gms | German Medical Science

Objective: 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).

Method: Patients operated between 2004 and 2011 diagnosed with iNPH were included. The 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 the treatment of over- and underdrainage symptoms. Planned reductions of the valve opening pressure are effective even if postoperative results are already satisfactory.