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Effect of Compound Muscle Action Potential After Peripheral Nerve Stimulation Normalization on Anesthetic Fade of Intraoperative Transcranial Motor-Evoked Potential. J Clin Neurophysiol 2021; 38:306-311. [PMID: 32187041 DOI: 10.1097/wnp.0000000000000692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE Anesthetic fade refers to the time-dependent decrease in the amplitude of the intraoperative motor-evoked potential. It is thought to be caused by the accumulation of propofol. The authors examined whether normalization by the compound muscle action potential (CMAP) after peripheral nerve stimulation could compensate for anesthetic fade. METHODS In 1,842 muscles in 578 surgeries, which did not exhibit a motor-neurologic change after the operation, the motor-evoked potential amplitude was normalized by the CMAP amplitude after peripheral nerve stimulation, and the CMAP amplitude and operation times were analyzed. RESULTS The amplitudes of both motor-evoked potential and CMAP increased over time after peripheral nerve stimulation because of the disappearance of muscle-relaxant action. Especially, after peripheral nerve stimulation, CMAP significantly increased from the beginning to the end of the operation. Anesthetic fade in transcranial motor-evoked potential monitoring seemed to occur at more than 235 minutes of surgery based on the results of a receiver operating characteristic analysis of the operation time and relative amplitudes. Although the mean amplitude without CMAP normalization at more than 235 minutes was significantly lower than that at less than 235 minutes, the mean amplitude with normalization by CMAP after peripheral nerve stimulation at more than 235 minutes was not significantly different from that at less than 235 minutes. CONCLUSIONS Compound muscle action potential after peripheral nerve stimulation normalization was able to avoid the effect of anesthetic fade. Anesthetic fade was seemed to be caused by a decrease in synaptic transmission at the neuromuscular junction because of propofol accumulation by this result.
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Matsuoka R, Takeshima Y, Hayashi H, Takatani T, Nishimura F, Nakagawa I, Motoyama Y, Park YS, Kawaguchi M, Nakase H. Feasibility of adjunct facial motor evoked potential monitoring to reduce the number of false-positive results during cervical spine surgery. J Neurosurg Spine 2020; 32:570-577. [PMID: 31835248 DOI: 10.3171/2019.9.spine19800] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 09/23/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE False-positive intraoperative muscle motor evoked potential (mMEP) monitoring results due to systemic effects of anesthetics and physiological changes continue to be a challenging issue. Although control MEPs recorded from the unaffected side are useful for identifying a true-positive signal, there are no muscles on the upper or lower extremities to induce control MEPs in cervical spine surgery. Therefore, this study was conducted to clarify if additional MEPs derived from facial muscles can feasibly serve as controls to reduce false-positive mMEP monitoring results in cervical spine surgery. METHODS Patients who underwent cervical spine surgery at the authors' institution who did not experience postoperative neurological deterioration were retrospectively studied. mMEPs were induced with transcranial supramaximal stimulation. Facial MEPs (fMEPs) were subsequently induced with suprathreshold stimulation. The mMEP and subsequently recorded fMEP waveforms were paired during each moment during surgery. The initial pair was regarded as the baseline. A significant decline in mMEP and fMEP amplitude was defined as > 80% and > 50% decline compared with baseline, respectively. All mMEP alarms were considered false positives. Based on 2 different alarm criteria, either mMEP alone or both mMEP and fMEP, rates of false-positive mMEP monitoring results were calculated. RESULTS Twenty-three patients were included in this study, corresponding to 102 pairs of mMEPs and fMEPs. This included 23 initial and 79 subsequent pairs. Based on the alarm criterion of mMEP alone, 17 false-positive results (21.5%) were observed. Based on the alarm criterion of both mMEP and fMEP, 5 false-positive results (6.3%) were observed, which was significantly different compared to mMEP alone (difference 15.2%; 95% CI 7.2%-23.1%; p < 0.01). CONCLUSIONS fMEPs might be used as controls to reduce false-positive mMEP monitoring results in cervical spine surgery.
