Managing patients with cluster headache in primary care.

Cluster headache is a strictly unilateral headache that occurs in association with cranial autonomic features. Although it can begin at any age, the most common age of onset is in the third or fourth decade of life. The diagnosis is purely clinical and it is therefore crucial to take a good history looking for its distinctive features. Although cluster attacks are unilateral, they may alternate sides. Pain is excruciating and located mainly around the orbital and temporal regions though any part of the head may be affected. Attacks have an abrupt onset and offset and usually last around 45-90 minutes but can range from 15 minutes to three hours. Attack frequency generally varies from one every other day to three a day, although the International Headache Society criteria state there may be up to eight attacks a day. The key feature of cluster headache is the presence of at least one cranial autonomic symptom during an attack. Alcohol, physical exertion, warm environments, sleep and the smell of volatile substances can all trigger acute attacks. The majority of patients will have episodic cluster headache with recurrent bouts separated by remission periods of more than a month. The remaining 10-20% have chronic cluster headache and no significant remission periods over the course of a year. Specialist advice should be sought at first presentation for confirmation of diagnosis, development of a plan for managing current and future cluster bouts and where first-line treatments fail.