Overview of Ventriculoperitoneal Shunt
A ventriculoperitoneal (VP) shunt is a device that’s used to drain extra brain fluid, also known as cerebrospinal fluid (CSF), when its normal exit is blocked or it is not absorbed properly. This brain device is used to manage a condition called hydrocephalus. If hydrocephalus is not treated in children, it can result in many issues, such as constant headaches, learning difficulties, problems with vision, and, in extreme cases, serious mental impairment.
The shunt helps to prevent the buildup of excess CSF, which can be harmful if left unchecked. Too much CSF can increase the pressure in the brain, resulting in a condition called cerebral edema (brain swelling) and, in severe cases, herniation (brain tissue squeezing). The shunt drains the excess brain fluid into a part of the body, which is why it’s named depending on where it drains: the peritoneal cavity (the stomach area), the atrium (the heart), or the pleura (the lungs).
A shunt includes a catheter (or tube) that’s placed inside the brain, connected to a valve, which is then attached to another catheter. This second catheter is usually positioned in the stomach area. What differentiates one shunt from another is the type of valve used and whether or not it can be adjusted. Developments in biotechnology are leading to improvements in these device parts, with the hope of reducing the chances of the shunt malfunctioning and improving brain patient care.
Anatomy and Physiology of Ventriculoperitoneal Shunt
The brain contains a collection of networked spaces known as ventricles. They are tucked away within the brain’s main tissue. These ventricles are made up of two side (lateral) ventricles, a third ventricle, a brain canal (cerebral aqueduct), and a fourth ventricle. The ventricles hold a special structure called the choroid plexus, which produces a fluid called cerebrospinal fluid (CSF). This fluid is continuously being made and soaked up, filling up the ventricles and a surrounding area known as the subarachnoid space. The cerebrospinal fluid then gets absorbed into the brain’s veins via structures known as Pacchionian (or arachnoid) granulations.
If the pathway for this fluid gets blocked, it can cause a condition known as obstructive hydrocephalus. If the blockage becomes permanent, a device known as a shunt may need to be implanted to relieve the buildup of fluid. There are times when the granulations themselves, through which the fluid gets absorbed, stop working properly due to blood products or high protein levels, leading to another form of hydrocephalus known as communicating hydrocephalus.
The placement of a shunt within the brain depends on the surgeon’s preference. It could be placed through the front of the head, into the front part of the side ventricles, or it could be placed from the back of the head into certain regions of the side ventricle. The catheter (a flexible tube) placed into the brain ventricle is known as the “proximal shunt” indicating it’s close to the brain. This is typically set up in the right side ventricle, to avoid complications with the dominant side of the brain. If there’s unevenness, the catheter is put in the larger ventricle. The other end of the catheter (distal catheter) can be placed in the abdomen, heart, chest cavity, and in rare cases into the urinary pipe (ureter) or bladder when all other options have been exhausted. The goal is for this distal catheter to be in a place where cells are capable of soaking up the excess cerebrospinal fluid.
For infants who are too small or premature to tolerate regular shunts, or have issues with fluid absorption in their abdominal cavity, a temporary shunt known as a “subgaleal shunt” is used. Here’s how it works: the surgeon creates a pocket under the scalp which allows the fluid to drain from the ventricles, causing a fluid-filled bump on the infant’s head. As the child grows, this temporary shunt can be replaced with a permanent one.
Why do People Need Ventriculoperitoneal Shunt
A ventriculoperitoneal (VP) shunt is often used to treat hydrocephalus, a medical term for when there is an excess of fluid in the brain. This harmful fluid build-up can occur due to a variety of disorders which may require a shunt to control. Here are some instances where hydrocephalus might occur:
* Genetic disorders like Congenital hydrocephalus after aqueductal stenosis: This is a rare condition that can cause changes in the nervous system and is associated with intellectual disabilities, positioning of the thumb away from the hand, and stiff, tight muscles.
* Tumors: These can block the fluid from flowing between different areas of the brain, causing a build-up.
* Issues due to infection and bleeding: Diseases like meningitis or a condition called subarachnoid hemorrhage where there is bleeding around the brain can lead to hydrocephalus.
* Myelomeningocele: A birth defect involving the spinal cord which can disrupt the flow of fluid in the brain.
* Craniosynostosis: This occurs when the joints in a baby’s skull close too early, while the brain is still growing. This can rarely lead to fluid build-up in the brain.
