Compression of the visual pathway by anterior cerebral artery aneurysm.

Visual failure is an uncommon presenting symptom of an intracranial aneurysm. It is even more uncommon in aneurysms arising from the anterior cerebral artery (ACA). We presented 2 patients with an aneurysm of the A1 segment of the anterior cerebral artery causing visual field defects. One patient presented with a complete homonymous hemianopia due to compression of the optic tract by a giant aneurysm of the proximal left A1 segment. The second patient had an almost complete unilateral anopia caused by compression of the optic nerve and chiasm by an aneurysm of the distal part of the A1 segment with a small chiasmatic hemorrhage and ventricular rupture.