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Affiliation(s)
| | | | | | - Tsunenori Takatani
- 3Division of Central Clinical Laboratory, Nara Medical University Hospital, Kashihara, Japan
| | | | | | | | - Young-Su Park
- 1Department of Neurosurgery, Nara Medical University
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Lo YL, Zhu L, Soh RC, Guo CM. Intraoperative Motor Evoked Potential Improvement in Cervical Spondylotic Myelopathy: Comparison of Cortical Stimulation Parameters. J Clin Neurol 2020; 16:102-107. [PMID: 31942765 PMCID: PMC6974831 DOI: 10.3988/jcn.2020.16.1.102] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 09/24/2019] [Accepted: 09/27/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND AND PURPOSE Intraoperative monitoring of the motor pathways is a routine procedure for ensuring the integrity of descending motor tracts during spinal surgery. Intraoperative motor evoked potential improvement (MEPI) may be associated with a better postsurgical outcome in cervical spondylotic myelopathy (CSM). To compare the efficacy of two cortical stimulation parameters in eliciting MEPI intraoperatively during CSM surgery. METHODS We studied 69 patients who underwent decompression surgery for CSM over a 9-month period using either 5 (Group 1) or 9 (Group 2) stimuli. MEPI was defined as the increase in the amplitude of MEPs from baseline at the end of CSM surgery just prior to skin closure. RESULTS An MEPI of 100% from baseline was observed in 10 patients (53%) in Group 1 and 36 patients (72%) in Group 2. Comparisons of the baseline mean MEP amplitudes of muscles bilaterally between Groups 1 and 2 did not reveal any significant differences. Supramaximal stimulation showed that a significantly higher mean intensity was required for Group 1 than for Group 2. CONCLUSIONS MEPI is observed in a much larger proportion of cervical decompression surgery cases than previously thought. Intraoperative MEPI with longer-train cortical stimulation may reflect adequacy of decompression and provide additional guidance for the surgical procedure.
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Affiliation(s)
- Yew Long Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.,Department of Neurology, Duke-NUS Medical School, College Road, Singapore.
| | - Lisa Zhu
- Department of Orthopedic Surgery, Singapore General Hospital, Singapore
| | - Reuben C Soh
- Department of Orthopedic Surgery, Singapore General Hospital, Singapore
| | - Chang Ming Guo
- Department of Orthopedic Surgery, Singapore General Hospital, Singapore
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Diagnostic Accuracy of Combined Multimodality Somatosensory Evoked Potential and Transcranial Motor Evoked Potential Intraoperative Monitoring in Patients With Idiopathic Scoliosis. Spine (Phila Pa 1976) 2016; 41:E1177-E1184. [PMID: 27172278 DOI: 10.1097/brs.0000000000001678] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Systematic review. OBJECTIVE The aim of the study was to determine the predictive value of combined multimodality somatosensory evoked potential (SSEP) and transcranial motor evoked potential (TcMEP) monitoring in detecting impending neurological injury during surgery for idiopathic scoliosis. SUMMARY OF BACKGROUND DATA The diagnostic of motor evoked potential monitoring and SSEP monitoring have been established. However, the predictive value of combined multimodality SSEP and TcMEP monitoring in detecting impending neurological injury during surgery for idiopathic scoliosis has not been evaluated. METHODS A systematic literature search was performed using PubMed/MEDLINE, Web of Science, and EMBASE from 1974 to January 2015. All titles and abstracts were independently reviewed by the authors. We included all studies that were (1) randomized controlled trials, prospective or retrospective cohort studies; (2) included patients with idiopathic scoliosis undergoing scoliosis correction surgery; (3) included multimodality SSEP and TcMEP monitoring during spinal surgery; (4) included immediate postoperative neurological assessment; (5) idiopathic scoliosis patient population n ≥25; and (6) published in English. RESULTS Seven studies comprising a total of 2052 patients with idiopathic scoliosis were included in our meta-analysis. The incidence of neurological deficit in this cohort was 0.93%. The pooled sensitivity, specificity, and Diagnostic Odds Ratio were 82.6% (95% CI 56.7%-94.5%), 94.4% (95% CI 85.1%-98.0%), and 106.16 (95% CI 24.952-451.667), respectively. The area under the curve was 0.928, indicating excellent discriminatory ability. CONCLUSION Idiopathic scoliosis corrective surgery patients who experience a new neurological deficit are 106.16 times more likely to have had an SSEP and/or TcMEP change during corrective procedures. The results of this meta-analysis demonstrate that combined multimodality SSEP and TcMEP monitoring possess some advantage over use of each alone, and that intraoperative neurophysiological monitoring may provide a valuable biomarker in detection of impending neurological injury. LEVEL OF EVIDENCE 2.
