Universal external carotid artery to proximal middle cerebral artery bypass with interposed radial artery graft prior to approaching ruptured blood blister-like aneurysm of the internal carotid artery.

Blood blister-like aneurysms are dangerous aneurysms with fragile walls arising from the supraclinoid internal carotid artery (ICA). Primary treatment of these aneurysms in the acute stage is challenging, due to the substantial risk of periprocedural bleeding. We describe a series of 4 patients who presented with ruptured blister-like aneurysm of the ICA and were treated with completion of extracranial-intracranial high-flow bypass followed by inspection and trapping of the aneurysm. All patients were treated in the acute stage, within 48 hours of bleeding. External carotid artery to proximal middle cerebral artery bypass with interposed radial artery (RA) graft was established followed by approach to the lesion and trapping of the parent vessels. The aneurysms in 3 patients ruptured during dissection of the lesion from the surrounding structures, but bleeding was easily controlled. RA grafts were patent in all patients and no postoperative symptomatic ischemic or hemorrhagic complications were encountered, resulting in excellent outcomes with modified Rankin scale scores of 0 at follow up after 3 months. Our present strategy for surgical treatment of blister-like aneurysms completely avoided the risk of devastating intraoperative hemorrhage, offering a most cautious strategy associated with minimal risk of intraoperative massive bleeding.