Congenital hydrocephalus is a condition present at birth in which too much cerebrospinal fluid (CSF) collects inside the brain. Fluid may not drain from the brain's passageways (ventricles) or may not be absorbed as it should be. This leads to increased pressure within the brain.

Usually a baby with this condition will have a bigger head than other babies the same age. Early treatment can help limit or prevent long-term problems.