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Motor and somatosensory abnormalities are significant etiological factors for adolescent idiopathic scoliosis. J Neurol Sci 2015; 359:117-23. [PMID: 26671099 DOI: 10.1016/j.jns.2015.10.048] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 10/13/2015] [Accepted: 10/28/2015] [Indexed: 11/22/2022]
Abstract
OBJECTIVE In adolescent idiopathic scoliosis (AIS), we explore the role of lateralized motor and somatosensory abnormalities as a possible etiological factor. METHODS Intraoperative transcranial electrical stimulation was performed in 15 AIS and 14 adult degenerative scoliosis (ADS) patients. Inter-side motor output balance (MOB) by comparing the ratios of right to left motor evoked potentials (MEP) amplitudes, and inter-side motor output excitability (MOE) computed with MEP amplitude, was determined separately for both patients groups. For somatosensory evoked potentials (SSEP), peak to peak P37 amplitudes from right and left lower limb SSEP and inter-side P37 amplitude ratios were obtained. RESULTS Inter-side MOB was significantly asymmetric in AIS patients, contributed mainly by inter-side MOB changes in the upper than the lower limbs. Inter-side MOE comparisons of ipsilateral and contralateral MEP amplitudes were significantly different between AIS and ADS patients. Mean upper limb MEP amplitudes were significantly reduced in AIS patients. Amplitude of the right upper limb MEPs were positively correlated with inter-side MEP ratio. AIS patients show larger mean MEP amplitudes on the same side as the scoliotic curve. Overall, no correlation of Cobb's angle or total levels of scoliosis involvement with inter-side MOB and MOE parameters was found. Inter-side SSEP ratios were significantly higher in AIS patients. CONCLUSIONS Primary dysfunctional and distributed motor output contributing to abnormalities of inter-side MOB and MOE changes involving the upper limbs is evident in AIS. Simultaneous but independent somatosensory and motor observations seen these patients suggest a central mechanism as an etiological factor.
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Intraoperative monitoring during decompression of the spinal cord and spinal nerves using transcranial motor-evoked potentials: The law of twenty percent. J Clin Neurosci 2015; 22:1403-7. [DOI: 10.1016/j.jocn.2015.03.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 02/25/2015] [Accepted: 03/03/2015] [Indexed: 11/19/2022]
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Salem KMI, Goodger L, Bowyer K, Shafafy M, Grevitt MP. Does transcranial stimulation for motor evoked potentials (TcMEP) worsen seizures in epileptic patients following spinal deformity surgery? EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2015; 25:3044-3048. [PMID: 25976014 DOI: 10.1007/s00586-015-3993-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 05/03/2015] [Accepted: 05/03/2015] [Indexed: 11/27/2022]
Abstract
PURPOSE To investigate the effect of Transcranial Motor Evoked Potentials (TcMEP) in increasing the severity or frequency of post-operative seizures in patients undergoing deformity corrective spine surgery with a known history of seizures pre-operatively. METHODS The information on all patients with history of epilepsy/seizures who underwent spinal TcMEP cord monitoring for deformity correction surgery was retrospectively collected through a review of the hospital notes. The benefits of TcMEP in the early detection of potential cord ischemia were deemed by the operating surgeon to outweigh the increased risks of seizures, tongue biting, etc. Data on age, gender, pre-operative diagnosis, curve type, intra-operative monitoring alerts, duration of hospital stay, and post-operative in-hospital seizures were collected. Additionally, the patients were contacted following discharge and data on any change in the frequency of the seizures or an alteration in seizure-related medication post-operatively was also collected. RESULTS The records of 449 consecutively monitored patients were reviewed and 12 (2.7 %) patients with a history of seizures pre-operatively were identified. The mean age was 23 (9-59) years, 7 females, 11 scoliosis corrections (4 neuromuscular, 1 degenerative, 6 idiopathic adolescent), and one sagittal balance correction surgery. Intra-operatively, all patients had TcMEP monitoring, were catheterised, and had no neuromonitoring alerts or record of tongue biting or laceration. Post-operatively, the mean hospital stay was 12 (4-25) days with no recorded seizures. At a mean of 23 (12-49) months post-discharge, none of the patients reported a worsening of seizures (pattern or frequency) or required an alteration in the seizure-related medications. CONCLUSION TcMEP does not appear to trigger intra-operative or post-operative seizures and is not associated with deterioration in the seizure control of patients suffering seizures pre-operatively.
