[Unruptured saccular aneurysm at the origin of the duplicated middle cerebral artery: reports of two cases and review of the literature].

We report on two rare cases of unruptured saccular aneurysm located at the origin of the duplicated middle cerebral artery. Case 1: On magnetic resonance (MR) angiography, a 56-year-old woman was diagnosed as having an unruptured right middle cerebral artery (MCA) bifurcation aneurysm. Right carotid angiography disclosed a duplicated MCA and four unruptured saccular aneurysms, including the origin of the duplicated MCA. Case 2: A 58-year-old man had a sudden onset of vertigo, and underwent MR imaging. The MR angiography detected a right internal carotid artery (ICA) aneurysm, and the subsequent angiography demonstrated duplication of the right MCA and two intracranial aneurysms; one at the origin of the posterior communicating artery (PcomA), the other at the origin of the duplicated MCA. Each aneurysm was successfully clipped through the transsylvian approach. The postoperative courses were uneventful and both patients were discharged in good condition. There have been only 19 previous reports of the duplicated MCA aneurysm in the literature.