Feature of cerebral aneurysm in Japan and our method against cerebral ischemia during cerebrl aneurysm surgery

Abstract

In this paper, we discuss about the feature of cerebral aneurysm in Japan, our method and ourcome of cerebral aneurysmal surgery and MEP monitoring during temporary vessels occlusion (TO). The incidence of subarachnoid hemorrhage in Finland and Japan is the highest in the world and rupture rate of unruptured cerebral aneurysm in Japan is reported to be about three times more than western countries. According to the Japan Standard Stroke Registry Study, the rate of poor outcome (modified Rankin scale 3-6) of almost ISAT criteria patients was 18.3% and 24.2% in surgical clipping (SC) and coil emblolization (CE) group, respectively. These rates were both superior to ISAT data (36.4% by SC and 25.4% by EC). According to the survey in Japan neurosurgical society from 2001 to 2011, the clipping rate for cerebral aneurysm was decreasing in number from 88.2% in 2001 to 71.2% in 2011. The number of clipping cases for ruptured cerebral aneurysm was decreasing, however, clipping for unruptured cerebral aneurysm was increasing. Our method against cerebral ischemia is keeping the systolic blood pressure over 100 mmHg, administration of brain protective drugs and extra-mild hypothermia during aneurysmal surgery. Number of postoperative major complication of unruptured cerebral aneurysm was 4 cases (2.2%), including 2 hemiparesis of symptomatic internal carotid artery aneurysm and 2 visual disturbance of paraclinoid aneurysms. Evaluation of transcranial motor evoked potential during TO revealed that the incidence of positive change due to TO was 10.3% and significant factor was body temperature over 37 degree Celsius.