Hydrocephalus (bottom) versus the normal brain (top) Hydrocephalus (bottom) versus the normal brain (top). Both sections in this image were taken from approximately the same region of two different brains. The section of the brain at the top is normal, and the section at the bottom exhibits marked hydrocephalus. Determining a communicating versus a noncommunicating hydrocephalus based upon one section of brain alone would be difficult unless a process such as fibrosis or hemorrhage were identified in the meninges (causing a communicating hydrocephalus), or the section included the lesion causing obstruction of the ventricular system (causing a noncommunicating hydrocephalus). In addition to obstructive processes, a loss of parenchyma may also cause enlargement of the ventricular system. Dilatation of the ventricular system secondary to tissue loss is usually referred to as hydrocephalus ex vacuo. Source: Chapter 11. Neuropathology, Pathology: The Big Picture Citation: Kemp WL, Burns DK, Brown TG. Pathology: The Big Picture; 2008 Available at: https://accessmedicine.mhmedical.com/DownloadImage.aspx?image=/data/books/kemp1/kemp1_c011f002.png&sec=41569916&BookID=499&ChapterSecID=41568294&imagename= Accessed: December 30, 2017 Copyright © 2017 McGraw-Hill Education. All rights reserved