Paroxysmal hemicrania and cluster headache: two discrete entities or is there an overlap?

Paroxysmal hemicrania has been described as an excruciating unilateral pain, which is usually ocular and frontotemporal with short-lasting (2-45 min), frequent attacks (usually more than five per day); with marked autonomic features (rhinorrhoea, nasal congestion, conjunctival injection, lacrimation) and unilateral to the pain. A response to indomethacin is essential using the current criteria for the diagnosis. It is a rare condition but when it occurs it is misdiagnosed as being due to sinusitis. A retrospective analysis of 11 patients seen in the period 1995-2001 suggests that there is an overlap between paroxysmal hemicrania and cluster headache. Four patients had all the characteristics of paroxysmal hemicrania and responded to indomethacin. Four other patients fulfilled the criteria except for the frequency and length of the attacks. They only had one attack per day and these lasted more than 2 h. Another patient had all the symptoms of paroxysmal hemicrania and did not respond to indomethacin, but responded to triptans and pizotifen. Patients with cluster headache typically respond to these. Two patients were unable to continue taking indomethacin owing to severe gastrointestinal upset. In the same period, we also had 30 patients with cluster headaches. There is increasing evidence that paroxysmal hemicrania and cluster headache share a similar pathogenesis and that they may not always be so discrete in either their response to indomethacin or their periodicity.