Classification and diagnosis of headache disorders

Headache is a common medical condition often associated with high personal and socioeconomic burdens. Before 1988, there were no internationally accepted means by which to identify, classify, and study the hundreds of different headache syndromes presenting to the medical community for evaluation. With the introduction of the International Classification of Headache Disorders (ICHD) in 1988, a system for headache classification became available that has standardized headache diagnosis for use in research and clinical practice. The second edition of the ICHD (ICHD-II) was published in 2004 and has introduced important revisions to the classification schema based on our growing understanding of the many headache types found in the general population and their pathogenesis. General principles related to the clinical evaluation and diagnostic classification of headache disorders using the ICHD-II are reviewed in this article.