New daily persistent headache: An evolving entity.

New daily persistent headache (NDPH) is characterized by an abrupt onset of headache that becomes a daily entity, is unremitting and continuous from the onset, and lasts for more than 3 months. Dr Walter Vanast first described NDPH in the year 1986. Originally, it was proposed as a chronic daily headache but it was placed under "other primary headaches" in the International Classification of Headache Disorder Second Edition (ICHD 2nd edition). However, with evolving literature and better understanding of its clinical characteristics, it was classified as a "chronic daily headache" in the ICHD 3rd edition beta. There are still many knowledge-gaps regarding the underlying cause, pathophysiology, natural history and treatment of NDPH. This review tries to revisit the entity and discusses the current status of understanding regarding NDPH.