gms | German Medical Science

Introduction: Following the current understanding of the pathophysiology of iNPH, the increased rigidity of the basal brain arteries leads to cappillary pulsations unlike the physiologically laminar flow. Hence the periventricular parenchyma is also pulsating and collides with the incompressible CSF inside the ventricles which is not able to exit through the aquaeductus cerebri fast enough. The main function of a ventriculoperitoneal shunt is to allow the CSF to exhaust from the ventricle synchronously to the pulse wave. Thus, very low valve opening pressures are needed. Gravitational shunt valves allow these low opening pressures without overdrainage complications.

Method and material: Since 1997, in 148 patients iNPH was diagnosed by invasive diagnostics including lumbar infusion test and spinal tap test. After implantation of ventriculo-peritoneal shunts with gravitational valves, patients were followed up up to seven years. The outcome was measured using the Kiefer score.

Results: The responder rates among the total of 148 patients ranged about 78–82% in the first four years and dropped to 70% after five years, 64% after six years and 50% after 7 years. Whilst re-operations were necessary in cases of underdrainage to improve the outcome before the year 2004 (19% of 68 patients), programmable gravitational valves allowed us to avoid re-operations by reprogramming the valves.

Conclusions: This long term follow up shows that gravitational valves are an adequate therapy in patients with normal pressure hydrocephalus considering the possibility to combine a low valve opening pressure and protection from overdrainage complications.