Natural history of cluster headache.

A follow-up study of 123 patients with episodic cluster headaches and of 9 patients with chronic cluster headaches was undertaken after 10-25 years, (mean 14.7 and 13.9 years respectively). This shows a significant but low remission rate for both episodic and chronic cluster headache. It confirms the observation that some patients change from episodic to chronic pattern, and that occasionally chronic clusters may become episodic.