Neurophysiologic Monitoring for Neurosurgery

Intra-operative neurophysiological monitoring (IOM) has evolved substantially since its beginnings in the 1970s with somatosensory evoked potentials (SSEP) and facial nerve electromyography (EMG). The introduction of new techniques (especially motor evoked potentials [MEP]) and refinements of older techniques have become important tools that the surgeon can use to enhance intra-operative decision making and improve patient outcome of surgical (e.g., intracranial, neurovascular, skull base and brainstem, spine and spinal cord, peripheral nerve) procedures. These monitoring modalities are used to map the anatomic location of neural structures and monitor the functional status of the neural tracts. The anaesthetist plays a key supportive role in monitoring and management when IOM indicates potential neural compromise.

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Transvertebral Transposition of the Spinal Cord for Recovery of Motor Evoked Potentials and Somatosensory Evoked Potentials After Acute Paraplegia During Kyphoscoliosis Surgery: Technique Note, Case Reports and Literature Review

10.21203/rs.3.rs-129833/v1 ◽

2020 ◽

Author(s):

Chao Chen ◽

Jing Li ◽

Bingjin Wang ◽

Lingwei Zhu ◽

Yong Gao ◽

...

Keyword(s):

Spinal Cord ◽

Evoked Potentials ◽

Somatosensory Evoked Potentials ◽

Motor Evoked Potentials ◽

Case Reports ◽

Deformity Correction ◽

Neurological Deficits ◽

Intraoperative Neurophysiological Monitoring ◽

Neurophysiological Monitoring ◽

Acute Paraplegia

Abstract Background: Neurological impairment during spinal deformity surgery was the most serious complication. When confronting intraoperative neurophysiological monitoring alerts, various surgical management methods such as the release of implants and decompression of the spinal cord are always performed. Transvertebral transposition of the spinal cord is rarely performed, and its role in the management of acute paraplegia is seldom reported.Methods: The authors present two patients with kyphoscoliosis experienced intraoperatively or postoperatively neurological deficits and abnormal neurological monitoring was detected during correction surgery. Acute paraplegia was confirmed by a wake-up test. Subsequent spinal cord transposition was performed. Intraoperative neurophysiological monitoring motor evoked potentials (MEP) and somatosensory evoked potentials (SEP) was performed to detect the changes during the process.Results: After transvertebral transposition of the spinal cord, the MEPs and SEPs were significantly improved in both patients during surgery. The spinal cord function was restored postoperatively and recovered to normal at the final follow-up in two patients. Conclusions： This case demonstrated that instead of decreasing the correction ratio of kyphoscoliosis, transvertebral transposition of the spinal cord under intraoperative neurophysiological monitoring could be an effective therapeutic strategy for acute spinal cord dysfunction caused by deformity correction surgeries.

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Spinal Cord Monitoring

Clinical Neurophysiology ◽

10.1093/med/9780190259631.003.0048 ◽

2016 ◽

pp. 798-832

Author(s):

Jeffrey A. Strommen ◽

Andrea J. Boon

Keyword(s):

Spinal Cord ◽

Evoked Potentials ◽

Motor Evoked Potentials ◽

Spinal Cord Tumor ◽

Tumor Resection ◽

Neurophysiological Monitoring ◽

Spinal Root ◽

Compound Muscle Action Potentials ◽

Aneurysm Repair ◽

Aortic Aneurysm Repair

Intraoperative neurophysiological monitoring is a valuable tool to preserve spinal cord and spinal root integrity during surgical procedures. A monitoring plan may include somatosensory evoked potentials (SEP), motor evoked potentials (MEP), compound muscle action potentials (CMAP), and electromyography (EMG). Such monitoring is individualized depending on the preoperative clinical deficit, the structures most at risk, and the surgical and anesthesia plan. The most common use of these techniques is in primary spine disease, where the spinal cord pathways will typically be monitored with both MEP and SEP. In cervical or lumbar spine surgeries, EMG monitoring will help protect the nerve root either during decompression or during pedicle screw placement. Monitoring during spinal cord tumor resection or vascular procedures (such as aortic aneurysm repair) not only helps prevent deficit, but also allows the surgeon to proceed with confidence and not unnecessarily terminate the procedure.

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

Neurosurgery ◽

10.1093/neuros/nyz310_610 ◽

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.

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Intraoperative monitoring

10.1093/med/9780199688395.003.0036 ◽

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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Provocative Testing for Embolization of Spinal Cord AVMs

Interventional Neuroradiology ◽

10.1177/15910199000060s130 ◽

2000 ◽

Vol 6 (1_suppl) ◽

pp. 191-194 ◽

Cited By ~ 8

Author(s):

Y. Niimi ◽

F. Sala ◽

V. Deletis ◽

A. Berenstein

Keyword(s):

Spinal Cord ◽

Evoked Potentials ◽

Motor Evoked Potentials ◽

False Negative ◽

Posterior Inferior Cerebellar Artery ◽

Neurophysiological Monitoring ◽

Monitoring Methods ◽

Catheter Position ◽

Negative Results ◽

Provocative Testing

The purpose of this study is to evaluate efficacy and reliability of chemical provocative testing using neurophysiological monitoring prior to embolization of spinal cord AVMs (SCAVMs). We performed retrospective analysis of provocative testing using sodium amytal and lidocaine injected superselectively in 41 angiography and / or embolization procedures in 26 patients with a SCAVM, including 23 amytal and 26 lidocaine injections. All procedures were performed under general anesthesia using neuroleptic drugs, and with monitoring of cortical somatosensory evoked potentials (SEPs) and trans-cranial motor evoked potentials (MEPs). After recording baseline SEPs and MEPs, 50mg of sodium amytal was injected through the microcatheter at the position of the intended embolization, followed by assessment of SEPs and MEPs. If no changes occurred, 40mg of lidocaine was then injected followed by recording of SEPs and MEPs. If again no changes were noted, embolization was performed using NBCA. If there was any change in either SEPs or MEPs, NBCA embolization was not performed from that catheter position. No false negative results of the provocative testing were experienced. One amytal test from the posterior spinal artery (PSA) was positive, causing loss of MEPs. Lidocaine testing was positive in 10 cases including 4 injections in the PSA (with loss of MEPs in two and SEPs in two), 5 injections in the anterior spinal artery (with loss of MEPs in four and SEPs in one), and 1 case involving the posterior inferior cerebellar artery (with loss of MEPs). Neither amytal nor lidocaine injection caused loss of both SEPs and MEPs. In conclusion, sodium amytal and lidocaine are complimentary as pharmacological agents for provocative testing, and SEPs and MEPs are complimentary to each other as physiologic monitoring methods. Provocative testing should be performed using both amytal and lidocaine with monitoring of both SEPs and MEPs.

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