Evaluation of the Endoscopic Third Ventriculostomy Success Score for Stereotactic Prepontine Stenting in Patients with Aqueductal Stenosis

Purpose: Stereotactic prepontine stenting (STS) has been shown to be a safe and effective alternative treatment to standard endoscopic third ventriculostomy (ETV) for the treatment of triventricular hydrocephalus. For ETV a success score (ETVSS) allows risk stratification for treatment failure. We sought to evaluate this score for patients undergoing STS. Methods: Patients with hydrocephalus due to obstruction of the aqueductal outflow tract undergoing either ETV or STS between January 2013 and July 2024 were retrospectively analyzed. Treatment failure was defined as absence of symptomatic and/or imaging improvement. ETVSS were calculated for each group and correlated with outcome. Predictive power of the score was compared. Various statistical approaches were applied in order to create an alternative score. Results: 50 STS patients had a mean ETVSS of 88.2 ± 3.9% versus a mean ETVSS of 81.8 ± 16.7% in 97 patients undergoing ETV (p = 0.009). Successful treatment of hydrocephalus was achieved in 87% of ETV and 96% of STS patients (p = 0.09). Mean ETVSS of patients with successful STS was 89.1 ± 2.9% compared to 81.7 ± 4.1% with STS failure and 84.1 ± 13.5% versus 71.7 ± 24.8% in the ETV group (p = 0.02 for successful treatment). ROC analysis showed poor performance of ETVSS in the STS (AUC = 0.553) and good performance in the ETV cohort (AUC 0.766). Univariate analysis and the importance plot showed significant influence of the clivus-basilar artery diameter on successfull ETV. The risk factors identified in our cohort did not allow for the establishment of a new scoring system. Conclusion: The ETVSS did not enable prediction of successful treatment of hydrocephalus by STS in our cohort, whereas prediction was good for ETV. Therefore, individual decision-making remains essential. Future studies must aim to identify additional risk factors to develop new scoring systems specifically for patients who are eligible for STS.