Two specific disorders might also require a VP shunt:
* Dandy-Walker syndrome: A brain malformation involving the cerebellum, which helps coordinate movement.
* Arachnoid cysts: These are collections of fluid trapped in the brain, disrupting the normal flow and hence leading to hydrocephalus.
Other specific conditions might be:
* Idiopathic intracranial hypertension: A rare disorder, usually found in adult women, in which the pressure inside the skull increases for no obvious reason, potentially leading to permanent vision loss.
* Normal-pressure hydrocephalus: It’s a condition mostly seen in elderly people which can lead to memory problems/dementia, problem in walking, and urine leakage.
When a Person Should Avoid Ventriculoperitoneal Shunt
There are certain conditions when it is absolutely necessary to avoid specific medical procedures. These include:
If there’s an infection at the site where the medical equipment must be inserted.
Being allergic to any parts of the catheter, which is a thin tube made from a material like silicone.
Other conditions make the procedure less advisable, but not impossible. These include:
If your blood isn’t clotting as well as it should be, or if there’s an unusually high level of protein in your cerebrospinal fluid (CSF), which is the clear fluid found in your brain and spinal cord. It’s also less advisable if your CSF contains blood.
Equipment used for Ventriculoperitoneal Shunt
A VP shunt is a device that a neurosurgeon puts into your body while you’re asleep under general anesthesia in the operating room. This procedure is undertaken by a specialist called a neurosurgeon.
This device consists of several parts that help drain extra fluid from your brain to your belly, which reduces pressure on your brain. The parts of this device include:
- An entire shunt system that includes a tube going into your brain (ventricular catheter), another tube going down to your belly (peritoneal catheter), and a valve that controls flow.
- A valve that can vary in size and pressure ranging from small to high pressure.
- A programmable valve that allows doctors to adjust the flow rate if necessary.
- Specimen tubes that are used to collect some of the fluid around your brain (CSF) for testing.
- A drill to create a small hole in the skull (burr hole).
- A shunt passer that helps guide the tubes into place.
- An image-guided navigation system. This is a specialized equipment that helps the surgeon to accurately place the shunt, especially if the fluid-filled spaces in the brain are small.
These tools and equipment ensure the procedure is carried out safely and efficiently.
Who is needed to perform Ventriculoperitoneal Shunt?
There are a few important people involved when you have brain or nervous system related surgery. Firstly, there is a special kind of doctor called a neurosurgeon who performs the surgery. This doctor is skilled in operating on the brain and the nervous system. Second, there’s the anesthesiologist, who takes care of providing the medicine that allows you to sleep during surgery (this is called anesthesia), ensuring that you’re comfortable and won’t feel any pain. Lastly, there are nurses who have specific duties. Some nurses, called circulating nurses, make sure everything needed for the surgery is available and in place. Others, called technical nurses, may assist the neurosurgeon during the operation. They all work together to make sure your surgery goes smoothly and safely.
Preparing for Ventriculoperitoneal Shunt
Before a doctor places a shunt – a tube that can move fluid from one part of the body to another – in the brain, they must plan where to put it. To assist with this, they examine images of your brain taken through two types of scanning techniques: an MRI (Magnetic Resonance Imaging) or a CT (Computed Tomography) scan.
Before the surgery, the medical team conducts a thorough check-up (known as a preoperative workup) which includes getting your consent for surgery under general anesthesia. This means you will be asleep and won’t feel anything during the surgery. Additionally, you would receive antibiotics before surgery to lessen the risk of an infection, which is normal procedure for most surgeries.
The actual surgery involves you lying on your back (or in a ‘supine’ position). If the shunt is to be placed through a parieto-occipital approach (which means from the top back part of your head), your head will be tilted to the side opposite where the shunt will be installed. All of this is done under sterile conditions to maintain cleanliness and further prevent infection.
How is Ventriculoperitoneal Shunt performed
The doctor will prepare you for surgery by shaving off any hair that’s in the way of the procedure area on the head. This step is optional as some surgeons choose to shave minimally. They’ll then cleanse the skin in the area with a special solution that kills bacteria and prevents infections. A clean and sterile covering, known as a drape, will be placed over the places the doctor plans to make incisions, which could be the head, neck, chest, or abdomen.
A cut in the shape of a “U” or “C” is made in the skin on the head. This is done to create an entry point for a thin tube called a ventricular catheter, which will help drain the fluids from your brain. Different parts of the head can be used for this, based on what’s best for your condition. Some common entry points include Kocher’s point, Keen’s point, or Dandy’s point which are all specific locations on the head. The tube is gently pushed into place through the cut until it’s at the right depth.
