[Imaging of an aberrant occipital artery arising from the extracranial segment of the internal carotid artery].

We report a case of asymptomatic occlusion of the right internal carotid artery owing to the presence of a rare anatomic variant (occipital artery originating from the extracranial segment of the internal carotid artery). During the preoperative workup for a coronary artery bypass grafting (CABG) in a 65-year-old patient, an occlusion of the right internal carotid artery was visualized on Duplex ultrasound. Distally to the occluded site, the artery was patent thanks to a vessel parallel to it but with a reverse blood flow. MRA and angiography of the brachiocephalic trunk confirmed the occlusion of the internal carotid artery and its opacification distally via an aberrant occipital artery arising at the supra-bulbar level and communicating with the right vertebral artery. Therapeutic abstention was decided and the patient was operated of CABG without any neurological complication. Occipital artery arising from the internal carotid artery is a rare anomaly. Its association with internal carotid artery occlusion may be beneficial because it makes surgery possible, even in a chronic stage, if the patient is symptomatic. If the patient is asymptomatic, therapeutic abstention could be considered.