Consensus Statement on Middle Meningeal Artery Embolization in Chronic Subdural Hematoma Treatment: A Guideline From the Society of Vascular and Interventional Neurology Guidelines and Practice Standards Committee

BACKGROUND Emerging evidence from observational studies, meta‐analyses, and clinical trials has reshaped the treatment landscape of chronic subdural hematoma (CSDH). This guideline provides updated recommendations on diagnosis, patient selection, and medical, surgical, and endovascular management. METHODS The Society of Vascular and Interventional Neurology Guidelines and Practice Standards committee formed a writing group of interdisciplinary experts to review current literature. Recommendations were based on clinical trial data, observational studies, and expert consensus, following the Society of Vascular and Interventional Neurology Class of Recommendation and Level of Evidence framework. RESULTS EMBOLISE (Embolization of the Middle Meningeal Artery With ONYX Liquid Embolic System for Subacute and Chronic Subdural Hematoma), STEM (SQUID Trial for the Embolization of the Middle Meningeal Artery for Treatment of Chronic Subdural Hematoma), MAGIC‐MT (Managing Non‐acute Subdural Hematoma Using Liquid Materials: A Chinese Randomized Trial of MMA Treatment), and MEMBRANE (Middle Meningeal Artery Embolization for the Treatment of Subdural Hematomas With TRUFILL n‐butyl cyanoacrylate) trials highlight the efficacy and safety of middle meningeal artery embolization (MMAE) in CSDH. EMBOLISE (n = 400; MMAE with surgery, n = 197; surgery alone, n = 203) showed that MMAE plus surgery reduced 90‐day hematoma recurrence to 4.1% versus 11.3% with surgery alone (relative risk = 0.36; 95% CI = 0.11–0.80; P = 0.008). Functional deterioration was 11.9% versus 9.8%, and 90‐day mortality was 5.1% versus 3.0%. Serious embolization‐related events, including 2 disabling strokes, occurred in 2.0% by 30 days. The STEM trial (310 patients enrolled: MMAE plus standard treatment, n = 149; standard treatment alone, n = 161) found that MMAE with Squid significantly reduced 180‐day recurrent/residual hematoma or reoperation/rescue surgery to 16% versus 36% with standard treatment (odds ratio = 0.36; 95% CI = 0.20–0.66; P = 0.001). 30‐day mortality or major disabling stroke was 3% in both groups. However, 180‐day mortality was 8% with the MMAE group, and 5% with standard treatment, and no death was attributed to MMAE or embolic agent. MAGIC‐MT (722 patients; MMAE plus standard treatment, n = 360; standard treatment alone, n = 362) reported 90‐day symptomatic recurrence or progression in 6.7% of the MMAE group (using Onyx) versus 9.9% in the standard treatment group (difference: −3.3%; 95% CI: −7.4–0.8; P = 0.10). Serious adverse events were less common in the MMAE group (6.7% versus 11.6%; P = 0.02). The MEMBRANE trial (376 patients; MMAE plus standard treatment, n = 188; standard treatment alone, n = 188) found that MMAE using n‐butyl cyanoacrylate plus surgery improved outcomes at 6 months. CONCLUSIONS These results suggest that MMAE plus standard treatment of CSDH shows promising results and may become a standard of care for managing CSDH in selected patients. These guidelines provide evidence‐based recommendations for the diagnosis, patient selection, and treatment of CSDH.