Anomalous branches of the cervical internal carotid artery: two cases of clinical importance.

Anomalous branches of the cervical portion of the internal carotid artery are rare. Reports in which these anomalous branches are of any clinical importance are even more rare. We are reporting two cases in which the anomalous branch maintained patency of the cervical portion of the proximally occluded internal carotid artery. Both patients initially had hemispheric symptoms appropriate to the affected internal carotid artery. This article details angiographic methods to demonstrate the unusual anatomic and pathologic aspects of these cases and the successful operative approach.