Clinical Analysis of Internal Carotid Artery Aneurysms with Reference to Classification and Clipping Techniques

 An intraoperative classification of intradural internal carotid artery (ICA) aneurysms not related to the arterial division but based on their operative presentation and clipping techniques is introduced. On the basis of the surgeon's view of the operative field via the pterional approach in 156 operated intradural ICA aneurysms in 143 patients, these aneurysms were classified according to their location in relation to the long axis of the ICA as either proximal, middle or distal in type and also according to their relation to the cross section of the ICA as either lateral, medial, ventral or dorsal in type. Numerically the largest in frequency is the middle type of aneurysm by axial location and the lateral type of aneurysms by cross sectional location. Eighty five percent of the lateral type aneurysms were at the arterial division. The majority of the large to giant aneurysms were of the ventral type and no dorsal type aneurysms were seen. About one third of the ICA aneurysms in this series were located free of the arterial division. All dorsal type aneurysms and most of the medial type aneurysms were not related to the arterial division.