The trigeminal autonomic cephalalgias (TACs) are a group of primary headache disorders characterized by unilateral trigeminal distribution pain that occurs in association with ipsilateral cranial autonomic features [1,2]. The TACs include cluster headache, paroxysmal hemicrania, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT), and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (SUNA) .
Despite their common elements, the TACs differ in attack duration and frequency, as well as the response to therapy (table 1).
- Cluster headache has the longest attack duration and relatively low attack frequency
- Paroxysmal hemicrania has intermediate duration and intermediate attack frequency
- SUNCT has the shortest attack duration and the highest attack frequency
The importance of recognizing these syndromes resides in their excellent but highly selective response to treatment. Hence, early diagnosis will often lead to appropriate treatment and rapid relief of pain. Paroxysmal hemicrania, unlike cluster headache and SUNCT, responds in a dramatic and absolute fashion to indomethacin.
This topic will review the epidemiology, clinical features, and diagnosis of paroxysmal hemicrania. Management is reviewed elsewhere. (See "Paroxysmal hemicrania: Treatment and prognosis".)