Cluster headache

Cluster headache is the most common trigeminal autonomic cephalalgia. This primary headache disorder is characterised by attacks of severe unilateral pain localised to the orbital, peri-orbital, and/or temporal areas that last from 15 to 180 minutes. It occurs from once every other day to 8 times per day.

In episodic cluster headache, attacks occur over a period of time (the cluster period), with periods of remission of at least 3 months between cluster periods. The cluster period usually lasts for several weeks, and often occurs at the same time during the year. Some patients can develop chronic cluster headache, where they experience attacks without a remission period or with remission periods lasting less than 3 months, for at least 1 year.

Attacks are accompanied by cranial autonomic symptoms or signs ipsilateral to the pain. Most patients are restless or agitated during attacks.

Pathophysiology is thought to result from hypothalamic activation with secondary trigeminal and autonomic activation. Triggers for cluster attacks include alcohol, strong smells, sleep, circadian disruption, and weather changes.

Diagnosis is based on International Headache Society International Classification of Headache Disorders, 3rd edition (ICHD-3) criteria.

Established options for acute treatment include triptans and high-flow oxygen. Several preventative medications (used to suppress attacks for the duration of a cluster period) are available, with verapamil usually considered as first-line therapy. Some patients may require a transitional therapy; options include a course of oral corticosteroids or greater occipital nerve block with corticosteroids. Newer therapies include non-invasive vagus nerve stimulation (for acute treatment of episodic cluster headache and preventative treatment of chronic cluster headache) and galcanezumab (for preventative treatment of episodic cluster headache).

Cluster headache is considered one of the most painful conditions known. The clinical picture consists of unilateral headache attacks lasting 15 to 180 minutes, associated with cranial autonomic symptoms secondary to parasympathetic hyperactivity and sympathetic hypo-activity. Pain is typically localised to the unilateral orbital, peri-orbital, and/or temporal areas and can occur from once every other day to 8 times per day.

During an attack the pain is strictly unilateral, although some patients report the pain shifting sides between or during bouts but not during an individual attack. Unilateral cranial autonomic features accompanying the unilateral pain include ptosis, conjunctival injection, lacrimation, rhinorrhoea, nasal stuffiness, eyelid and facial swelling, aural fullness, facial sweating, and redness. Most patients become very restless or agitated during an acute attack. During a cluster attack, a person may prefer to pace around the room or rock back and forth.

Approximately 80% of patients have episodic cluster headache, which consists of at least two cluster periods of attacks lasting from 7 days to 1 year when untreated, separated by remission periods lasting at least 3 months.[1]Schindler EAD, Burish MJ. Recent advances in the diagnosis and management of cluster headache. BMJ. 2022 Mar 16;376:e059577. http://www.ncbi.nlm.nih.gov/pubmed/35296510?tool=bestpractice.com Both cluster bouts and attacks during a cluster period can show cyclical periodicity, occurring at the same time of year and/or the same time of day.

The chronic form of cluster headache is seen in approximately 20% of patients and consists of attacks that occur for 1 year or longer without remission, or with remission periods lasting less than 3 months.[1]Schindler EAD, Burish MJ. Recent advances in the diagnosis and management of cluster headache. BMJ. 2022 Mar 16;376:e059577. http://www.ncbi.nlm.nih.gov/pubmed/35296510?tool=bestpractice.com [2]Headache Classification Committee of the International Headache Society (IHS). The International Classification of Headache Disorders, 3rd edition. Cephalalgia. 2018 Jan;38(1):1-211. https://journals.sagepub.com/doi/10.1177/0333102417738202 http://www.ncbi.nlm.nih.gov/pubmed/29368949?tool=bestpractice.com The condition may be chronic from onset or may evolve over time from the episodic form.