Treatment A shunt is the primary therapy for hydrocephalus. A shunt is a tiny tube that is installed in the brain to drain excess CSF to another region of the body (usually the abdominal cavity, the space around the colon) where it may be absorbed into the circulation. A valve regulates the flow of CSF. The two main types of shunts are external and internal. External shunts involve placing a tube called a "shunt catheter" into the brain outside of the skull. This can be done surgically or using CT scans and imaging software. Internal shunts go through the skull and into the brain tissue itself. These usually require a second surgery to place the shunt reservoir and valve inside the brain. External shunts have several problems associated with them. One problem is that they are prone to infection. This is due to the fact that bacteria find their way into the brain through the open wound where the catheter enters the skin. Another problem is that they can come out of place. This would be very dangerous because fluids could start leaking into the brain from this shunt instead of going through the nose or ears. Internal shunts have their own set of problems. One problem is that they can leak. If any part of the shunt breaks or leaks then fluid can enter the brain through other parts of the skull. This can cause serious problems if the fluid enters the brain through an area of damage or disease. Internal shunts can also cause seizures by touching off small blood vessels in the brain.