Acute-phase bypass surgery for ruptured intracranial aneurysm: Selection criteria in the endovascular era

Background: Although endovascular treatment (EVT) has become the predominant modality for intracranial aneurysms, a subset of ruptured aneurysms still requires bypass surgery in the acute phase. However, clear criteria for selecting candidates remain limited. This study aimed to evaluate the outcomes of acute-phase bypass surgery and to propose a pragmatic framework for treatment selection in the endovascular era. Methods: Among 138 consecutive patients with aneurysmal subarachnoid hemorrhage treated between 2019 and 2024, we retrospectively analyzed 13 patients who underwent bypass surgery within 24 h of ictus. All cases were classified using a predefined three-step framework assessing (1) the need for parent artery trapping, (2) the presence of a branch arising from the aneurysm, and (3) the risk of parent artery compromise with direct clipping. Clinical characteristics, procedural details, bypass patency, complications, and functional outcomes were reviewed. Results: Seven patients were categorized as Type I, three as Type II, and three as Type III. Intraoperative and postoperative imaging confirmed bypass patency in all cases. One patient developed a postoperative infarction following endovascular internal trapping, but no ischemic events attributable to bypass occlusion occurred. The median follow-up duration was 18 months, and at the last follow-up, 7 of 13 patients (54%) achieved favorable outcomes (modified Rankin Scale 0–2). Conclusion: Acute-phase bypass surgery, when guided by a structured framework, can be performed with high patency and acceptable outcomes in selected patients with ruptured aneurysms. This streamlined strategy may support consistent treatment selection and appropriate referral in the EVT era.