Paroxysmal Hemicrania

Paroxysmal hemicrania (PH) is a primary headache disorder belonging to the group of trigeminal autonomic cephalalgias(TACs). Patients typically experience intense lateralzsed headaches with pain primarily in the ophthalmic trigeminal distribution (V1) associated with superimposed ipsilateral cranial autonomic features. PH is distinguished from other TACs by an exquisite responsiveness to therapeutic doses of indomethacin. Patients may need to be maintained on indomethacin for several months before trials of reduction can be attempted. The disorder does have a tendency toward chronicity. PH is uncommon, but early recognition will prompt initiation of effective treatment to avoid unsuccessful trials of drugs effective in other primary headaches. As with other TACs, hypothalamic and trigeminovascular mechanisms are implicated in the pathophysiologic mechanism of PH. Neuroimaging findings in PH demonstrate a posterior hypothalamic activation similar to that observed in the other TACs. This review will address the epidemiology, clinical presentation, pathophysiology, evaluation, and treatment of PH.