Chronic daily headache: a rational approach to a challenging problem.

Chronic daily headache (CDH) is a significant public health problem with 3 to 5% of the population worldwide experiencing daily or near-daily headaches. Patients with CDH can be particularly challenging, and clinicians require a systematic approach to help guide investigations and management. The revised 2004 International Headache Society Classification Criteria introduces formalized criteria for several CDH disorders including chronic migraine and medication overuse headache as well as new daily persistent headache, hemicrania continua, hypnic headache, and SUNCT syndrome. Medication overuse is common in patients with CDH who present to physicians. Familiarity and comfort with drug-withdrawal and detoxification strategies is therefore essential. Patients with chronic migraine and chronic cluster experience significant disability and diminished quality of life. The ability to manage these patients effectively is a rewarding clinical experience.