THE INTERNATIONAL-HEADACHE-SOCIETY CLASSIFICATION OF CHRONIC DAILY AND NEAR-DAILY HEADACHES - A CRITIQUE OF THE CRITICISM

The classification of the International Headache Society (IHS) publish ed in 1988 has been positively received throughout the world. However, the classification of headaches occurring daily or almost daily has b een criticized repeatedly. This criticism is discussed in the present review. It is possible to classify virtually all chronic headache pati ents using the IHS Classification and there seems to be more need for emphasizing a correct application of the classification than for a rev ision in this regard. The entity of transformed migraine is disputed a nd so is the existence of hemicrania continua. Neither of these syndro mes has been adequately defined nor studied. Chronic daily headache of sudden onset (new persistent daily headache) is not adequately classi fied at present and should be included as a separate entity in the nex t edition of the IHS Classification. In a future revision it should al so be possible to classify drug-related headache simply on the basis o f drug consumption and without mandatory demands for withdrawal. Bette r longitudinal studies of patients with chronic daily headache are nec essary to evaluate finally whether a revision of the classification of these headache syndromes is necessary. Eventually the ongoing discove ry of migraine genes is likely to change radically the classification of migraine.