Deterioration of non-lesional side evoked potential during unilateral single unruptured intracranial aneurysm clipping: incidental finding or true warning signal?

Abstract

To investigate patients presenting non-lesional side evoked potential (EP) deterioration without lesional side EP change during unruptured intracranial aneurysm (UIA) clipping surgery. This single-center, retrospective study included patients who underwent single UIA clipping with intraoperative neuromonitoring between March 2017 and December 2021. For targeting lateralized surgery group, we included the UIAs located in middle cerebral artery bifurcation, middle cerebral artery, anterior choroidal artery, and internal carotid artery. Motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) were measured during surgery. Postoperative neurologic deficits (PNDs) were defined using the modified Rankin Scale. A total of 315 patients were enrolled. Twenty-seven patients (8.6%) presented with deterioration of one or more EPs. Nine patients showed non-lesional side EP deterioration first without lesional side EP change. Five patients showed only non-lesional side EP deterioration and did not present PNDs or radiologic complications. Three patients showed non-lesional side EP deterioration followed by bilateral EP warnings, one of which had PND due to postoperative subarachnoid hemorrhage. The other two patients had no PND but showed postoperative cerebral vasospasm. This study provides a basis for decisions regarding the firstly appeared non-lesional side EP deterioration without lesional side EP change during unilateral UIA clipping. Further studies with larger sample sizes are needed to generalize these findings.