High-Flow Bypass and Clip Trapping of a Giant Fusiform Middle Cerebral Artery (M1) Aneurysm: Technical Case Instruction.

Background And Importance: Giant intracranial aneurysms have a poor natural history with mortality rates of 68% and 80% over 2-year and 5-year, respectively. Cerebral revascularization can provide flow preservation while treating complex aneurysms requiring parent artery sacrifice. In this report, we describe the microsurgical clip trapping and high-flow bypass revascularization for a giant middle cerebral artery (MCA) aneurysm.

Clinical Presentation: A 19-year-old man was diagnosed with a giant left MCA aneurysm after he suffered a left hemispheric capsular stroke 6 months ago. Since then, the patient recovered from the right hemiparesis and dysarthria with residual symptoms. Neuroimaging demonstrated a giant fusiform aneurysm encompassing the entire M1 segment. The bilobed aneurysm measured 37 × 16 × 15 mm. Endovascular treatment options included partial coiling of the aneurysm followed by deployment of flow-diverting stent spanning from the M2 branch-through the aneurysm neck-into the internal carotid artery. Because of the high risk of lenticulostriate artery stroke with endovascular treatment, the patient opted for microsurgical clip trapping and bypass. The patient consented to the procedure. High-flow bypass from internal carotid artery to M2 MCA was performed using radial artery graft, followed by aneurysm clip trapping using 3 clips.

Conclusion: We demonstrate the successful microsurgical treatment for a complex case of giant M1 MCA aneurysm with fusiform morphology. High-flow revascularization using radial artery graft helped in achieving good clinical outcome with complete aneurysm occlusion with flow preservation despite the challenging morphology and location. Cerebral bypass continues to be a useful tool to tackle complex intracranial aneurysms.