ABSTRACT
Headache is one of the most common symptoms in mankind (1,2). Given the range of disorders that present with headache, a systematic approach to headache classification and diagnosis is essential both for good clinical management and for useful research. The first edition of the International Classification of Headache Disorders (ICHD-1) (3) was the accepted standard for headache diagnosis, from its publication (1988) to the release of the ICHD-2 (2004) (4). It established uniform terminology and consistent operational diagnostic criteria for the entire range of headache disorders. It was translated into 22 languages, providing the basis for clinical trial guidelines for primary headaches (5).
