New daily persistent headache: a syndrome, not a discrete disorder.

The term New Daily Persistent Headache (NDPH) has been used for nearly 25 years and yet the entity remains enigmatic. It can be argued the simplest, indeed most appropriate, approach is to use the term to mean simply what it says- i.e. as an umbrella description, rather like chronic daily headache. NDPH should be used as a diagnostic umbrella inviting better characterization, not be an achievement in itself. This would mean the term required no further elaboration- there would be no mimics- simply primary and secondary NDPH. A detailed examination of the literature reveals considerable heterogeneity in the phenotypic descriptions labelled as NDPH. The first effort in a patient with a NDPH presentation is to discern if secondary causes are present; some are obvious, such as subarachnoid bleeds and some can be more troublesome, such as syndromes of abnormal CSF pressure/volume, either high or low. A cohort of primary NDPH headaches can be seen in practice and in the literature and these should be sub-divided into a migrainous type, with appropriate phenotypic manifestations and a featureless type. Patients with any one of the NDPH presentations are best managed according to the more detailed pathophysiology-based diagnosis then lumped together into a single group, since a single disorder is unlikely to exist.