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Affiliation(s)
- Khalid M I Salem
- Nottingham University Hospital NHS Trust, Queen's Medical Centre Campus, Centre for Spinal Studies and Surgery, Nottingham, NG7 2UH, UK.
| | - Laura Goodger
- Nottingham University Hospital NHS Trust, Queen's Medical Centre Campus, Centre for Spinal Studies and Surgery, Nottingham, NG7 2UH, UK
| | - Katherine Bowyer
- Nottingham University Hospital NHS Trust, Queen's Medical Centre Campus, Centre for Spinal Studies and Surgery, Nottingham, NG7 2UH, UK
| | - Masood Shafafy
- Nottingham University Hospital NHS Trust, Queen's Medical Centre Campus, Centre for Spinal Studies and Surgery, Nottingham, NG7 2UH, UK
| | - Michael P Grevitt
- Nottingham University Hospital NHS Trust, Queen's Medical Centre Campus, Centre for Spinal Studies and Surgery, Nottingham, NG7 2UH, UK
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Affiliation(s)
- Alan D. Legatt
- Montefiore Medical Center Albert Einstein College of Medicine Bronx, New York
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Affiliation(s)
- Michael R. Isley
- Intraoperative Neuromonitoring Department and Neurosciences Institute Orlando Regional Medical Center Orlando, Florida
| | - Jeffrey R. Balzer
- Department of Neurosurgery University of Pittsburgh Medical Center Pittsburgh, Pennsylvania
| | - Ronald C. Pearlman
- School of Communication Howard University Washington, District of Columbia
| | - Xiao-Feng Zhang
- Intraoperative Neuromonitoring Department and Neurosciences Institute Orlando Regional Medical Center Orlando, Florida
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Macdonald DB, Skinner S, Shils J, Yingling C. Intraoperative motor evoked potential monitoring - a position statement by the American Society of Neurophysiological Monitoring. Clin Neurophysiol 2013; 124:2291-316. [PMID: 24055297 DOI: 10.1016/j.clinph.2013.07.025] [Citation(s) in RCA: 302] [Impact Index Per Article: 27.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2013] [Revised: 07/20/2013] [Accepted: 07/22/2013] [Indexed: 12/12/2022]
Abstract
The following intraoperative MEP recommendations can be made on the basis of current evidence and expert opinion: (1) Acquisition and interpretation should be done by qualified personnel. (2) The methods are sufficiently safe using appropriate precautions. (3) MEPs are an established practice option for cortical and subcortical mapping and for monitoring during surgeries risking motor injury in the brain, brainstem, spinal cord or facial nerve. (4) Intravenous anesthesia usually consisting of propofol and opioid is optimal for muscle MEPs. (5) Interpretation should consider limitations and confounding factors. (6) D-wave warning criteria consider amplitude reduction having no confounding factor explanation: >50% for intramedullary spinal cord tumor surgery, and >30-40% for peri-Rolandic surgery. (7) Muscle MEP warning criteria are tailored to the type of surgery and based on deterioration clearly exceeding variability with no confounding factor explanation. Disappearance is always a major criterion. Marked amplitude reduction, acute threshold elevation or morphology simplification could be additional minor or moderate spinal cord monitoring criteria depending on the type of surgery and the program's technique and experience. Major criteria for supratentorial, brainstem or facial nerve monitoring include >50% amplitude reduction when warranted by sufficient preceding response stability. Future advances could modify these recommendations.
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Affiliation(s)
- D B Macdonald
- Section of Clinical Neurophysiology, Department of Neurosciences, King Faisal Specialist Hospital & Research Center, MBC 76, PO Box 3354, Riyadh, Saudi Arabia.
