Introduction: Flow-replacement revascularization surgery is mandatory for safe deconstruction of complex MCA aneurysms. While EC-IC bypass is most commonly performed, little attention has been paid to the potential value of IC-IC bypass, particularly in situ options. We present the largest series to date of in situ side-to-side MCA-MCA bypass for complex MCA aneurysms, including an illustrative video of the surgical technique.
Methods: All consecutive patients who underwent this revascularization technique for a complex MCA aneurysm between 2007 and 2017 were included. Charts were retrospectively reviewed and demographic, clinical, imaging, operative, and outcome data were recorded.
Results: Eight patients, 5 women and 3 men with mean age 58 years (47-67), were identified. Aneurysm location: MCA bifurcation in 6, M2 in 1, M3 in 1, left side in 4, right side in 4. Morphology: 6 saccular, 2 non-saccular, 7 unruptured, 1 ruptured. Mean size was 15 mm (10-20). Bypass location: M2-M2 in 4, M2-M3 in 1, M3-M3 in 2, M4-M4 in 1, concomitant STA-MCA in 3. Aneurysm deconstruction: microsurgical in 7, combined microsurgical-endovascular in 1. Seven (87.5%) were technically successful. One M2-M3 bypass failed because of severe atherosclerosis in recipient and robust leptomeningeal collaterals. However, the concomitant STA-MCA bypass was patent and no stroke occurred. All patients had complete aneurysm obliteration with no mortality or permanent morbidity. Transient and/or minor postoperative complications occurred in 5 (62.5%): transient neurologic deficits in 2, small perianeurysmal infarcts in 2, cerebral edema requiring decompressive craniectomy in 1. After a mean follow-up of 11 months (3-36), all had either stable or improved functional status with stable aneurysm occlusion and patent bypass.
Conclusions: By recreating a more distal bifurcation, the in situ side-to-side MCA-MCA bypass simplifies the revascularization strategy for complex MCA aneurysms by an order of magnitude. This technique should be attempted routinely, particularly when the MCA bifurcation is being deconstructed.
Patient Care: This paper will introduce neurosurgeons to an innovative way of managing complex MCA aneurysms, the in situ side-to-side MCA-MCA bypass, a technique that allows the "resurrection" of an MCA bifurcation that is being deconstructed. In addition to being safe and effective, this bypass technique tends to simplify the overall revascularization strategy for complex MCA aneurysms by an order of magnitude.
Learning Objectives: 1. Recognize the importance and value of IC-IC bypass options in the management of complex MCA aneurysms, particularly the in situ side-to-side MCA-MCA bypass.
2. Understand the importance of flow demand and the role of competitive local blood flow in determining the success of cerebral revascularization surgery, irrespective of the surgeon's technical skills.