Direct cerebral revascularization remains a central therapeutic approach for Moyamoya disease (MMD) and Moyamoya syndrome (MMS). However, existing outcome data are largely derived from East Asian populations, with limited evidence characterizing North American cohorts. This study presents the experience of a Canadian university hospital with superficial temporal artery–middle cerebral artery (STA–MCA) bypass for MMD and MMS, focusing on perioperative management, surgical outcomes and graft durability.

A retrospective case series was conducted, including nine patients with MMD/MMS who underwent STA–MCA bypass between December 2021 and March 2026 at the Hôpital du Sacré-Coeur de Montréal. Data on demographics, clinical presentation, perioperative care and follow-up outcomes were analyzed. Primary outcomes included bypass graft patency and ischemic or hemorrhagic events. Secondary outcomes included functional status assessed via the modified Rankin Scale and perioperative complications.

All patients (n = 9) demonstrated sustained graft patency, with a median clinical follow-up of 16 months and a median radiological follow-up of 14 months. Eight patients (89%) experienced stable functional outcomes, while one (11%) experienced significant neurological decline due to postoperative complications. No ischemic events were observed during follow-up; however, one patient experienced a subdural hematoma in the immediate postoperative period, necessitating surgical intervention.

Direct STA–MCA bypass is a viable revascularization strategy for MMD/MMS, achieving high graft patency and preventing recurrent ischemic events. It can be safely established in a Canadian center. However, the potential for complications, particularly in high-risk patients, highlights the critical importance of meticulous perioperative management and careful patient selection.