Architecture-guided reconstructive decision-making for large and giant intracranial aneurysms: A 42-case strategy-oriented series

Objective: To describe an architecture-guided reconstructive decision-making framework for large and giant intracranial aneurysms and to illustrate its clinical applicability using a consecutive institutional series. Methods: We retrospectively reviewed 42 consecutive patients harboring 42 large or giant intracranial aneurysms treated between January 2017 and July 2025. Lesions were classified according to lesion architecture and reconstructive controllability. Clinical outcomes, angiographic aneurysm exclusion, and procedure-related complications were analyzed. Results: Thirty-one aneurysms (73.8%) were classified as non-terminal type and 11 (26.2%) as terminal type. Flow diversion was primarily applied to non-terminal aneurysms, whereas terminal aneurysms were preferentially treated by microsurgical reconstruction. Favorable clinical outcomes (modified Rankin Scale [mRS] 0-2) were achieved in all patients treated with flow diversion and in 95.5% of those treated microsurgically. Complete aneurysm exclusion was confirmed at follow-up angiographic evaluation in all cases, including O'Kelly-Marotta (OKM) grade D at the predefined 1-year angiographic endpoint in all endovascularly treated aneurysms. Terminal aneurysms frequently incorporated branch origins, limiting complete aneurysm exclusion by flow diversion alone because preservation of branch patency necessitated persistent flow across the bifurcation. Among the 42 aneurysms, 39 (92.9%) were classified as large aneurysms (10-24 mm) and 3 (7.1%) as giant aneurysms (≥25 mm). Conclusions: Treatment selection for large and giant intracranial aneurysms may be guided by lesion architecture through the assessment of reconstructive controllability rather than morphology alone. The proposed framework provides a modality-neutral approach for integrating microsurgical and endovascular reconstructive strategies according to the anatomical characteristics of individual lesions.