Standardized Occipital Artery–Posterior Cerebral Artery Bypass With Encephalo-Duro-Pericranial Synangiosis Using a Cortical P4 Recipient for Posterior Circulation–Involved Moyamoya Disease

BACKGROUND AND OBJECTIVES: Posterior cerebral artery involvement in moyamoya disease (MMD) is associated with occipital hypoperfusion, visual disturbance, recurrent ischemic events, and worse neurological status. In selected patients, posterior circulation-targeted revascularization may represent an important component of surgical management. We evaluated outcomes after a standardized occipital artery-posterior cerebral artery (OA-PCA) bypass strategy using a cortical P4 recipient combined with encephalo-duro-pericranial synangiosis (EDPS) in patients with posterior circulation-involved MMD. METHODS: We retrospectively reviewed consecutive posterior circulation revascularization procedures performed from August 2012 through December 2024. All procedures used a standardized OA-PCA bypass to a cortical P4 recipient combined with EDPS. The primary outcome was bypass patency on follow-up imaging. Secondary outcomes included collateral formation, perfusion improvement, early visual improvement, modified Rankin Scale improvement, and procedure-related perioperative adverse events. RESULTS: A total of 113 procedures in 109 patients were included. Early postoperative computed tomography angiography confirmed bypass patency in all evaluable procedures (112/112, 100%). At 12 months or later, bypass patency was observed in 59 of 102 procedures (57.8%), collateral formation in 63 of 102 procedures (61.8%, grades A-B), and perfusion improvement in 63 of 102 procedures (61.8%). Among 72 procedures with documented preoperative visual disturbance, early visual improvement occurred in 31 (43.1%). Modified Rankin Scale improvement of at least 1 point at last follow-up occurred in 69 of 113 procedures (61.1%). Procedure-related perioperative adverse events were infrequent, and no bypass-related reoperation occurred within 30 days. CONCLUSION: In this single-center retrospective series, standardized OA-PCA bypass using a cortical P4 recipient combined with EDPS was associated with reliable early graft patency and favorable angiographic, perfusion, and clinical outcomes in selected patients with posterior circulation-involved MMD. Late graft status should be interpreted together with collateral development, perfusion findings, and clinical course rather than in isolation.