scholarly journals Improved potential quality of intraoperative transcranial motor-evoked potentials by navigated electrode placement compared to the conventional ten-twenty system

2021 ◽  
Author(s):  
Arthur Wagner ◽  
Sebastian Ille ◽  
Caspar Liesenhoff ◽  
Kaywan Aftahy ◽  
Bernhard Meyer ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Intraoperative Monitoring ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Vascular Lesions ◽  
Electrode Placement ◽  
Neurophysiological Monitoring ◽  
Electrode Pair ◽  
Significant Difference ◽  
Transcranial Motor Evoked Potentials

AbstractIntraoperative neurophysiological monitoring of transcranial motor-evoked potentials (tcMEPs) may fail to produce a serviceable signal due to displacements by mass lesions. We hypothesize that navigated placement of stimulation electrodes yields superior potential quality for tcMEPs compared to the conventional 10–20 placement. We prospectively included patients undergoing elective cranial surgery with intraoperative monitoring of tcMEPs. In addition to electrode placement as per the 10–20 system, an electrode pair was placed at a location corresponding to the hand knob area of the primary motor cortex (M1) for every patient, localized by a navigation system during surgical setup. Twenty-five patients undergoing elective navigated surgery for intracranial tumors (n = 23; 92%) or vascular lesions (n = 2; 8%) under intraoperative monitoring of tcMEPs were included between June and August 2019 at our department. Stimulation and recording of tcMEPs was successful in every case for the navigated electrode pair, while stimulation by 10–20 electrodes did not yield baseline tcMEPs in two cases (8%) with anatomical displacement of the M1. While there was no significant difference between baseline amplitudes, mean potential quality decreased significantly by 88.3 µV (− 13.5%) for the 10–20 electrodes (p = 0.004) after durotomy, unlike for the navigated electrodes (− 28.6 µV [− 3.1%]; p = 0.055). For patients with an anatomically displaced M1, the navigated tcMEPs declined significantly less after durotomy (− 3.6% vs. 10–20: − 23.3%; p = 0.038). Navigated placement of tcMEP electrodes accounts for interindividual anatomical variance and pathological dislocation of the M1, yielding more consistent potentials and reliable potential quality.

Transcranial electrical stimulation through screw electrodes for intraoperative monitoring of motor evoked potentials

2004 ◽  
Vol 100 (1) ◽  
pp. 155-160 ◽  
Author(s):  
Katsushige Watanabe ◽  
Takashi Watanabe ◽  
Akio Takahashi ◽  
Nobuhito Saito ◽  
Masafumi Hirato ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Motor Cortex ◽  
Evoked Potentials ◽  
Intraoperative Monitoring ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Transcranial Electrical Stimulation ◽  
Content Type ◽  
Motor Pathways ◽  
Fine Print

✓ The feasibility of high-frequency transcranial electrical stimulation (TES) through screw electrodes placed in the skull was investigated for use in intraoperative monitoring of the motor pathways in patients who are in a state of general anesthesia during cerebral and spinal operations. Motor evoked potentials (MEPs) were elicited by TES with a train of five square-wave pulses (duration 400 µsec, intensity ≤ 200 mA, frequency 500 Hz) delivered through metal screw electrodes placed in the outer table of the skull over the primary motor cortex in 42 patients. Myogenic MEPs to anodal stimulation were recorded from the abductor pollicis brevis (APB) and tibialis anterior (TA) muscles. The mean threshold stimulation intensity was 48 ± 17 mA for the APB muscles, and 112 ± 35 mA for the TA muscles. The electrodes were firmly fixed at the site and were not dislodged by surgical manipulation throughout the operation. No adverse reactions attributable to the TES were observed. Passing current through the screw electrodes stimulates the motor cortex more effectively than conventional methods of TES. The method is safe and inexpensive, and it is convenient for intraoperative monitoring of motor pathways.

scholarly journals Neuroanesthesia Guidelines for Optimizing Transcranial Motor Evoked Potentials Neuromonitoring During Deformity and Complex Spinal Surgery: A Delphi Consensus Study

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Corey T Walker ◽  
Han Jo Kim ◽  
Paul Park ◽  
Lawrence Lenke ◽  
Justin S Smith ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Neurophysiological Monitoring ◽  
Delphi Consensus ◽  
Optimal Method ◽  
Modified Delphi ◽  
Spine Surgeon ◽  
Transcranial Motor Evoked Potentials ◽  
Inhaled Anesthetic

