Bilateral anomalous anterior cerebral artery and infraoptic aneurysm.

A CT scan demonstrated a subarachnoid hemorrhage. A followup four-vessel cerebral angiogram demonstrated bilateral anomalous ACAs, with the origin at the level of the ophthalmic artery proximal to the posterior communicating and anterior choroidal arteries. The proximal portion of each ectopic proximal segment was horizontal , suggesting that both ACAs coursed below the optic nerves (Figs . 1 A and 2A). In addition, there was a broad-based saccular aneurysm off the proximal segment of the right ACA, pointing anteriorly and inferiorly below the optic nerve (Fig . 18). The anterior communicating artery (ACoA) was slightly high and posterior in location , and there was a saccular ACoA aneurysm pointing upward (Fig . 28).