[Surgical treatment of the middle cerebral artery aneurysm--from the experiences of 174 cases (author's transl)].

174 cases of middle cerebral artery aneurysm submitted to surgical operations without using microscope were reviewed. At operation, the head is set on the neutral and slightly chin up position, not turned to any directions. Small craniotomy, which is about half as much as the ordinary unifrontal craniotomy, is performed. The merit of our method is as follows; the M1 portion (Fisher) of the middle cerebral artery runs horizontally, so that we can keep the parent artery during the operation, and owing to the chin up position the strong retraction of the frontal lobe can be avoided. Of 174 cases, 9 were dead (mortality rate 5.2%) and 18 were poor (10.4%). Bad operative outcome is due to the obstruction of the middle cerebral artery around the aneurysmal neck. Therefore, we should always keep in mind to preserve the blood flow of the parent artery as well as that of its branches. Study was made mainly on this point of view such as the general technical process of the aneurysmal neck treatment, the treatment of the cases with severe arteriosclerosis and with large aneurysms having the blood coagula inside.