Evaluation of Surgery for Aneurysms that arise from a Non-Branching Site of the Intracranial Internal Carotid Artery (ICA)

두개강 내 내경동맥의 분지가 없는 부위에서 발생한 동맥류 수술의 분석

Object : Surgery for aneurysms at non-branching sites of an internal carotid artery (ICA) is considered based on the size, shape, direction and site of the aneurysm. In this study, we analyzed characteristics of aneurysms that have arisen from non-branching sites of an ICA from the viewpoint of surgery. Methods : From 2003 to 2007, 346 intracranial aneurysms were treated at our institute. 19 (5.5%) aneurysms were non-branching site aneurysms of an ICA. Surgery for these aneurysms was retrospectively analyzed in view of the treatment strategy according to the site, size, and configuration of the aneurysms in videos obtained during surgery. Results : There were 13 cases of a ruptured aneurysm (68.4%) and six cases of an unruptured aneurysm (31.6%). There were ten cases of a saccular type of aneurysm (52.6%) and nine cases of a blood blister-like aneurysm (47.4%). There were seven aneurysms that arose from the dorsal wall of an ICA (36.8%), six aneurysms that arose from the ventral wall (31.6%), four aneurysms that arose from the lateral wall (21.1%) two aneurysms that arose from the medial wall (10.5%). Three patients with unruptured blood blister-like aneurysms underwent simple wrapping and wrapping with the use of clip. Three unruptured saccular aneurysms could be clipped perpendicular to an ICA or at a slant to an ICA. Three out of six (50%) ruptured blood blister-like aneurysms were ruptured during surgery. These aneurysms were clipped with the partial wall of an ICA, resulting in ICA stenosis. We treated 15 (84%) of 19 cases by only clipping, one case (5.2%) was treated by clipping with bypass surgery and three cases (15%) were treated by wrapping. Conclusion : Ruptured aneurysms of nonbranching sites of an ICA such as blister-like or dorsal saccular aneurysms have a high risk of rupture and can be difficult to clip. If clipping of the aneurysms is possible, preoperative balloon test occlusion should be performed to avoid ICA stenosis after clipping of the aneurysm neck with the arterial wall. Clipping after bypass or trapping can vary the treatment strategy and improve patient outcome. For small-unruptured aneurysms from nonbranching sties of an ICA, wrapping with the use of clip may be a useful method for treatment regardless of the clipping direction.