What Is a Brain Shunt?
There are certain conditions affecting one’s head, resulting in large-scale fluid accumulation inside the brain (hydrocephalus). This excess fluid keeps increasing the pressure inside the head (intracranial hypertension), causing damage to the brain tissue. This is a critical condition that requires immediate medical attention. A brain shunt is a flexible tube the surgeon places inside one brain to drain this excess fluid. The other end of the tube is connected to another part of the body, which can absorb the fluid so that the pressure inside the brain stays regulated. When one’s brain is incapable of regulating the pressure from excess fluid collections, shunting is the best long-term option.
When Does One Require a Brain Shunt?
There are some fluid-filled spaces inside the brain called the ventricles, where a fluid known as cerebrospinal fluid or CSF is produced. Normally, the CSF circulates around the brain and gets absorbed back into the bloodstream so that its volume remains the same. Under certain circumstances, this mechanism fails, and CSF builds up in excess inside the brain. The pressure build-up from this accumulated fluid can go extremely high to the point it can actually damage the brain. This is when surgical placement of a brain shunt is advised to drain the fluid. The excess build-up of CSF can be due to:
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Overproduction of CSF.
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Blocks in the pathway inside the brain through which CSF normally circulates.
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The excess fluid fails to get absorbed back into the blood vessels.
Following are the conditions where one may require shunting:
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Hydrocephalus - A condition characterized by an enlarged head, frequent seizure attacks, headaches, drowsiness, incontinence, poor appetite, cognitive issues, behavioral issues, poor coordination, memory, and vision.
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Inflammation inside the brain.
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Presence of tumors or cysts that block the CSF channel.
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Excess bleeding (hemorrhage) inside the brain from trauma to the head.
How Does a Shunt in the Brain Work?
A shunt is a flexible tube in the form of a catheter. It has an inflow catheter that drains the CSF from inside the brain once it is properly positioned. Additionally, there is a valve mechanism connected to the shunt, which regulates the fluid flow while draining. The valve works under preprogrammed pressure levels so that just the right amount of fluid is drained and the normal pressure is maintained. The last part is an outflow catheter that runs under the skin and opens out into another part of the body, where the fluid gets absorbed.
What Are the Common Types of Shunting Mechanisms?
Based on which part of the body the catheter is draining to, shunts are of four types. They are:
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Ventriculoperitoneal Shunt (VP) - Where the last part of the catheter is attached to the abdomen next to the intestines. The fluid will get absorbed into the blood vessels of this area and excreted through urine.
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Ventriculoatrial (VA) Shunt - In this type of shunt, the last part of the catheter is fitted into a vein in the neck and guided into the heart. The CSF gets drained into the right chamber of the heart and becomes a part of the circulation. Eventually, it is excreted through urine.
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Ventriculopleural (VPL) Shunt - Pleura is a membrane that covers the lung that lodges the pleural fluid. The end part of the catheter is connected to the pleural cavity, where it becomes one with the pleural fluid and later on gets excreted through urine.
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Lumboperitoneal (LP) Shunt - This one is different from the other types since the draining part of the catheter is not inserted into the brain but into the spinal column (intrathecal space). It is connected to the abdomen (peritoneal cavity). From here, just like in a VP shunt, the fluid gets absorbed into the blood vessels next to the intestine and gets excreted through urine.
How Is a Shunt Inserted Into the Brain?
Shunt placement is a surgical procedure conducted after one is put to sleep (general anesthesia). The duration of the procedure is approximately 90 minutes. After shaving a small area of the scalp behind the ear, the surgeon will make a tiny cut and drill a hole into the skull. The draining end of the catheter is inserted through this hole. The tip of the drain is made to reach the fluid-filled space inside the brain. The part with the valve is placed behind the ear under the skin and connected to the first part. The end of the tube is guided to the respective body part, where the fluid will get absorbed. The wounds are closed with stitches followed by bandaging. The individual is put to rest and kept under observation for a few days. Once they leave the hospital, periodic follow-ups are required to make sure the shunt is working properly.
What Could Go Wrong With a Shunt?
Possible risks involving the shunt are:
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Shunt Blockage - Blocks inside the shunt, affecting drainage. It may get blocked partially and cause poor drainage or get fully clogged allowing no amount of fluid through the tubes. This leads to accumulation of excess CSF inside the brain and cause damage to brain tissues.
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Over Drainage of CSF - When too much CSF is drained too quickly, there may be bleeding inside the brain along with headaches, vomiting, and seizures. Here the space called ventricles inside the brain tend to collapse.
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Under Drainage of CSF - If adequate drainage does not happen with the shunt, one may develop hydrocephalus and increased intracranial pressure. Which totally fails the purpose of shunt placement.
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Infection at the Site of Shunt Placement - May spread to the cerebrospinal fluid and eventually affect the brain, which could turn fatal.
Conclusion:
Shunting is one of the best methods to relieve the intracranial pressure on a long-term basis. Though it can be attached to the brain permanently, one has to go to the doctor for a regular check-up. Also, it may need repair or replacement if necessary. The doctor may educate the patient and their family on how to check if the shunt is working properly and how to care for it at home. A correctly operating shunt can effectively eliminate the complications from hydrocephalus.
