The ruptured blister-like aneurysm originating from the anterior wall of the internal carotid artery (BLA) was known to have several pitfalls in diagnosis and treatment. Because of their unusual size and shape, BLAs are apt to be overlooked in the initial conventional examination. Furthermore, BLAs with fragile walls can rupture easily during microsurgery and cause postoperative fatal rebleeding more frequently than other aneurysms. We retrospectively reviewed 8 patients with BLA seen at our institution during the past 8 years to discuss couterplans for pitfalls in diagnosis and treatment. Seven of 8 patients were women between the age of 28 and 62 years (mean 48.6 years). BLAs were localized in the right side in 6 patients. In 4 patients, multiple angiographies were required to confirm the diagnosis because of lack of awareness of these lesions. We believe the key point to avoid misdiagnosis is to focus on the anterior wall of the internal carotid artery using several 3-dimensional images such as 3D-CTA. We treated all the BLAs with the so-called clipping on wrapping method (CWM). All patients except the first 1, who died of postoperative rebleeding due to incomplete obliteration of the neck, achieved favorable clinical outcomes. We describe the detailed procedure of CWM, which we modified to prevent poor clinical outcomes.
