Precise MEP monitoring with a reduced interval is safe and useful for detecting permissive duration for temporary clipping

Masahiro Kameda,Takao Yasuhara,Masafumi Hiramatsu,Tomohito Hishikawa,Kazuhiko Kurozumi,Isao Date

doi:10.1038/s41598-020-60377-9

Abstract

Although temporary clipping of the parent artery is an indispensable technique in clipping surgery for intracranial aneurysms, the permissive duration of temporary clipping is still not well known. The aim of this study is to confirm the safety of precise motor evoked potential (MEP) monitoring and to estimate the permissive duration of temporary clipping for middle cerebral artery (MCA) aneurysm based on precise MEP monitoring results. Under precise MEP monitoring via direct cortical stimulation every 30 seconds to 1 minute, surgeons released a temporary clip and waited for MEP amplitude to recover following severe (>50%) reduction of MEP amplitude during temporary clipping. Precise MEP monitoring was safely performed. Twenty-eight instances of temporary clipping were performed in 42 MCA aneurysm clipping surgeries. Because precise MEP monitoring could be used to determine when to release a temporary clip even with a severe reduction in MEP amplitude due to lengthy temporary clipping, no patients experienced permanent postoperative hemiparesis. Based on logistic regression analysis, if a temporary clip is applied for 312 seconds or more, there is a higher probability of a severe reduction in MEP amplitude. We should therefore release temporary clips after 5 minutes in order to avoid permanent postoperative hemiparesis.

Highlights

Temporary clipping of the parent artery is an indispensable technique in clipping surgery for intracranial aneurysms, the permissive duration of temporary clipping is still not well known
Precise motor evoked potential (MEP) monitoring could be used to determine the appropriate timing to release a temporary clip in middle cerebral artery (MCA) aneurysm clipping surgeries and prevent the occurrence of permanent postoperative hemiparesis
Even if we experienced a severe reduction in MEP amplitude during temporary clipping, we could confirm the recovery of the amplitude after releasing the clip

Summary

Introduction

Temporary clipping of the parent artery is an indispensable technique in clipping surgery for intracranial aneurysms, the permissive duration of temporary clipping is still not well known. Because precise MEP monitoring could be used to determine when to release a temporary clip even with a severe reduction in MEP amplitude due to lengthy temporary clipping, no patients experienced permanent postoperative hemiparesis. MEP monitoring via direct cortical stimulation (DCS) can be more reliably performed on an immobile subject even during microscopic procedures, compared with that via transcranial electrical stimulation (TES)[3,7] Based on this background, we hypothesized that precise MEP monitoring via DCS at a reduced interval (every 30 seconds to 1 minute) could be used to determine the appropriate timing for releasing a temporary clip without permanent postoperative hemiparesis, even in cases involving lengthy temporary clipping. We statistically estimated the permissive duration of temporary clipping by analyzing instances of temporary clipping during MCA aneurysm surgeries

Objectives

Results

Conclusion