Dorsal internal carotid artery aneurysm: classification, pathogenesis, and surgical considerations.

Despite the rarity of dorsal internal carotid artery (ICA) aneurysms they still offer surgical challenge to achieve a safe successful clipping due to their peculiar projection. In the past 13 years, 24 cases of dorsal ICA aneurysm were operated upon in our hospitals. Three separate groups of such aneurysms could be identified: group 1; where the aneurysms were located most proximally at the carotid-ophthalmic region, group 3; in which the aneurysms were present most distally just proximal to the ICA bifurcation, and group 2; where the aneurysms were located in between. All cases in this surgical series will be reviewed stressing upon the classification, pathogenesis, and surgical tactics of such a rare type of aneurysm.