The Efficacy of Motor-evoked Potentials on Cerebral Aneurysm Surgery and New-onset Postoperative Motor Deficits

Abstract

Surgical clipping may cause stenosis of parent arteries or occlusion of perforating arteries in cerebral aneurysm surgery. To prevent postoperative motor deficits, motor-evoked potentials (MEPs) have been used. This enables to detect cerebral ischemia. However, the rate of false negatives (motor deficits with preserved MEP) has been relatively higher than in aortic surgery. We hypothesized that postoperative motor deficits with preserved intraoperative MEP do not always represent false negatives. We reviewed medical records of patients for cerebral aneurysms surgery with transcranial MEP monitoring from September 2003 to March 2009. We reviewed aneurysm location and size, abnormal computed tomography findings, and clinical outcome. Motor status was evaluated immediately after extubation and anytime when the symptom of motor deficits was found. One hundred and eleven patients underwent cerebral aneurysm clipping with transcranial MEP. Ninety-eight patients manifested no intraoperative MEP changes and no postoperative motor deficits. Six patients showed intraoperative MEP changes, resulting in no motor deficits in 4 patients with MEP recovery and hemiparesis in 2 without MEP recovery. Four patients of 6 had aneurysm in anterior choroidal artery (AchA). Other 6 patients showed postoperative motor deficits despite preserved intraoperative MEP. Two of 6 patients showed no motor deficits just after extubation, but developed deficits 5 hours after coming out of anesthesia. Only 1 of the 6 patients had aneurysm in AchA. In AchA aneurysm surgery, intraoperative MEP monitoring seems to be useful. False negative in MEP monitoring may include new-onset hemiparesis despite preserved intraoperative MEP.

Treatment outcomes of surgical clipping for unruptured anterior circulation aneurysm—single institute experiences in the era of neurophysiologic monitoring and endovascular treatment

“…These results suggest that clip rotation or other causes of a delayed ischemic event can occur in MCA aneurysmal surgery, and they cannot be detected during the operation [10,20]. SSEP is known to help detect parenchymal injury and to reduce postoperative complication.…”

“…reported that 40 % of the patients with no changes in MEP during surgery showed a delayed motor deficit [10]. These results suggest that clip rotation or other causes of a delayed ischemic event can occur in MCA aneurysmal surgery, and they cannot be detected during the operation [10,20].…”

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.…”