Management of Aneurysms of the Proximal (A1) Segment of the Anterior Cerebral Artery

OBJECTIVE: Aneurysms originating from the proximal segment (A1) of the anterior cerebral artery are rare; however, because of their small size, the risk of injury of perforating arteries, and the location of the aneurysm in the surgical field, they are challenging to treat. We report on 15 patients with A1 aneurysms and review surgical views according to the direction of aneurysms. METHODS: Fifteen patients were diagnosed with A1 aneurysms and underwent surgical clipping or endovascular coiling at our institution between January 2006 and March 2012. We conducted a retrospective review of clinical and radiological features of all patients with A1 aneurysms. RESULTS: Nine patients underwent surgical clipping, and six patients received endovascular coiling. Six patients (40%) had multiple aneurysms. A1 aneurysms ranged in size from 1.5 to 8.2 mm, with an average size of 3.26 mm. Most A1 aneurysms (73%) had a posterior direction. In the surgical view, A1 aneurysms projecting posteriorly were located behind the A1 trunk. The A1 aneurysm projecting posteroinferiorly was completely eclipsed by the parent artery. In A1 aneurysms with a posterosuperior or superior direction, finding and clipping the aneurysm neck was relatively easy. Thirteen patients (87%) had an excellent outcome, one had moderate disability, and one died. CONCLUSION: A1 aneurysms have certain characteristics; small size, multiple aneurysms, and, usually, a posterior direction. A1 aneurysms with a posterosuperior or superior direction are relatively easy to assess, however, clipping of A1 aneurysms with a posterior or posteroinferior direction is more difficult. Endovascular coiling is an alternative therapeutic option when surgical clipping is expected to be difficult.