[Progression from episodic migraine to chronic migraine].

Migraine is, essentially, an episodic disease. However, characteristics of headache of some episodic migraine change like as tension-type headache and number of headache days also increased, as a result, develop into chronic migraine.However, it is difficult to distinguish chronic migraine and medication oversuse headache. For this reason, and because of the general rule, The international Classification of Headache Disorders, 3rd edition, beta version (ICHD- 3beta) defined the patients meeting criteria for chronic migraine and for medication overuse headache should be given both diagnoses. The pathophysiology of transformation from episodic to chronic migraine is still unknown. Epidemiological study revealed several risk factors such as medication overusue, frequency of headache, obesity, low education, low income, snoring, depression, neck/head trauma and so on. It is important to control these risk factors for migraine chronification.