Direct Versus Indirect Bypass in Early-Stage Moyamoya (Suzuki I-III): A Propensity Score-Weighted Study

Moyamoya angiopathy (MMA) lacks stage-specific comparative evidence for surgical strategy. Because many studies mix Suzuki grades, potential technique effects may be obscured. We compared direct revascularization (DR) with indirect revascularization (IR) in a stage-restricted cohort (Suzuki I-III), using propensity score weighting (PSW). We conducted a multicenter retrospective cohort study across 13 academic centers. Adults with confirmed MMA (Suzuki I-III) who underwent DR or IR were included. Patients < 16 years and combined procedures were excluded. Outcomes were symptomatic stroke, overall perioperative stroke, intraoperative complications, discharge NIHSS/mRS, length of stay, and follow-up stroke. PSW used Covariate Balancing Propensity Scores (CBPS) with absolute standardized mean difference (ASMD) diagnostics. Group differences were modeled with logistic/linear regression, and stroke-free survival was compared by Kaplan-Meier/log-rank. We analyzed 208 hemispheres (IR = 104; DR = 104). Baseline demographics and comorbidities were similar. Unadjusted analyses showed no significant differences in overall perioperative stroke (10.5% IR vs. 8.6% DR; p=.63), symptomatic perioperative stroke, intraoperative complications, discharge NIHSS/mRS, length of stay, or follow-up stroke (8.6% IR vs. 5.8% DR; p=.43). Stroke-free survival did not differ (log-rank p=.40). After PSW, findings remained unchanged across endpoints (e.g., all perioperative stroke OR 1.82; 95% CI, 0.61 to 5.45; p=.27). In adults with MMA at Suzuki I-III, no significant between-group differences were detected between DR and IR in the studied clinical outcomes. Technique selection can be individualized to anatomy, hemodynamics, and center expertise. Prospective, stage-stratified studies with standardized angiographic and hemodynamic endpoints are warranted.