Emergency superficial temporal artery-superior cerebellar artery bypass for hyperacute basilar artery occlusion following elective middle cerebral artery aneurysm clipping: illustrative case.

BACKGROUND: Basilar artery occlusion (BAO) is a threatening condition requiring rapid reperfusion to preserve brainstem function. Although endovascular thrombectomy is considered standard treatment, underlying pathology or limited resources may require surgical intervention. The authors performed an emergency superficial temporal artery-superior cerebellar artery (STA-SCA) bypass in the hyperacute setting of BAO following elective aneurysm surgery. The bypass prevented stroke progression and dramatically improved consciousness. LESSONS: This case demonstrates that with early recognition, protocolized monitoring, and microsurgical capability, STA-SCA bypass is a viable effective strategy for revascularization in acute posterior circulation stroke and can prevent progression of the ischemic core. OBSERVATIONS: A 69-year-old man with a recent history of bilateral cerebellar infarction underwent elective microsurgical clipping of a left M1 middle cerebral artery aneurysm. The authors confirmed complete aneurysm exclusion with postoperative CTA. Eight hours later, the patient developed aphasia and deep state coma. CTA perfusion revealed BAO, with extensive cerebellar penumbra and a small core. Due to severe preexisting right vertebral and basilar intracranial atherosclerotic disease, urgent STA-SCA bypass was performed with a right subtemporal approach. Intraoperative studies confirmed graft patency reperfusion. The patient recovered consciousness and was discharged with a modified Rankin Scale score of 3. https://thejns.org/doi/10.3171/CASE25710.