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 pressure valve

Fixed pressure valve

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

Adjustable pressure valve

About Siphon Control Devices

Both of these valve types can include a siphon control device. The purpose of this device is to minimise 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: 27 Sep 2010

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