Application of clinically recorded ICP patterns--an extension of conventional shunt testing

Various methods of laboratory testing are currently being used to explore the hydrodynamic properties of shunts. We constructed a novel shunt-testing rig with a human-like compliance to be able to subject shunts to in-vivo recorded ICP patterns. The human-like situation was realized with a pear-shaped glass container with a non-linear, third-order pressure/volume characteristic similar to the CSF system. The new device also allows conventional shunt testing. Shunt performance in conventional pressure/flow tests (linear compliance) was compared to tests with human-like compliance. No clinically relevant differences were seen. Clinically recorded ICP waves (Lundberg type A and B) were reproduced before and after shunt implementation. Shunt insertion reduced pressure in the A-wave pattern to slightly negative values. Reproducing B-waves, the shunt dampened wave amplitude and pressure decreased below the opening pressure of the valve. In conclusion, the presented device allows a standardized reproduction of ICP patterns. The effects of shunt implantation can be studied.