Intraoperative Transcranial Motor-evoked Potential Monitoring Research Articles

Transcranial Motor Evoked Potentials as a Predictive Modality for Postoperative Deficit in Cervical Spine Surgery – A Meta-analysis (P6-4.006)

<h3>Objective:</h3> To evaluate whether intraoperative transcranial motor evoked potential (TcMEP) changes can predict postoperative neurologic complications in patients undergoing cervical spine surgery. <h3>Background:</h3> Cervical decompression and fusion surgeries are commonly performed to relieve spinal cord and nerve root impingement. Potential intraoperative injury to the spinal cord and nerve roots poses a nontrivial risk for consequent postoperative deficits. Although neuromonitoring with intraoperative TcMEPs is often used in cervical spine surgery, its therapeutic value remains controversial. <h3>Design/Methods:</h3> A meta-analysis of the literature using PubMed to retrieve literature on intraoperative TcMEP monitoring during cervical spine surgery, excluding aneurysms, tumors, and trauma, was performed. Data collection included study design, patient demographics, procedure type/approach/indication, modalities used, TcMEP alarm criteria, TcMEP changes (including reversible and irreversible changes), and postoperative neurological deficit. The sensitivity, specificity, and diagnostic odds ratio (DOR) of overall, reversible, and irreversible TcMEP changes for predicting postoperative neurological deficit were calculated. <h3>Results:</h3> Nineteen studies were included in the final analysis. The total cohort consisted of 45,367 patients, and the incidence of postoperative neurological deficits was 0.37% (168/45367). Of the total cohort, 1.36% (619/45367) had a significant intraoperative TcMEP change. The incidence of postoperative neurological deficits in patients with intraoperative TcMEP changes was 15.67% (97/619), while the incidence in those without was 0.16% (71/44677). TcMEP changes had a sensitivity of 59%, specificity of 95%, and DOR of 26.92 for predicting neurologic deficit. Reversible and irreversible changes had sensitivities of 17% and 47%, specificities of 95% and 98%, and DORs of 3.02 and 56.29, respectively. <h3>Conclusions:</h3> TcMEP monitoring has high specificity but low sensitivity for predicting deficits in cervical spine surgery. Patients with postoperative deficits were 27 times more likely to have experienced intraoperative TcMEP changes than those without deficits, with irreversible changes indicating a higher risk of injury than reversible changes. <b>Disclosure:</b> Mr. Reddy has nothing to disclose. Dr. Gorijala has nothing to disclose. Mr. Chang has nothing to disclose. Dr. Anetakis has nothing to disclose. Jeffery Balzer has nothing to disclose. Donald Crammond has nothing to disclose. Dr. Shandal has nothing to disclose. Dr. Lee has nothing to disclose. The institution of Dr. Shaw has received research support from LSRS. The institution of Dr. Shaw has received research support from CSRS. The institution of Dr. Shaw has received research support from AO Spine. Dr. Shaw has received intellectual property interests from a discovery or technology relating to health care. The institution of Dr. Thirumala has received research support from University of Pittsburgh.

Characteristics of Tc-MEP Waveforms in Spine Surgery for Patients with Severe Obesity.

Prospective multicenter study. The aim of this study was to evaluate transcranial motor evoked potential (Tc-MEP) waveform monitoring in spinal surgery for patients with severe obesity. Spine surgeries in obese patients are associated with increased morbidity and mortality. Intraoperative Tc-MEP monitoring can identify neurologic deterioration during surgery, but has not been examined for obese patients. The subjects were 3560 patients who underwent Tc-MEP monitoring during spine surgery at 16 centers. Tc-MEPs were recorded from multiple muscles via needle or disc electrodes. A decrease in Tc-MEP amplitude of ≥70% from baseline was used as an alarm during surgery. Preoperative muscle weakness with manual muscle test (MMT) grade ≤4 was defined as a motor deficit, and a reduction of one or more MMT grade postoperatively was defined as deterioration. The 3560 patients (1698 males, 47.7%) had a mean age of 60.0 ± 20.3 years. Patients with body mass index >35 kg/m2 (n = 60, 1.7%) were defined as severely obese. Compared with all other patients (controls), the rates of preoperative motor deficit (41.0% vs. 29.6%, P < 0.05) and undetectable baseline waveforms in all muscles were significantly higher in the severely obese group (20.0% vs. 1.7%, P < 0.01). Postoperative motor deterioration did not differ significantly between the groups. The sensitivity and specificity of the alarm criterion for prediction of postoperative neurologic complications were 75.0% and 83.9% in severely obese patients and 76.4% and 89.6% in controls, with no significant difference between the groups. Tc-MEPs can be used in spine surgery for severely obese cases to predict postoperative motor deficits, but the rate of undetectable waveforms is significantly higher in such cases. Use of a multichannel waveform approach or multiple modalities may facilitate safe completion of surgery. Waveforms should be carefully evaluated and an appropriate rescue procedure is required if the alarm criterion occurs.Level of Evidence: 3.

