A case of remitting hemicrania continua with seasonal variation and clustering: a diagnostic confusion with cluster headache.

Hemicrania continua (HC) is an indomethacin responsive primary headache that is characterised by a continuous strictly unilateral headache with periodic exacerbations. About 15% may have a remitting subtype of HC. Herein, we are reporting a 36-year-old man who had a 5-year history of episodic right-sided headaches. The headaches used to occur in a discrete series lasting 4-6 weeks, separated by pain-free remissions of 10-11 months. In each relapse, he had continuous background pain with superimposed exacerbations. The superimposed exacerbations were 1-2 attacks per day, lasting for 2-5 hours, and were associated with ipsilateral cranial autonomic symptoms. However, the patient did not respond to usual therapies of custer headache (CH). He had a complete response to indomethacin. We suggest that remitting subtype of HC may mimic CH. A therapeutic trial of indomethacin should be done in all strictly unilateral headaches who are not responding to other drugs.