The Headache Classification Committee of the International Headache Society (1988) listed the following criteria for cluster headache (CH): at least 5 attacks of severe unilateral orbital, supraorbital, and/or temporal pain, lasting 15 to 180 minutes, associated with at least 1 of 8 local autonomic signs, and occurring once every other day to 8 per day. Approximately 85% of CH patients have the episodic subtype, in which the headaches occur in cluster periods lasting from 7 days to 1 year and separated by attack-free intervals of 1 month or more. The remainder of patients have the chronic subtype, in which attacks recur for greater than 1 year without remission or with remissions lasting less than 1 month (Lipton et al., 2004).