Hemodynamic Angioarchitecture as a Determinant of AVM Radiosurgery Outcome: A Systematic Review

Background Stereotactic radiosurgery (SRS) is an established treatment for intracranial arteriovenous malformations (AVMs). Current grading systems—principally the modified Radiosurgery-Based AVM Score (mRBAS)—assign all non-eloquent lobar locations to a single risk tier and incorporate only binary venous drainage depth as an angioarchitectural variable. ¹ Whether granular angioarchitecture—encompassing transit time, draining vein number and depth, feeder artery calibre, and perinidal angiogenesis—independently modifies radiosurgical outcome beyond currently graded anatomical location has not been systematically synthesized. Methods A PRISMA 2020-compliant systematic review of PubMed/MEDLINE, Cochrane Central, Embase, and Scopus was performed (1990–2026). Studies reporting SRS outcomes stratified by anatomical location or angioarchitecture variables were included. Primary outcome was complete obliteration confirmed on imaging. Secondary outcomes included symptomatic radiation-induced changes (RICs), post-SRS hemorrhage, and functional status (modified Rankin Scale). Pooled analysis employed DerSimonian–Laird random-effects meta-analysis; heterogeneity was assessed with I ² and Cochran's Q. This review is registered with PROSPERO (CRD420261356041). Results Forty-six studies encompassing approximately 38,000 patients met inclusion criteria. Overall pooled obliteration was 69.4% (95% CI 65.2%–73.6%; I ² = 87.4%). Within mRBAS Tier-0 locations, pooled obliteration ranged from 82%–88% (frontal) to 70%–78% (occipital; Kruskal–Wallis p < 0.001). Angioarchitecture variables demonstrated substantially larger effect sizes: transit time (OR 4.3; 95% CI 3.2–5.8; p < 0.001), ^2,3 draining vein number (OR 3.1; 95% CI 2.5–3.8; p < 0.001), and venous drainage depth (OR 2.4; p = 0.008) each individually exceeded the location-tier effect. Perinidal angiogenesis (OR 0.26) ⁴ and feeder artery enlargement (OR 0.30) were the most adverse individual predictors. Conclusions Hemodynamic angioarchitecture—as assessed on pre-treatment digital subtraction angiography (DSA)—is the primary determinant of AVM radiosurgery outcome, overriding the prognostic advantage of favorable anatomical location. Angioarchitecture variables individually and collectively outperform the mRBAS location tier as predictors of obliteration. Prospective studies should mandate standardized pre-treatment DSA characterization of transit time, draining vein number, venous drainage depth, and perinidal angiogenesis as pre-specified primary outcome predictors.