Epidemiology
Cluster headache is relatively uncommon affecting between 0.1% and 0.4% of the population.
The male: female ratio is 4-6:1. The usual age of onset is between 30 and 50 years.
Pathophysiology
The aetiology is unknown. Recent evidence suggests dysfunction in the posterior hypothalamic grey matter and the trigeminal-autonomic reflex.
The headache is characteristically unilateral, around or behind the eye.
It lasts between 20 minutes and 2 hours.
It is very severe; "the worst pain I ever had", "I felt like banging my head against the wall" represent the vivid way in which the pain is often described.
It typically occurs at night, waking the person from sleep. It can occur in the day.
Associated features are of a runny eye and a blocked or runny nose on the same side as the pain. An observer may notice a red eye or a droopy eyelid on the side of the pain.
Examination is normal, apart from occasional ipsilateral ptosis.
The term cluster headache derives from the characteristic periodicity of the headache. It occurs nightly for weeks or months, followed by a period of remission for several months or years. In chronic cluster headache, the typical headache continues without clusters.
Investigation
No investigation is required if the clinical features are typical. Atypical presentations require the exclusion of an underlying structural lesion with imaging (CT or MRI).
Management
Sumatriptan (a 5HT1 agonist) by injection is the treatment of choice. Dihydroergotamine, by injection, is an alternative although is not generally available in the UK. Nasal preparations of these products are sometimes used, but oral preparations are often ineffective. Oxygen inhalation is sometimes effective. A variety of treatments are used to try and abort a cluster, with very mixed results: Verapamil, lithium carbonate, oral prednisolone and methysergide. Conventional migraine prophylatic agents are usually ineffective. Indomethacin (a NSAID) is given specifically for chronic cluster headache.
Trigeminal rhizotomy of the first and second divisions is the surgical treatment. It is reserved for a few refractory cases.
Prognosis
Cluster headache is not life threatening. In most cases of cluster headache, the clusters settle after a few years. Chronic cluster headache may be persistent.
By Dr Will Honan FRCP
Last Editorial Review: 21/1/2010
