Hemicrania Continua: The Essentials

Hemicrania Continua is a trigeminal autonomic cephalalgia with symptoms are sometimes mistaken as Migraine. Unlike Migraine, which is made worse by movement, people with Hemicrania Continua are restless, agitated, and unable to be still during attacks. It is also characterized by severe pain and autonomic symptoms such as nasal congestion, runny nose, involuntary tears, eyelid drooping or swelling, and facial sweating. Unlike its better-known cousin, Cluster Headache, Hemicrania Continua affects predominantly women.

Hemicrania continua and Migraine share some symptoms

• One-sided pain
• Photophobia
• Phonophobia

But hemicrania continua also shares symptoms with Cluster Headache:

1. Restlessness and agitation (as opposed to migraine attacks which are made worse by movement)
2. One-sided autonomic symptoms:
   • Conjunctival injection – eye redness
   • Lacrimation – involuntary tearing of eye
   • Rhinorrhea – runny nose
   • Nasal congestion
   • Ptosis – drooping upper eyelid
   • Miosis – pupil constriction
   • Eyelid edema
   • Facial redness & sweating

Hemicrania Continua can be classified as remitting or unremitting. Unlike migraine, which usually starts episodic and progresses to chronic, Hemicrania Continua often begins as the unremitting type without breaks longer than one day for over a year. Over time, patients may experience periods of relief longer than one day. Sometimes diagnosis is not so simple. It takes time to determine whether a patient has Hemicrania Continua or something else. Fortunately, part of the differential diagnosis is a trial of medication which can narrow down the possibilities.

One of the unique characteristics of Hemicrania Continua is its nearly universal response to the prescription NSAID, indomethacin. As with most NSAIDs, indomethacin can cause stomach irritation. In fact, it’s notorious for it. Most doctors will also prescribe a proton-pump inhibitor such as Prilosec to be used while taking it. Oral doses usually start at 150 mg daily with a gradual increase up to 225 mg. Injection doses range from 100m to 200mg with smaller maintenance doses given over time.

Another headache disorder in the same category, Paroxysmal Hemicrania, also responds to indomethacin. This commonality, plus the symptoms shared with Cluster Headache and SUNCT/SUNA and brain imaging that implicated hypothalamus activation led to Hemicrania Continua being listed as one of four Trigeminal Autonomic Cephalalgias in the ICHD-3. Prior editions listed it under “Other primary headache disorders.”

ICHD-3 Diagnostic Criteria:

Description:

Persistent, strictly unilateral headache, 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. The headache is absolutely sensitive to indomethacin.

Diagnostic criteria:

1. Unilateral headache fulfilling criteria B-D
2. Present for >3 months, with exacerbations of moderate or greater intensity
3. Either or both of the following:
   1. at least one of the following symptoms or signs, ipsilateral to the headache:
      • conjunctival injection and/or lacrimation
      • nasal congestion and/or rhinorrhoea
      • eyelid oedema
      • forehead and facial sweating
      • miosis and/or ptosis
   2. a sense of restlessness or agitation, or aggravation of the pain by movement
4. Responds absolutely to therapeutic doses of indomethacin
5. Not better accounted for by another ICHD-3 diagnosis.

Note:

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.

Comment:

Migrainous symptoms such as photophobia and phonophobia are often seen in 3.4 Hemicrania continua.

3.4 Hemicrania continua is included under 3. Trigeminal autonomic cephalalgias in ICHD-3 on the basis that the pain is typically unilateral, as are the cranial autonomic symptoms when present (in ICHD-II it was under 4. Other primary headache disorders).

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.

Sources

1. International Headache Society (IHS) (2018). 3.4 Hemicrania Continua. (n.d.). Retrieved April 23, 2018, from https://www.ichd-3.org/3-trigeminal-autonomic-cephalalgias/3-2-paroxysmal-hemicrania/