A Trial of High and Low Pressure Level Settings on a Programmable Ventriculoperitoneal Shunt Valve for Idiopathic Normal Pressure Hydrocephalus

in the intervention group, the performance level(PL) of the valve of the VP shunt, preset at the highest PL (meaning highest resistance) is lowered stepwise in the follow-up period at 1,3 and 9 months postoperatively after implantation until improvement occurs or signs of overdrainage are encountered on a new CT scan of the brain. In the control group the PL is preset and fixed at the second lowest PL and these patients serve as a control group.