Robin Bond, of Sefton, asks :-

What causes migraine headaches?

Nick Cutfield and John Mottershead, neurologists at the University of Otago, responded.

Many people will experience warning symptoms like irritability, yawning and fatigue in the hours leading up to a migraine attack. During this time, research has shown that there is increased blood flow in a part of the brain called the hypothalamus. Receptors in the brain that respond to the neurotransmitter dopamine may also be important.

For some people, what happens next is an aura, where neurological symptoms such as tingling in a part of the body or a zig-zag visual disturbance occur for around twenty minutes. Studies suggest that the aura is due to a wave of electrical changes spreading between adjacent brain cells in the gray matter. This is known as “cortical spreading depression”. This phenomenon is associated with changes in the arteries in and around the brain. The arteries initially contract and later dilate, and consequently blood flow is initially reduced and then is increased. Most often the headache is prominent after the aura and during arterial dilation. A chemical called calcitonin gene-related peptide (CGRP) is involved in the generation of headache. Many people with migraine do not experience an aura, and develop headache directly.

Studies looking at brain activity in between and during migraine attacks suggest that brain pathways that regulate pain are not normal in people with migraine. This involves parts of the brain such as the brain stem and the thalamus. Migraine sufferers may have a reduced ability to dampen down the pain networks, with resulting vulnerability to migraine.

Greater understanding of all of this is required to help develop new, more effective prevention and treatment of migraine.