Table 2

ICHD-II criteria for episodic and chronic cluster headache

3.1.1 Episodic cluster headache
     A. All fulfilling criteria A through E of 3.1
     B. At least two cluster periods lasting from 7 to 365 days and separated by pain free remissions of > 1 month.

3.1.2 Chronic cluster headache
     A. All fulfilling criteria A through E of 3.1
     B. Attacks recur for > 1 year without remission periods or with remission periods lasting < 1 month.

Leroux and Ducros Orphanet Journal of Rare Diseases 2008 3:20   doi:10.1186/1750-1172-3-20