New international classification of headache disorders (ICHD-II)

It has been almost 15 years since the first edition of the International Headache Classification appeared in 1988. It was widely accepted and well tolerated. However, rapid progress of the headache research is pushing for a drastic revision of the classification. The new International Classification of Headache Disorders (ICHD-II) was disclosed in September 2003 as a preprinted version and formally published in January 2004. The ICDH-II classifies headache disorders into 3 parts: the primary headache, the secondary headache and cranial neuralgia, central and primary facial pain and other headaches. Basically, the most important diagnostic criteria, those of migraine and tension-type headache, remain unchanged. Several new entities such as chronic migraine, hypnic headache, hemicrania continua, benign thunderclap headache and medication overuse headache have been added. This will encourage intensified headache researches in the future.