Hemicrania continua: a third case in which attacks alternate sides.

Hemicrania continua (HC) is an uncommon, primary headache disorder characterized by a continuous unilateral headache of moderate intensity with superimposed exacerbations of more severe pain. HC exists in two temporal subtypes, a continuous form in which headaches persist continuously without remission periods, and a less common remitting form in which bouts of continuous headaches are separated by pain-free remissions. There have been more than 100 prior reports of HC; in the majority of which the headache is strictly unilateral and without side shift. We now report the third patient in whom headaches alternated sides during different attacks.