Is it Cluster Headache or Something Else
Many women with Cluster Headache are often misdiagnosed with Migraine because of the incorrect assumption that only men get Cluster Headache. As difficult as it is to obtain a diagnosis of Cluster Headache, only the most skilled headache specialists are able to differentiate between Cluster Headache and other Trigeminal Autonomic Cephalalgias (TACs). You see, there are actually 5 different TAC headache disorders: Cluster Headache, Hemicrania Continua, Paroxysmal Hemicrania, SUNCT, and SUNA. It isn’t all that unusual for people who have been told they have Cluster Headache to experience 10 or more attacks per day. Because the diagnostic criteria for Cluster Headache limit the daily frequency to around 8 attacks per day, it’s worth another look at possible alternatives when attack frequency is much higher.
A Possible Diagnosis
One of the TACs that does involve very frequent daily attacks is Paroxysmal Hemicrania. Attacks are relatively brief (˃30 minutes each) and can occur up to 40 times in a single day. Some reports state that attacks can last up to 45 minutes, but that has not been reflected in the current diagnostic criteria. Otherwise, the attack symptoms are identical to Cluster Headache. Unlike Cluster Headache, Paroxysmal Hemicrania is more common in women. Like many other headache disorders, Paroxysmal Hemicrania can be either episodic or chronic. The episodic variety will have active periods of 7 days up to 1 year with pain-free periods of more than 1 month. Chronic Paroxysmal Hemicrania is continuous for a year or more with less than 1 month pain-free. To the untrained eye, it can be difficult to distinguish Paroxysmal Hemicrania from Cluster Headache. Attack frequency, duration, and treatment responsiveness are what set the two apart.
ICHD-3 Diagnostic Criteria:
Description: Attacks of severe, strictly unilateral pain which is orbital, supraorbital, temporal or in any combination of these sites, lasting 2–30 minutes and occurring several or many times a day. The attacks are associated with ipsilateral conjunctival injection, lacrimation, nasal congestion, rhinorrhoea, forehead and facial sweating, miosis, ptosis and/or eyelid oedema. They respond absolutely to indomethacin.
A. At least 20 attacks fulfilling criteria B-E
B. Severe unilateral orbital, supraorbital and/or temporal pain lasting 2–30 minutes
C. At least one of the following symptoms or signs, ipsilateral to the pain:
1. conjunctival injection and/or lacrimation
2. nasal congestion and/or rhinorrhoea
3. eyelid oedema
4. forehead and facial sweating
5. forehead and facial flushing
6. sensation of fullness in the ear
7. miosis and/or ptosis
D. Attacks have a frequency above five per day for more than half of the time
E. Attacks are prevented absolutely by therapeutic doses of indomethacin
F. 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: In contrast to cluster headache, there is no male predominance. Onset is usually in adulthood, although childhood cases are reported.
Acute attacks will often respond to both high-flow oxygen and sumatriptan injections. However, due to the high frequency of attacks, frequent use of triptans is discouraged and preventive treatment is required. Paroxysmal Hemicrania is responsive to treatment with indomethacin, where Cluster Headache is rarely responsive. Not everyone can tolerate the side effects of indomethacin, so second-line preventives include Celebrex, verapamil, and corticosteroids.
Comorbidities Cloud the Picture
Patients with Paroxysmal Hemicrania may also meet criteria for Trigeminal Neuralgia with both attacks triggering one another. What can be even more confusing is that either of these headache disorders can occur in people with Migraine. It is possible to experience attacks of Paroxysmal Hemicrania or Cluster Headache in the middle of a Migraine attack, making an accurate diagnosis even more difficult.
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