Extracranial-intracranial bypass using a cephalic vein graft for iatrogenic internal carotid artery injury during functional endoscopic sinus surgery: illustrative case.

backgroundInjury to the internal carotid artery (ICA) during functional endoscopic sinus surgery is a rare but potentially fatal complication. Although treatment algorithms have been developed, guidelines for effectively managing iatrogenic ICA injury have not been established. A case of ICA perforation during functional endoscopic sinus surgery treated with cerebral bypass utilizing a cephalic vein graft is presented. OBSERVATIONS: A woman in her late 50s presented with a left cavernous ICA injury that had occurred during endoscopic nasal polypectomy at an outside hospital. Hemostasis was achieved with intranasal Foley catheter placement. Left common carotid artery angiography revealed a high-flow carotid-cavernous fistula. Cerebral revascularization was chosen as the optimal procedure. The initial intent was to use a radial artery graft, but the radial artery was found to be occluded intraoperatively. Postoperatively, the patient experienced decreased vision and left eye movement but was otherwise neurologically intact. Postoperative angiography showed complete resolution of the fistula. LESSONS: In cases involving ICA injury and carotid-cavernous fistula formation, microsurgical trapping with high-flow bypass is a favorable treatment option. The cephalic vein is a viable graft option when unexpected challenges arise with a radial artery graft. https://thejns.org/doi/10.3171/CASE24222.