Postoperative ischemic sequelae are the most frequent complication of aneurysm surgery. We have performed various types of intraoperative monitoring to prevent postoperative ischemic complications. In this manuscript, we report methods and results of motor evoked potential (MEP), visual evoked potential (VEP) and fluorescence angiography (FAG) with representative cases. MEP monitoring enables us to predict the blood flow insufficiency of arteries that supply the corticospinal tract. We can detect the blood flow insufficiency of not only the perforating artery, such as the anterior choroidal artery or lenticulostriate artery, but also the cortical artery of the middle cerebral artery. VEP monitoring enabled us to detect the ischemia and mechanical damage of the visual pathway from the optic nerve to the occipital lobe. FAG by intravenous administration of fluorescein sodium made it possible to detect the patency of the arteries, such as the hypothalamic artery or posterior thalamoperforating artery, which could not be detected by various electrophysiological monitoring methods. Ischemic complications after aneurysm surgery were markedly reduced after introduction of these monitoring methods. We discuss the usefulness and limitation of these methods.
