cluster headache

Cluster headache is a neurological disorder characterized by episodes of severe headaches on one side of the head, typically around the eye and temple, lasting between 15 minutes to three hours. Episodes are often accompanied by eye watering, nasal congestion, drooping eyelids, or swelling around the eye on the affected side. Cluster headaches are unique in their periodicity and regularity: the headaches occur at around the same hour every day during a cluster period, which typically lasts 8–10 weeks a year. Between cluster periods are pain-free intervals without headaches, which last a little less than one year, but some patients can have chronic cluster headaches without remission periods. The disease is considered among the most painful conditions known to medical science.

Triggers of cluster headaches may include alcohol, nitroglycerin, and histamine; a history of exposure to tobacco smoke (whether personal or secondhand smoke) is a significant risk factor. The underlying cause is unknown, but may include a genetic component, as a family history of migraines increases risk. Structurally, the disease is likely related to dysfunction of the posterior hypothalamus.