Surgery to Treat Hydrocephalus
Hydrocephalus treatment usually requires surgery to drain the excess fluid from the brain by diverting it to another place in the body.
A shunt is a soft, flexible tube usually made of silicone rubber or plastic. Most shunts consist of a valve that promotes drainage and a catheter, a tube that connects the drainage site to the deposit site. If there is high intracranial pressure, a small sensor may be added near the valve. This sensor allows the neurosurgeon to monitor pressure levels.
The shunt used for treating hydrocephalus is usually permanent. The shunt is inserted with one tip in one of the ventricles of the brain and the other tip in the abdominal (peritoneal) cavity. This is known as a ventriculoperitoneal (VP) shunt. Less commonly used drainage sites include the right ventricle of the heart, the gall bladder, and the pleural space around the lungs. Depending on the location of the obstruction, fluid also may be drained from the subarachnoid space that surrounds the brain.
Although insertion and immediate operation of the shunt is usually uncomplicated, problems can arise.
- Abdominal problems:
- Bowel twisting
- Excess fluid collection
- Blockage of the shunt
- Brain injury:
- Clots on brain surface
- Loss of sensation
- Memory loss
- Speech problems
- Headaches caused by overdraining
- Mechanical failure (e.g., separation of parts, valve failure)
Other complications include bleeding, problems with anesthesia, and infection. The body may react negatively to the shunt because it is made of foreign material.
Approximately 70 percent of shunts fail within 10 years of placement. To accommodate normal growth and to ensure long term function, shunts in infants and children are replaced frequently until adulthood. A child may require as many as five shunts during this period. A neurosurgeon periodically checks shunt function in adults.
Third ventriculostomy involves entering the brain through the bones at the top of the skull. The neurosurgeon passes an endoscope (a thin telescopic instrument) through the lateral ventricle into the third ventricle and uses a laser to make a hole in its floor. Excess fluid drains through the hole into the subarachnoid space.
The overall success rate of third ventriculostomy is about 65 percent. When used to treat blockage caused by tumor or by aqueductal stenosis, success rates are slightly higher. In hydrocephalus caused by hemorrhaging or infection, they are slightly lower.
There are few risks associated with third ventriculostomy. CSF drains through a hole in the ventricle floor instead of a valve, so there is no risk of overdrainage. The absence of a tube eliminates the risk associated with a shunt.
Rarely, the basal artery near the third ventricle is injured during the procedure, which can cause life threatening hemorrhaging in the brain. However, use of the endoscope has lowered this risk.