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One of the most common shunt complications is an obstruction of either the proximal (ventricular) or distal catheter.

Subdural hematomas have the same
symptoms as a malfunctioning shunt system...

Shunt infections...
commonly occur within one to two months following a placement or revision procedure.

If you suspect a shunt infection, contact your primary care physician or neurosurgeon immediately.

Shunt Revisions: Part 2

The following excerpt is taken from Chapter Six of Hydrocephalus: A Guide for Patients, Families, and Friends by Chuck Toporek & Kellie Robinson, copyright 1999 by O'Reilly & Associates, Inc. For book orders/information, call (800) 998-9938. Permission is granted to print and distribute this excerpt for noncommercial use as long as the above source is included. The information in this article is meant to educate and should not be used as an alternative for professional medical care.


One of the most common shunt complications is an obstruction of either the proximal (ventricular) or distal catheter.

Proximal catheter obstructions

The proximal catheter is the most likely to be obstructed. When CSF is drawn into the shunt system, the catheter creates a suction effect within the ventricle, similar to that of the drain in a bathtub. This suction could possibly draw the choroid plexus, blood, and debris toward the holes at the end of the catheter and contribute to obstruction.

Obstructions of the proximal catheter can be caused by a variety of factors, including:

  • In-growth by the choroid plexus.

  • Collapsed ventricles, which occlude (block) the holes at the end of the ventricular catheter.

  • Blood clots resulting from hemorrhaging during placement or removal of the ventricular catheter.

  • Buildup of tissue debris.
When the proximal catheter is inserted into the ventricles, brain matter can sometimes get caught in the holes of the catheter. In some cases, bleeding may occur when the ventricles are catheterized. When this happens, blood and/or brain matter can get sucked into the catheter along with CSF. If the matter is too large, it can block one or more of the holes of the catheter or get pulled into the catheter and cause a complete obstruction.

In some cases, such as obstruction of the proximal catheter by the choroid plexus, your neurosurgeon may decide it is safer to leave the existing catheter in place rather than removing it, to eliminate the risk of causing an intraventricular hemorrhage. Your neurosurgeon will be able to tell if the catheter has been obstructed by the choroid plexus or other adhesions if the catheter resists being removed when it is pulled.

When the neurosurgeon came out of the operating room to talk to us, he told us that they had to leave the end of the catheter in Brian's ventricle. It had become so clogged with the choroid plexus that it would not come out easily. This has happened many times. Now his CT scans show many "shunt artifacts" in his ventricles, and they cannot be removed safely.
If a hemorrhage does occur, your neurosurgeon will flush the ventricles with Ringers lactate to stop the bleeding before reinserting a new proximal catheter. A slight degree of bleeding is not uncommon, and usually results in no consequences. However, in cases where the bleeding is severe, the patient might experience some form of neurological deficit as a result of the intracranial hemorrhage. The true extent of the damage may only be determined after recovery from the operation.
When my shunt was originally placed in 1972, I was in the hospital for 47 days. The only complication during that procedure was an intraventricular hemorrhage. I became paralyzed and had to learn how to walk and use my right hand all over again. I also had problems remembering who I was.

Distal catheter obstructions

Distal catheter obstructions are less common than proximal catheter obstructions, but they do occur.

The distal catheter for VP shunts can be obstructed if debris in the peritoneal cavity accumulates around the tip of the catheter. This is more common in distal catheters that have slit valves rather than an open end to allow CSF to flow out of the system. Loss of absorptive ability by the peritoneal cavity or the growth of peritoneal pseudocysts also contribute to distal catheter obstructions.

Ventriculoatrial shunts can become obstructed when the distal catheter migrates out of the right atrium of the heart and lies against the wall of the superior vena cava (one of two main veins that deliver blood to the right atrium of the heart). If the tip of the distal catheter resides outside the heart, it is also at risk of clotting.

Subdural hematomas

A subdural hematoma (SDH) is an accumulation of blood (hematoma) between the dura mater and the arachnoid layers of the meninges. This area is known as the subdural space.

When a proximal catheter is inserted into the ventricles and a working shunt system is attached to drain the excess CSF, the ventricles can deflate fairly rapidly, and the surrounding brain matter will move inward to assume a smaller form. However, if the ventricles deflate too quickly, the veins that bridge between the brain and dura can be stretched and torn, resulting in an accumulation of blood in the subdural space.

Subdural hematomas can also be caused by trauma to the head (e.g., getting hit in the head with a fast-moving baseball). In these instances, the hematoma results from an intracranial hemorrhage.

Detecting subdural hematomas

Subdural hematomas have the same symptoms as a malfunctioning shunt system, particularly lethargy, gait disturbances, headaches, numbness or loss of sensation to one side of the body, and reduced mental faculties.

An SDH is detected with imaging equipment, usually ultrasound for infants and small children, and CT or MRI in older children and adults. Once detected, your neurosurgeon will determine the proper course of action to treat the SDH.


Treatment for SDHs requires hospitalization to relieve the hematoma. If the SDH is caused by a faulty or improper shunt valve, the entire system may be revised.

There are many schools of thought on how to treat SDHs. The long-standing debate revolves about whether to evacuate (or drain) the SDH by creating a burr hole or to perform a craniotomy directly over the area of the subdural accumulation of blood.

The burr hole operation is performed by drilling a hole through the cranium directly over the deepest area of the SDH. Your neurosurgeon will create a small hole in the dura layer to relieve the pressure of the hematoma. Interoperative CT scans may be taken at this time to determine if additional drainage of the hematoma is required. Upon completion of the procedure, the burr hole will be capped and the incisions will be cleansed and closed, either with sutures or surgical staples.

