gms | German Medical Science

Objective: Idiopathic normal pressure hydrocephalus (iNPH) has a naturally deteriorating course over time. A secondary deterioration during VP-Shunt (VPS) treatment is due to either natural deterioration of disease, insufficient VPS function or development of concomitant disease i.e. Alzheimer’s disease (AD). The cause of this secondary deterioration cannot be determined without further investigation by i.e. a shunt infusion exam (SIE) or revision surgery.

Methods: All SIE data conducted 2013-2015 were reviewed. Exams and digital patient records of iNPH patients were included and reviewed for clinical course, shunt function and Alzheimers’ CSF-testing.

Results: Between 2013 and 2015 132 patiens with iNPH had contact with our neurosurgical department. Twenty SIEs were conducted in 19 patients, in whom VPS were implanted between 2009 and 2014 (mostly ProGAV valves, Miethke). Eleven exams showed an increased outflow resistance and exceeded the allowed critical shunt pressure. CSF of 1 of 4 patients with deteriorated dementia as primary symptom showed a high score for Alzheimer’s. Ten revision operations were conducted in 9 patients. In 5 cases no clear defect was found. In these patients 2 ProGAV valves were replaced, 2 Miethke fixed gravitational devices were replaced for ProSA programmable gravitational devices. In 2 of these patients nothing was changed. The peritoneal catheter showed a higher resistance in 3 patients, 1 was operated twice and received a ProSA during the second operation. All operated patients showed an improvement in at least the first postoperative month. Patients who received a ProSA showed a prolonged improvement of at least 6 months.

Conclusion: SIE and CSF-Alzheimer’s markers are valuable tools to distinguish a natural deterioration from insufficient VPS-function and concomitant Alzheimer’s disease. Unnecessary revision operations can thereby be avoided. ProSA enables more CSF drainage and clinical improvement in patients with secondary deterioration.