Programmable (proSA®) vs. fixed (SHUNTASSISTANT®) gravitational valves in pediatric patients with hydrocephalus: a 16-year retrospective single-center comparative study with biomechanical analysis

Abstract

Purpose: In pediatric hydrocephalus (HC) treatment, programmable gravitational valves offer greater flexibility to manage overdrainage during children's growth. However, it remains unclear whether these devices provide better outcomes rather than their precursors. The study assessed the benefit from programmability of gravitational valve, i.e., programmable-SHUNTASSISTANT (proSA®) vs. SHUNTASSISTANT® (SA®).

Methods: Clinical records and imaging of pediatric patients with hydrocephalus of non-tumoral etiology treated with fixed (SA®) or programmable (proSA®) gravitational valves between January 2006 and January 2022 were analyzed in a retrospective single-center study. Valve survival was compared in relation to age and etiology. Lately explanted valves received biomechanical analysis.

Results: A total of 391 gravitational valves (254 SA® and 137 proSA®) were inserted in 244 patients (n = 134 males). One hundred thirty-three SA® (52.4%) and 67 proSA® (48.9%) were explanted during a follow-up of 81.1 ± 46.3 months. Valve survival rate at 1 and 5 years with proSA® was 87.6% and 60.6% compared to 81.9% and 58.7% with SA®, with mean survival time 56.4 ± 35.01 and 51.4 ± 43.0 months, respectively (P = 0.245). Age < 2 years at implantation correlated with significantly lower valve survival rates (P < 0.001), while HC etiology showed no significant impact. Overdrainage alone accounted for more SA® revisions (39.8% vs. 3.1%, P < 0.001), while dysfunctions of the adjustment system represented the first cause of valve replacement in proSA® cohort (45.3%). The biomechanical analysis performed on 41 proSA® and 31 SA® showed deposits on the valve's internal surface in 97.6% and 90.3% of cases.

Conclusion: Our comparative study between proSA® and SA® valves in pediatric HC demonstrated that both valves showed similar survival rates, regardless of etiology but only with young age at implantation. The programmability may be beneficial in preventing sequelae of chronic overdrainage but does not reduce need for valve revision and proSA® valve should be considered in selected cases in growing children older than 2 years.

Keywords: Gravitational valve; Hydrocephalus; Overdrainage; SHUNTASSISTANT®; Underdrainage; proSA®.

Fig. 1

Flow diagram illustrating the process of inclusion and exclusion of the study cohort

Fig. 2

Intercohort analysis with Kaplan-Meier survival curves comparing proSA® and SA® valves. Curve A compares the entire proSA® and SA® cohorts while B, C, D, and E, F, and G compare the two cohorts under etiological and age subgroups, respectively. Etiological subgroups include posthemorrhagic (A), idiopathic aqueductal stenosis (B), and Chiari malformation type II (C). Age subgroups include 0–2 (E), 2–10 (F), and 10–18 (G) years

Fig. 3

Intracohort comparative analysis with Kaplan-Meier survival curves evaluating the proSA® and SA® valves separately about age (A; D), hydrocephalus etiology (B; E), and primary vs. secondary implantations (C; F). Curves A, B, and C refer to proSA®, and curves E, F, and G refer to SA® valves

Fig. 4

Internal deposition and deformation of the external valve housing. Figure A illustrates a severe deformation of the proSA®, while grade I, II, and III deposits can be observed in figures B, C, and D, respectively. Yellow lines divide the valves into quadrants to evaluate the deposit grade (I < 25%, II 25–50%, III > 50%). Red arrows indicate the presence of deposits in the quadrants