Rupture of symptomatic blood blister-like aneurysm of the internal carotid artery

Background. Aneurysms at nonbranching sites in the supraclinoid internal carotid artery (ICA), known as blood blister-like aneurysms (BBAs), are rare entities and differ from saccular aneurysms. In this study, we attempt to describe our clinical experience and the outcome of treatments for BBAs. Method. Thirteen of 745 patients with aneurysmal subarachnoid hemorrhage (SAH) who visited our institution between March 2005 and July 2010, and were confirmed to have BBAs at nonbranching sites of the supraclinoid ICA by digital subtraction angiography (DSA) or computed tomography angiography, were followed-up. In these patients, several therapeutic managements were provided depending on their clinical condition. Data analyzed included patient age, sex, World Federation of Neurologic Surgeons (WFNS) scale, time interval from first DSA to second DSA, treatment of aneurysms, and the modified Rankin scale score at follow-up, 6 months after SAH. Result. Of these 13 patients, 5 underwent rapid configuration change from blood blister-like aneurysm to saccular-shaped. Different therapeutic managements were provided, including clipping on wrapping material in 2 patients, ICA trapping without extracranialintracranial (ECIC) bypass in 3 patients, ECIC bypass and ICA trapping in 3 patients, transarterial endovascular therapy in 3 patients, direct clipping in 1 patient, and external ventricular drainage in 1 patient. Good clinical outcome was achieved in 4 patients, whereas the other 9 patients had moderate to severe disability due to rebleeding of aneurysms, large cerebral infarction, or severe cerebral vasospasm. Conclusions. BBAs of the supraclinoid ICA have special neuroradiological and clinicopathological characteristics. Direct clipping or endovascular coil embolization along may not be sufficient and sometimes have undesirable results. ICA trapping or ligation including the lesion segment can be considered an alternative choice if the balloon occlusion test (BOT) is successful. However, if the patient does not tolerate the BOT, ECIC bypass surgery with ICA ligation or trapping is another option.