Tailored flow alteration treatment for intracranial internal carotid artery aneurysms: strategy beyond parent artery occlusion with bypass. Case report.

A 58-year-old woman with multiple right internal carotid artery (ICA) aneurysms detected incidentally was referred to us. Three-dimensional computed tomography (CT) angiography revealed a broad-necked paraclinoid aneurysm and an aneurysm on the C(1) segment. Aneurysm clipping with preservation of the anterior choroidal artery and posterior communicating artery was not possible because these vessels could not be adequately identified. Intraoperative digital subtraction angiography during obliteration of the cervical portion of the ICA confirmed retrograde flow from the extracranial-intracranial (EC-IC) bypass to the right ophthalmic artery and stagnation of flow in the aneurysms. The cervical portion of the ICA was ligated. Postoperative three-dimensional CT angiography confirmed complete occlusion of both aneurysms and absence of ischemic lesions involving branches of the ICA. Reversal of the blood flow in the ICA via the EC-IC bypass primarily into the ophthalmic artery as the flow outlet by obliterating the cervical portion of the ICA was successful. To prevent ischemia in the territory fed by the perforating arteries of the ICA, tailored flow alteration treatment may be superior to simple parent artery occlusion of the ICA with/without bypass. The pattern of flow alteration should be deliberately based on individual anatomic variations, especially the preservation of flow outlets.