[Migraine Mechanisms: In Relation to the Premonitory Phase and CGRP/CGRP Receptor Antagonists]

Migraine is the sixth most common cause of disability worldwide. Historically, three theories regarding the etiology of headache have been suggested: vascular, neuronal, and trigeminovascular. However, the mechanism of migraine is still unknown. The advantages of studying the premonitory phase are several as it is the earliest clinical change during a migraine attack, and hence, is likely to disclose brain areas involved right at the beginning. Studying this phase may also allow to reveal the generator of migraine. In human neurophysiology, human functional neuroimaging, and preclinical biochemical studies, the relationship between the premonitory phase and hypothalamus has been suggested. On the other hand, calcitonin gene-related peptide (CGRP) has now been firmly established as a key player in migraine. Trigeminal CGRP and its roles in vasodilation, neurogenic inflammation, and peripheral sensitization are likely to be the most relevant peripheral actions causing the condition. CGRP could also be acting as a neuromodulator of light aversion, central sensitization, and cortical spreading depression (CSD).