A systematic review and Meta-Analysis of Middle meningeal artery embolization for Non-Acute Subdural Haematoma: A proposed treatment algorithm

OBJECTIVE: To synthesize the evidence from recent large randomized controlled trials (RCTs) on middle meningeal artery embolization (MMAE) for non-acute subdural haematoma (SDH) and to propose a unified, evidence-based treatment algorithm to guide clinical practice. METHODS: We conducted a systematic review and meta-analysis of large (n ≥ 100), multicentre RCTs comparing MMAE with surgical evacuation or conservative management for non-acute SDH. A comprehensive search of PubMed/MEDLINE, Embase, and CENTRAL was performed to August 2025. The primary outcome was treatment failure, a composite of radiological recurrence, symptomatic progression, or need for repeat surgery/surgical rescue at 90-180 days. Key secondary outcomes included functional status (modified Rankin Scale, mRS) and safety. Random-effects models were used for pooled analyses. RESULTS: Four RCTs involving 1,774 patients were included. For patients managed non-surgically, standalone MMAE was associated with a 64% relative risk reduction in treatment failure compared to conservative management (Risk Ratio [RR] 0.36, 95% CI [0.22, 0.60]). The number needed to treat was 4. As a surgical adjunct, MMAE offered a more modest but significant benefit in reducing recurrence or progression (RR 0.65, 95% CI [0.48, 0.89]). MMAE did not significantly improve functional outcomes or all-cause mortality but demonstrated a favourable safety profile with low rates of serious complications. CONCLUSIONS: MMAE significantly reduces treatment failure in non-acute SDH, with the most profound benefit seen in non-surgical patients by lowering the need for surgical rescue. Its role as a routine surgical adjunct is less clear, suggesting a stratified approach for patients at high risk of recurrence.