ABSTRACT
OBJECTIVE: In the case of internal carotid-posterior communicating (ICPCom) artery aneurysm it is possible to successfully clip the aneurysmal neck without any difficulty. However, if the aneurysmal neck is wide, the aneurysmal sac is giant, the aneurysmal sac is hidden by the anterior clinoid process (ACP), or its dome is located in ventral portion or low-lying ICPCom aneurysm, it is difficult to open the proximal aneurysmal neck and we encounter a barrier in controlling bleeding in case of premature rupture of the aneurysm. They need to be resected the ACP for successful aneurysmal clipping. We propose angiographic criteria for predicting necessity of resection of the ACP before clipping of the ICPCom artery aneurysm. METHODS: Between 1999 and 2003, 16 patients with ICPCom artery aneurysm were treated with the resection of the ACP prior to applying the clip on the neck of the aneurysm. We retrospectively analyzed the preoperative cerebral angiographies, and the clinical and operative findings. We measured various radiometric parameters to reveal the angiographic characteristics. RESULTS: The mean value of the radiographic measurement in case of the cerebral angiography in 16 patients is as follows: angle A (the angle between the midline of the skull and the axis of the C1 segment on A-P view) ranged from 15 to 80 degrees (mean+/-SD, 42+/-5 degrees), angle B (the angle between the axes of the C1 and C2 segments on A-P view) ranged from 70 to 150 degrees (mean+/-SD, 110+/-15 degrees), and distance C (the distance between the tip of the ACP and the most proximal portion of the aneurysmal neck on the lateral view) ranged from 2 to 9 mm (mean+/-SD, 4.5+/-1 mm). CONCLUSION: We have resected the ACP in 16 of the 40 ICPCom aneurysms. The mean values of angle A, angle B, and distance C is 42+/-5 degrees, 110+/-15 degrees, and 4.5+/-1 mm, respectively. We did not encounter any difficulty in clipping in all the cases in which there was no premature rupture of the aneurysm. Most of cases had a good outcome.