In order to provide an update of clinical, pathogenic, diagnostic and therapeutic aspects of chronic paroxysmal hemicrania (CPH), also known as Sjaastad syndrome, we review the relevant literature. The term CPH was proposed by Sjaastad in 1976. Although continuous and non continuous cases have been described, Sjaastad prefers to use the term "prechronic" for the non continuous form, given that the adjective "chronic" denotes an important defining feature of CPH. CPH, which has been included in International Headache Society classification system since 1988, is much less common than cluster headache. CPH can be defined as pain that mainly affects women, is unilateral, always on the same side, and generally oculo-fronto-temporal. It can appear at any hour of the day or night, can be triggered by various phenomena and is accompanied by dysautonomic phenomena, generally on the same side as the pain, such as red eyes, tearing, nasal congestion and sometimes rhinorrhea. This headache is distinguished by its response to indomethacin therapy. The pathogenesis of CPH is unknown, although it is believed to resemble cluster headache, at least in its final stages (involving the trigeminal vascular system). Differential diagnosis should include cluster headache, SUNCT syndrome, continuous hemicrania and cervical headache, as well as facial neuralgia.