Reduced risk of shunt revision with adjustable valves: a populationbased cohort study over three decades

Acta Neurochirurgica (2026) 168:29

This population-based retrospective cohort study compares shunt revision rates in 809 idiopathic normal pressure hydrocephalus (iNPH) patients treated with adjustable versus fixed-pressure ventriculoperitoneal valves at Kuopio University Hospital from 1991 to 2023. The study findings indicate a significantly lower overall revision rate and fewer hydrodynamic failures with adjustable valves. Peritoneal catheter malposition and infection were the predominant causes of revision in the adjustable group.

The study provides detailed methods, valve types, follow-up durations, and statistical analyses. It discusses the study’s strengths, such as the use of comprehensive national registries, and limitations, including the retrospective design and shorter follow-up period for adjustable valves. The authors conclude that adjustable valves improve revision-free survival and recommend their use in iNPH despite their higher cost.

Adjustable shunt valves significantly reduce the risk of shunt revision surgeries in idiopathic normal pressure hydrocephalus (iNPH) patients compared to fixed-pressure valves (14% vs. 30% revision rate, p < .001).

Hydrodynamic failures (overdrainage and underdrainage) are much less common causes of revision in adjustable valve patients than in those with fixed-pressure valves.

Revision-free survival is better in iNPH patients with adjustable valves, with a lower hazard ratio for first revision (HR = 1.76 for fixed-pressure valves, p < 0.001).

Peritoneal catheter malposition is the most common cause of revision with adjustable valves, while shunt underdrainage is most common with fixed-pressure valves.

Multiple revisions are less frequent in the adjustable valve group (27% of revised patients) compared to the fixed-pressure group (32%).

No significant difference in revision risk was found between adjustable valves with and without a gravitational unit.

Clinical improvement is possible after well-timed shunt revision surgery, emphasizing the need for rapid detection of malfunctions.

Recommendation: Adjustable shunt valves are advised for iNPH patients, as they decrease revision rates and improve revision-free survival, justifying their higher cost.