Characteristics and surgery of aneurysms of the proximal (A1) segment of the anterior cerebral artery

Abstract

Aim: Proximal anterior cerebral artery (A1) aneurysms are considered to be rare or even unique. Proper surgical planning around A1 segment is particularly essential in order to avoid injury of tiny perforating arteries.

Methods: In 17 patients with angiographically or intraoperatively diagnosed A1 aneurysms, representing 0.8% of 2 124 aneurysm patients treated surgically at our institution between 1991 and 2003, clinical presentation, neuroradiological findings, surgical treatment methods and outcome were retrospectively analyzed.

Results: Sixteen patients presented with subarachnoid hemorrhage; A1 aneurysms were ruptured in 13 cases. Five patients (29%) had multiple aneurysms. In all cases A1 aneurysms were saccular and their maximum diameter ranged from 4 to 25 mm, average, 7.2 mm; in 4 cases they projected from the origin of the perforating artery, in 6 at the bifurcation of the internal carotid artery, in 5 at the anterior communicating artery and in 2 from the convexity of the parent artery. In 15 patients aneurysms were clipped via ipsilateral pterional approach and in the remaining 2, including a case with a second middle cerebral artery aneurysm, through contralateral approach. Eleven patients had excellent outcome, three good, and three died.

Conclusions: Angiograms must be thoroughly analyzed to correctly assess origin of the aneurysmal neck, and to plan the operative procedure as radiological presentations of distal or proximal A1 lesions resemble those of anterior communicating artery and internal carotid artery bifurcation aneurysms, respectively. Contralateral approach may facilitate surgical elimination of selected A1 aneurysms or enable one-stage clipping in patients with multiple bilateral aneurysms.