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Maruta Y, Fujii M, Imoto H, Nomura S, Oka F, Goto H, Shirao S, Yoshikawa K, Yoneda H, Ideguchi M, Suehiro E, Koizumi H, Ishihara H, Kato S, Kajiwara K, Suzuki M. Intra-operative monitoring of lower extremity motor-evoked potentials by direct cortical stimulation. Clin Neurophysiol 2012; 123:1248-54. [PMID: 22104472 DOI: 10.1016/j.clinph.2011.09.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2011] [Revised: 09/09/2011] [Accepted: 09/30/2011] [Indexed: 10/15/2022]
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Senft C, Forster MT, Bink A, Mittelbronn M, Franz K, Seifert V, Szelényi A. Optimizing the extent of resection in eloquently located gliomas by combining intraoperative MRI guidance with intraoperative neurophysiological monitoring. J Neurooncol 2012; 109:81-90. [PMID: 22528791 DOI: 10.1007/s11060-012-0864-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 03/29/2012] [Indexed: 10/28/2022]
Abstract
Several methods have been introduced to improve the extent of resection in glioma surgery. Yet, radical tumor resections must not be attempted at the cost of neurological deterioration. We sought to assess whether the use of an intraoperative MRI (iMRI) in combination with multimodal neurophysiological monitoring is suitable to increase the extent of resection without endangering neurological function in patients with eloquently located gliomas. Fifty-four patients were included in this study. In 21 patients (38.9 %), iMRI led to additional tumor resection. A radiologically complete resection was achieved in 31 patients (57.4 %), while in 12 of these, iMRI had depicted residual tumor tissue before resection was continued. The mean extent of resection was 92.1 % according to volumetric analyses. Postoperatively, 13 patients (24.1 %) showed new or worsening of pre-existing sensory motor deficits. They were severe in 4 patients (7.4 %). There was no correlation between the occurrence of either any new (P = 0.77) or severe (P = 1.0) sensory motor deficit and continued resection after intraoperative image acquisition. Likewise, tumor location, histology, and tumor recurrence did not influence complication rate on uni- and multivariate analysis. We conclude that the combination of iMRI guidance with multimodal neurophysiological monitoring allows for extended resections in glioma surgery without inducing higher rates of neurological deficits, even in patients with eloquently located tumors.
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Affiliation(s)
- Christian Senft
- Department of Neurosurgery, Johann Wolfgang Goethe-University, Schleusenweg 2-16, 60528, Frankfurt, Germany.
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Tanaka S, Tashiro T, Gomi A, Takanashi J, Ujiie H. Sensitivity and specificity in transcranial motor-evoked potential monitoring during neurosurgical operations. Surg Neurol Int 2011; 2:111. [PMID: 21886884 PMCID: PMC3162799 DOI: 10.4103/2152-7806.83731] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Accepted: 07/20/2011] [Indexed: 11/20/2022] Open
Abstract
Background: Intraoperative transcranial motor-evoked potential (TCMEP) monitoring is widely performed during neurosurgical operations. Sensitivity and specificity in TCMEP during neurosurgical operations were examined according to the type of operation. Methods: TCMEP monitoring was performed during 283 neurosurgical operations for patients without preoperative motor palsy, including 121 spinal operations, 84 cerebral aneurysmal operations, and 31 brain tumor operations. Transcranial stimulation at 100–600 V was applied by screw electrodes placed in the scalp and electromyographic responses were recorded with surface electrodes placed on the affected muscles. To exclude the effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supramaximal stimulation of the peripheral nerve immediately after transcranial stimulation was used for compensation of TCMEP. Results: In spinal operations, with an 80% reduction in amplitude as the threshold for motor palsy, the sensitivity and specificity with CMAP compensation were 100% and 96.4%, respectively. In aneurysmal operations, with a 70% reduction in amplitude as the threshold for motor palsy, the sensitivity and specificity with CMAP compensation were 100% and 94.8%, respectively. Compensation by CMAP was especially useful in aneurysmal operations. In all neurosurgical operations, with a 70% reduction in amplitude as the threshold for motor palsy, the sensitivity and specificity with CMAP compensation were 95.0% and 90.9%, respectively. Conclusions: Intraoperative TCMEP monitoring is a significantly reliable method for preventing postoperative motor palsy in both cranial and spinal surgery. A 70% reduction in the compensated amplitude is considered to be a suitable alarm point in all neurological operations.
