are devices which allow the passage of cerebrospinal fluid from the
brain to the abdomen, through a ventricular catheter (tube in the
brain) which is connected to a peritoneal tube (tube tunneled under
the skin) to enter the abdomen. This is used to treat hydrocephalus.
The pressures for which the shunt drains may be low, medium or high,
or a programmable valve may be placed by the surgeon.