Episodic cluster headaches are the most common
type of cluster headaches. People with episodic cluster headaches have cluster
periods of 1 to 3 months when they are prone to having headaches. The cluster
periods are followed by headache-free periods (remissions) of 6 months or more.
About 90 out of 100 people who have cluster headaches have episodic cluster
Chronic cluster headaches are
those that occur during a period of at least 12 months without a headache-free
period (remission) or when remissions last less than one month.footnote 2 About 10 out of 100 people who have cluster headaches have chronic
cluster headaches.footnote 1
Evans RW (2009). Headache. In EG Nabel, ed., ACP Medicine, section 11, chap. 8. Hamilton, ON: BC Decker.
Headache Classification Subcommittee of the International Headache Society (2004). International classification of headache disorders: 2nd ed. Cephalalgia, 24(Suppl 1): 9–160.