Pre-surgical Embolization of Meningiomas: Analysis of Safety and Efficacy in a Mexican National Center And Proposal for a Classification of Preoperative Embolization of Meningiomas Based on Embolic Agent Penetration.

Introduction: Meningiomas are the most common primary central nervous system tumors, often requiring surgical resection. Presurgical embolization (PSE) is used to reduce intraoperative bleeding, although its effectiveness varies. This study evaluates the safety and efficacy of PSE using ethyl-vinyl alcohol (EVOH) in meningioma surgeries.

Methodology: This study included 48 patients with intracranial meningiomas treated between January 2022 and August 2024. Patients were divided into two groups: Group A (n=24) underwent surgery without PSE, while Group B (n=24) underwent surgery with PSE using EVOH. Outcomes assessed included anesthetic and surgical times, resection bleeding, total bleeding, and transfusion requirements. Meningioma size and bleeding per cm³ were also evaluated. PSE was classified into four grades based on embolic liquid (LE) penetrability, and its relationship with bleeding during resection was analyzed.

Results: PSE significantly reduced anesthetic (270 vs. 372 minutes) and surgical times (222 vs. 348 minutes). Group B exhibited less resection bleeding (450 vs. 1,400 ml) and total bleeding (650 vs. 1,700 ml) compared to Group A, with statistically significant differences (p < 0.01). Bleeding per cm³ was significantly lower in Group B (9.33 ml/cm³) than Group A (31.39 ml/cm³). No complications related to PSE were observed. LE penetrability grades correlated with resection bleeding, where higher-grade embolizations led to reduced bleeding.

Discussion: This study highlights five advantages: 1) objective measurement of resection time and bleeding based on precise and standardized parameters, including strict quantification of aspirator container content (subtracting saline solution used during the procedure), bleeding assessment from gauze and cottonoids, and dedicated personnel tracking surgical, anesthetic, and resection times; 2) accurate correlation between meningioma size and bleeding; 3) absence of PSE complications; 4) standardized PSE grading based on LE penetrability; and 5) established relationship between PSE grades and resection bleeding. The results suggest that PSE with EVOH is a safe and effective method to minimize intraoperative bleeding and reduce surgical time in meningioma resection.

Conclusion: Presurgical embolization using EVOH significantly decreases surgical bleeding and time in meningioma resections without associated complications. The proposed PSE grading system (Preoperative Embolization of Meningiomas, Mexican Classification (PEMMCO)) may enhance the predictability of intraoperative bleeding control. While we acknowledge the relatively small sample size of 48 cases, we believe this study serves as a foundation to encourage the inclusion of more patients and collaboration with additional centers, aiming to further validate and standardize the classification.