Flow-regulated versus differential pressure valves for idiopathic normal pressure hydrocephalus: comparison of overdrainage rates and neurological outcome
To compare flow-regulated (FR) and differential pressure (DP) valves for treatment of patients with idiopathic normal hydrocephalus (iNPH) focusing on overdrainage and neurological outcome.
This is a retrospective study of patients with iNPH treated with FR and DP valves at a single institution between 2008 and 2018. The neurological status was evaluated retrospectively with the Kiefer scale at baseline, after shunt placement and at the 6-month follow-up. Groups were compared using inverse probability of treatment weighting based on propensity scores.
The study cohort consisted of 38 patients treated with FR valves and 49 with DP valves. The mean patient age was 72.0 ± 7.6 years. Based on the Kiefer scale score, neurological improvement at the 6-month follow-up was recorded in 79.6% in the DP group and 89.5% in the FR group (p = 0.252). The overdrainage rates were higher among DP valves (10.2%) than among FR valves (2.6%, adjusted p = 0.002). Valve malfunction occurred in 2.0% in the DP group and 5.3% in the FR group (adjusted p = 0.667).
The current study demonstrates a comparable neurological improvement between DP and FR valves, with potentially lower overdrainage rates among FR valves. Long-term studies will be necessary to draw a definite conclusion on FR valves for treatment of iNPH patients.
KeywordsDifferential pressure valve Flow-regulated valve iNPH Normal pressure hydrocephalus Overdrainage
This study was supported by a grant provided by Integra® LifeSciences (Integra LifeSciences Services, Lyon, France).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
For this type of study formal consent is not required.
Informed consent was obtained from all individual participants included in the study.
The sponsor had no role in the design or conduct of this research.
- 5.Carmel PW, Albright AL, Adelson PD, Canady A, Black P, Boydston W, Kneirim D, Kaufman B, Walker M, Luciano M (1999) Incidence and management of subdural hematoma/hygroma with variable-and fixed-pressure differential valves: a randomized, controlled study of programmable compared with conventional valves. Neurosurg Focus 7:E8CrossRefGoogle Scholar
- 12.Lemcke J, Meier U, Müller C, Fritsch MJ, Kehler U, Langer N, Kiefer M, Eymann R, Schuhmann MU, Speil A (2013) Safety and efficacy of gravitational shunt valves in patients with idiopathic normal pressure hydrocephalus: a pragmatic, randomised, open label, multicentre trial (SVASONA). J Neurol Neurosurg Psychiatry 84:850–857CrossRefGoogle Scholar