Abstract
OBJECTIVE: Extracranial-to-intracranial(EC-IC)bypasses are established techniques for treating complex aneurysms, cerebrovascular insufficiency, and moyamoya disease. Intracranial-to-intracranial (IC-IC) bypasses that are entirely intracranial and do not rely on the extracranial circulation are less established alternatives for revascularization. A consecutive clinical experience with IC-IC bypass applied to aneurysm therapy is reviewed. METHODS: During a 9.75 year period, 64 bypasses were performed for complex aneurysms, including 25 IC-IC bypasses : in situ bypasses in 7 patients, reanastomosis in 9 patients, reimplantation in 5 patients, and intracranial bypasses using grafts in 4 patients. RESULTS: In situ bypasses consisted of 4 PICA-PICA bypasses, 2 A3-A3 ACA bypasses, and one ATA-MCA bypass. Aneurysm excision with reanastomosis of the parent artery was performed for 5 MCA aneurysms and 4 PICA aneurysms. Two PICAs were reimplanted onto vertebral arteries I one pericallosal artery was reimplanted onto a callosomarginal artery; one M2 MCA trunk was reimplanted onto another M2 MCA trunk; and one MCA bifurcation was reconstructed with a double reimplantation technique. Intracranial bypasses included two petrous-to-supraclinoid ICA bypasses using saphenous vein grafts; one vertebral artery-to-superior cerebellar artery bypass using a radial artery graft; and one ACA-to-pericallosal artery bypass using a radial artery graft, with reimplantation of the callosomarginal artery. Postoperative angiography confirmed graft patency in 23 patients (92%) and complete aneurysm occlusion in all cases. By Glasgow Outcome Scale scores, good outcomes were observed in 22 patients (88% GOS 5 or 4). CONCLUSION: IC-IC bypasses are appealing because they are entirely intracranial, are less vulnerable to injury or occlusion, do not require harvesting an extracranial artery, and use donor and recipient arteries with diameters that are well matched. When grafts are needed, radial arteries are well suited. These bypasses often require end-to-end or side-to-side anastomoses not normally used with traditional EC-IC bypasses. When appropriate, an IC-IC bypass can be a safe and effective treatment for complex intracranial aneurysms.
