What is hemicrania continua (HC)
Hemicrania continua (HC) is a rare disorder that may have a prevalence of up to 1% of the population. HC is more common in females than males, 1.6:1. The onset is often during the third decade of life with a range from the first to seventh decades.
The pain is strictly unilateral most commonly in the orbital, frontal, and temporal areas but can be occipital or other areas of the head or neck. The pain can be mild to severe throbbing or sharp.
The pain is typically constant, but 20% have pain-free periods for 1 day to several months. Exacerbations occur in 75% of patients and typically last 20 minutes to several days.
The pain can be associated with nausea, vomiting, light and noise sensitivity, and rarely a visual aura.
Cranial autonomic symptoms, most commonly tearing and conjunctival injection, occur in 75% of patients.
HC is a mimic of chronic migraine.
5 Interesting Facts of Hemicrania Continua
- Headache is unilateral, continuous, moderately intense, and occurs daily; also includes episodes of occasional short, piercing head pain
- Lasts 3 months or longer without shifting sides or pain-free periods
- Involves at least 1 of the following:
- Eye redness and/or lacrimation
- Nasal congestion and/or rhinorrhea
- Ptosis and/or miosis
- Completely responsive to treatment with indomethacin
- Differentiated based on history and physical examination
Hemicrania continua is a primary headache disorder that is classified as a trigeminal autonomic cephalgia that shares characteristics of both cluster headache and migraine headache.
Similar to cluster headache, hemicrania continua is a severe, unilateral headache with associated signs of autonomic dysfunction, including lacrimation, scleral injection, eyelid ptosis, and nasal stuffiness syndrome.
In contrast to cluster headache, which occurs 10 times more commonly in men, hemicrania continua occurs more commonly in women, a characteristic it shares with migraine.
Like migraine headache, hemicrania continua is associated with nausea and vomiting, as well as sonophobia and phonophobia. Unlike the pain of cluster and migraine headache, the pain of hemicrania continua is continuous with intermittent severe exacerbations of pain. This pain is unilateral and is side locked (i.e., it does not change sides like migraine headache occasionally does).
Hemicrania continua is an indomethacin responsive headache, with complete resolution of headache and associated symptoms with therapeutic doses of indomethacin. The cause of hemicrania continua is unknown, but like other trigeminal autonomic cephalgias, functional magnetic resonance scanning and positron emission tomography reveal activation in the posterior hypothalamus during exacerbation of headaches.
Comparison of Cluster Headache and Hemicrania Continua
|Comparison Factors||Cluster Headache||Hemicrania Continua||Migraine Headache|
|Absolute response to indomethacin||Negative||Positive||Negative|
|Length of attacks||Longer||Continuous, with exacerbations||Longer than cluster headache|
|Autonomic symptoms, lacrimation, scleral injection, eyelid ptosis, nasal stuffiness syndrome||Present||Present||Negative|
|Nausea and vomiting||Negative||Positive||Positive|
|Continuous pain with exacerbations||Negative||Positive||Negative|
What are the Symptoms of Hemicrania Continua
During attacks of hemicrania continua, patients exhibit the following physical findings suggestive of Horner syndrome on the ipsilateral side of the pain:
- • Conjunctival and scleral injection
- • Lacrimation
- • Nasal congestion
- • Rhinorrhea
- • Ptosis of the eyelid
As in cluster headache, the patient may become agitated during attacks, rather than seeking dark and quiet as does the patient with migraine. In contrast to cluster headache, alcohol consumption does not seem to trigger attacks of hemicrania continua. Between attacks, the neurological examination of a patient with hemicrania continua should be normal.
How is Hemicrania Continua diagnosed?
Magnetic resonance imaging (MRI) of the brain provides the best information regarding the cranial vault and its contents. MRI is highly accurate and helps identify abnormalities that may put the patient at risk for neurological disasters secondary to intracranial and brainstem pathological conditions, including tumors and demyelinating disease.