Determination of cutoff points of intraoperative transcranial motor-evoked potential monitoring during spinal operations

Determination of cutoff points of intraoperative transcranial motor-evoked potential monitoring during spinal operations

Clinical Usefulness of Intraoperative Motor-Evoked Potential Monitoring during Temporal Lobe Epilepsy Surgery.

Background and PurposeWe aimed to determine the effectiveness of intraoperative neurophysiological monitoring focused on the transcranial motor-evoked potential (MEP) in patients with medically refractory temporal lobe epilepsy (TLE).MethodsWe compared postoperative neurological deficits in patients who underwent TLE surgery with or without transcranial MEPs combined with somatosensory evoked potential (SSEP) monitoring between January 1995 and June 2018. Transcranial motor stimulation was performed using subdermal electrodes, and MEP responses were recorded in the four extremity muscles. A decrease of more than 50% in the MEP or the SSEP amplitudes compared with baseline was used as a warning criterion.ResultsIn the TLE surgery group without MEP monitoring, postoperative permanent motor deficits newly developed in 7 of 613 patients. In contrast, no permanent motor deficit occurred in 279 patients who received transcranial MEP and SSEP monitoring. Ten patients who exhibited decreases of more than 50% in the MEP amplitude recovered completely, although two cases showed transient motor deficits that recovered within 3 months postoperatively.ConclusionsIntraoperative transcranial MEP monitoring during TLE surgery allowed the prompt detection and appropriate correction of injuries to the motor nervous system or ischemic stroke. Intraoperative transcranial MEP monitoring is a reliable modality for minimizing motor deficits in TLE surgery.

A novel mouthpiece prevents bite injuries caused by intraoperative transcranial electric motor-evoked potential monitoring.

Intraoperative transcranial motor-evoked potential monitoring causes contraction of the masseter muscles, which may cause injuries to the oral cavity and damage to the orotracheal tube. We developed a mouthpiece made from vinyl-silicone impression material to prevent these injuries. The purpose of this study was to examine its efficacy and safety. Twenty-two patients undergoing spinal surgery under transcranial motor-evoked potential monitoring were fitted with bespoke vinyl-silicone mouthpieces by dentists before surgery. On induction of general anesthesia and orotracheal intubation, the mouthpiece was attached to the upper and lower dental arches. A lateral cervical X-ray was taken at the end of surgery to examine the condition of the orotracheal tube. The incidence of endotracheal tube deformation was compared with an historic control group of 20 patients in whom a conventional gauze bite block had been previously used before induction of the mouthpiece. The oral cavity was examined by a dentist the day before surgery and 3days postoperatively, and intraoral injuries were recorded. No endotracheal tube deformation was found in 22 patients fitted with the new mouthpiece. The incidence of tube deformation (none of 22 patients, 0%) was significantly lower than in those who had been fitted with the gauze bite block (9 of 20 patients, 45.0%; p<0.001). Application of the mouthpiece resulted in no tongue or tooth injuries. A novel mouthpiece reduced the incidence of damage to the endotracheal tube caused by intraoperative transcranial motor-evoked potential monitoring.

