Primary continuous unilateral headaches: a nosologic model for hemicrania continua.

ABSTRACT

BACKGROUND: Hemicrania continua was originally described as a strictly unilateral, continuous headache with an absolute response to indomethacin. Recognition of an increasing number of patients with the same clinical features except for a lack of response to indomethacin has generated controversy about whether the responsive/non-responsive phenotypes belong to the same disorder. DISCUSSION: We suggest that the non-responsive phenotype should be differentiated from the original concept of hemicrania continua, because it probably indicates a separate type of headache of undetermined nature, i.e. hemicrania incerta. However, differentiating hemicrania incerta from hemicrania continua does not imply that the two headaches are unrelated. Both hemicranias may outline a continuum, giving rise to a broader diagnostic field. CONCLUSION: There seems to be a syndrome of 'primary continuous unilateral headache' with at least two distinctive categories hemicrania continua and hemicrania incerta, which are differentiated by their respective response to indomethacin. This division means plurality but adds precision, and allows a clear-cut diagnosis of some controversial cases.