Objective: Blood blister-like aneurysms are small hemispherical bulges from the dorsomedial wall of the internal carotid artery that resemble berry aneurysms but differ in their clinical and surgical features. On the basis of our literature review, blister-like aneurysms have been reported to occur only at nonbranching sites of the dorsomedial internal carotid artery. In this report on our series of five patients, we describe blister-like aneurysms of the anterior communicating artery (AComA) and discuss important diagnostic and therapeutic aspects unique to them.
Methods: In our retrospective review of 719 patients with nontraumatic subarachnoid hemorrhage admitted to our service from 1998 to 2003, 181 (25.17%) patients harbored AComA aneurysms. Five (2.76%) patients (four women, one man) had blister-like aneurysms that were recognized at the time of surgery.
Results: Initial digital subtraction angiography was diagnostic in only one patient. A second digital subtraction angiogram was diagnostic in one patient but failed to reveal an aneurysm in the remaining three patients; these were eventually diagnosed by computed tomographic angiography. All aneurysms were clipped. At the time of surgery, the aneurysms arose from the horizontal portion of the AComA without any involvement of the branches of the anterior cerebral artery. All presented as blister-like aneurysms that were thin-walled and lacking a surgical neck. On dissection, two of the lesions ruptured. All lesions were treated with straight fenestrated clips through the A1-AComA junction, thus remodeling the AComA. No delayed rupture was noted at the time of the last follow-up evaluation. At the time of discharge, outcomes were good in two patients, fair in two, and poor in the remaining patient.
Conclusion: Blister-like aneurysms constitute technically challenging lesions that may occur at the AComA. Computed tomographic angiography is valuable in diagnosis. Blister-like aneurysms should be suspected when digital subtraction angiography findings are negative for subarachnoid hemorrhage.