[A case of symmetrical aneurysms at the bilateral middle cerebral arteries associated with the deep seated arteriovenous malformation in the midline].

A case of symmetrical aneurysms at the bilateral middle cerebral arteries (MCA) associated with the deep seated arteriovenous malformation (AVM) in the midline was presented. Because symmetrical aneurysms at the MCA are 1.17% of all aneurysms, and those associated with the deep seated AVM in the midline are very rare. A 75-year-old female suffered from a sudden onset of a severe headache and a loss of consciousness, and was admitted to our department on June 14, 1996. Computed tomography(CT) showed a subarachnoid hemorrhage (SAH) in the right sylvian fissure (Fisher's Group 4). Bilateral symmetrical MCA's aneurysms and the deep seated AVM were clarified by angiography. The symmetrical aneurysms stood out anterior lateral side and the right aneurysm had bleb. On the other hand, the afferent vessels of the AVM were the branches of bilateral posterior cerebral arteries, and the efferent vessel was the vein of Galen. So we determined SAH due to right MCA aneurysm, and performed the neck clipping of the ruptured aneurysm. The symmetrical aneurysms at the MCA associated with AVM in midline have not been reported. Each parent's artery was not connected each other. These origins, therefore, are suggested to be related not only to acquired factors like hypertension, hemodynamic stress etc, but also to a congenital factor. The origin of the saccular aneurysm is suggested congenital either but it isn't definite.