Summary

Occlusion of the basilar artery can be treated with endovascular thrombectomy, although the results have not been well studied. Persistent fetal cerebrovascular anatomy can lead to unusual presentation of carotid atherosclerotic disease and can be a barrier to successful mechanical thrombectomy if not recognized. This case presents a rare persistent carotico–basilar anastomosis which resulted in basilar occlusion via the persistent hypoglossal artery and coincident absence of contralateral vertebral arterial access due to a left vertebral artery terminating in the left posterior inferior cerebellar artery. Preoperative recognition of this anatomy afforded by review of cross-sectional imaging was critical to success during this emergent procedure.