Segmental occlusion of the internal carotid artery with collateral reinjection downstream from the carotid sinus

The preoperative evaluation before coronary bypass led to the discovery of complete atheromatous obstruction of the internal carotid artery sinus in a 79-year-old man free of any neurological symptom. Downstream from the carotid sinus, the patency of the internal carotid artery was ensured by a collateral branch fed by the ipsilateral external carotid artery. This exceptional anatomic variation can be explained by a persistent embryonic artery. The recognition of this atypical feature is clinically relevant because surgery may be possible in some cases, while it is not technically feasible in patients with total obstruction.