Active singling out of shunt independence.

The availability of telemetric devices for intracranial pressure (ICP) measurements in line with a multipurpose valve (MPV) was shown to be the ideal condition for safe investigation of the problem of shunt independence in 21 patients. After percutaneous closure of the shunt, all but 4 patients developed some degree of intracranial hypertension. The time lapse between blockade of the MPV and appearance of the morphology, in the tracing, that suggests ICP is different for each patient and could reflect individual conditions such as the residual pathways of CSF, ventricular size and compliance of the system.