Combined Application Of Intraoperative Evoked Potentials Monitoring In Microsurgical Treatment Of Intracranial Aneurysms

Background Although remarkable progress has been made in the field of microsurgical technique, intracranial aneurysm surgery still associates with various complications. Cerebral ischemia and postoperative impairment of nervous system can be caused by many specific operative techniques. To further improve the safety of intracranial aneurysm surgery and minimize the occurrence of postoperative ischemic complications, it is necessary to perform real-time monitoring on ischemic damages to the corresponding functional areas. In the present study, we utilized intraoperative combined monitoring of Motion Evoked Potential (MEPs), Somatosensory Evoked Potential (SSEPs)and Brainstem Auditory Evoked Potential (BAEPs), which was meant to elevate the sensitivity of EPs changes for the detection of cerebral ischemia induced by operative technique in cases of intracranial aneurysm and evaluated the feasibility, safety, and sensitivity of the combined application for monitoring motor function, as well as the impact on surgical strategy..Methods MEPs, SSEPs, and BAEPs were recorded intraoperatively for 43 cases of intracranial aneurysms. Monitoring results and clinical outcome were correlated in a prospective observational design.Results Both TES-MEPs and SSEPs could be elicited in 34 of 39 patients (87.1%) intraoperatively. No complication was observed of evoked potentials monitoring in all patients. MEPs indicated inadequate temporary clipping, inadvertent occlusion, inadequate retraction, vasospasm, or compromise to perforating vessels in 7 of 39 cases, SSEPs in 6 of 43 cases and BAEPs in 1 of 3 cases. Three patients sustained new motor dysfunction, which had been detected by TES-MEPs in 3 monitored cases with sensitivity of 100% (3/3) and SSEPs in only 1 patient with sensitivity of 33.3% (1/3). Three patients developed new weakness, which had been detected by SSEPs in only one patient and MEPs in 3 monitored cases. Those cases without intraoperative abnormal EPs findings all did not have postoperative new weakness.Conclusions There was a good relevance between the postoperative motor function and the results of TES-MEPs monitoring, which was a safe, invasive and practical method for intraoperative monitoring function of motor nervous system. TES-MEPs monitoring is superior to SSEPs in the detection of motor dysfunction, but the combined application of both methods could increase the sensitivity and the feasibility. The correlation between monitoring results and clinical outcome is satisfactory. Combined use of EPs monitoring during keyhole microsurgery of intracranial aneurysms can improve the sensitivity in detecting insufficient distal collateral flow, allowing safe completion of potentially hazardous maneuvers. However, the usefulness of the intraoperative monitoring on decreasing the overall mortality still needs further investigation and verification.