Magnetic resonance angiography (MRA) also may be useful in identifying aneurysms, which may be responsible for the patient’s neurological findings. In patients who cannot undergo MRI, such as a patient with a pacemaker, computed tomography (CT) is a reasonable second choice.
Radionuclide bone scanning and plain radiography are indicated if fracture or bony abnormality such as metastatic disease is considered in the differential diagnosis. Positron emission tomography may help further delineate and characterize tumors responsible for the patient’s pain and neurological symptoms.
Screening laboratory tests consisting of complete blood cell count, erythrocyte sedimentation rate, and automated blood chemistry testing should be performed if the diagnosis of hemicrania continua is in question. Intraocular pressure should be measured if glaucoma is suspected.
Hemicrania continua is a clinical diagnosis supported by a combination of clinical history, abnormal physical examination during exacerbation of baseline headache, radiography, and MRI. Pain syndromes that may be confused for hemicrania continua include cluster headache, chronic paroxysmal hemicrania, trigeminal neuralgia involving the first division of the trigeminal nerve, demyelinating disease, ice pick headache, and other indomethacin responsive headaches.
Trigeminal neuralgia involving the first division of the trigeminal nerve is uncommon and is characterized by trigger areas and tic-like movements. Demyelinating disease is generally associated with other neurological findings, including optic neuritis and other motor and sensory abnormalities.
The pain of cluster headache is episodic, whereas the pain of hemicrania continua is continuous with acute severe exacerbations.
Cluster headache also has a male predominance, a chronobiological pattern of attacks, and a lack of response to treatment with indomethacin.
How is Hemicrania continua treated?
HC is defined by the fact that is resolves completely with indomethacin.
One regimen is the following: 25 mg three times a day for 3 days, subsequently increasing, if ineffective, to 50 mg three times a day for a further 3 days and then, if ineffective, to 75 mg three times per day for 3 days.
Hemicrania continua uniformly responds to treatment with indomethacin. Failure to respond to indomethacin puts the diagnosis of hemicrania continua in question. A starting dose of 25 mg daily for 2 days and titrating to 25 mg three times per day is a reasonable treatment approach.
This dose may be carefully increased up to 150 mg per day. Indomethacin must be used carefully, if at all, in patients with peptic ulcer disease or impaired renal function.
Anecdotal reports of a positive response to cyclooxygenase-2 (COX-2) inhibitors in the treatment of hemicrania continua have been noted in the headache literature. Underlying sleep disturbance and depression are best treated with a tricyclic antidepressant compound, such as nortriptyline, which can be started at a single bedtime dose of 25 mg.
The lowest effective dose is continued. Because of the risk of gastroduodenal mucosal injury, indomethacin is typically taken with a proton pump inhibitor.
For those who cannot tolerate indomethacin, other treatments, although much less effective, include topiramate, melatonin 6 to 12 mg at bedtime, verapamil, and gabapentin.
Failure to diagnose hemicrania continua correctly may put the patient at risk if intracranial pathological conditions or demyelinating disease, which may mimic the clinical presentation of hemicrania continua, is overlooked. MRI is indicated in all patients thought to have hemicrania continua. Failure to diagnose glaucoma, which may cause intermittent ocular pain, may result in permanent loss of sight.
Hemicrania continua is classified as a trigeminal autonomic cephalgia. The trigeminal autonomic cephalgias are a group of distinct headache syndromes that share a number of common and often overlapping clinical characteristics.
The diagnosis of hemicrania continua is made by obtaining a thorough, targeted headache history. Between attacks, patients with hemicrania continua should have a normal neurological examination.
If the neurological examination is abnormal between attacks, the diagnosis of hemicrania continua should be discarded and a careful search for the cause of the patient’s neurological findings should be undertaken.
Characteristics of the Trigeminal Autonomic Cephalgias
• Short duration
• High frequency
• Orbital, periorbital, or temporal
• Associated autonomic symptoms
• Conjunctival injection
• Nasal congestion
• Eyelid edema