An excessive accumulation of cerebrospinal fluid (CSF) within the ventricular spaces of the brain, hydrocephalus occurs most commonly in neonates. It can also occur in adults as a result of injury or disease. In infants, hydrocephalus enlarges the head, and in both infants and adults, the resulting compression can damage brain tissue.
With early detection and surgical intervention, the prognosis improves but remains guarded. Even after surgery, such complications as developmental delay, impaired motor function, and vision loss can persist. Without surgery, the prognosis is poor: Mortality may result from increased intracranial pressure (ICP) in people of all ages; infants may also die prematurely of infection and malnutrition.
Hydrocephalus may result from an obstruction in CSF flow (noncommunicating hydrocephalus) or from faulty absorption of CSF (communicating hydrocephalus).
In noncommunicating hydrocephalus, the obstruction occurs most commonly between the third and fourth ventricles, at the aqueduct of Sylvius, but it can also occur at the outlets of the fourth ventricle (foramina of Luschka and Magendie) or, rarely, at the foramen of Monro.
This obstruction may result from faulty fetal development, infection (syphilis, granulomatous diseases, meningitis), a tumor, a cerebral aneurysm, or a blood clot (after intracranial hemorrhage).
In communicating hydrocephalus, faulty absorption of CSF may result from surgery to repair a