Anatomic features of distal anterior cerebral artery aneurysms: A detailed angiographic analysis of 101 patients

Objective: Distal anterior cerebral artery (DACA) aneurysms have special anatomic features such as small size, broad base with originating branches, association with anterior cerebral artery (ACA) anomalies, and multiple aneurysms. Our aim is to evaluate incidences of these findings from pretreatment angiograms to help both microsurgical and endovascular treatment planning. Methods: We performed detailed angiographic analysis of 101 consecutive patients diagnosed with DACA aneurysms from 1998 to 2007 in the Department of Neurosurgery at the Helsinki University Central Hospital in Helsinki, Finland. All patients underwent either digital subtraction angiography (n = 39) or computed tomographic angiography (n = 62). Results: Of the 101 patients, 50 patients (50%) had multiple aneurysms, 7 patients (7%) had multiple DACA aneurysms, and 1 patient (1%) had an associated arteriovenous malformation. The 108 DACA aneurysms were found in seven different locations: frontobasal branches (n = 2); A2 segment (n = 5); A3 segment inferior to genu of corpus callosum (n = 19), anterior to genu of corpus callosum (n = 70), and superior to genu of corpus callosum (n = 1); A4 or A5 segments (n = 7); and distal branches (n = 4). Mean sizes were 7.4 mm (range, 2-35 mm) and 4.2 mm (range, 1-9 mm) for the 67 ruptured and 41 unruptured aneurysms, respectively. A broad base, wider than the parent artery, was seen in 68% of patients, and 94% of patients had a branch origin at the base. The neck-to-dome ratio was 1:1 in 25% of patients. Anomalies of the ACA were seen in 23 patients (23%): azygos ACA in 4 patients (4%), bihemispheric ACA in 15 patients (15%), and triplication of ACA in 4 patients (4%). Conclusion: The special neurovascular features and frequent ACA anomalies, best identified from computed tomographic angiography or rotational digital subtraction angiography, must be taken into account when planning occlusive treatment of DACA aneurysms.