Endovascular treatment of blood blister-like aneurysms of the internal carotid artery

OBJECT: Because of its thin wall, an aneurysm arising from the posterior wall of the internal carotid artery (ICA), the so-called blood blister-like aneurysm (BBA), is difficult to manage surgically and is often associated with high morbidity and mortality rates. The authors treated these aneurysms endovascularly. In this paper, they present angiographic and clinical results obtained in patients with ICA BBAs treated endovascularly. METHODS: In seven patients with ICA BBAs who presented with subarachnoid hemorrhage, a total number of 12 endovascular treatments were performed, including seven endosaccular coil embolizations (four conventional, two stent-assisted and one balloon-assisted procedure) in four patients and five endovascular ICA trapping procedures in five patients. Repeated endovascular treatments were undertaken in four patients. In two patients, the endovascular treatment was performed after failure of surgical treatment (one case of rebleeding after clip placement and one aneurysmal regrowth after wrapping). A balloon occlusion test (BOT) was performed in all patients prior to ICA trapping. All four patients treated by endosaccular coil embolization showed aneurysmal regrowth. Neither stents nor balloons helpfully prevented aneurysmal regrowth. Of these four patients, two experienced rebleeding. These two patients remained vegetative at the last follow-up examination. After the BOT, ICA trapping was performed with coils and balloons without complication in five patients; excellent outcomes were achieved in all cases but one in which the patient had been in poor neurological condition due to rebleeding after surgical clip therapy. CONCLUSIONS: All ICA BBAs that were treated by endosaccular coil embolization exhibited regrowth of the aneurysm. Some of the lesions rebled. The majority of patients who underwent ICA trapping experienced excellent outcomes. Based on the authors' experiences, they suggest that ICA trapping including the lesion segment should be considered as a first option for definitive treatment if a BOT reveals satisfactory results. Regarding trapping methods, endovascular treatment may be preferred because of its convenience and safety.