Stent-assisted coil embolization for a graft-related aneurysm following high-flow bypass: illustrative case.

backgroundHigh-flow bypass (HFB) combined with parent artery occlusion is an established treatment for complex cerebral aneurysms. Graft-related aneurysm (GA) at the anastomotic site is a rare late complication of HFB, and its optimal management remains poorly defined. The authors report a case of an unruptured GA that enlarged more than 10 years after HFB and was treated with stent-assisted coil embolization (SACE). OBSERVATIONS: A 50-year-old woman had undergone HFB using a radial artery (RA) graft for a cavernous segment aneurysm of the internal carotid artery 10 years earlier. A small aneurysmal dilation at the anastomosis was detected 2 years postoperatively, but long-term follow-up was interrupted. Ten years after the initial surgery, imaging revealed enlargement of a saccular GA with a bleb at the anastomotic site. SACE was performed through the tortuous RA graft using a distal access catheter for stable support, with deployment of an intracranial stent across the anastomosis to secure coil stability. Complete aneurysm occlusion was achieved without procedural complications. Follow-up cerebral angiography confirmed durable occlusion with preserved bypass patency. LESSONS: GA can occur as a late complication after HFB, underscoring the importance of long-term follow-up and medical management. Endovascular treatment may represent a less invasive treatment option in selected cases. https://thejns.org/doi/10.3171/CASE26249.