Neurobiology of chronic migraine.

Chronic daily headache (CDH) is an important problem for clinicians. It is frequent in tertiary care structures, although at present there is no clear consensus about definitions and operational criteria. In fact, CDH is a group of headache disorders that includes chronic migraine (CM). CDH usually evolves from an episodic headache form, which was migraine in most cases. Several psychopathological factors (e.g. psychiatric comorbidity, personality traits or stressful life events) and some somatic disorders (e.g. like arterial hypertension, allergic condition, sleep disturbances) are frequent in CM patients. Caffeine consumption, alcohol overuse and medication overuse (abortive drugs for migraine) could favour chronicity. The possible role of these factors remains poorly understood. Prospective studies and research about the pathophysiology of chronic pain will lead to a better understanding of CM.