- Much less common than migraine (55-70/100000)
- 5:1 male predominance; onset usually in 30s
- Cause unknown but (compared to migraine)- lacks genetic predisposition, provoking dietary factors etc
- More common in smokers and patients with alcohol excess (these can be triggers)
- Excess abnormal hypothalamic activity has been implicated
- Strictly periodic runs of identical headaches beginning at the same time of day for weeks at a time (cluster). Between clusters, the patient is usually normal and may not relapse for months-years.
- Can have more than one attack per day
- Usually characterised by brief (30-90 minutes) episodes of severe, unilateral periorbital pain with autonomic features e.g.
- lacrimation (tearing)
- nasal congestion
- conjunctival injection
- The patient is often agitated during headaches
- Acute attacks can be treated by subcut sumatriptan and/or oxygen treatment
- Steroids (short-term/low-dose) and verapamil can be used in patients who suffer frequent clusters for prophylaxis