Intraoperative Transcranial Motor-Evoked Potential Monitoring of the Facial Nerve during Cerebellopontine Angle Tumor Resection

Objective To determine whether transcranial motor-evoked potential (TCMEP) monitoring of the facial nerve (FN) during cerebellopontine angle (CPA) tumor resection can predict both immediate and long-term postoperative FN function. Design Retrospective review. Setting Tertiary referral center. Main Outcome Measures DeltaTCMEP (final-initial) and immediate and long-term facial nerve function using House Brackmann (HB) rating scale. Results Intraoperative TCMEP data and immediate and follow-up FN outcome are reported for 52 patients undergoing CPA tumor resection. Patients with unsatisfactory facial outcome (HB >2) at follow-up had an average deltaTCMEP of 57 V, whereas those with HB I or II had a mean deltaTCMEP of 0.04 V (t = -2.6, p < 0.05.) Intraoperative deltaTCMEP did not differ significantly between groups with satisfactory (HB I, II) and unsatisfactory (HB > 2) facial function in the immediate postoperative period. Conclusion Intraoperative TCMEP of the facial nerve can be a valuable adjunct to conventional facial nerve electromyography during resection of tumors at the CPA. Intraoperative deltaTCMEP >57 V may be worrisome for long-term recovery of satisfactory facial nerve function.

Intraoperative Transcranial Motor-Evoked Potential Monitoring of the Facial Nerve during Vestibular Schwannoma Resection: An 8-Year Review

Objective: To determine whether multipulse transcranial motor-evoked potential (mpTCMEP) monitoring of the facial nerve (FN) during vestibular schwannoma (VS) tumor resection can predict both immediate and 1-year postoperative FN functional grade.

Intraoperative Transcranial Motor-Evoked Potential Monitoring of the Facial Nerve during Cerebellopontine Angle Tumor Resection

Intraoperative Transcranial Motor-Evoked Potential Monitoring of the Facial Nerve during Cerebellopontine Angle Tumor Resection

Compensation of Intraoperative Transcranial Motor-Evoked Potential Monitoring by Compound Muscle Action Potential After Peripheral Nerve Stimulation

It is often difficult to evaluate the results of transcranial motor-evoked potential (TCMEP) monitoring in patients under general anesthesia because these results are strongly affected by anesthetics and muscle relaxants. To exclude effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supramaximum stimulation of the median nerve immediately after transcranial stimulation (300 to 600 V) was recorded in 70 neurosurgical operations. A relative amplitude index (RAI) was defined as the amplitude of TCMEP after the operative procedure divided by the amplitude of TCMEP before the operative procedure. The RAI was calculated and was compensated by the amplitude of CMAP in 141 limbs. In 12 limbs of 7 patients with postoperatively progressed motor paresis, the compensated RAI was less than 0.2. The compensated RAI in all other 129 limbs of 63 patients without postoperative motor palsy was more than 0.2. These results suggest that compensation of TCMEP monitoring by CMAP is an easy and accurate method for removing the effects of muscle relaxants in TCMEP.

脳血管障害における術中経頭蓋ＭＥＰモニタリングの有用性

We clinically examined the efficacy of motor evoked potential (MEP) by transcranial high-voltage electrical stimulation for intraoperative monitoring in cerebro-vascular disease. In 49 neurosurgical operations for cerebro-vascular disease, transcranial MEP (TCMEP) was recorded by 300-1000 V bipolar stimulation using the screw electrodes with the anode on the affected side. Surface electrodes for electromyographic responses were placed on the bilateral abductor pollicis brevis (APB) and bilateral abductor hallucis (AH) muscles. To remove effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supra-maximum stimulation of the median nerve 2 seconds after transcranial stimulation was recorded in 30 recent operations. In all 40 operations under propofol anesthesia and 6 among 7 cases under volatile anesthesia, MEP was successfully recorded. Postoperative motor paresis occurred in 6 limbs of 4 patients among 54 limbs of 30 patients who had received TCMEP compensated by CMAP by peripheral nerve stimulation and all compensated relative amplitude indexes (CRAIs) of these 6 limbs were less than 0.2. In contrast, in all 48 limbs of 26 patients who had no postoperative motor dysfunction, CRAI had been more than 0.2. These results suggest that our intraoperative TCMEP monitoring by relatively low-voltage (300-400 V) stimulation and compensated by CMAP after peripheral nerve stimulation was safe, easy (no need to expose the motor cortex), relatively accurate and less invasive, and useful especially in cerebro-vascular disease, which often requires a temporary occlusion of the cerebral arteries.