EC-IC Bypass for Inflammatory Intracranial Stenosis: Institutional Series and Prisma Systematic Review

Introduction: Extracranial–intracranial (EC–IC) bypass is an established revascularization technique for moyamoya disease, atherosclerotic occlusion, and complex aneurysms. Its role in inflammatory intracranial stenosis has been described only in isolated reports and remains poorly defined. Key unanswered questions include optimal surgical timing relative to inflammatory activity, the role of vessel-wall imaging, donor/recipient vessel selection, and perioperative immunosuppressive management. Methods: We conducted a PRISMA-based systematic review of revascularization for vasculitis-related intracranial stenosis. Only three surgical cases were identified, including one occipital artery–MCA bypass, underscoring the scarcity of reported experience. We also reviewed three institutional patients with vasculitis-related MCA stenosis refractory to optimized immunosuppression who developed recurrent ischemia and hemodynamic failure. All underwent STA–MCA bypass. Preoperative work-up included vessel-wall MRI, digital subtraction angiography, and perfusion imaging with acetazolamide challenge to define inflammatory activity, donor suitability, and target territory compromise. Immunosuppressive therapy was maintained and adapted perioperatively in collaboration with rheumatology. Results: All three bypasses were technically successful, with immediate graft patency, restoration of distal flow, and resolution of ischemic symptoms. No perioperative complications occurred. At follow-up, grafts remained patent and neurological status stable. Combined with published cases, our series supports several principles: (1) bypass can be performed safely even if donor vessels show inflammatory changes, provided they are not stenotic; (2) alternative donors such as the occipital artery may be considered when the STA is affected; (3) surgical timing should be driven by hemodynamic failure and cerebrovascular reserve testing rather than systemic remission; and (4) continued or escalated immunosuppression is critical for long-term vessel stability and graft patency. Conclusion: Though limited, integrating our experience with the literature provides practical guidance for EC–IC bypass in inflammatory intracranial stenosis. Timing, preoperative imaging, vessel selection, and perioperative immunosuppression emerge as central considerations. Collectively, these elements support bypass as a viable treatment option in carefully selected refractory patients. Publication History Article published online: 27 February 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany