brainstem and its interactions with the trigeminal nerve, a major pain pathway.[1]This response also delays the emptying of the stomach into the small intestine (affecting food absorption), decreases blood circulation (leading to cold hands and feet), and increases sensitivity to light and sound.