Congenital Absence of the Right Internal Carotid Artery


The right common carotid is visible on the most inferior slices of the scan and is diminutive. The left common carotid is 2 to 3 times the size of the right. The right external carotid artery is patent and normal size however the right internal carotid artery is absent and there is no carotid canal at the skull base suggesting congenital absence. The left internal carotid has a normal course through the carotid canal and cavernous sinus and appears normal at the circle of Willis. There are also large posterior communicating arteries that reconstitute the circle of Willis. The right middle cerebral artery is hypoplastic but opacifies normally. Both anterior cerebral arteries are fed from the left carotid system. Vertebral arteries and basilar artery appear normal.