Adult Hydrocephalus Adult Hydrocephalus is a condition where there is excessive Cerebrospinal Fluid (CSF) in the brain. When the production and absorption of CSF are affected, the cavities (ventricles) of the brain enlarge, increasing brain pressure. [Please download the PDF file if you are unable to view the image below.] Content serves as a guide only. Seek the advice of your doctor for more details Information correct as of September 2020 Reproduced with permission from the National Neuroscience Institute (NNI)