The Wonderful World of Hydrocephalus: Part 4, How Shunts Work

One of two ways to control hydrocephalus and the most common.
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The quick version.
A flexible 1/8″ in diameter tube (ventricular catheter)–usually made of Silastic plastic well tolerated by body tissue–is placed into the CSF system via the ventricles, and diverts the flow of CSF to another region of the body, most commonly the abdominal cavity (peritoneal catheter) or the right atrium of the heart (atrial catheter). In the upper half of this tubing is the valve that controls the pressure and prevents backward flow of spinal fluid toward the ventricles. Pretty simple really.
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Here’s more.
Most shunts have a reservoir used for taping CSF. Taping occurs when the neurosurgeon thinks there may be a shunt malfunction or to do further analysis to test for an infection. Some reservoirs can act as flushing devices–pushing fluid toward or away from the head. Some shunt have double reservoirs allowing for fluid to be pushed out in both directions.
For ease of explanation, many people say that the shunt drains fluid from the brain into the stomach. To be accurate, a ventriculoperitoneal (VP) shunt diverts fluid from the ventricle(s) into the peritoneal cavity, a space in the abdomen near loops of the intestine and bowel (between digestive organs) but NOT inside the stomach. There the CSF is reabsorbed into the bloodstream. A ventriculoatrial (VA) shunt diverts fluid from the ventricle(s) into the right atrium of the heart. The atrial catheter is placed into a vein in the neck and advanced through that vein into the heart. Again, the CSF is reabsorbed into the bloodstream. Shunts can be placed in other parts of the body however the VP shunt is the most common as it comes with fewer risks and is an easier procedure to perform. Only in rare circumstances are shunts placed in other sites other than the peritoneal cavity or the atrium of the heart.
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Shunt valves.
Some shunts are programmable. Some are not. Programmable shunts vary from 3 settings up to 200 depending on how much flexibility the patient needs. Programmable shunts work great for those who need the pressure changed frequently but do not want to go into surgery. Some programmable shunts work magnetically so all they do is put up a magnet to the valve and move it. Watch out iPad users. iPads can accidentally reprogram a shunt. The iPad would actually have to be right next to the valve in order to do it, so it’s pretty unlikely to happen accidentally. Shunts that aren’t programmable have three settings: low, med, high. Your neurosurgeon will choose the best setting for you. If the setting needs to change, surgery is necessary. I’ve always wondered why everyone wouldn’t automatically get a programmable shunt. This is where you put your trust in your neurosurgeon.
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Ellisa’s Shunt.
On my daughter, her shunt was placed on her right side. I’ve been told the side is dependent on how the surgeon best performs the surgery. If looking, you can see and feel the valve just below her ear and slightly over to the left (her hair covers it well). From there you can see a tube running down the right side of her neck (it’s only really noticeable when she’s looking left) going towards her chest. I used to be able to see the tubing in her chest when she was under 1 year old, but no longer can. There’s a small scar on her belly and a 1-2″ scar on her head above the valve (again covered by her hair) from the initial surgery. The tubing looks like a vein (thick for her age) and I don’t think anyone would think it was anything else but a vein unless they were clued into hydrocephalus. I have no idea if Ellisa has a reservoir. I would think she does. I’ll be sure to add this question to my list for the neurosurgeon (this is why I’m doing this series!). And her shunt is not programmable. I’m not sure what setting it is on. I’m not sure I need to know.
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The second way to control hydrocephalus is an ETV, endoscopic third ventriculostomy. I really don’t know much about this since my daughter didn’t have this procedure done and her neurosurgeon has never brought it up as an option. I do know most people with hydrocephalus don’t match the criteria for an ETV. Neurosurgeons will not perform this procedure on infants or young toddlers.
When an ETV is performed, a tiny hole is put into your third ventricle to naturally allow free flow of CSF into the spaces around the brain. I believe because this is a newer procedure, that is why it isn’t as widely used. Not as many neurosurgeons are experienced with it.
If someone already has a shunt and becomes a candidate for an ETV, the neurosurgeon will not take out the already placed shunt. This would require an extra surgery and risks. There are less risks to leave the shunt in along with the ETV. This makes it hard to determine if the ETV was successful. As my neurosurgeon says, “If it’s not broken, we’re not going in to fix it.”
It seems so much more natural to get an ETV. I wonder if some day Ellisa will have this done. It’s easy for many patients who have a successful ETV to forget they have hydrocephalus. Keep in mind an ETV is not a cure for hydrocephalus, it’s an alternative treatment. An ETV can fail after years, so you must not forget the symptoms of a failure.
Again, hydrocephalus is not a disease it’s a condition that does not have a cure (as of yet).
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Next time I’ll touch shunt malfunctions. This is a topic that is never ending. Until then.
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The Wonderful World of Hydrocephalus: Part 1, The Facts

The Wonderful World of Hydrocephalus: Part 3, How Hydrocephalus Works

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My amazing neurosurgeon-Dr. George


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