THE GRAVITATIONAL SHUNT - AN ALTERNATIVE APPROACH TO CEREBROSPINAL-FLUID SHUNTING

Current cerebrospinal fluid shunts use complex differential pressure v alues to regulate drainage. Such systems are prone to overdrainage and obstruction, and thus have an unpredictable effect on intracranial pr essure (ICP). The gravitational shunt (GS) introduces an alternative a pproach. It uses a single, simple valve to balance the pressures gener ated within a vertical shunt system. The ICP is then regulated by the position of the valve along the cranioabdominal shunt axis and not by the mechanical properties of the valve. Bench testing demonstrated tha t when using the GS (1) a linear correlation (r = 0.91, p < 0.001) exi sts between the ICP and the position of the valve along the vertical s hunt axis, (2) positive and negative ICPs are maintained, and (3) the ICP can be predicted by an equation derived from theoretical principle s. The GS uses a single, simple valve as a pressure regulator and an a ntisiphon device. It allows the maintenance of a normal negative ICP i n the upright position without risk of over-drainage. The other benefi ts of this system are discussed.