Hemicrania continua is considered a primary headache disorder, meaning that it’s not caused by another condition. It’s rare, but not as rare as once thought, and it’s a treatable disorder. According to the International Headache Society’s (IHS) International Classification of Headache Disorders, 3rd Edition (ICHD-3), hemicrania continua is a:
“Persistent, strictly unilateral headache, associated with ipsilateral conjunctival injection (forcing of a fluid into the conjuctiva, the mucous membrane that lines the eyelids), lacrimation, nasal congestion, rhinorrhoea, forehead and facial sweating, miosis, ptosis and/or eyelid oedema (swelling), and/or with restlessness or agitation. The headache is absolutely sensitive to indomethacin.”1
The IHS diagnostic criteria for hemicrania continua is:
3.4 Hemicrania continua
A. Unilateral headache fulfilling criteria B-D
B. Present for more than three months, with exacerbations of moderate or greater intensity
C. Either or both of the following:
- 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
- a sense of restlessness or agitation, or aggravation of the pain by movement
D. Responds absolutely to therapeutic doses of indomethacin (1)
E. Not better accounted for by another ICHD-3 diagnosis.
(1) In an adult, oral indomethacin should be used initially in a dose of at least 150 mg daily and increased if necessary up to 225 mg daily. The dose by injection is 100–200 mg. Smaller maintenance doses are often employed.
Migrainous symptoms such as photophobia and phonophobia are often seen in 3.4 Hemicrania continua.
3.4 Hemicrania continua has been included under 3. Trigeminal autonomic cephalalgias in ICHD-3 beta (previously it was under 4. Other primary headache disorders) on the basis that the pain is typically unilateral, as are the cranial autonomic symptoms when present. Brain imaging studies show important overlaps between all disorders included here, notably activation in the region of the posterior hypothalamic grey. In addition, the absolute response to indomethacin of 3.4 Hemicrania continua is shared with 3.2 Paroxysmal hemicrania.
Hemicrania continua usually presents a mild to moderate daily headache. However, along with the daily, one-sided headache, it also causes exacerbations of more severe headache, which occurs on the same side as the daily headache and is characteristic of Migraine pain. These more severe episodes can last from 45 minutes to days. During these exacerbations, symptoms of other disorders may be present:
A. Migraine symptoms:
a. throbbing pain
b. nausea and/or vomiting
c. phonophobia (increased sensitivity to sound)
d. photophobia (increased sensitivity to light)
B. Cluster headache symptoms:
a. conjunctival injection (forcing of a fluid into the conjuctiva, the mucous membrane that lines the eyelids) and/or lacrimation (tearing)
b. nasal congestion and/or rhinorrhoea
c. ptosis and/or miosis
These Migranous symptoms can cause hemicrania continua to be misdiagnosed as Migraine or chronic Migraine. The factor that allows hemicrania continua and its exacerbations to be differentiated from Migraine attacks and cluster headaches is that hemicrania continua is completely responsive to indomethacin. Triptans and other abortive medications do not affect hemicrania continua.
The cause of hemicrania continua is unknown. As with Migraine disease and many other headache disorders, there is no definitive diagnostic test for hemicrania continua. Tests such as an MRI may be performed to rule out other causes for the headache. When a patient has the symptoms of hemicrania continua, it’s considered “diagnostic” if they respond completely to indomethacin.
Headache Classification Committee of the International Headache Society. “The International Classification of Headache Disorders, 3rd edition (beta version).” Cephalalgia. July 2013 vol. 33 no. 9 629-808 10.1177/0333102413485658
Young W, Silberstein S, Nahas J, Marmura M. Jefferson Headache Manual. Demos Medical Publishing, LLC. 2011.
Updated on: September 12, 2017.
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