Idiopathic Normal Pressure Hydrocephalus

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January 26, 2015

Normal pressure hydrocephalus (NPH) was first described by Raymond Adams and Salomon Hakim in 1965. The constellations of symptoms include gait apraxia, urinary incontinence, and cognitive decline. Radiologic investigations demonstrate ventricular enlargement, not entirely caused by cerebral atrophy. Estimates of the incidence of idiopathic NPH vary widely, owing possibly to differences in interpretations of diagnostic criteria. In a recent longitudinal study in a rural community, the incidence was 1.2/1000 persons per year, in contrast to an incidence of 5.5/100,000 previously reported in Scandinavian cohorts [1]. Potential biomarkers to assist in diagnosis of idiopathic NPH are increasingly investigated with recent reports demonstrating decreased levels of soluble amyloid precursor protein in cerebrospinal fluid, more so in shunt-responsive disease, and independent of amyloid beta isoform levels [2].


  1. Iseki C, Takahashi Y, Wada M, et al. Incidence of idiopathic normal pressure hydrocephalus (iNPH): A 10-year follow-up study of a rural community in Japan. J Neurol Sci 2014; Epub ahead of print.
  2. Pyykko OT, Lumela M, Rummukainen J, et al. Cerebrospinal fluid biomarker and 

Submitted by Dr. Adam Numis

Dr. Numis is a member of the Resident and Fellow Section of Neurology.

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