This document discusses hydrocephalus, including its characteristics, causes, and methods of diagnosis. Hydrocephalus is an abnormal dilatation of the cerebral ventricles. It can be communicating or non-communicating, depending on whether there is intraventricular obstruction. Non-communicating hydrocephalus has multiple potential causes of obstruction within the ventricles or at openings between ventricles. CT scans and MRI are useful for examining ventricle size and detecting obstructions or masses that may be causing hydrocephalus.