Subarachnoid infusion and shunt function: Technical note

✓ A simplified technique for subarachnoid cerebrospinal fluid infusion of Ringer's lactate is described and evaluated as a method for determining shunt patency. An infusion index (change in pressure divided by volume infused) of 11 or greater is highly suggestive of shunt occlusion while an index of 6 or less strongly suggests a patent shunt. Further accuracy results when a baseline index and pressure-volume-time curve are obtained at a time of known shunt patency and compared with subsequent infusions. Using these criteria, the proper evaluation of shunt patency has been made in 18 out of 19 verified shunt problems.