Posterior projecting carotid-A1 junctional aneurysms.

The authors report on two types of carotid-A(1) junctional aneurysms projecting backwards. In the two A(1)-type examples, the aneurysm originated at the posterior wall of the proximal A(1) joining the carotid termination and could be clipped using an ipsilateral pterional approach. However, in the carotid-type example, the aneurysm originated at the posterior wall of the carotid termination just below the A(1) origin, and required a contralateral pterional approach to expose the aneurysm. Although the carotid-A(1) junctional aneurysms are rare, their exact location and size can affect the side of the operative approach.