Mike had two subdural hematomas drained externally during a revision. Postop I was told how Mike could not be allowed to move--yeah, he is 18 months old and he certainly will agree to lie flat on his back now that he is feeling free of headache! I was also told how the drains had to be a specific amount of inches off the floor, etc. The nurses and doctors kept checking it over and over again, then checking the fluid that flowed into the two bags hanging on the side of the bed.
A craniotomy is more complex than a burr hole operation, requiring your neurosurgeon to remove temporarily a small section of the skull to access the hematoma. This allows him to access a larger area of the dura in order to treat the hematoma. To relieve the SDH, your neurosurgeon will create a small hole in the dura layer. Once drainage is complete, the section of skull will be put back into place, where it will fuse together with the surrounding skull.

In both types of operations, additional drainage of the hematoma may be required. This is done by inserting a drainage tube through the dura layer into the hematoma to suction out additional fluid.

Most neurosurgeons perform burr hole operations to relieve SDHs, since craniotomies are more invasive and require longer hospitalization.

Shunt infections

Shunt infections are the most serious complication related to the treatment of hydrocephalus. They most commonly occur within one to two months following a placement or revision procedure. Although a shunt system can develop an infection many months or years after insertion, these cases are extremely rare.

Symptoms of shunt infections

Symptoms of a shunt infection include:
  • A persistent low-grade fever (usually greater than 100°F or 38°C), or a high-grade fever (102-104°F or 39-40°C) if the infection is more aggressive.

  • Irritability and changes in mood or personality.

  • Changes in cognitive ability.

  • Redness and/or tenderness along the shunt tract.

  • Swelling or tenderness of the abdomen (with VP shunts).

  • Sudden, frequent vomiting or persistent nausea.

  • Headaches.

  • Soreness of the neck and/or shoulder muscles.
Any of the above symptoms, especially in combination with a high fever, could indicate the possibility that something is wrong. If you suspect a shunt infection, contact your primary care physician or neurosurgeon immediately.
Shaun had had a revision the week before and he began to have a low-grade fever with some general aches and pains. I thought it was a flu that maybe he had picked up in the hospital, but he began to look sicker as the day went on. He did not respond to Tylenol and actually looked very sick, even though his fever was low. We went to the emergency room and they found out he had a shunt infection.

What causes shunt infections?

Shunt infections can be caused by a number of various factors, including:
  • Bacteria being introduced to one of the incisions during surgery.

  • Placement of an improperly sterilized shunt valve or catheter.

  • Meningitis.

  • An infection near the distal end of the shunt system, such as peritonitis for VP shunt placements. An infection near the distal end is also termed a pseudocyst, which is a collection of infected fluid that forms a cyst around the tip of the distal catheter.

  • Length of time the shunt procedure takes. The longer the shunt procedure is, the greater the risk of infection.
The most common types of infections in shunts are Staphylococcus aureus (65 percent) and Gram-negative bacteria (GNB, 19-22 percent). Shunt infections occur in approximately 2 to 10 percent of all newly placed systems, including revisions (J.K. Stamos, "Ventriculoperitoneal shunt infections with Gram-negative bacteria," Neurosurgery 33, no. 5, 1993: 858-62).

Treating shunt infections

Treatment of shunt infections can be a long and arduous process that requires hospitalization. If you have a shunt infection, you will be placed on high doses of intravenous antibiotics to fight off the infection. Removal of the entire shunt system--including the ventricular catheter--is necessary to prevent any possibility of reintroducing the infection to your body.

After removal of the shunt system, CSF is drained through an external ventricle drainage (EVD) system. An EVD consists of a ventricular catheter, a shunt valve, and a bag which collects CSF at the distal end. With the EVD in place, you will continue to receive intravenous antibiotics until further tests of CSF indicate that the infection has been cured. This could take anywhere from two to fourteen days. If ventricular CSF cultures continue to show signs of infection, antibiotics can be injected into the ventricles through the EVD. After the CSF has been proven to be sterile for seven to ten days, your neurosurgeon will insert a new shunt system.

Our 13-year-old son was born premature, and was shunted for hydrocephalus at 13 months. He is doing absolutely great! He has had three revisions.

At the age of 5, his tube became clogged with tissue at the valve, and required a revision (#1). They placed the tube in the wrong spot, and had to go through another operation that evening (revision #2).

Then last year, at the age of 12, he developed an infection in his stomach that put him in the hospital for emergency surgery. They externalized his shunt and fought the infection with antibiotics for 10 days. His neurosurgeon replaced the shunt (revision #3) and sent him home on an IV to continue the antibiotics.

How to avoid shunt infections

Most shunt infections occur at the time the shunt is inserted or revised and make their presence known within the first month following placement. These infections were probably introduced to the shunt system or the incisions during or immediately following the operation.

Following surgery, you can help reduce the risk of contracting a shunt infection by:

  • Not scratching or picking at the area around the incisions (or not allowing your child to do so). Although the incisions may itch, scratching them before they have healed properly could possibly introduce bacteria, which may cause an infection.

  • If the area surrounding the incisions starts to redden, swell, or ooze, contact your doctor immediately.

  • Since bacteria travel through the body in the blood, some neurosurgeons recommend that patients with VA shunts take antibiotics at least 24 hours prior to visiting their dentist. This is not necessary for people with VP shunts since the catheters are outside the bloodstream. Your dentist can prescribe the antibiotics for you.

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