Pseudo-occlusion and/or pseudo-stenosis of the intracranial internal carotid artery

This report summarizes our recent experience with two patients who presente d with symptoms ipsilateral to a severe carotid stenosis at the bifurcation , with one having a severe stenosis at the siphon and the other an occlusio n of the internal carotid artery in its intracranial portion. These lesions were documented on preoperative angiography. In both instances, persistenc e of symptoms, despite maximal medical therapy, led us to proceed with caro tid endarterectomy. In both cases, intraoperative angiography confirmed a n ormal intracranial internal carotid artery, contrary to what had been seen on preoperative angiography. Carotid endarterectomy was performed, with res olution of clinical symptoms in both cases. This experience suggests that t he appearance of the intracranial portion of the carotid artery can be sign ificantly affected by the presence of a proximal lesion at the bifurcation. Stenosis and/or occlusion of the intracranial portion of the carotid arter y may appear on preoperative angiography secondary to flow alterations as a result of the more proximal lesion. This, in part, may explain why many pa tients with combined extracranial and intracranial arterial disease improve after carotid endarterectomy and suggests that, in the presence of a sever e extracranial lesion, further evaluation be undertaken to exclude the poss ibility of pseudo-stenosis or pseudo-occlusion of the intracranial carotid artery.