What is a Shunt?
A shunt is a mechanical device designed to transport the excess CSF from or near the point of obstruction to a re-absorption site and it is implanted under the skin.
There are many different types of shunts, but there is no perfect shunt. The quest continues for one, the shunt manufacturers are always trying to achieve this goal.
The shunt has 3 components. The first portion is the called the shunt catheter or proximal portion of the shunt. This is a small narrow tube (catheter), which is implanted into the ventricle of the brain, above where the obstruction has occurred. It is then connected to the valve and reservoir. The valve controls how much fluid is withdrawn from the brain, it is then stored in the reservoir until it is released to drain down the distal (bottom) end. The distal end is a small, narrow piece of tubing (catheter) which leads to the point where the excess CSF will drain and be absorbed by the body.
The absorption site is usually the abdomen (peritoneum). This is the preferred location for the placement of the distal end of the shunt. This type of shunt implantation is referred to as a ventriculo-peritoneal (VP) shunt. The pleural (lung) cavity (ventriculo-pleural) shunt, or the atria of the heart, ventriculo- atrial (VA) shunt can be used also. The gallbladder or bladder can be used, but this is only when there is no other site that is suitable.
Shunts are composed of a silicone elastomer (plastic) and are often impregnated with barium. In general, there are fixed shunts or programmable shunts. The fixed shunts usually have a choice of three different types of valves (low, medium, and high). A programmable shunt allows your physician a greater range of choices in choosing the pressure at which the fluid drains. The pressure can be easily changed as the neurosurgeon has a magnetic device to change the setting, in the convenience of his office. Newborns and infants often are implanted with a fixed shunt, when they are older and in need of a revision, the doctor may then decide to replace the valve and reservoir unit with a programmable one.
You should know that the shunt performs two functions. It allows fluid to go only in one direction and the valve allows fluid to flow out only when the pressure in the head has exceeded some value (usually referred to as the “opening pressure”). This system regulates the amount of the CSF in the body so that not too much is taken, nor too little.
Having a shunt is a lifetime commitment. Once a shunt is implanted, it is not a “one time” operation. Life expectancy of a shunt averages 10 years. However, a shunt can last 5 minutes to many years. It is wise to always be aware of the warning signs for a “shunt malfunction.” (Please refer to the Signs of Hydrocephalus and Shunt Malfunctions.)Third
Some patients can be treated with an alternative procedure called an Endoscopic Third Ventriculostomy (often referred to as an ETV, Third Ventriculostomy, or Third Vent). For this operation, a tiny burr hole is made in the skull and a neuroendoscope (a small camera which is attached to medical instrument) is utilized to enter the brain. The physician will then make a small hole (several millimeters) in the floor of the third ventricle. This allows the CSF to flow from the blocked ventricles into the open spaces surrounding the brain.
If the operation is successful, it will eliminate the need for a shunt. However, not everyone with hydrocephalus can qualify for this type of operation. It is also meant for patients older that 6 months of age, and many physicians prefer that the patient is older than 2 or 3 years of age.
Although a Third Ventriculostomy eliminates the need for a shunt, it is by no means a cure for hydrocephalus.
Are There Complications?
Either in the shunt implantation or a revision, there is a very small chance of a complication occurring.
As stated previously, hydrocephalus (and in most cases, shunts) are life-long conditions. There will be revisions from time-to-time.
If an obstruction or other problem is found within the shunt system, one or more components of the shunt may need to be replaced. When this occurs, surgery is necessary.
Some of the problems that can cause a shunt malfunction are:
- Calcification or breakage of the catheters
- Separation (catheters may disconnect from the valve and reservoir unit)
- Valve is broken or stuck
- Wrong pressure valve (usually found in a fixed shunt)
- Catheter needs lengthening
- Over-drainage or under-drainage
When a patient shows signs, it is best to make an appointment with the neurologist or neurosurgeon. Usually, if you advise the doctor’s personnel of ‘a possible shunt malfunction’ they will try to arrange an appointment with the doctor as soon as possible. Should the patient’s condition worsen – and you are unable to reach the doctor’s office, you should take the patient to the emergency room of the hospital and advise the desk personnel of ‘a possible shunt malfunction.’ If you are the patient, have someone assist you.
Some children do require intervention in the way of physical and occupational therapy. Your physician will let you know if this is needed.
As we often tell parents who want to know what the future holds for their child – ‘your child can be anything he wants to be.’
Some problems may develop for adults. The most common complaint we hear from adults relates to their short-term memory. We give them “tricks-of-the-trade,” but ultimately, just like the children, the adult must figure out a solution to his/her particular situation.
Research is being conducted all over the country. You may not hear about the testing of new medications or new medical equipment until after they have passed all the testing requirements and have been approved by the FDA (Food and Drug Administration).
