The figure above shows our understanding of what happens during a migraine attack. It is now thought that a migraine is triggered when a wave of electricity which starts in the trigeminal nerve on the side of the face stimulates the release of peptides such as CGRP and other substances that cause inflammation and makes other nerves more sensitive to pain. The wave of electricity then enters the brain and ripples across the surface of the brain – and together with CGRP causes blood vessels to dilate, as shown in Inset A above. In this way sensitization of the nerves often progresses from peripheral nerve cells on the skin to central neurons in the brain.
(Adapted from the American Society for Neuroscience).