Agenesis of the right internal carotid artery with an unusual transsellar intracavernous intercarotid connection.

Unilateral agenesis of the internal carotid artery (lCA) is a very rare anomaly. Generally, when the ICA is congenitally absent, blood is carried to the affected side through the circle of Willis by the basilar artery and the opposite ICA. We report a case of unilateral agenesis of the ICA in which the affected hemisphere was supplied by an anomalous artery between the cavernous parts of the two ICAs. Only nine other angiographic reports of intercarotid anastomosis of this type are in the literature [1 -8].