Abstract
A 63-year-old male suffered from right hypertensive putaminal hemorrhage and was admitted to hospital. Although his left paresis was improved by conservative treatment, cerebral angiography demonstrated a rare case of unruptured anterior communicating artery aneurysm associated with agenesis of left internal carotid artery (ICA). 3DCT revealed absence of petrous carotid canal on the left side. He underwent coil embolization for this aneurysm, and the postoperative course was uneventful. Although congenital absence of ICA is extremely rare, high occurrence of aneurysm formation is secondary to the altered hemodynamics of arterial blood flow. These aneurysms are high risk for rupture and require aggressive interventions.
