The surgical procedure to implant a VP (ventricular peritoneal) shunt usually requires less than an hour in the operating room. After the patient is placed under general anesthesia, their scalp is shaved and the patient is scrubbed with an antiseptic from the scalp to the abdominal area. These steps are taken in order to reduce the chances of an infection. Incisions are then made on the head and in the abdomen to allow the neurosurgeon to pass the shunt's tubing through the fatty tissue just under the skin. A small hole is made in the skull, opening the membranes between the skull and brain to allow the ventricular end of the shunt to be passed through the brain and into the lateral ventricle. The abdominal (peritoneal) end is passed into the abdominal cavity through a small opening in the lining of the abdomen where the excess CSF will eventually be absorbed. The incisions are then closed and sterile bandages are applied.
The patient generally stays under careful neurological observation for the first 24 hours following the procedure. Some neurosurgeons prefer to keep the patient flat in bed until nearly all the subdural air introduced during surgery dissipates. The bandages placed on the head and abdomen, covering the incision sites, are monitored for signs of infection. The patient will generally need to stay in the hospital from three to seven days. Follow-up visits will be necessary to check post-operative status and resolution of symptoms. Additional treatment, such as physical therapy, may be advised to help the patient attain previous levels of motor skills.
Although shunt surgery is a relatively simple neurosurgical procedure, the decision to undergo insertion of a shunt should not be taken lightly. The treatment of normal pressure hydrocephalus carries greater risks compared to the treatment of children with hydrocephalus, and therefore the operation should be undertaken only if the degree of disability or the progression of the disorder warrants.
The potential complications of shunt surgery should be viewed as those related to the actual operation, plus those that may occur days to years later. A complication can be thought of as any unwanted event related to the surgical procedure itself or the presence of the shunt. Potential complications may include the infection of the surgical wound or of the CSF (meningitis), bleeding into the brain or ventricles, or a seizure. A shunt infection may be indicated by fever, redness or swelling along the shunt track. Fortunately, these complications are uncommon and can be managed successfully in most cases.
Unlike may other operations in which the surgical risks are highest during the operation itself, most of the common and serious problems associated with shunting can occur weeks or even years after the surgery. The most common problem with shunt systems is that they can become obstructed (clogged). This can occur hours or years after the operation, sometimes multiple times. The likelihood of a shunt obstruction is thought to be about 50% for most patients. For patients with NPH, a shunt obstruction is usually discovered when the original symptoms recur. Fortunately, shunt obstructions in NPH are easily fixed and rarely result in serious problems.
The most serious complication that can occur following insertion of a shunt is a subdural hematoma (blood clot). Because most shunts drain CSF from the center of the brain (the ventricles), this may cause the surface of the brain to pull away from the skull, thus stretching and tearing blood vessels on the surface of the brain. The symptoms of a subdural hematoma vary from increasing headache to paralysis or even coma or death. Shunt-related subdural hematomas most commonly occur following a fall, even one involving only a minor bump to the head. Therefore, a patient with NPH should not hesitate to seek medical attention if abnormal symptoms develop. The risk of a subdural hematoma in a patient with NPH is approximately 10%. Given these potential complications, individuals need to assess their own situation to determine if the possible benefits of surgery outweigh the possible risks.