Evaluation of Combined Use of Transcranial and Direct Cortical Motor Evoked Potential Monitoring During Unruptured Aneurysm Surgery

Abstract

The feasibility and reliability of combined use of transcranial and direct cortical motor evoked potential (MEP) monitoring during unruptured aneurysm surgery were evaluated. Forty-eight patients with unruptured cerebral aneurysms underwent craniotomy and neck clipping accompanied by muscle MEP monitoring. MEPs were elicited successfully by transcranial electrical stimulation in all patients. Direct cortical stimulation elicited MEPs in 44 patients. Reduction in MEP amplitude to less than 50% of baseline was considered significant. No postoperative motor paresis occurred in 39 patients in whom transcranial and direct MEPs remained unchanged. Four patients in whom direct MEPs could not be recorded had no intraoperative abnormality in transcranial MEPs and no postoperative motor dysfunction. Four of the other 5 patients manifested significant transient direct MEP changes without transcranial MEP changes. The transient MEP changes were observed in 3 patients during temporary clipping of the parent artery and in one patient with inadequate clipping of an middle cerebral artery aneurysm, and were considered due to insufficiency of blood flow. Decrease or disappearance of direct MEP waves recovered immediately after re-application of the clip and release of the temporary clip. Direct MEP waves disappeared and did not recover until the end of microsurgical procedures in one patient, although transcranial MEP amplitude remained at less than 50% of baseline. She developed hemiparesis postoperatively, which recovered within 6 hours. The duration of temporary occlusion in patients with direct MEP changes was significantly longer than that in patients without (p º 0.05). Direct MEP was sensitive in detecting ischemic stress to descending motor pathways during aneurysm surgery. Transcranial MEPs could be elicited in patients in whom direct MEPs could not be obtained, and during periods such as craniotomy or after dural closure, in which direct MEPs could not be recorded. These findings suggest that combined transcranial and direct cortical MEP recording may improve the feasibility and reliability of MEP monitoring during unruptured aneurysm surgery.

The Incidence of Unacceptable Movement with Motor Evoked Potentials During Craniotomy for Aneurysm Clipping

“…More recently, other investigators have had better success rates with transcranial MEP monitoring during intracranial aneurysm clipping, but they have used very high stimulus intensity with a continuous infusion of muscle relaxant for partial neuromuscular blockade, or they have monitored only upper extremities (10,18,31). The use of muscle relaxant in these patients has several drawbacks.…”

The Diagnostic Accuracy of Evoked Potential Monitoring Techniques During Intracranial Aneurysm Surgery for Predicting Postoperative Ischemic Damage: A Systematic Review and Meta-Analysis

“…Fourteen of these studies met the inclusion criteria ( Fig. 1) 11,12,14,15,24,26,[35][36][37][38][39][41][42][43] . They include 1597 patients (95% CI: 276, 2881) with a total of 1689 (336, 3042) aneurysms; 1556 (92.0%) aneurysms in the anterior circulation and 134 (8.0%) in the posterior circulation.…”

“…Tables 1, 2 and 3 summarise the characteristics of the eight studies 11,14,24,26,35,37,38,43 that used SSEP as the index test, six studies that used TcMEP 11,15,24,39,41,42 , and five that used DMEP 12,14,15,36,41 , respectively. Two studies 11,24 employed both SSEP and TcMEP monitoring techniques as the index test, two 15,41 used TcMEP and DMEP, and none of the studies measured both SSEP and DMEP.…”

Effect of pre/postconditioning at temporary clipping

“…Decrease or disappearance of direct MEp waves were recovered immediately after re-application of the clip and release of the temporary clip and they showed that combined transcranial and direct cortical MEP recording may improve the feasibility and reliability of MEP monitoring during unruptured aneurysm surgery (35).…”

“…Motoyama et al studied the reliability of combined use of transcranial and direct cortical motor evoked potential (MEp) monitoring during unruptured aneurysm surgery (35). Decrease or disappearance of direct MEp waves were recovered immediately after re-application of the clip and release of the temporary clip and they showed that combined transcranial and direct cortical MEP recording may improve the feasibility and reliability of MEP monitoring during unruptured aneurysm surgery (35).…”