Another Migraine Look-Alike
According to the International Classification of Headache Disorders, 3rd Edition, primary headache disorders are classified in one of three ways: Migraine, Tension-Type Headaches, or Trigeminal Autonomic Cephalalgias. As our name implies, most of the time we focus on the Migraine classification. However, it is rare for someone with Migraine to only experience one type of headache disorder. Plus, patients sometimes are diagnosed incorrectly. Both doctors and patients may mistakenly believe the problem is Migraine, when it’s really something else entirely. You may recall an earlier article about Cluster Headache. In it, I offered very specific diagnostic criteria that can be used to distinguish Cluster Headache from Migraine. Now I’d like to introduce you to one of Cluster Headache’s cousins – Hemicrania Continua.
In the absence of very specific training in headache medicine, even a skilled neurologist may not be able to tell the difference between Migraine and Hemicrania Continua. That’s in part because they just don’t know what kind of questions to ask. Because so few people actually talk to their doctor about their headaches, many patients also assume incorrectly that they are experiencing Migraine.
Hemicrania continua and Migraine share some symptoms
But hemicrania continua also shares symptoms with Cluster Headache:
- Restlessness and agitation (as opposed to migraine attacks which are made worse by movement)
- One-sided autonomic syptoms:
- 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 start 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 Cluster Headache, SUNCT/SUNA, Paroxysmal Hemicrania, or Hemicrania Continua. Fortunately, part of the differential is a trial of medicine which can narrow down the possibilities.
One of the unique characteristics of Hemicrania Continua is its nearly universal response to the prescription NSAID, indomethacin. Like most NSAIDs indomethacin can cause stomach irritation, in fact, it’s notorious for it. Most prescribers will also prescribe a proton-pump inhibitor like 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 Cephalalgia in the ICHD-3. Prior editions listed it under “Other primary headache disorders.”
At any rate, this is not a condition that most primary care physicians will recognize or know how to treat. It is a good example of the importance of seeing a headache specialist.
*Short-lasting Unilateral Neuralgiform headache attacks with Conjunctival injection and Tearing and Short-lasting Unilateral Neuralgiaform headache attacks with cranial Autonomic symptoms
International Classification of Headache Disorders (ICHD-3) Diagnostic Criteraia for Hemicrania Continua
A. Unilateral headache fulfilling criteria B-D
B. Present for >3 months, with exacerbations of moderate or greater intensity
C. Either or both of the following:
1. at least one of the following symptoms or signs, ipsilateral (same side) 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
h. a sense of restlessness or agitation, or aggravation of the pain by movement
2. Responds absolutely to therapeutic doses of indomethacin
D. Not better accounted for by another ICHD-3 diagnosis.
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