Insurance and Flow-Alteration Superficial Temporal Artery to Middle Cerebral Artery (STA-MCA) Bypass in Management of Complex Anterior Intracranial Circulation Aneurysms in Postendovascular Era

Abstract

Background: Optimal management of complex anterior circulation aneurysms is an enigmatic challenge because of frequent involvement of major vessel bifurcation, choroidal vessels, and lenticulostriate/thalamostriate perforators. Cerebral ischemia associated with prolonged clipping time is a major concern pertinent to their surgical management, especially in patients with poor cross-flow. To circumvent this hurdle, single/double-barrel low-flow superficial temporal artery (STA) to middle cerebral artery (M3/M4-MCA) can be performed, which can maintain distal cerebral perfusion while facilitating safe clip reconstruction of complex MCA and supraclinoidal internal carotid artery (ICA) aneurysms involving ICA bifurcation or supraclinoidal ICA aneurysms with poor cross-circulation-insurance bypass, as well as supplement/alter blood flow after MCA aneurysm trapping-flow-alteration bypass.

Methods: A retrospective chart review of consecutive neurosurgical patients operated over 2 years at this center was performed. Patients with complex MCA and ICA aneurysms who were treated with STA-MCA bypass were included. The clinical profile, pre- and postoperative images, intraoperative imaging, and patient outcomes were recorded. Surgical reconstruction of aneurysm was the treatment of choice due to involvement of choroidal/thalamostriate perforators, MCA/ICA bifurcation, complex aneurysm morphology, or dissecting/thrombosed nature of aneurysm. STA-MCA low-flow bypass was performed using M3/M4 segment of MCA as the recipient in anticipation of prolonged temporary clipping time on M1-MCA, supraclinoidal ICA aneurysms with suspected ICA terminus involvement, or need for possible trapping of fusiform MCA aneurysm. The saccular/fusiform part of aneurysm was clip reconstructed and the partially thrombosed dissecting segment was opened for thrombectomy and trapped using proximal and distal clips after good patency of bypass was confirmed. The distal MCA flow was restored adequately and confirmed intraoperatively using indocyanine green angiography and micro-Doppler ultrasonography.

Results: MCA (n = 4) and supraclinoid-ICA (n = 1) aneurysms were managed successfully using this strategy, which involved 6 STA-MCA bypass procedures (insurance and flow-alteration bypass, 3 each). Postoperative check angiograms demonstrated patent bypass in all 5 patients. Four patients had favorable outcome (modified Rankin Scale score 0/1); one had recovering hemiparesis and aphasia (modified Rankin Scale score 4).

Conclusions: This series highlights the surgical strategy and safety for successfully managing complex MCA and ICA aneurysms using low-flow STA-MCA revascularization procedures.

Keywords: Internal carotid artery aneurysms; Middle cerebral artery aneurysms; STA-MCA bypass; Surgical strategy; Technical nuances.