Blood blister-like aneurysms at nonbranching sites of the internal carotid artery

Object The clinical features of blood blister–like aneurysms (BBAs) that arise at nonbranching sites of the internal carotid artery (ICA) differ from those of saccular aneurysms. In this study, the authors attempt to describe optimal treatments for BBAs, which have yet to be clearly established. Methods Ten of 483 patients with aneurysmal subarachnoid hemorrhage who had been seen at the authors’ institution between March 2001 and June 2005 had intraoperatively confirmed BBAs at nonbranching sites of the ICA. All ten patients were women between the ages of 37 and 64 years (mean age 49.3 years); five had a history of hypertension. The BBAs were localized to the right side of the ICA in seven cases. All patients were successfully treated; clipping was undertaken in six, clipping combined with wrapping in three, and trapping in one. These methods were used in conjunction with various other surgical techniques such as brain relaxation by draining cerebrospinal fluid, anterior clinoidectomy, exposing the cervic...