Literally means "water on the brain"; increase in the size of ventricles and amount of cerebrospinal fluid (CSF) in the brain. There are numerous causes, including congenital birth defect, brain tumor, and brain injury.
Communicating hydrocephalus is caused by a lack of CSF absorption.
Non-communicating hydrocephalus is caused by a blockage of CSF flow.
Hydrocephalus ex vacuo is caused by an apparent increase in ventricular size due to loss of ancilliary brain tissue.