Abstract
Fourth-generation bypass techniques are novel constructs that may be useful when standard bypass methods fail.
They involve the use of an unconventional (i.e., intraluminal) suturing technique (type 4A) or vascular orientation (type 4B).
We report the use of a type 4B fourth-generation reimplantation bypass for treatment of a recurrent middle cerebral artery (MCA) aneurysm. A woman in her mid-60s presented with recurrence of a previously treated unruptured MCA aneurysm. Her aneurysm was partially coiled, and recurrence developed at the base of the coil mass. Informed consent was obtained from the patient. The MCA bifurcation was exposed with a pterional-transsylvian approach (Video 1). The aneurysm fundus was mobilized to visualize the origin at the bifurcation between the middle and frontal trunk of the MCA. Clip reconstruction was attempted via a “picket-fence” technique.
Indocyanine green videoangiography revealed occlusion of the middle trunk. The middle trunk was transected and reimplanted to the frontal trunk in end-side fashion, with intraluminal suturing (type 4A bypass). Indocyanine green videoangiography showed no flow because of endothelial damage from the endovascular therapy. The middle trunk was transected off the frontal trunk and diverted to the temporal trunk, where a type 4B side-to-side reimplantation bypass was performed using a longer arteriotomy to maximize the anastomotic area. Patency and aneurysm occlusion were confirmed with Yellow 560 fluorescence. The patient tolerated the procedure well, and no postoperative neurologic deficits were noted. The fourth-generation bypass concepts allow the surgeon to conceive atypical constructs, which are especially useful for troubleshooting challenging revascularization scenarios.