To create an entry point, a small hole called a “burr hole” is made in the skull, and a cut is made in the outermost layer of the brain tissue, known as the dura. A tiny incision is then made in the brain tissue. Once everything is set, the doctor collects some cerebral spinal fluid (CSF) samples for further examination. The shunt (a device for draining fluids) is then connected to the valve of the tube and is secured with a type of thread called silk tie.
To connect the shunt to the fluid disposal site, another incision is made in the abdomen, exactly where depends on the surgeon’s preference. A shunt passer, a device previously used to connect the shunt to the tube, is used again to link the abdomen to the head incision. The doctor would then check for a good fluid flow before tucking the tube carefully into the abdomen. After ensuring everything is in place, the doctor sews closed all the cuts, layer by layer, following the same order in which they were opened.
Lastly, the CSF sample is sent to a lab for further tests to check for any infections or conditions. It is checked for various measures such as the number of cells, sugar content, protein level, bacteria, amongst others.
Possible Complications of Ventriculoperitoneal Shunt
There could be various complications associated with medical procedures called shunts, such as:
- Infection from bacteria entering the shunt
- Bleeding within the brain or fluid-filled areas of the brain (ventricles)
- An improperly positioned shunt
- Damage or puncture to the abdomen during shunt placement
- Shunt pushing through the skin
- Shunt draining too much fluid, causing ventricles to narrow
- Kidney inflammation related to shunt (Shunt nephritis)
- Shunt getting disconnected or blocked
- Blood clots between the brain and its outermost coverings (subdural hematomas)
- Build-up of cerebrospinal fluid in the abdomen, forming a sort of false cyst
- Shunt breaking at any point
- Rare cases might include viscera (internal organ) perforation or hernia
- Seizures may also occur
If a shunt malfunction is suspected, it has to be checked for its functionality. Here’s the procedure:
- Cleaning the skin with germ-killing solution
- Covering the incision area with a sterile cloth with a hole in the middle
- Inserting a small needle into the shunt’s reservoir
- Checking if cerebrospinal fluid fills the needle
- Measuring the pressure of the fluid in the shunt with a manometer
- Drawing out fluid with a syringe
- Collecting 5 ml of this fluid in a sterile container
- Removing the needle from the reservoir
- Apply gauze to the site
- Sending the cerebrospinal fluid sample for further tests including sugar and protein levels, cell count, and checking for any bacteria
However, this inspection process also might have some complications:
- Bleeding from the vessels beneath the skin during the tap
- Leakage of cerebrospinal fluid from the puncture site
- Brain ventricle collapsing due to rapid fluid aspiration
- Incorrect tap could potentially damage the tubing or the reservoir
What Else Should I Know About Ventriculoperitoneal Shunt?
Ventriculoperitoneal shunts are special tools used by doctors to treat a medical condition known as hydrocephalus, where there is too much fluid in the brain. These shunts work by moving this extra fluid into a space in the belly area called the peritoneum. Having a shunt inserted and periodically checked, or ‘tapped,’ can be done for treatment reasons as well as for diagnosing whether the shunt has an infection or isn’t working properly. Such a shunt is a greatly important development in terms of treating brain health conditions.
People who have these shunts inserted are routinely checked to see if they show signs that the shunt may be malfunctioning or causing complications. These signs can include: headaches, low energy levels, double vision, feeling sick with or without vomiting, seizure, irritability, poor feeding in children, an enlarged head if the skull bones aren’t completely fused, a bulging fontanelle (the soft spot on a baby’s head), fever, stiff neck. The shunt system is manually checked to ensure that it’s working properly and checked visually for any redness or swelling along where the shunt has been implanted. X-rays of the shunt system are done to check its condition, and medical scans like a CT scan or MRI are done to check how much fluid is currently in the brain.
Although ventriculoperitoneal shunts can be life-saving and can lead to great outcomes for many people, exactly how effective they are depends on why the person needed the shunt to be inserted in the first place. For less serious disorders, most people have good outcomes from getting a shunt. However, for malignant tumors, the situation is usually not as good, and these patients often pass away from causes that are unrelated to the shunt. The rate of complications from getting one of these shunts varies widely between 2-20%. Additionally, about 5-10% of newborn babies and young children who have a shunt inserted will need their shunt to be replaced or ‘revised’.
