Hemicrania continua (HC) is a
primary headache disorder characterized by a continuous, moderate to severe,
unilateral headache and defined by its absolute responsiveness to
indomethacin. However, some patients with the clinical phenotype of HC do not respond to
indomethacin. We reviewed the records of 192 patients with the putative diagnosis of HC and divided them into groups based on their
headaches' response to
indomethacin. They were compared for age, gender, presence or absence of specific autonomic symptoms,
medication overuse, rapidity of
headache onset, and whether or not the
headaches met criteria for
migraine when severe. Forty-three patients had an absolute response and 122 patients did not respond to adequate doses of
indomethacin. The two groups did not differ significantly in terms of age, sex, presence of rapid-onset
headache, or
medication overuse. Autonomic symptoms, based on a questionnaire, did not predict response. Eighteen patients could not complete a trial of
indomethacin due to adverse events. Nine patients could not be included in the HC group despite improvement with
indomethacin: one patient probably had
primary cough headache, another
paroxysmal hemicrania; three patients improved but it was uncertain if they were absolutely
pain free, and four patients dramatically improved but still had a baseline
headache. We found no statistically significant differences between patients who did and did not respond to
indomethacin. All patients with continuous,
unilateral headache should receive an adequate trial of
indomethacin. Most patients with
unilateral headache suggestive of HC did not respond to
indomethacin.