Migraine. I. Classification and pathogenesis

MIGRAINE is a common yet poorly understood disorder. Although prevalence estimates vary considerably, a recent survey¹suggests that as many as 15% to 19% of men and 25% to 29% of women may experience a migraine attack during their lifetime. Despite migraine's prevalence and long history in the annals of recorded medicine, this condition has succeeded in defying a firm understanding of its pathogenesis, an objective method of establishing a diagnosis, or a consistently reliable therapy. In 1962, attempting to encourage uniformity in the diagnosis of chronic headache conditions, the Ad Hoc Committee on Classification of Headache²proposed guidelines for the diagnosis of migraine as well as other headache disorders. Despite the wellintended effort, many researchers as well as independent clinicians persist in establishing the diagnosis of headache conditions with considerable arbitrariness and inconsistency. A glaring example of this problem can be illustrated by examining the misunderstanding that