Hydrocephalus is the symptomatic accumulation of cerebrospinal fluid (CSF) inside the cerebral ventricles. This accumulation may be due to obstruction in the normal flow of the CSF, or to problems with absorption into the venous system by the Pacchionian arachnoid granulations, or due to excessive production of CSF. Dandy first describes hydrocephalus as communicating and non-communicating (obstructive) in early 1913, and since then, many more classifications were proposed. In adults, there are four different types; obstructive, communicating, hypersecretory, and normal pressure hydrocephalus (NPH). Congenital or developmental hydrocephalus is often present at birth and is often part of a genetic syndrome or spinal dysraphism.
Surgical treatment with a ventricular shunt placement is the first treatment option. Endoscopic third ventriculostomy (ETV) and choroid plexus cauterization are possible options in suitable forms of hydrocephalus. Acute hydrocephalus without prompt treatment can result in brain herniation and death. In children, hydrocephalus has a mortality rate of 0 to 3% depending on the duration of the follow-up.