Surgical selection algorithms and long-term functional outcomes in microsurgical revascularization for complex aneurysms: a six-year analysis

Complex intracranial aneurysms represent a significant challenge when their morphology or location limits the use of direct clipping or standard endovascular techniques. In such cases, microsurgical revascularization remains a critical option, although patient selection and strategy optimization are essential to achieve durable outcomes. This study aimed to evaluate long-term functional outcomes and the technical reliability of a hemodynamically driven surgical selection algorithm in patients with complex intracranial aneurysms. We analyzed a consecutive cohort of 29 patients with complex intracranial aneurysms treated between 2019 and 2025. Ruptured aneurysms accounted for 55.2% of cases, while 44.8% were unruptured. Surgical strategies were categorized into three generations of bypass according to anatomical features and cerebral hemodynamic requirements. Functional outcomes were assessed using the modified Rankin Scale (mRS) at discharge and at 1, 3, 6, and 12 months. Longitudinal functional changes were analyzed using the Friedman test, and technical correlations were assessed with the Kruskal–Wallis test. A significant correlation was found between aneurysm diameter and the bypass generation selected (p = 0.0057). Functional outcomes demonstrated a favorable and stable trajectory over time (p < 0.0001). Median mRS improved from 2 (IQR 1–3) at discharge to 1 (IQR 0–1) at 12 months, with 86.2% of patients remaining functionally independent (mRS 0–2) at one year. Ischemic complications occurred in 13.8% of cases; however, intraoperative and follow-up imaging confirmed 100% bypass patency using indocyanine green videoangiography and digital angiography. Microsurgical revascularization is a reliable and effective strategy for managing complex intracranial aneurysms when simpler techniques are not feasible. A hemodynamically guided selection algorithm enables excellent graft patency and supports favorable long-term functional outcomes.