Diagnosing Malfunctioning Hydrocephalic Shunt Valves With a Flow Sensor

The study hypothesis is that a transit-time ultrasonic sensor can help doctors diagnose a malfunctioning shunt valve. The study will simulate an implanted shunt flow monitoring system by placing the flow sensor and a programmable shunt valve into the patient's Extra-Ventricular Drainage line. Flow will be measured as the doctor raises/lowers the drainage bag to simulate the patient sitting up/lying down. The doctor will simulate a malfunctioning shunt by changing the valve's pressure release settings for each cycle of raising/lowering the bag. By monitoring shunt flow during these changes, the doctors hope to develop new ways to diagnose malfunctioning shunt valves when implanted shunt flow monitors become available.