Microsurgical management of giant intracranial aneurysms in the endovascular era

Giant intracranial aneurysms (GIAs; ≥ 25 mm) are a distinct subset of aneurysms with worse outcomes compared with other aneurysms. The aim of this review was to analyze patient and aneurysm-related factors that influenced management decisions, including the need for bypass procedures, and to assess outcomes, including morbidity and mortality, associated with the procedures.

This retrospective analysis included patients with GIAs treated microsurgically at a single institution from 2010 to 2023. Aneurysms were classified by location as infraclinoidal internal carotid artery (ICA), supraclinoidal ICA, anterior cerebral artery (ACA), middle cerebral artery (MCA), and basilar artery. Techniques included direct clipping, bypass with trapping, and parent artery ligation. Preoperative imaging included CT, DSA, and balloon occlusion testing. Intraoperative adjuncts, such as indocyanine green video angiography and Doppler ultrasonography, ensured procedural efficacy. Outcomes were measured by the modified Rankin Scale (score ≤ 2 indicating good outcomes), aneurysm obliteration rates, and complication rates. Descriptive statistics were used to compare patients with ruptured versus unruptured aneurysms and those with anterior versus posterior circulation aneurysms.

Among 77 patients (mean age 44.7 years) with GIAs included in the analysis, 20 had infraclinoidal ICA, 25 had supraclinoidal ICA, 10 had ACA, 20 had MCA, and 2 had basilar artery aneurysms. Sixty-one patients (79.2%) achieved good outcomes, with an overall 96.8% (61/63) complete obliteration rate. Infraclinoidal ICA aneurysms had the lowest morbidity (10%), while supraclinoidal ICA aneurysms had 28% morbidity and 12% mortality. High-flow bypass procedures were required for 24.7% (19/77) of patients. MCA and ACA aneurysms each had a 20% morbidity rate. Overall complications included infarcts (13%, 10/77), persistent hemiparesis/paraparesis (15.6%, 12/77), and infections (1.3%, 1/77). The surgical mortality rate was 5.2% (4/77). Despite a higher proportion of ruptured GIAs (42%, 32/77), this series demonstrated clinical equivalence in microsurgical results compared with contemporary series.

Microsurgical management of GIAs is effective, with high obliteration rates and good outcomes in 79.2% of patients, particularly for anterior circulation aneurysms. Location-specific strategies delivered optimized results, with bypass procedures required in selected cases. Preoperative collateral flow assessment is critical. Despite endovascular advancements in the management of GIAs (which might need retreatment in 20% of patients), microsurgery had a complete occlusion rate of 96.8%, demonstrating superior durability. These findings underscore the role of microsurgery in GIAs, emphasizing tailored approaches to minimize risks.