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What Is a Shunt?

Shunts have been used to treat hydrocephalus for more than 50 years. The devices allow excess cerebrospinal fluid to drain to another area of the body.

How It Works

A shunt usually consists of two catheters and a one-way valve. The valve regulates the amount, flow direction, and pressure of cerebrospinal fluid out of the brain’s ventricles.

As the pressure of cerebrospinal fluid inside the brain increases, the one-way valve opens and the excessive fluid drains to the downstream cavity.

Typically, the fluid gets "shunted" (moved) using the following shunt types:

  • A ventriculoperitoneal shunt moves fluid from the ventricles of the brain to the abdominal cavity
  • A ventriculoatrial shunt moves fluid from the ventricles of the brain to a chamber of the heart
  • A lumboperitoneal shunt moves fluid from the lower back to the abdominal cavity

Fixed and Adjustable Pressure Cerebrospinal Fluid Valves

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

  • Fixed pressure valves – These regulate the flow rate of cerebrospinal fluid based on a predetermined pressure setting
  • Adjustable pressure valves – These valves regulate the flow of cerebrospinal fluid based on a pressure setting that can be adjusted. Using specially designed magnetic tools, your clinician can non-invasively change the pressure setting of the implanted adjustable valve during an office visit, without the need for another surgical procedure.

Minimizing Excessive Drainage With a Siphon Control Device

Both valve types can include overdrainage protection in the form of a siphon control device. The purpose of a siphon control device is to minimize excessive drainage due to gravity, which can cause more cerebrospinal fluid to drain when the individual is upright.

Your surgeon will choose the valve based on your type of hydrocephalus and other medical conditions you may have.

About Reservoirs on Valves

Some valves include a reservoir that can be used for a variety of reasons. By flushing the reservoir, your neurosurgeon can test shunt function. He or she can also sample cerebrospinal fluid for the purpose of lab studies.

Valve pumping to test shunt function

Detail - Valve pumping to test shunt function

Cerebrospinal fluid sampling for use in lab studies

Detail - Cerebrospinal fluid sampling for use in lab studies

About Catheters

For the treatment of non-communicating (obstructive) hydrocephalus, one catheter must be inserted into the brain’s ventricle. For communicating (non-obstructive) hydrocephalus, the cerebrospinal fluid may be drained from the brain ventricles or from the lumbar spine to another cavity of the body (usually the peritoneal cavity). Lumbo-peritoneal shunts (LP) are usually reserved for, but not entirely limited to, the adult population.

Information on this site should not be used as a substitute for talking with your doctor. Always talk with your doctor about diagnosis and treatment information.

Last updated: 22 Sep 2010

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