Classification of headaches.

It was not until 1962 that the Ad-Hoc Committee of the National Institute of Health first published a classification of headache syndromes by brief glossary definitions. The general disadvantage of such glossary definitions is that they require subjective interpretation. Therefore under the chairmanship of Prof. Jes Olesen, Copenhagen, the International Headache Society published in 1988 on the basis of empirical findings a first ever headache classification using operationalized criteria. The headache classification of the International Headache Society was immediately translated into the world's major languages and was adopted by all national headache societies represented in the International Headache Society, the World Health Organisation and the World Federation of Neurology. The new classification proved so successful and enjoyed such rapid international acceptance that no revision was undertaken until 1999. The second edition, again under the chairmanship of Prof. Jes Olesen, will probably be completed in 2002. The classification produced such a high degree of inspiration and motivation of pathophysiological and epidemiological research work that knowledge in the field of headache has displayed growth unparalleled in any other field of neurological research. This development was made possible by the determined work of the Chairman of the Headache Classification Committee, Prof. Jes Olesen. He succeeded in bringing together international researchers, motivating them and jointly turning the current fund of knowledge into a evidence-based classification. Prof. Jes Olesen thus performed the decisive pioneering work for all those who have to do with headaches-patients, doctors and scientists. The IHS classification is the most frequently cited text and one of the most important milestones in the history of the scientific study of headaches.