[Ruptured frontopolar artery aneurysm: two cases].

We report two very rare cases of subarachnoid hemorrhage due to a ruptured frontopolar artery aneurysm in the cingulate sulcus. Only two surgically treated cases have been reported. Case 1: A 69-year-old woman suffered headache and was admitted to our hospital the next day. Computed tomography (CT) revealed focal subarachnoid hemorrhage (SAH) in the interhemispheric fissure. Cerebral angiography on admission failed to show an aneurysm, but follow-up study on day 14 revealed a small aneurysm in the cingulate sulcus at the origin of the frontopolar artery arising from the callosomarginal trunk. The aneurysm was successfully clipped on day 15 and the post-operative course was uneventful. Case 2: A 43-year-old man was transferred to our hospital complaining of severe headache. CT revealed diffuse SAH in the basal and interhemispheric cistern. Cerebral angiography showed an aneurysm at the origin of the callosomarginal trunk arising from the anterior communicating artery complex and another at the callosomarginal-frontopolar bifurcation in the cingulate sulcus. Both aneurysms were successfully clipped on the day of admission, and the frontopolar artery aneurysm was shown to be the cause of the SAH.