Lumbar-peritoneal shunt for idiopathic normal pressure hydrocephalus and secondary normal pressure hydrocephalus

Objectives: Normal-pressure hydrocephalus is a clinical syndrome consisting of dilated cerebral ventricles with the clinical triad of gait disturbance, cognitive impairment and/or urinary dysfunction. Lumbar-peritoneal (LP) shunt could improve idiopathic normal pressure hydrocephalus (iNPH) while its effectiveness on secondary NPH (sNPH) is elusive. We compared the clinical results of the patients who received LP shunt surgery between iNPH and sNPH. Materials and Methods: We retrospectively analyzed the patients who received LP shunt surgery in a single center from January 1, 2017, to June 30, 2017. Patients selected for LP shunt placement had at least two of three cardinal symptoms of iNPH. The symptoms should persist for more than 3 months with compatible brain magnetic resonance imaging findings. All patients were followed up with iNPH grading scale (iNPHGS) and Modified Rankin Scale (MRS) for evaluation. Results: Thirty-three patients (23 male and 10 female patients) with mean age 76-year-old completed follow-up in this study, and 17 patients received lumbar drainage tests and intracranial pressure measurements. Both iNPH (n = 22) and sNPH (n = 11) groups did not have major complications such as infection, nerve root injury, or shunt failure. Both groups have significant improvement in iNPHGS and MRS. Interestingly, we found the correlation between both opening intracranial pressure and pressure gradient difference to the improvement percentage from LP shunt. Conclusion: The safety and effectiveness for sNPH patients who received LP shunt placement are equivalent to the iNPH patients. Lumbar drainage test provides prerequisite outcome prediction and should be considered to identify NPH patients planned to receive LP shunt.