Cluster headache

Cluster headache
Trigeminal nerve
SymptomsRecurrent, severe headaches on one side of the head, eye watering, stuffy nose[1]
Usual onset20 to 40 years old[2]
Duration15 min to 3 hrs[2]
TypesEpisodic, chronic[2]
Risk factorsTobacco smoke, family history[2]
Diagnostic methodBased on symptoms[2]
Differential diagnosisMigraine, trigeminal neuralgia,[2] other trigeminal autonomic cephalgias[3]
PreventionSteroid injections, civamide, verapamil[4]
TreatmentOxygen therapy, triptans[2][4]
Frequency~0.1% at some point in time[5]

Cluster headache (CH) is a neurological disorder characterized by recurrent, severe headaches on one side of the head, typically around the eye.[1] There is often accompanying eye watering, nasal congestion, or swelling around the eye, on the affected side.[1] These symptoms typically last 15 minutes to 3 hours.[2] Attacks often occur in clusters which typically last for weeks or months and occasionally more than a year.[2]

The cause is unknown.[2] Risk factors include a history of exposure to tobacco smoke and a family history of the condition.[2] Exposures which may trigger attacks include alcohol and nitroglycerin.[2] They are a primary headache disorder of the trigeminal autonomic cephalalgias type.[2] Diagnosis is based on symptoms.[2]

Recommended management includes lifestyle changes such as avoiding potential triggers.[2] Treatments for acute attacks include oxygen or a fast acting triptan.[2][4] Measures recommended to decrease the frequency of attacks include steroid injections, civamide, or verapamil.[4][6] Nerve stimulation or surgery may occasionally be used if other measures are not effective.[2]

The condition affects about 0.1% of the general population at some point in their life and 0.05% in any given year.[5] The condition usually first occurs between 20 and 40 years of age.[2] Men are affected about four times more often than women.[5] Cluster headaches are named for the occurrence of groups of headache attacks (clusters).[1] They have also been referred to as "suicide headaches".[2]

Signs and symptoms

Cluster headaches are recurring bouts of excruciating unilateral headache attacks[7] of extreme intensity.[8] The duration of a typical CH attack ranges from about 15 to 180 minutes.[2] Most untreated attacks (about 75%) last less than 60 minutes.[9]

The onset of an attack is rapid and most often without preliminary signs that are characteristic in migraine. Preliminary sensations of pain in the general area of attack, referred to as "shadows", may signal an imminent CH, or these symptoms may linger after an attack has passed, or even between attacks.[10] Though CH is strictly unilateral, there are some documented cases of "side-shift" between cluster periods,[11] or, extremely rarely, simultaneous (within the same cluster period) bilateral cluster headaches.[12]


The pain occurs only on one side of the head (unilateral), around the eye (orbital), particularly above the eye (supraorbital), in the temple (temporal), or in any combination. The pain of CH attack is remarkably greater than in other headache conditions, including severe migraine. The pain is typically described as burning, stabbing, boring or squeezing, and may be located near or behind the eye.[13] As a result of the pain, those with cluster headaches may experience suicidal thoughts during an attack (giving the alternative name "suicide headache" or "suicidal headache").[14][15] It is reported as one of the most painful conditions.[16]

Other symptoms

The typical symptoms of cluster headache include grouped occurrence and recurrence (cluster) of headache attack, severe unilateral orbital, supraorbital and/or temporal pain. If left untreated, attack frequency may range from one attack every two days to eight attacks per day.[2][17] Cluster headache attack is accompanied by at least one of the following autonomic symptoms: drooping eyelid, pupil constriction, redness of the conjunctiva, tearing, runny nose, and less commonly, facial blushing, swelling, or sweating, typically appearing on the same side of the head as the pain.[17]

Restlessness (for example, pacing or rocking back and forth) may occur. Similar to a migraine, sensitivity to light (photophobia) or noise (phonophobia) may occur during a CH. Nausea is a rare symptom, although it has been reported.[7] Secondary effects may include inability to organize thoughts and plans, physical exhaustion, confusion, agitation, aggressiveness, depression and anxiety.[14]

People with CH may dread facing another headache and adjust their physical or social activities around a possible future occurrence. Likewise they may seek assistance to accomplish what would otherwise be normal tasks. They may hesitate to make plans because of the regularity, or conversely, the unpredictability of the pain schedule. These factors can lead to generalized anxiety disorders, panic disorder,[14] serious depressive disorders,[18] social withdrawal and isolation.[19]


Cluster headaches may occasionally be referred to as "alarm clock headache" because of the regularity of their recurrence. CH attacks often awaken individuals from sleep. Both individual attacks and the cluster grouping can have a metronomic regularity; attacks typically striking at a precise time of day each morning or night. The recurrence of headache cluster grouping may occur more often around solstices, or seasonal changes, sometimes showing circannual periodicity. Conversely, attack frequency may be highly unpredictable, showing no periodicity at all. These observations have prompted researchers to speculate an involvement, or dysfunction of the hypothalamus. The Hypothalamus controls the body's "biological clock" and circadian rhythm.[20][21] In episodic cluster headache, attacks occur once or more daily, often at the same time each day for a period of several weeks, followed by a headache-free period lasting weeks, months, or years. Approximately 10–15% of cluster headaches are chronic, with multiple headaches occurring every day for years, sometimes without any remission.[medical citation needed]

In accordance with the International Headache Society (IHS) diagnostic criteria, cluster headaches occurring in two or more cluster periods, lasting from 7 to 365 days with a pain-free remission of one month or longer between the headache attacks, may be classified as episodic. If headache attacks occur for more than a year without pain-free remission of at least one month, the condition is classified as chronic.[17] Chronic CH both occurs and recurs without any remission periods between cycles; there may be variation in cycles, meaning the frequency and severity of attacks may change without predictability for a period of time. The frequency, severity and duration of headache attacks experienced by people during these cycles varies between individuals and does not demonstrate complete remission of the episodic form. The condition may change unpredictably, from chronic to episodic and from episodic to chronic.[22]

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