Abstract INTRODUCTION Intraoperative neurophysiological monitoring of transcranial motor evoked potentials (MEPs) provides the most reliable method for assessing spinal cord functional integrity during deformity and other complex spinal surgeries. MEPs are affected by pharmacological and physiological parameters. It is the responsibility of the spine surgeon and neuroanesthesia team to understand how they can best maintain high quality MEP signals throughout surgery. Nevertheless, varying approaches to neuroanesthesia are seen in clinical practice. METHODS We identified 19 international spinal deformity expert teams for participation in our study. A modified Delphi process utilizing 2 rounds of surveying was performed. Greater than 50% and 75% agreement on the final statements was considered achieving “agreement” and “consensus,” respectively. RESULTS Anesthesia regimens and protocols were obtained from the expert centers. A large amount of variability in these centers was witnessed. Two rounds of consensus surveying were then performed, and all centers participated in both rounds of the surveying. Consensus was obtained in 12 of 15 statements and majority agreement in 2 of the remaining. Agreement on specific safe neuroanesthesia practices in the setting of MEP monitoring was obtained. Total intravenous anesthesia (TIVA) was identified as the optimal method of maintenance with few centers allowing for low MAC concentrations of inhaled anesthetic. While no strict cutoff values of propofol concentrations or opioid doses were identified, most centers advocated for less than 150 mcg/kg/min of propofol with titration to the lowest dose that maintains appropriate anesthesia depth based on bispectral index or electroencephalography awareness monitoring. Utilization of adjuvant intravenous anesthetics, including ketamine and lidocaine, may help to reduce propofol and opioid requirements without negatively impacting MEP signals. Low-dose dexmedetomidine was also routinely used with the same purpose, but with knowledge that higher doses may be suppressive. Maintenance of blood pressure parameters near the patient's preoperative baseline or with mean arterial pressure greater than 80 mmHg ensures appropriate spinal cord perfusion and prevents loss of MEPs. CONCLUSION Spine surgeons and their neuroanesthesia teams should be familiar with the methods for optimizing IOM of MEPs during deformity and complex spinal cases. While variability in practices exist, consensus exists among international deformity centers regarding best practices.

scholarly journals Clinical and functional characteristics of intraoperative motor evoked potentials monitoring in microdiscectomy

2016 ◽  
Vol 97 (3) ◽  
pp. 371-376
Author(s):  
E V Gulaev ◽  
V V Lin’kov
Keyword(s):  
Evoked Potentials ◽  
General Anesthesia ◽  
Motor Evoked Potentials ◽  
Body Height ◽  
Herniated Disc ◽  
Neurophysiological Monitoring ◽  
Imaging Data ◽  
Abductor Hallucis ◽  
Healthy Side ◽  
Transcranial Motor Evoked Potentials

Aim. To assess motor evoked potentials parameters in a complex of intraoperative neurophysiological monitoring at the time of discectomy for a herniated intervertebral disc under general anesthesia, to determine their dependence on age, sex, height.Methods. Intraoperative motor evoked potentials monitoring during microdiscectomy under inhalational anesthesia was conducted in 43 patients for the herniated disc at L4-L5 or L5-S1 levels. In all patients, the herniated disc diagnosis was confirmed by the magnetic resonance imaging data. Monitoring was performed using the «Neuro-IOM» device («Neurosoft», Russia). Latency and amplitude of muscle response for m. abductor hallucis and m. tibialis anterior were analyzed.Results.. The obtained data suggest that the motor evoked potentials allow to objectify the presence of motor disorders, which persist at the end of microdiscectomy. The data on the relationship between latency of muscles responses on the side of radiculopathy and the healthy side with patients’ age, body height and weight are obtained. The motor evoked potentials amplitude had a direct correlation with the patients’ body weight. Increase in latency of transcranial motor evoked potentials on the side of the clinical motor fall-out compared with the healthy limb was defined. Due to the expressed variability of motor evoked potentials responses amplitude under general anesthesia, significant differences for a given parameter were not obtained.Conclusion. There is relationship between latency of motor evoked potentials and patients’ age, body height and weight; an increase in the latency of transcranial motor evoked potentials on the side of the clinical motor fall-out compared with the healthy limb was revealed.