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Affiliation(s)
- Satoshi Tanaka
- Department of Neurosurgery, Shioya Hospital, International University of Health and Welfare, Yaita, Tochigi, Japan
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Abstract
STUDY DESIGN Review of the literature with analysis of pooled data. OBJECTIVE To assess common intraoperative neuromonitoring (IOM) changes that occur during the course of spinal surgery, potential causes of change, and determine appropriate responses. Further, there will be discussion of appropriate application of IOM, and medical legal aspects. The structured literature review will answer the following questions: What are the various IOM methods currently available for spinal surgery? What are the sensitivities and specificities of each modality for neural element injury? How are the changes in each modality best interpreted? What is the appropriate response to indicated changes? Recommendations will be made as to the interpretation and appropriate response to IOM changes. SUMMARY OF BACKGROUND DATA Total number of abstracts identified and reviewed was 187. Full review was performed on 18 articles. METHODS The MEDLINE database was queried using the search terms IOM, spinal surgery, SSEP, wake-up test, MEP, spontaneous and triggered electromyography alone and in various combinations. Abstracts were identified and reviewed. Individual case reports were excluded. Detailed information and data from appropriate articles were assessed and compiled. RESULTS Ability to achieve IOM baseline data varied from 70% to 98% for somatosensory-evoked potentials (SSEP) and 66% to 100% for motor-evoked potentials (MEP) in absence of neural axis abnormality. Multimodality intraoperative neuromonitoring (MIOM) provided false negatives in 0% to 0.79% of cases, whereas isolated SSEP monitoring alone provided false negative in 0.063% to 2.7% of cases. MIOM provided false positive warning in 0.6% to 1.38% of cases. CONCLUSION As spine surgery, and patient comorbidity, becomes increasingly complex, IOM permits more aggressive deformity correction and tumor resection. Combination of SSEP and MEP monitoring provides assessment of entire spinal cord functionality in real time. Spontaneous and triggered electromyography add assessment of nerve roots. The wake-up test can continue to serve as a supplement when needed. MIOM may prove useful in preservation of neurologic function where an alteration of approach is possible. IOM is a valuable tool for optimization of outcome in complex spinal surgery.
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Intraoperative neurophysiological monitoring during complex spinal deformity cases in pediatric patients: methodology, utility, prognostication, and outcome. Childs Nerv Syst 2010; 26:523-44. [PMID: 20213189 DOI: 10.1007/s00381-010-1115-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 02/10/2010] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Complex spinal deformity (CSD) problems in pediatric patients result from a wide variety of congenital, acquired, neoplastic, or traumatic abnormalities that result in a combination of spinal deformity and spinal cord impingement. While these problems are rare, decompression, correction, instrumentation, and fusion are quite hazardous. Intraoperative neurophysiological monitoring (IONM) seems particularly beneficial in these patients. METHODOLOGY Somatosensory evoked potentials, transcranial electrical motor evoked potentials (MEPs), direct waves, and electromyography were used in a variety of CSD cases over a period when IONM was routine for most spinal cases. Examples of cases in which IONM provided important intraoperative information and significantly affected the course of the operation are illustrated. RESULTS IONM is a useful tool particularly in CSD cases in pediatric patients but requires special expertise and anesthetic considerations. Loss of MEP appears to have particularly important adverse prognostic information. Conversely, maintenance of IONM provides significant reassurance that the spinal cord function is being maintained. Preserved but persistently diminished MEPs usually predict a neurological injury that will significantly improve and possibly completely recover. Issues concerning training, certification, oversight, standardization of equipment, and technique are partially but incompletely resolved. DISCUSSION IONM is an extremely valuable tool for management of CSD pediatric patients. The utility of IONM is such and the detection of unexpected or unanticipated neurological injury frequent enough that a strong argument that it be used in every spinal surgery case can be made.
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Skinner SA, Transfeldt EE, Mehbod AA, Mullan JC, Perra JH. Electromyography detects mechanically-induced suprasegmental spinal motor tract injury: Review of decompression at spinal cord level. Clin Neurophysiol 2009; 120:754-64. [DOI: 10.1016/j.clinph.2008.11.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Revised: 11/26/2008] [Accepted: 11/27/2008] [Indexed: 10/21/2022]
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Szelényi A, Gasser T, Seifert V. Intraoperative Neurophysiological Monitoring in an Open Low-field Magnetic Resonance Imaging System: Clinical Experience and Technical Considerations. Oper Neurosurg (Hagerstown) 2008; 63:268-75; discussion 275-6. [DOI: 10.1227/01.neu.0000310705.72487.f9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Abstract
Objective:
The intraoperative combination of an open magnetic resonance imaging (MRI) system with neurophysiological localization and continuous monitoring techniques allows for the best available anatomic and physiological orientation as well as real-time functional monitoring. Methodological aspects and technical adaptations for this combination of methods and the experience in 29 patients with tumors in the central region are reported.
