Distal anterior cerebral artery aneurysms: report of 26 cases.

Distal anterior cerebral artery (ACA) aneurysms are rare, and constitute approximately 1.5% to 9% of all intracranial aneurysms. They show some unique features compared with other aneurysms in the cerebral circulation and are frequently treated with a different technique. Twenty-six of 364 patients with cerebral aneurysms treated at our department between 1996 and 2004 had distal ACA aneurysms (7.1%). Twenty-three of the 26 patients were treated through an anterior interhemispheric approach and two with a pterional approach. All saccular aneurysms were successfully clipped except one which was embolized after the surgery. The only fusiform aneurysm spontaneously thrombosed and resolved with parent artery occlusion. Two of the 26 patients had multiple aneurysms. The surgical mortality was 8%. Distal ACA aneurysms have higher mortality and morbidity than other anterior circulation aneurysms. They should be aggressively treated even if very small because of the tendency to rupture. Endovascular treatment is an alternative in the management of these aneurysms. The most important factors affecting the outcome are grade on admission and the neurosurgeon's experience.