Inferior wall aneurysms of the internal carotid artery represent a special group of the internal carotid artery aneurysms. These aneurysms arise from the inferior wall of the internal carotid artery and project inferiorly into the carotid and interpeduncular cisterns. The lesions are large, have an ill-defined or absent neck, and may be fusiform, often including more than half the circumference of the internal carotid artery. They frequently show significant sclerosis with calcification and are often partially to subtotally thrombosed. The origins of the posterior communicating and anterior choroidal arteries may be included within the neck.
We have experienced 5 cases with aneurysms at this location, 4 in women and 1 in a man. Ages range from 67 to 78. All patients presented with subarachnoid hemorrhage. Surgery was performed in all cases in the acute stage. Four patients were treated by creation of a neck and clipping of aneurysm and 1 by coating with Bemsheet. GR was achieved in only 1 patient. One patient treated by coating alone developed rerupture postoperatively, but recovered to MD. Three patients showed cerebral infarction caused by intraoperative temporary occlusion of the internal carotid artery. They remained SD or VS. Because of the characteristics of these aneurysms, it is not possible to give a standard approach to operation as has been given for the more frequent internal carotid artery aneurysms. Each case must be individually evaluated, and several treatment methods tailored to each particular lesion. In respect to timing of the surgery, delayed surgery also should be considered.