Hemicrania continua is a one-sided continuous headache of moderate severity with superimposed severe exacerbations of pain often associated with ipsilateral autonomic symptoms. The frequency of hemicrania continua in the general population is unknown. Hemicrania continua may begin at any age, but peaks in the third decade of life. It is twice as common in women than men.
The pathophysiology of hemicrania continua is incompletely understood. However, a PET study of seven patients with hemicrania continua showed significant activation of the contralateral posterior hypothalamus and ipsilateral rostral pons during baseline pain that were blocked by administration of indomethacin. PET in one patient with hemicrania continua without autonomic features, who had dorsal pontine activation but no hypothalamic activation, suggests that the hypothalamus may play a role in autonomic activation, perhaps via disinhibition of the trigeminal-autonomic reflex.
Hemicrania continua is a unilateral headache that is continuous in nature. Continuous pain is generally moderate in intensity. There are superimposed severe attacks of pain that last minutes to several days classically associated with autonomic features (lacrimation, miosis, etc.). Although not fulfilling the diagnostic criteria, a subgroup of patients with continuous one-sided headaches completely responsive to indomethacin do not have autonomic symptoms. Mild migrainous features may be present, and some patients develop superimposed headaches consistent with migraine headaches. Ipsilateral ocular discomfort or an ocular foreign body sensation and a superimposed stabbing headache ("jabs and jolts") are often reported. ICHD-2 diagnostic criteria are as follows:
Headache for >3 months fulfilling Criteria 2 through 4
All of the following characteristics:
Unilateral pain without side-shift
Daily and continuous, without pain-free periods
Moderate intensity, but with exacerbations of severe pain
At least one of the following autonomic features occurs during exacerbations and ipsilateral to the side of pain:
Conjunctival injection and/or lacrimation
Nasal congestion and/or rhinorrhea
Ptosis and/or miosis
Complete response to therapeutic doses of indomethacin
Not attributed to another disorder
Secondary headaches mimicking primary hemicrania continua (including response to indomethacin) have been reported, including internal carotid artery dissection, unruptured aneurysm, pineal cyst, pituitary tumor, ipsilateral mesenchymal tumor of the sphenoidal bone involving the clinoid process at the base of the skull, lung adenocarcinoma, and pontine stroke.[125–130] Diagnostic studies must therefore be ordered as necessary.
If hemicrania continua is suspected, an oral indomethacin test can be used for the diagnosis of hemicrania continua. One of several methods is as follows: 50 mg twice per day for 3 days, 50 mg three times per day for 3 days, 50 mg four times per day for 3 days. Indomethacin response is typically fast. In a prospective study of 12 hemicrania continua patients, complete pain relief was obtained within 48 hours in all cases, within 24 hours in 10 of the patients, and within 8 hours in nine. Completion of the test without headache resolution is considered a failed trial.
Due to absolute response to indomethacin, it is the treatment of choice for hemicrania continua. The appropriate dose will vary among patients. The initial dose is that dose which results in resolution of headache, determined during the diagnostic indomethacin trial. Oral doses ranging from 25 mg to 300 mg per day have been reported effective. However, given adverse side effects of indomethacin, the lowest effective dose is the desired dose. Periodic attempts to decrease the dose should be made. Potential side effects from indomethacin are numerous. Administration of indomethacin with food can reduce gastrointestinal side effects. Treatment with gastric mucosal protectants, such as proton-pump inhibitors, may also decrease this risk and is common practice. Many of these potential side effects are dose-related. Approximately one of three patients report side effects attributable to indomethacin therapy. Contraindications to treatment with indomethacin and/or discontinuation due to intolerance have led to the search for alternative therapies. There have been case reports of efficacy with melatonin, topiramate, verapamil, cox-2 inhibitors, gabapentin, botulinum toxin type A, and occipital nerve stimulation.[119,133–138]
Semin Neurol. 2010;30(2):154-166. © 2010 Thieme Medical Publishers
Cite this: Diagnosis and Management of Chronic Daily Headache - Medscape - Apr 01, 2010.