[Anterior cerebral artery aneurism presenting as a third ventricular mass and hydrocephalus. Case report].

Aneurysms which appear as third ventricular masses are uncommon; most are giant aneurysms arising from the basilar apex. We present the case of a 67-year-old male who was admitted to hospital with a 4-week history of gait instability, urinary incontinence and progressive visual loss. A cranial computed tomography scan revealed a hyperdense mass in the third ventricle with triventricular dilatation. Cerebral magnetic resonance imaging, magnetic resonance-angiography and conventional angiography identified this lesion as a partially thrombosed aneurysm of the anterior cerebral artery. To our knowledge, this is the first report of an anterior cerebral artery aneurysm with these clinical and radiological features.