2002 Volume 30 Issue 2 Pages 113-119
We present a small series of 3 surgical cases with lateral paraclinoid carotid aneurysms. Since the lateral wall of the internal carotid artery in the vicinity of dural ring is uncommon as a site of aneurysmal origin, little experience has been reported in the literature. Discrepancies were encountered between preoperative prediction and operative findings regarding the location of dural ring. On preoperative angiogram, 2 aneurysms were diagnosed as totally intradural and 1 as partially intradural. At surgery, 1 aneurysm was purely intradural, another 1 had both intra- and extradural component, and the other was located completely proximal to the dural ring.
Difficulties in specifying the location of dural ring, especially the lateral margin, on preoperative imaging studies arise in the fact that the dural ring intersects the internal carotid artery at an oblique angle, which varies from case to case. The origin of the ophthalmic artery on lateral angiogram was an unreliable landmark for the lateral margin of dural ring. One of more useful landmarks is the anterior clinoid process visualized on angiogram before subtraction or 3D-CT. Lateral paraclinoid aneurysms that have a component above the anterior clinoid process are likely to be located entirely or at least partially intradural. Surgery should be preserved for those aneurysms because they are at risk of causing subarachnoid hemorrhage.
