Microsurgery alone versus preoperative embolisation: A meta-analysis of outcomes in brain AVMs by Spetzler-Martin grade.

Preoperative embolisation is frequently used an adjunct to microsurgery for brain arteriovenous malformations (AVMs), yet high-level evidence supporting its routine use remains limited. This meta-analysis compares outcomes of microsurgery alone versus combined microsurgery and preoperative embolisation, stratified by Spetzler-Martin (SM) grade. A systematic review of Embase, Medline, Scopus, Emcare, and the Cochrane Library identified 43 studies encompassing 3916 patients, equally divided between microsurgery alone (n = 1958) and combination therapy (n = 1958). Primary endpoints included functional dependence (modified Rankin Scale score > 2), angiographic obliteration, haemorrhagic complications, and intraoperative blood loss. Pooled analyses demonstrated no significant differences in functional dependence (OR 0.65, 95 % CI 0.32-1.32, p = 0.21), obliteration rates (OR 1.15, 95 % CI 0.60-2.19, p = 0.63), haemorrhagic complications (OR 1.67, 95 % CI 0.71-3.95, p = 0.20), or intraoperative blood loss (MD -98.90 mL, 95 % CI -417.38-219.57, p = 0.44). Subgroup analysis for SM grade I-II and III-V AVMs found no significant differences in outcomes between treatment modalities. For SM grade III AVMs, angiographic cure rates were comparable, though data scarcity precluded a robust assessment of functional dependence, postoperative haemorrhage, and intraoperative blood loss. While theoretical advantages exist for preoperative embolisation in higher-grade or high-flow AVMs, current evidence does not demonstrate consistent benefits in outcomes or complication rates. Further studies, particularly for SM grade III AVMs, are needed to determine whether combination therapy provides a meaningful advantage over microsurgery alone.