Occipital artery to upper posterior circulation bypass through the presigmoid approach in revascularization of the posterior circulation: An anatomical study.

We describe a novel extracranial (EC)-to-intracranial (IC) bypass technique between the occipital artery and upper posterior circulation (UPC) for revascularization of the posterior circulation through the presigmoid approach. Five formalin-fixed human heads were examined to demonstrate the detailed anatomy of the occipital artery and UPC and illustrate the step-by-step bypass procedure. The occipital artery, a branch of the external carotid artery, can be anastomosed to the P2/P3 segment of the posterior cerebral artery and S1/S2 segments of the superior cerebellar artery as an alternative to EC bypass donor segments for treatment of affection requiring revascularization. Presigmoid approach for the anastomosis of the occipital artery to the UPC provides a shorter distance, due to resection of some bones.