Influence of tumor vascularization in surgical outcomes of patients with Grade IV Vestibular Schwannomas: Role of CD34, Perfusion rates, and VEGF.

Analyze the influence of tumor vascularization and intraoperative bleeding on surgical outcomes of Grade IV Vestibular Schwannoma (VS). This single-center analytical study included patients with sporadic Grade IV VS operated on by the same surgeon in Argentina between 2011 and 2023. Clinical, imaging, surgical and pathology variables were prospectively analyzed. Tumor vascularization was assessed via preoperative perfusion MRI and correlated with intraoperative bleeding, microvascular density (CD34), and VEGF expression. Associations with facial nerve (FN) outcomes and extent of resection (EOR) were evaluated. Thirty-five adult patients (mean age 46.6; 74% male) were included. Hydrocephalus was present in 17%, and 40% had cystic tumors. High perfusion MRI values were observed in 54% (mean ratio 1.96). Arachnoid planes were clear in 49%, and 26% showed intense intraoperative bleeding. Gross-total and near-total resection were achieved in 40% and 29%, respectively. Favorable FN outcomes (House-Brackmann I-II) were seen in 52% short-term and 80% long-term. We observed a trend toward worse postoperative FN outcomes in tumors with higher intraoperative bleeding. Higher perfusion indices were associated with increased bleeding and reduced EOR. Tumor microvascular density (CD34) correlated with bleeding severity and perfusion metrics. Vascular endothelial growth factor (VEGF) expression showed a weak association with perfusion and bleeding. Preoperative perfusion imaging may help identify highly vascularized VSs prone to bleeding and poorer FN and EOR outcomes. Increased intraoperative bleeding was linked to worse postoperative FN function and limited resection. This information may assist surgeons in tailoring their strategy toward an oncofunctional resection.