Predictors for Revascularization Patterns After Bypass Procedures for Moyamoya Disease in Adults

OBJECTIVE: Combined revascularization procedures have proven effective in reducing ischemic events in patients with moyamoya disease (MMD). However, patient-specific predictors for the degree of revascularization remain unclear. The objective of this study was to identify preoperative factors associated with postoperative revascularization patterns in adults with MMD. METHODS: Clinical and radiographic data from adult MMD patients undergoing combined revascularization between 2020 and 2025 were analyzed. Baseline demographics, perioperative parameters, and imaging findings were collected. Postoperative revascularization patterns were categorized by Matsushima grade (MG), and clinical outcomes by the modified Rankin Scale (mRS). Predictors including anterograde flow through the internal carotid artery (ICA) terminus prior to revascularization, degree of preoperative collateral flow to the middle cerebral artery (MCA) territory, severe MMD (Berlin grade 3), age, sex, and cerebrovascular reserve (CVR) were assessed for association with MG. To mitigate small-sample bias, Firth's penalized logistic regression was used. Associations between MG and postoperative improvements in perfusion, CVR, and mRS were also evaluated. RESULTS: Thirty-three patients (22 females, median age: 47 years, IQR: 37-52) were included. Severe MMD (Berlin grade 3) was present in 13 patients, and anterograde ICA flow was absent prior to surgery in 10. Postoperative outcomes included stable mRS (n = 25), improvement (n = 7), and worsening (n = 1). Matsushima grades were A (n = 17), B (n = 7), and C (n = 9). Multivariable Firth logistic regression showed that absent anterograde ICA flow was an independent predictor of achieving MG A (OR 46, P = 0.001). Patients with MG A were more likely to demonstrate improved cerebral perfusion (P = 0.008), while no significant association with mRS improvement was observed (P = 0.739). CONCLUSIONS: The absence of anterograde ICA flow independently predicted robust postoperative revascularization in adult MMD after combined revascularization. Preoperative assessment of ICA patency may represent a practical imaging biomarker for identifying patients most likely to benefit from direct bypass surgery.