normal pressure hydrocephalus

n.
  1. A hydrocephalic condition in which the spinal fluid pressure remains normal, resulting from the inability of the arachnoid granulations to absorb cerebrospinal fluid, and characterized by progressive dementia.occult hydrocephalus
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.