scholarly journals Influence of iTBS on the Acute Neuroplastic Change After BCI Training

2021 ◽  
Vol 15 ◽  
Author(s):  
Qian Ding ◽  
Tuo Lin ◽  
Manfeng Wu ◽  
Wenqing Yang ◽  
Wanqi Li ◽  
...  
Keyword(s):  
Prefrontal Cortex ◽  
Functional Connectivity ◽  
Motor Cortex ◽  
Evoked Potentials ◽  
Primary Motor Cortex ◽  
Motor Evoked Potentials ◽  
Silent Period ◽  
Single Pulse ◽  
Functional Near Infrared Spectroscopy ◽  
Significant Difference

Objective: Brain-computer interface (BCI) training is becoming increasingly popular in neurorehabilitation. However, around one third subjects have difficulties in controlling BCI devices effectively, which limits the application of BCI training. Furthermore, the effectiveness of BCI training is not satisfactory in stroke rehabilitation. Intermittent theta burst stimulation (iTBS) is a powerful neural modulatory approach with strong facilitatory effects. Here, we investigated whether iTBS would improve BCI accuracy and boost the neuroplastic changes induced by BCI training.Methods: Eight right-handed healthy subjects (four males, age: 20–24) participated in this two-session study (BCI-only session and iTBS+BCI session in random order). Neuroplastic changes were measured by functional near-infrared spectroscopy (fNIRS) and single-pulse transcranial magnetic stimulation (TMS). In BCI-only session, fNIRS was measured at baseline and immediately after BCI training. In iTBS+BCI session, BCI training was followed by iTBS delivered on the right primary motor cortex (M1). Single-pulse TMS was measured at baseline and immediately after iTBS. fNIRS was measured at baseline, immediately after iTBS, and immediately after BCI training. Paired-sample t-tests were used to compare amplitudes of motor-evoked potentials, cortical silent period duration, oxygenated hemoglobin (HbO2) concentration and functional connectivity across time points, and BCI accuracy between sessions.Results: No significant difference in BCI accuracy was detected between sessions (p > 0.05). In BCI-only session, functional connectivity matrices between motor cortex and prefrontal cortex were significantly increased after BCI training (p's < 0.05). In iTBS+BCI session, amplitudes of motor-evoked potentials were significantly increased after iTBS (p's < 0.05), but no change in HbO2 concentration or functional connectivity was observed throughout the whole session (p's > 0.05).Conclusions: To our knowledge, this is the first study that investigated how iTBS targeted on M1 influences BCI accuracy and the acute neuroplastic changes after BCI training. Our results revealed that iTBS targeted on M1 did not influence BCI accuracy or facilitate the neuroplastic changes after BCI training. Therefore, M1 might not be an effective stimulation target of iTBS for the purpose of improving BCI accuracy or facilitate its effectiveness; other brain regions (i.e., prefrontal cortex) are needed to be further investigated as potentially effective stimulation targets.

Intraoperative monitoring

2016 ◽  
Author(s):  
Marc R. Nuwer
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Operating Room ◽  
Intraoperative Monitoring ◽  
Motor Evoked Potentials ◽  
Neurological Injury ◽  
Neurophysiological Monitoring ◽  
Spinal Cord Monitoring ◽  
Neurological Outcomes ◽  
Anaesthesia Monitoring

Intraoperative monitoring and testing is conducted to improve neurological outcomes from surgery that incurs risk of neurological injury. Many techniques are familiar from the outpatient neurodiagnostic laboratory, and can be applied with minor modifications to the operating room setting. Other techniques are specific to the operating room. Transcranial electrical motor evoked potentials cannot be applied to awake patients, but are commonly used under general anaesthesia. Monitoring teams understand the tactics for obtaining quality recordings and calling alarms when potentials change past preset limits. Surgeons and anaesthesiologists have a variety of tactics for responding to adverse neurodiagnostic changes beginning with easy actions. In experienced hands, intraoperative neurophysiological monitoring substantially reduces post-operative deficits. For example, in spinal cord monitoring the risk of paraplegia and paraparesis is reduced by 60%. Monitoring is carried out by a technologist in the operating room under the supervision of an experienced neurophysiologist. In straightforward cases, the neurophysiologist may remotely monitor from outside the operating room.

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