Monitoring of Somatosensory Evoked Potentials During Intracranial Aneurysm Surgery

ABSTRACT

Somatosensory evoked potentials(SEPs) in response to median nerve stimulation have been recorded as a guide to cortical function during temporary occlusion of the parent vessels in the treatment of 27 aneurysms of middle cerebral artery and internal carotid artery. The central conduction time(CCT), the time between the N14 peak and the N20 peak, were preserved for variable times during temporary occlusion, ranging from no significant change after 18 minutes of occlusion to disappearance of the N20 after 2 minutes. The rapid disappearance of N20 within three minutes after temporary occlusion was observed in all three cases which was developed new postoperative neurological deficits, neither permanent, and in one case of death. The total arterial occlusion time of each of these postoperative deficit cases was no longer than 20 minutes and the shortest time was 12 minutes. The rapid loss of the cortical wave after temporary occlusion, therefore, suggests the safty duration of the temporary occlusion would be short. Monitoring of the SEPs during intracranial aneurysm surgery can help the surgeon in the management of proximal vessel control and reduce the morbidity of aneurysm operation.