Cluster and chronic daily headache

Cluster headache, although relatively uncommon, is one of the most painful primary headache disorders. Approximately 90% of affected individuals experience daily attacks for several weeks to months (cluster periods) separated by attack-free intervals lasting for months to years (remission periods). The other 10% of sufferers exhibit a more chronic pattern marked by attacks that persist for longer than 1 year with no remission or only short periods of remission. The most striking feature of cluster headache is its circadian and circannual periodicity, which has implicated the hypothalamic pacemaker (the suprachiasmatic nucleus) in the pathogenesis of the disorder. The unique attack profile of cluster headache mandates the use of rapid-acting symptomatic therapy, such as oxygen or subcutaneous sumatriptan. Preventive treatment is two-pronged and consists of transitional treatment, usually with prednisone, to produce rapid suppression of attacks, and maintenance treatment (typically with verapamil) for the expected duration of the cluster period. Chronic daily headache (CDH) is defined as a headache that occurs for at least 15 days per month and for at least 4 hours per day. The prevalence of CDH is only 4% in the general population but is as high as 80% in headache clinic populations. More than three quarters of patients with CDH have chronic (transformed) migraine. The pathophysiologic mechanisms of CDH remain undetermined. Pharmacotherapy is aimed at relieving daily pain and periodic superimposed acute migraine attacks. Aggressive treatment is required for rebound syndromes, and hospitalization is sometimes required for particularly difficult cases.