Outcomes of Preoperative Embolization in WHO Grade I Versus. WHO Grade II/III Intracranial Meningiomas: A Multicenter Propensity-matched Analysis

Introduction: Preoperative embolization is an adjunctive treatment for intracranial meningiomas, though limited data exists on its efficacy for high-grade tumors. This study aims to assess its outcomes in treating low WHO Grade (I) versus high WHO Grade (II/III) meningiomas.

Methods: We conducted a retrospective review of consecutive patients who underwent preoperative embolization for meningioma across 12 centers worldwide between 2013 and 2024. Propensity score matching (PSM) was used to create comparable groups, with a logistic regression model fitted for propensity score estimation based on patient demographics and tumor characteristics. In a subgroup analysis, tumor location was categorized as skull base, non-skull base, and supra- or infratentorial.

Results: A total of 153 low-grade and 122 high-grade meningioma patients underwent preoperative embolization. High-grade meningiomas had a significantly larger mean maximum tumor diameter compared to low-grade tumors (36.6 ± 8.1 mm). After PSM, 214 matched pairs of WHO Grade I and high-grade meningiomas showed no significant differences in embolization-associated complications (9.3% vs. 5.6%; p=0.437), surgery-related complications (36.4% vs. 26.2%; p=0.14), unplanned rescue surgery (16.8% vs. 9.3%; p=0.155), favorable modified Rankin Scale (mRS) outcomes (mRS 0-2: 67.3% vs. 75.7%; p=0.226), or mortality (1.9% in both groups). Estimated surgical loss (ESL) was similar between the groups, with a median of 300 mL (IQR [187.5-500]) for WHO Grade I versus 350 mL (IQR [200-600]) for high-grade meningiomas (p=0.540). Procedure time was also comparable, with a median of 332.5 minutes (IQR [223-573.25]) for WHO Grade I and 336 minutes (IQR [241-535.5]) for high-grade meningiomas (p=0.264). Gross total resection rates were similar across groups (65.4% vs. 66.4%; p=0.99). In a subgroup analysis across three tumor location categories, no significant differences were observed in ESL or procedure time between low- and high-grade tumors.

Conclusion : These findings suggest that preoperative embolization may be a viable adjunctive treatment for high-grade meningiomas, with similar safety and efficacy to that observed in low-grade meningiomas.