There are several organizations around the U.S., which primarily focus on fundraising so that grants may be given to researchers working on an idea or product relating to hydrocephalus or related neurological conditions. There are other hydrocephalus organizations that not only focus on helping the family or individual, but also make donations to research.
Other Hydrocephalus Organizations
870 Market St., Suite 955
San Francisco, CA 94102
E-Mail: [email protected]
Hydrocephalus Association of North Texas
P.O. Box 670552
Dallas, TX 74637
Hydrocephalus Family Support Group of Central Florida
Kay Taylor R.N., Pediatric Neurosurgery
22 Lake Beauty Drive, Suite 204
Orlando, FL 32806
E-Mail: [email protected]
910 Rear Broadway
Saugus, MA 01906
Hydrocephalus Support Group, Inc.
P.O. Box 4236
Chesterfield, MO 63006
Hydrocephalus Support Group of Northeast Ohio
9500 Euclid Ave., Desk P87
Cleveland, OH 44195
3 Emeritus St.
Rutland, VT 05701
E-Mail: [email protected]
Seeking Techniques Advancing Research in Shunts (S*T*A*R*S)
165 S. Opdyke #105
Auburn Hills, MI 48326
Children’s Neurological Center, Support Group
JFK Medical Center
65 James St.
Edison, NJ 08818
732-321-7000 ext. 65362 (Nancy Vassallo)
E-Mail: [email protected] (Nancy Vassallo)
Pediatric Hydeocephalus Foundation
E-Mail: [email protected]
If you know of a support group which has not been listed, please advise our office so that we may add it to our list.
Acquired Hydrocephalus – Resulting from an outside factor; not inherited nor congenital
Aqueductal Stenosis – A blockage or narrowing of the path from the third to the fourth ventricle
Arachnoid Villi – See Arachnoid Granulations
Arachnoid Granulations – Protrusions of the arachnoid membrane of the brain. The arachnoid villi (or granulations) are very similar to a one-way valve, as they allow the CSF to drain from the subarachnoid space into the superior sagittal sinus, where it can be reabsorbed into the blood system
Benign External Hydrocephalus – (Also referred to as External Hydrocephalus.) An accumulation of CSF found on the outside of the brain, which usually presents itself at birth or soon thereafter. The child’s head size will increase, but scans show no internal problems in the ventricles or pathways. The condition corrects itself within about 18 months of age (of the child)
Cerebrospinal Fluid (CSF) – The water-type fluid that bathes the brain and spinal cord
Communicating Hydrocephalus – A type of hydrocephalus where the pathways and the ventricular system are not obstructed, however, the problem appears to be that of re-absorption of the used CSF
Congenital Hydrocephalus – A child diagnosed in utero or at the time of birth as having hydrocephalus
Distal (Catheter) – The catheter connected to the shunt valve and directed to the point where the CSF can drain and be re-absorbed
Endoscopic Third Ventriculostomy – A surgery in which a hole is punctured in the floor of the third ventricle. This allows a new pathway for the CSF to be absorbed by the body
External Hydrocephalus – See Benign External Hydrocephalus
Fixed Shunt – A type of shunt that comes with a valve for either high, medium, or low pressure
Intraventricular Hemorrhage (IVH) – A bleed within the ventricular system of the brain (also referred to as a brain bleed)
Lateral Ventricles – There are two, one on each side of the brain
Lumbar Tap – (Also called Lumbar Puncture and/or a Spinal Tap.) The insertion of a hollow needle to remove some of the CSF either for pathological testing (i.e. for infection), or to relieve some pressure and see if the patient improves
Non-Communicating Hydrocephalus – Hydrocephalus that is caused by an obstruction in the flow of the CSF
Normal Pressure Hydrocephalus – Type of hydrocephalus, where the ventricles are enlarged but there is no obstruction in the ventricular system. The cause appears to be that the CSF is not being absorbed
Programmable Shunt – Type of shunt where the physician can raise or lower the amount of CSF taken from the brain
Proximal (Catheter) – A catheter that is placed in the ventricle of the brain
Reservoir – Part of the shunt where the CSF is stored and then released periodically
Revision – When an operation is needed to replace part or all of the shunt
Subarachnoid – Space where CSF travels over the surface of the brain and the spinal cord
Valve – That which controls how much CSF is taken from the brain
Ventricles – Four chambers of the brain that produce the CSF – lateral ventricles (2), one on each side of the hemispheres which then flows into the third ventricle, which is located in the center of the brain, and onto the fourth ventricle, which is located in the lower back of the skull
Ventriculo-Artial (VA) Shunt – Type of shunt where the distal catheter tip lies in the right atrium of the heart. This allows the CSF to enter the bloodstream directly
Ventriculo-Pleural Shunt – Type of shunt where the distal catheter is located in the pleural space that surrounds the lungs
Ventroperitional (VP) Shunt – Type of shunt where the distal catheter is located in the lower part of the abdomen