The mechanism of head pain, provocative stimuli, and receptors involved in drug treatment are reviewed from the Stroke Research Laboratory, Neurosurgery and Neurology, Massachusetts General Hospital, Boston, MA. A primitive defensive fiber network surrounds the brain and its blood vessels which is derived principally from trigeminal ganglia neurons. Headaches develop from activity within the trigeminal vascular system and are controlled by serotonin agonists that couple with 5-HT receptors on unmyelinated C fibers to block activity in the trigeminovascular system. Neuropeptide release and neurogenic inflammation within the coverings of the brain are inhibited. Altered physiologic states (stress, fatigue), bright lights and sleep deprivation may precipitate migraine and act by modulating neuronal activity and synaptic events within cortical gray matter. Local increases in cortical blood flow modulated by trigeminovascular fibers facilitate removal of potentially noxious chemicals. 
COMMENT:. That vasospasm contributes to monosodium glutamate-induced headache has been demonstrated by Merritt JE and Williams PB in the Department of Pharmacology, Eastern Virginia Medical School, Norfolk, VA . The direct effects of glutamate and its metabolite glutamine on arterial contractility were examined using rings of rabbit aorta. High concentrations of glutamate caused significant concentration dependent contractions. At high concentrations the calcium channel blocker Verapamil inhibited the glutamate response. Monosodium glutamate has a direct effect on peripheral arterial tone and may represent a serious health hazard to certain individuals with vascular disease.
A study of treatments used by patients for migraine prior to attending the City of London Migraine Clinic showed that alternative medical treatments were popular including acupuncture, hypnotherapy, homeopathy, feverfew, osteopathy, yoga, and vitamin supplements. The authors emphasize the importance of an accurate history of all medications used, whether prescribed or over-the-counter.