What Is a Shunt? Normal Pressure Hydrocephalus



How It Works


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:

Fixed pressure valves with siphon control devices

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

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.
