Adjustable differential pressure versus adjustable gravitational valves in pediatric hydrocephalus

Hydrocephalus in children is mostly treated with a CSF-diverting shunt system as a lifelong implant. Presently, a variety of shunt valves are available on the market, but there is a lack of evidence guiding valve type selection for the management of pediatric hydrocephalus. The aim of this study was to compare two shunt valve types in the treatment of pediatric hydrocephalus.

A retrospective analysis of synchronized patient databases was conducted at two pediatric neurosurgical centers. At one center, an adjustable differential pressure (aDP) valve with a fixed gravitational unit was utilized (aDP group). At the other center, an adjustable gravitational (aG) valve was combined with a fixed differential pressure unit (aG group). Inclusion criteria were an age less than 2 years at shunt implantation and a follow-up of 3 years. Patient demographics, revision-free shunt and valve survival rates, total number of revisions per patient, and ventricle width were compared between the two institutional cohorts.

Among 227 patients eligible for study inclusion, 141 received an aDP valve and 86 received an aG valve. The two patient cohorts showed no differences in overall revision-free shunt survival rates: 59.6% in the aDP group versus 58.1% in the aG group (p = 0.42, HR 0.8, 95% CI 0.6-1.3). The revision-free valve survival rate was significantly lower in the aDP group than in the aG group (69.5% vs 86.0%, p = 0.01, HR 2.3, 95% CI 1.3-3.9), but the revision-free nonvalve shunt components survival rate was higher (85.8% vs 65.1%, p < 0.001, HR 0.3, 95% CI 0.2-0.6). The total number of shunt revisions in the patients who underwent revision was significantly higher in the aG group (2 [IQR 1-2] vs 1 [IQR 0], p < 0.01). At follow-up, median valve settings were higher in the aDP group than in the aG group (10 [IQR 8-12]/30 [IQR 29-34] cmH2O vs 5 [IQR 0]/25 [IQR 20-25] cmH2O for lying/standing, respectively), which resulted in a significant, more pronounced reduction in the mean frontooccipital horn ratio as a measure of ventricle width in the aG group (-0.2 ± 0.1 vs -0.13 ± 0.09, p < 0.001).

Differences in valve and nonvalve component revision rates were inverted for the aDP and aG groups and may reflect subtle differences in shunt surgery strategies at the two centers. Overall, lower valve settings led to a greater reduction in ventricle width measurements. Head circumference and ventricular width may need further analysis as possible surrogate parameters for intracranial pressure-guided CSF diversion and should be combined with neurodevelopmental outcome parameters in future studies.