A316 Angiographic grading of liquid embolic penetration in middle meningeal artery embolization: a novel grading system for predicting chronic subdural hematoma resolution

<h3>Introduction</h3> Middle meningeal artery (MMA) embolization has become a standard adjunct treatment for chronic subdural hematoma (cSDH) following surgical evacuation. However, no standardized system exists to assess the angiographic extent of embolization or its impact on outcomes. <h3>Aim of Study</h3> We introduce a novel grading system to evaluate liquid embolic penetration and correlate it with clinical outcomes. <h3>Method</h3> Consecutive patients undergoing MMA embolization for cSDH with Onyx or n-BCA between 2019 and 2023 were included. Prospectively collected and retrospectively analyzed data encompassed demographics, hematoma size, laterality, and up to 12 months of follow-up. Intraoperative angiograms were graded on a four-point scale: (1) proximal ligation, (2) branch penetration without midline reach, (3) penetration reaching midline, and (4) penetration crossing midline. Postoperative CT assessed hematoma volume and recurrence. Univariate linear and logistic regressions correlated angiographic grade with outcomes (p &lt; 0.05). <h3>Results</h3> Among 110 patients, 31.8% achieved grade 4 embolization, 42.7% grade 3, and 25.4% grade 2. Complete cSDH resolution within three months occurred in 24% of patients, with a mean time to resolution of 6.18 ± 3.82 months. Higher embolization grades were associated with faster resolution, decreasing time to complete resolution by 1.31 months per grade increase (p = 0.04). Greater embolization also significantly increased the likelihood of three-month resolution (OR 2.29, 95% CI 1.16–4.83, p = 0.021). <h3>Conclusion</h3> This novel angiographic grading system demonstrates that deeper liquid embolic penetration correlates with faster and more complete cSDH resolution following MMA embolization. Validation in future multicenter prospective studies is warranted. <h3>Conflict of Interest</h3> No