Hydrocephalus
A clear, saltwater-like liquid called cerebrospinal fluid surrounds the brain. This fluid protects and nourishes the brain, carries away wastes from brain cells and contains important chemicals and nutrients. Each day the brain produces about 500 mL of cerebrospinal fluid (CSF), which flows in a continuous circuit through the brain cavities (ventricles) and over the surface of the brain and spinal cord until it is absorbed.
In approximately 90 per cent of people with spina bifida, the flow of cerebrospinal fluid is obstructed. A blockage at the base of the brain results in a build-up of fluid in the ventricles of the brain, which then expand and push against brain tissue and the bones of the skull.
Hydrocephalus can also develop without spina bifida from a number of other causes. New research seems to show that the picture is not simply a blockage in the circulation of fluid and more work is being undertaken to get a better understanding of hydrocephalus.
In some babies born with hydrocephalus the condition is arrested if the blocked passage opens or the fluid is channelled elsewhere. If it continues to develop there is continuing pressure on the brain, which if untreated will cause brain damage.
Hydrocephalus is usually treated by insertion of a shunt. A shunt is a device which is designed to drain excess cerebrospinal fluid from the brain and carry it to other parts of the body. A one-way valve is used, which usually sits outside the skull, but beneath the skin, somewhere behind the ear.
Although a shunt generally works well, it may stop working if it disconnects, becomes blocked, or is outgrown. If this happens the cerebrospinal fluid will begin to accumulate again and a number of symptoms will develop.
It is important to get medical attention if any of the following symptoms appear.
Symptoms of a malfunctioning shunt
- Headache.
- Vomiting.
- Fever.
- Irritability and personality changes.
- Deterioration in performance of, for example, school work, gait, balance and concentration.
- Lethargy and drowsiness.
- Dizziness.
- In more severe cases, vision disturbances and seizures.
Another surgical procedure called an endoscopic third venticulostomy can sometimes be used instead of a shunt to treat hydrocephalus. In this procedure a small hole is created in the floor of the third ventricle to allow the fluid to flow through. Because it doesn’t involve the implantation of any mechanical devices, it does have the advantage of having no mechanical problems, but it is only suitable in a small number of cases.
Last Reviewed: 17 September 2007
