Hemicrania continua should not be classified as a trigeminal autonomic cephalalgia.

Background: The pain of the so-called functional or primary headache disorders, such as tension headache, migraine, or cluster headache, can be associated with autonomic symptoms that are localized in nature. The localized autonomic symptoms probably involve higher centers of autonomic regulation, for example the hypothalamus, for which there is support from functional magnetic resonance imaging studies.
Method: Hemicrania continua, a continuous, unilateral, side-locked headache, absolutely responsive to preventive treatment with indomethacin, is contrasted with so-called medication-overuse headache, in which the paradoxical situation exists of tremendous suffering despite excessive use of abortive medications.
Conclusion: In classification, clinical presentation trumps experimental testing: Not only is there no basis to classify hemicrania continua in the category of the so-called trigeminal autonomic cephalalgias, also the very existence of this category lacks solid foundation.
(© 2013 American Headache Society.)