The middle communicating artery: a novel fourth-generation bypass for revascularizing trapped middle cerebral artery bifurcation aneurysms in 2 cases.

The anterior and posterior communicating arteries are natural connections between arteries that enable different adjacent circulations to redistribute blood flow instantly in response to changing supply and demand. An analogous communication does not exist in the middle cerebral circulation. A middle communicating artery (MCoA) can be created microsurgically between separate middle cerebral artery (MCA) trunks, enabling flow to redistribute in response to changing supply and demand. The MCoA would draw blood flow from an adjacent circulation such as the external carotid circulation. The MCoA requires the application of fourth-generation techniques to reconstruct bi- and trifurcations after occluding complex MCA trunk aneurysms. In this report, the authors describe two recent cases of complex MCA bi- and trifurcation aneurysms in which the occluded efferent trunks were revascularized by creating an MCoA. The first MCoA was created with a "double-barrel" superficial temporal artery-M2 segment bypass and end-to-end reimplantation of the middle and inferior MCA trunks. The second MCoA was created with an external carotid artery-radial artery graft-M2 segment interpositional bypass and end-to-side reimplantation of the inferior trunk onto the superior trunk. Both aneurysms were occluded, and both patients experienced good outcomes. This report introduces the concept of the MCoA and demonstrates two variations. Angioarchitectural and technical elements include the donation of flow from an adjacent circulation, a communicating bypass, the application of fourth-generation bypass techniques, and a minimized ischemia time. The MCoA construct is ideally suited for rebuilding bi- and trifurcated anatomy after trapping or distally occluding complex MCA aneurysms.