Hydrocephalus is an abnormal accumulation of cerebrospinal fluid (CSF) within cavities called ventricles inside the brain. (The word “hydrocephalus” comes from the Greek: “hydro” means water, “cephalus” means head.) CSF is produced in the ventricles, circulates through the ventricular system and is absorbed into the bloodstream. CSF, which surrounds the brain and spinal cord, acts as a protective cushion against injury. It also contains nutrients and proteins necessary for the nourishment and normal function of the brain, as well as carries waste products away from surrounding tissues.

Hydrocephalus occurs when there is an imbalance between the amount of CSF produced and the rate at which it is absorbed. As the CSF builds up, it causes the ventricles to enlarge and the pressure inside the head to increase. Prolonged pressure on the optic nerves from hydrocephalus can lead to permanent vision loss. Hydrocephalus can also cause vision loss due to brain injury (cortical visual impairment). Cortical visual impairment may not be permanent if its cause is treated promptly.

Congenital hydrocephalus is thought to be caused by a complex interaction of environmental and perhaps genetic factors. Aqueductal stenosis and spina bifida are two examples. Acquired hydrocephalus may result from intraventricular hemorrhage, meningitis, head trauma, tumors and cysts. Hydrocephalus is believed to occur in about two out of 1,000 births.

Imaging studies of the brain are typically used in diagnosis, including computed tomography (CT scan) and magnetic resonance imaging (MRI). These scans can reveal enlarged ventricles and may indicate a specific cause, as well as detect such abnormalities as tumors and hemorrhages. In some cases, a spinal tap may be used to help determine CSF pressure.

Treatment usually involves draining the excess fluid from the brain by diverting it to another place in the body through surgical insertion of a shunt. This soft, flexible tube is usually made of silicone rubber or plastic. Often, the shunt will drain from the brain into the stomach or heart.

Endoscopic third ventriculostomy (ETV) is a relatively new surgical treatment for hydrocephalus. The surgery involves making a hole in the floor of the third ventricle to allow free flow of spinal fluid into the basal cisterns for absorption. This technique is not appropriate for all patients.

Other Information

If you are the parent or guardian of someone with hydrocephalus, please go to the Hydrocephalus Association’s website and register in their research database.