How does a shunt work?

As with many other technical developments, there are many different shunt systems from different manufacturers. I will now try to explain the functionality of a shunt as simple and understandable as possible, which of course is always the same in principle, no matter which company it comes from. I don’t want to go into detail about the types of shunts and how they work, because this topic is very complex and I’m not a doctor. On the page with the LINKS there are useful redirections, directly to the manufacturers, which help there.

 

What is a shunt?


Shunts have been used to treat hydrocephalus for over 50 years now. Surplus cerebrospinal fluid, which in hydrocephalus is not regulated by the body itself, is derived by the shunt.

A shunt diverts the cerebrospinal fluid from the nervous system to another part of the body. This allows the enlarged brain ventricles to shrink back to normal size, which is intended to reduce the symptoms of hydrocephalus.

A shunt cannot heal the hydrocephalus, but it alleviates the symptoms of the disease and allows the affected person a relatively normal life.

Function mode shunt


There are different shunt systems and manufacturing companies but the principle is usually always the same. A shunt consists of two catheters and a check valve. The valve controls the amount of cerebrospinal fluid, the flow direction and the pressure in the cerebral ventricles. With increasing cerebrospinal fluid pressure in the brain, the non-return valves open and discharge the excess fluid into the abdominal cavity or the atrium.

In general, the fluid is discharged with the following shunt types:
A ventriculoperitoneal shunt drains the fluid from the ventricles into the abdominal cavity. A lumboperitoneal shunt drains the fluid from the lower back into the abdominal cavity.

There are different types of shunt valves. The two most common are:

    • Fixed pressure valves – You regulate the flow of cerebrospinal fluid using a preset pressure value

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  • Valves with adjustable pressure – you regulate the flow of cerebrospinal fluid according to an adjustable pressure value.
  • Your doctor can use special magnetic devices to change the pressure setting of the implanted adjustable valve non-invasively on an outpatient basis and without further intervention.

Liquor valves with fixed and adjustable pressure

  • Make by Medtronik GmbH: Anti-siphon valve to avoid excessive drainage
  • At the manufacturer Miethke: Gravitational unit

Both valve types can contain an additional protection device against excessive drainage in the form of an anti-siphon valve. In the upright position, gravity causes an increased discharge of cerebrospinal fluid. An anti-siphon valve can prevent excessive discharge.

Valve reservoirs

Some valves have a reservoir that can be used for various purposes. Your neurosurgeon can test the shunt by flushing the reservoir. Liquor can also be taken from the reservoir for laboratory tests.

catheter

To treat hydrocephalus without connection (HC occlusivus), a catheter must be inserted into the cerebral ventricle. In a hydrocephalus with a connection (HC communicans), the cerebrospinal fluid can be diverted from the brain ventricles or the spinal cord to another part of the body (usually the abdominal cavity).

Lumboperitoneal shunts (LP shunts) are generally reserved for adults.

Brain water drainage into the abdominal cavity (ventriculo-peritoneal shunt, VP shunt):

In the event of a disturbance of the cerebrospinal fluid circulation, the cerebrospinal fluid (cerebrospinal fluid) can be discharged from the (usually) right lateral ventricle into the abdominal cavity. This is called a ventriculo-peritoneal drainage of cerebrospinal fluid.

A catheter is inserted into the cerebral ventricle (central catheter) and connected to the upper end of a valve which is inserted (implanted) under the skin on the side of the head. The valve is usually protected against excessive drainage of brain water (overdrainage), a so-called anti-sog valve (anti-siphon device, ASD).

The abdominal catheter (peripheral catheter) is attached to the lower end of the valve and placed under the skin. Small incisions in the neck and abdomen – these areas can be recognized by a skin scar – indicate the areas where the catheter was inserted under the skin. The catheter enters the abdominal cavity at about the same level as the scar on the abdomen.

Brain water drainage into the heart (ventriculo-atrial shunt):

In the event of a disturbance of the cerebrovascular circulation, the cerebrovascular fluid (cerebrospinal fluid) can be discharged from the (usually) right lateral ventricle via a central catheter, a valve and a peripheral catheter inserted into the atrium of the right heart (lat. atrium, atrium).

The cardiac catheter (peripheral catheter) is inserted through a small incision in the neck (this location can be recognized by a skin scar) into the internal cervical vein (internal jugular vein), and via the upper cavernous vein (superior vena cava) into the atrium (lat. atrium, atrium). atrium) or the cardiac ear (Latin auriculum, cardiac ear, part of the cardiac atrium), which is why this form of derivation is also called a ventriculo-atrial or ventriculo-auricular shunt (short: v.a.-shunt)

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This post is also available in: German

William C. Hilberg
As an author, Mr. Hilberg has published several papers on health issues that have gained international recognition. He is close to nature and loves the seclusion and activity as a freelance journalist. In his function as editor William C. Hilberg manages the entire content of PENP. Our team greatly appreciates his expertise and is proud to have him on board.