Cluster headache is arguably one of the most painful conditions a GP will see. Cluster headache is very distinct from migraine - it is one of a group of headaches known as the trigeminal autonomic cephalalgias characterised by strictly unilateral pain and autonomic features.
- Annual prevalence 0.1-0.2 per cent.
- Male:female ratio is 5:1.
- It can begin at any age; the most common age of onset is the third or fourth decade.
- 10 per cent of patients have chronic cluster headache where remissions last less than one month.
- Cluster headache is a life-long disease but attacks can become less frequent with age.
The cluster attack
- The attacks are strictly unilateral although the headache may alternate sides with attacks.
- The pain is excruciatingly severe and is associated with restlessness or agitation.
- Located mainly around the orbital and temporal regions.
- Headache lasts from 15 minutes to three hours. It has an abrupt onset and cessation.
- The condition can have a striking circadian rhythmicity, with some attacks occurring at the same time each day.
- There are associated cranial autonomic symptoms on the side of the pain and lasting with it. For example, conjunctival injection, lacrimation, miosis, ptosis, eyelid oedema, rhinorrhoea, nasal blockage and forehead or facial sweating.
- Nausea, photophobia and phonophobia are usually absent.
- Alcohol, exercise and elevated environmental temperature can precipitate an attack but not outside a cluster period. Allergies, food sensitivities, reproductive hormonal changes and stress do not appear to have a role in precipitating attacks.
The cluster period
A cluster period (or bout) is an episode during which there are frequent cluster attacks following which the individual is in remission.
- The average cluster period lasts between six to 12 weeks but there is variation between patients.
- Most patients have one or two annual cluster periods, each lasting between one and three months. Often, a striking circannual periodicity is seen with periods occurring in the same month of the year, often spring or autumn.
Approximately 1 per cent of cluster headache presentations will have an underlying pathology. Pituitary tumours are most common. All new cluster headache should be imaged.
If a patient presents with a history of many years of stable cluster this can be relaxed.
- Subcutaneous sumatriptan 6mg is the drug of choice. Unlike in migraine, it can be prescribed twice daily on a long-term basis without reduction in effectiveness, side-effects or rebound.
- Oral triptans are ineffective but there is evidence to support the nasal route.
- Oxygen (see box). The mechanism of its action is unknown.
- Steroids give rapid relief and are useful where there are only two to three attacks each year. Prednisolone 1mg/kg, to a maximum of 60mg once daily for five days and thereafter decrease over a three-week period.
Relapse can occur as the dose is tapered and in this case steroids are used as an initial therapy in conjunction with preventives until the latter are effective.
- Methysergide is a potent agent but prolonged treatment has been associated with fibrotic reactions so it is best used under specialist supervision.
- Verapamil is the preventive drug of choice in both episodic and chronic cluster headache but higher doses than those used in cardiological indications are needed. After performing a baseline ECG, start on 80mg three times daily and thereafter the total daily dose is increased in increments of 80mg every 10-14 days until the cluster attacks are suppressed. Perform an ECG prior to each increment up to a maximum of 960mg daily.
- Lithium, topiramate, sodium valproate, and gabapentin are used but their impact is often marginal. Lithium is the most effective aiming for a serum level in the upper part of the therapeutic range. Occipital nerve injection can be helpful.
- Surgery is a last resort, either destructive procedures or neuromodulatory procedures with implanted electrodes.
|Differences between migraine and cluster headache|
|Using oxygen in cluster headache|
Based on the British Association for the Study of Headache guidelines for oxygen in cluster headache
|Differential diagnosis of cluster headache|
|Diagnosis||Type of pain||Severity||Location||Duration||Frequency|
|Cluster headache||Boring||High||Orbital||15-180 minutes||One to eight a day|
|Boring||High||Orbital||One to 30 minutes||Three to 30 a day|
|*SUNCT||Stabbing||Moderate||Orbital||15-240 seconds||One a day to 30 an hour|
|*short acting unilateral neuralgia form headaches with conjunctival|
injection and tearing
- Dr Kernick is a GP in Exeter and RCGP headache champion
The patient support group - the organisation for the understanding of cluster headache www.clusterheadache.org