Angiographic differentiation of carotid cave aneurysms from ventral paraclinoid carotid aneurysms of Nutik type.

Although it appears that carotid cave and ventral paraclinoid carotid aneurysms are different types of internal carotid artery (ICA) aneurysms, it can be difficult to differentiate the two on the basis of angiograms, because their locations are very close. The purpose of this study was to review the angiographic findings in 21 cases with carotid cave aneurysms and 7 cases with ventral paraclinoid carotid aneurysms of less than 15 mm in diameter (Nutik aneurysm) operated upon in our unit during the last 14 years, and to discuss the difference between the two groups. The results showed that in the anteroposterior view of the angiogram, all carotid cave aneurysms projected medially in semicircular, or berry shape, while only slight medial projection was noted in 3 cases with Nutik aneurysm, the remainder being superimposed on the ICA. In the lateral view of the angiogram, we found that in 6 of the 7 Nutik aneurysms there was a space between the axilla (area inside the genu of the ICA) and the anterior or anteroinferior wall of the aneurysm. This space was absent in all carotid cave aneurysms since these aneurysms projected inferoposteriorly from the genu of the ICA. It is concluded that predominant medial projection in the anteroposterior view and absence of space in the lateral view are two characteristic features of carotid cave aneurysms which can be used to differentiate them from most Nutik aneurysms.