Neuroradiology

Agenesis, internal carotid artery

a congenital condition in which one internal carotid artery is absent. A minor form is internal carotid artery hypoplasia. When this is the case the carotid canal in the petrous bone is absent and not seen radiographically or at CT examination. The intracranial circulation is maintained via anastomosis from the contralateral side through the circle of Willis or by branches of the ipsilateral external carotid artery that enter the skull through the foramen ovale and rotundum to reconstitute the distal part of the internal carotid artery.

GS