Paroxysmal Hemicrania

A rare primary headache disorder characterized by multiple attacks of unilateral pain that occur in association with ipsilateral cranial autonomic symptoms. The hallmarks of this syndrome are the relative shortness of the attacks and the complete response to indomethacin therapy.

Epidemiology

Paroxysmal hemicrania (PH) prevalence is unknown. There is a male-to-female ratio of 1:1.

Clinical description

The mean age of onset is 40 years (range 3-81 years). PH patients experience purely unilateral, severe to very severe attacks of head pain. The pain is often in the temporal, orbital or supraorbital region. The pain has an abrupt start and cessation and is accompanied by ipsilateral autonomic features, including lacrimation, conjunctival injection, rhinorrhoea, nasal congestion, periorbital oedema, facial flushing, miosis and/or ptosis. PH attacks last 2-30 minutes and occur more than 5 times a day up to 40 times a day with a mean of 11 a day. Patients can have unilateral photophobia and phonophobia ipsilateral to the side of the attack. Osmophobia, nausea or vomiting during the attacks has been reported. Although attacks are most usually spontaneous, attacks can be triggered by neck movements, or pressure over the neck or greater occipital nerves. PH can be classified as episodic or chronic, depending on the duration of pain-free period when untreated. Episodic paroxysmal hemicrania patients have bouts lasting from 7 days to 1 year and separated by pain-free periods more than 3 months, whereas in chronic patients the pain-free period is less than 3 months. As this is a primary headache disorder, patients have normal neurological tests.

Etiology

Etiology remains unclear.

Diagnostic methods

Diagnosis is based on clinical history and response to indomethacin. Patients with suspected paroxysmal hemicrania should undergo an oral indomethacin trial or placebo-controlled intramuscular indomethacin test. In adults, one could start with 25mg three times a day, titrating up to 75mg three times a day over the course of 3 weeks. With intramuscular indomethacin 100-200 mg could be used.

Differential diagnosis

Cluster headache is the main differential diagnosis, given the overlap in duration of the attacks. It is very important to differentiate PH from cluster headache, as treatment differs greatly.

Genetic counseling

Rare cases of familial PH have been reported.

Management and treatment

A complete response to indomethacin confirms the diagnosis of PH. Treatment with indomethacin with a median dose of 150 mg/day (ranging from 30-300mg/day) results in dramatic relief of the disabling symptoms caused by PH.

Prognosis

This is a debilitating headache condition if not accurately diagnosed and managed.