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, and hemicrania continua .
Despite their common elements, the TACs differ in attack duration and frequency, as well as the response to therapy (table 1).
●Hemicrania continua is characterized by continuous pain with exacerbations
●Cluster headache has a relatively long attack duration and relatively low attack frequency
●Paroxysmal hemicrania has an intermediate attack duration and frequency