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

Abstract

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 cervical ICA, gentle subpial dissection (for aneurysms that adhered to the frontal lobe), complete trapping of the ICA before clipping, and protecting the brain. Clip slippage occurred at the end of dural closing in two cases; the aneurysm was completely obliterated using multiple clips combined with ICA stenosis in one of these cases and ICA trapping with good collateral flow in the other. An excellent clinical outcome was achieved in eight patients, whereas two patients were disabled from massive vasospasm. The authors retrospectively reviewed radiological and surgical data in all cases to determine which treatment methods produced a favorable outcome. Conclusions Blood blister–like aneurysms located at nonbranching sites of the ICA are difficult to treat. Preoperative awareness and careful consideration of these lesions during surgery can prevent poor clinical outcomes.