Ventriculo-peritoneal shunt. implanting a device known as a shunt to divert the excess CSF away from the brain. The body cavity in which the CSF is diverted is usually the peritoneal cavity (the area surrounding the abdominal organs). The surgeon makes a hole in the skull and another small surgical cut is made in the belly. A small hole is drilled in the skull. A small thin tube called a catheter is passed into a ventricle of the brain. This can be done with or without a computer as a guide. It can also be done with an endoscope that allows to see inside the ventricle. Another catheter is placed under the skin behind the ear and moved down the neck and chest, and usually into the belly area. Sometimes, it stops at the chest area. The doctor may make a small cut in the neck to help position it. A valve (fluid pump) is placed underneath the skin behind the ear. The valve is connected to both catheters. When extra pressure builds up around the brain, the valve opens, and excess fluid drains out of it into the belly or chest area. This helps decrease intracranial pressure. The valves can be programmed to drain more or less fluid from the brain.