Cluster Headache is characterized by severe “stabbing” or “burning” pain located in or around one eye. The pain may spread across the temple and over the ear. It lasts 15 minutes to 3 hours and can recur many times per day for months or years. Patients are restless and agitated. They pace and rock about, moaning, screaming, and even cursing uncontrollably. Other neurological symptoms affect only the painful side: excessive tears, nasal congestion or runny nose, swelling of the eyelid, excessive sweating, flushing of the face, sense of ear fullness, eyebrow and/or eyelid droop, and constricted pupils.

Cluster Headaches are classified as a trigeminal autonomic cephalalgias (TAC). Other headache disorders in this same classification are SUNCT (Short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing), SUNA (Short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms), Hemicrania Continua, and Paroxysmal Hemicrania. All of these disorders activate the trigeminal parasympathetic reflex, resulting in one-sided involuntary tears, nasal congestion, runny nose, dropping eyelid, or redness and swelling of the eyelid.

Cluster headaches are also called “suicide headaches” because many patients deliberately take their own lives to escape the pain. Some patients who were not suicidal have seriously injured or killed themselves with their desperate attempts to stop the pain. It is not uncommon to observe a patient beat his head against the wall, hit his head with hard objects, or tighten belts around the head during the worst of an attack. If not treated, the risk of fatal injury is quite high.

“There is no more severe pain than that sustained by a cluster headache sufferer and if not for the rather short duration of attacks most cluster sufferers would choose death rather than continue suffering.”   — Todd Rozen, MD

 Theories on Causation

Attacks have shown to activate the posterior hypothalamic grey matter. No cortical spreading depression is present. Vascular inflammation is secondary to onset of attack.

They have been nicknamed “alarm clock” headaches because they tend to occur with precision-like regularity at the same time each day. It is thought that human “biological clock” is disrupted as many patients are wakened by attacks in the early morning hours. Cluster attacks have a preference for REM sleep so many patients wake to an attack just a few hours after falling asleep. Sleep disorders are common.

For some patients, sleep apnea is an aggravating factor. Once treated with a CPAP, these patients will see a dramatic reduction in nighttime and early morning attacks.

ICHD-3 Description

Attacks of severe, strictly unilateral pain which is orbital, supraorbital, temporal or in any combination of these sites, lasting 15-180 minutes and occurring from once every other day to eight times a day. The pain is associated with ipsilateral conjunctival injection, lacrimation, nasal congestion, rhinorrhoea, forehead and facial sweating, miosis, ptosis and/or eyelid oedema, and/or with restlessness or agitation.

Diagnostic criteria:

A. At least five attacks fulfilling criteria B-D
B. Severe or very severe unilateral orbital, supraorbital and/or temporal pain lasting 15-180 min (when untreated)
C. Either or both of the following:

1. at least one of the following symptoms or signs, ipsilateral to the headache:

a) conjunctival injection and/or lacrimation
b) nasal congestion and/or rhinorrhoea
c) eyelid oedema
d) forehead and facial sweating
e) forehead and facial flushing
f) sensation of fullness in the ear
g) miosis and/or ptosis

2. a sense of restlessness or agitation

D. Attacks have a frequency between one every other day and 8 per day for more than half of the time when the disorder is active
E. Not better accounted for by another ICHD-3 diagnosis.


  1. Cluster Headache. American Migraine Foundation. 28 Nov 2017. Retrieved 11 April 2018 from
  2. International Headache Society (2013-2018). 3.1 Cluster Headache. Retrieved 16 April 2018 from
  3. Robbins M, Starling A, Pringsheim T, et al. (2016), Treatment of Cluster Headache: The American Headache Society Evidence‐Based GuidelinesHeadache, 56: 1093-1106. doi:10.1111/head.12866
  4. Rozen T and Fishman R (2012), Cluster Headache in the United States of America: Demographics, Clinical Characteristics, Triggers, Suicidality, and Personal BurdenHeadache, 52: 99-113. doi:10.1111/j.1526-4610.2011.02028.x

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.