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 or spine 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 the cerebrospinal fluid based on a predetermined pressure setting
Fixed pressure valves with siphon control devices

Fixed pressure valve with siphon control device

  • Adjustable valves – These valves can be non-invasively adjusted using magnetic tools to different pressure settings after surgery
Adjustable pressure valves with siphon control devices

Adjustable pressure valve with siphon control device

Both of these valve types can include over-drainage protection in the form of a siphon control device. The purpose of this device is to minimize excessive drainage due to gravity when a person is in the upright position.

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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