Safety and efficacy of gravitational shunt valves in patients with idiopathic normal pressure hydrocephalus: a pragmatic, randomised, open label, multicentre trial (SVASONA)

Abstract

ObjectivesTo investigate whether gravitational valves reduce the risk of overdrainage complications compared with programmable valves in ventriculoperitoneal (VP) shunt surgery for idiopathic normal pressure hydrocephalus (iNPH).BackgroundPatients with iNPH may benefit from VP shunting but are prone to overdrainage complications during posture changes. Gravitational valves with tantalum balls are considered to reduce the risk of overdrainage but their clinical effectiveness is unclear.MethodsWe conducted a pragmatic, randomised, multicentre trial comparing gravitational with non-gravitational programmable valves in patients with iNPH eligible for VP shunting. The primary endpoint was any clinical or radiological sign (headache, nausea, vomiting, subdural effusion or slit ventricle) of overdrainage 6 months after randomisation. We also assessed disease specific instruments (Black and Kiefer Scale) and Physical and Mental Component Scores of the Short Form 12 (SF-12) generic health questionnaire.ResultsWe enrolled 145 patients (mean (SD) age 71.9 (6.9) years), 137 of whom were available for endpoint analysis. After 6 months, 29 patients in the standard and five patients in the gravitational shunt group developed overdrainage (risk difference −36%, 95% CI −49% to −23%; p<0.001). This difference exceeded predetermined stopping rules and resulted in premature discontinuation of patient recruitment. Disease specific outcome scales did not differ between the groups although there was a significant advantage of the gravitational device in the SF-12 Mental Component Scores at the 6 and 12 month visits.ConclusionsImplanting a gravitational rather than another type of valve will avoid one additional overdrainage complication in about every third patient undergoing VP shunting for iNPH.

A randomized controlled dual-center trial on shunt complications in idiopathic normal-pressure hydrocephalus treated with gradually reduced or “fixed” pressure valve settings

“…Our observation of a significantly lower rate of overdrainage symptoms in patients with an ASD could be due to a preventive effect of the ASD, but a confounding factor was that its use was site dependent and therefore not assessed in a randomized controlled manner. The gravitational valve is a siphon regulatory device that in a recent study 17 was associated with a lower rate of overdrainage symptoms compared with differential pressure valves without an ASD. It would be valuable to investigate the ASD variable in a randomized clinical trial to further evaluate its effect on SDH and overdrainage symptoms.…”

Outcome of modern shunt therapy in patients with idiopathic normal pressure hydrocephalus 6 years postoperatively

“…Thus, gravitational valves have been proven to significantly increase patient safety and should be seen as the standard of care. 17,18 After conducting an earlier MEDLINE search, some authors concluded that 24%-100% of patients with shunted iNPH experience improvement postoperatively. 7 Recent publications have shown that 84% of the patients who underwent shunt surgery for iNPH have good postoperative results and that dependency on nursing care can be reduced 1 year after treatment.…”

Securing Cranial Horizontal-Vertical Valve in Proper Orientation For Use in Ventriculoperitoneal Shunting: Technical note

“…There were 46 patients treated with a HV valve LP shunt, and in nine patients, there were complications related to disconnection, migration, or obstruction of the valve system. Based on the reports of a recent European trial using a HV valve for a VP shunt system, we decided to explore the use of this valve and realized that, similar to the LP shunt valve system, there was no defined method for securing the valve orientation to ensure proper consistent function [7][8]. The method described above appears to secure the valve in optimal position without mechanical or cosmetic problems.…”

“…They have been demonstrated to be safe and durable [7]. A recent randomized, controlled clinical trial indicated that they are associated with statistically significantly lower rates of overdrainage compared to standard VP shunt systems [8]. Position of the HV valve on the head is important [9].…”