Indications for valve-pressure adjustments of gravitational assisted valves in patients with idiopathic normal pressure hydrocephalus.
BACKGROUND
Modern ventriculoperitoneal shunts (VPS) are programmable, which enables clinicians to adjust valve-pressure according to their patients' individual needs. The aim of this retrospective analysis is to evaluate indications for valve-pressure adjustments in idiopathic normal pressure hydrocephalus (iNPH).


METHODS
Patients operated between 2004 and 2011 diagnosed with iNPH were included. Kiefer-Scale was used to classify each patient. Follow-up exams were conducted 3, 6, and 12 months after shunt implantation and yearly thereafter. Initial valve-pressure was 100 or 70 mmH2O. Planned reductions of the valve-pressure to 70 and 50 mmH2O, respectively, were carried out and reactive adjustment of the valve-pressure to avoid over- and under-drainage were indicated.


RESULTS
A total of 52 patients were provided with a Medos-Hakim valve(Codman®) with a Miethke shunt-assistant(Aesculap®) and 111 patients with a Miethke-proGAV(Aesculap®). 180 reductions of the valve-pressure took place (65% reactive, 35% planned). Most patients (89%) needed one or two adjustments of their valve-pressures for optimal results. In 41%, an improvement of the symptoms was observed. Gait disorder was improved most often after valve-pressure adjustments (32%). 18 times an elevation of valve-pressure was necessary because of headaches, vertigo, or the development of subdural hygroma. Optimal valve-pressure for most patients was around 50 mmH2O (36%).


CONCLUSIONS
The goal of shunt therapy in iNPH should usually be valve-pressure settings between 30 and 70 mmH2O. Reactive adjustments of the valve-pressure are useful for therapy of over- and underdrainage symptoms. Planned reductions of the valve opening pressure are effective even if postoperative results are already satisfactory.
Department of Neurosurgery, Unfallkrankenhaus Berlin, Warener Straße 7, 12686, Berlin, Germany.
Leonie
L
Gölz
Johannes
J
Lemcke
Ullrich
U
Meier
Adjustments; gravitational valve; iNPH; idiopathic normal pressure hydrocephalus; indications; valve-pressure