Ruptured blister-like aneurysm of distal internal carotid artery: a distinct entity.

OBJECTIVE Blister-like aneurysms are small hemispherical bulges that usually originate from the anteromedial wall of the distal internal carotid artery and cause significant subarachnoid hemorrhage. It is very important to recognize this novel lesion as a different type of aneurysm than ordinary berry aneurysms. CASE DESCRIPTION We report the case of a 43-year-old man who underwent a diagnostic procedure and was awaiting surgery elsewhere before being transferred to our institution. A right sided blister-like aneurysm was seen on angiograms. Although the aneurysm bled intraoperatively, 2 clips were placed with one slightly catching the medial artery wall. The outcome was excellent. CONCLUSIONS Since blister-like aneurysms are different than saccular aneurysms both morphologically and histologically, their treatment also differs making surgical exploration and standard clipping a more hazardous situation than usual. In fact, surgical decision for blister aneurysms should be individual with alternative plans in case the initial treatment strategy fails. Such a flexible strategy also necessitates preoperative cerebrovascular flow testing and a variety of additional hardware like encircling graft clips, microsutures or wrapping material ready in the operating room on top of traditional aneurysm clips.