Methods:
MRI-compatible platinum/iridium electrodes for intraoperative neuromonitoring were attached to the patient’s head. All other electrodes located outside the magnet were stainless steel needle-electrodes for recording of motor evoked potentials and for stimulating somatosensory evoked potentials. Intraoperative MRI was performed using a 0.15-T intraoperative magnetic resonance scanner (PoleStar N20; Medtronic Surgical Navigation Technologies, Louisville, KY).
Results:
The calculated and measured values of the maximum induced magnetic field (2 × 10−6T), induced voltage (0.1 V), and force (0.01 N) by the static or changing magnetic field within all attached electrodes were negligible and proved the method’s safety. In 29 patients, platinum/iridium electrodes with low susceptibility showed no interference with the imaging quality. Furthermore, neurophysiological monitoring could be performed with unaffected recording quality. Side effects (e.g., thermal induction) were not observed.
Conclusion:
Neurophysiological monitoring for evoked potentials and direct cortical stimulation can be performed with standard quality within a low-field intraoperative MRI system. Electrodes fixed to the head should be of low magnetic susceptibility to guarantee optimal imaging quality. The combined use of an open ultra low-field MRI system and intraoperative monitoring allows for resection control and continuous functional monitoring.
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Affiliation(s)
- Andrea Szelényi
- Department of Neurosurgery, Johann Wolfgang Goethe University Hospital, Frankfurt, Germany
| | - Thomas Gasser
- Department of Neurosurgery, Johann Wolfgang Goethe University Hospital, Frankfurt, Germany
| | - Volker Seifert
- Department of Neurosurgery, Johann Wolfgang Goethe University Hospital, Frankfurt, Germany
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Human central nervous system circuits examined through the electrodes implanted for deep brain stimulation. Clin Neurophysiol 2008; 119:1219-31. [DOI: 10.1016/j.clinph.2007.12.020] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2007] [Revised: 12/19/2007] [Accepted: 12/22/2007] [Indexed: 11/21/2022]
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Deletis V, Sala F. Intraoperative neurophysiological monitoring of the spinal cord during spinal cord and spine surgery: a review focus on the corticospinal tracts. Clin Neurophysiol 2007; 119:248-64. [PMID: 18053764 DOI: 10.1016/j.clinph.2007.09.135] [Citation(s) in RCA: 248] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2003] [Revised: 09/05/2007] [Accepted: 09/07/2007] [Indexed: 12/28/2022]
Abstract
Recent advances in technology and the refinement of neurophysiological methodologies are significantly changing intraoperative neurophysiological monitoring (IOM) of the spinal cord. This review will summarize the latest achievements in the monitoring of the spinal cord during spine and spinal cord surgeries. This overview is based on an extensive review of the literature and the authors' personal experience. Landmark articles and neurophysiological techniques have been briefly reported to contextualize the development of new techniques. This background is extended to describe the methodological approach to intraoperatively elicit and record spinal D wave and muscle motor evoked potentials (muscle MEPs). The clinical application of spinal D wave and muscle MEP recordings is critically reviewed (especially in the field of Neurosurgery) and new developments such as mapping of the dorsal columns and the corticospinal tracts are presented. In the past decade, motor evoked potential recording following transcranial electrical stimulation has emerged as a reliable technique to intraoperatively assess the functional integrity of the motor pathways. Criteria based on the absence/presence of potentials, their morphology and threshold-related parameters have been proposed for muscle MEPs. While the debate remains open, it appears that different criteria may be applied for different procedures according to the expected surgery-related morbidity and the ultimate goal of the surgeon (e.g. total tumor removal versus complete absence of transitory or permanent neurological deficits). On the other hand, D wave changes--when recordable--have proven to be the strongest predictors of maintained corticospinal tract integrity (and therefore, of motor function/recovery). Combining the use of muscle MEPs with D wave recordings provides the most comprehensive approach for assessing the functional integrity of the spinal cord motor tracts during surgery for intramedullary spinal cord tumors. However, muscle MEPs may suffice to assess motor pathways during other spinal procedures and in cases where the pathophysiology of spinal cord injury is purely ischemic. Finally, while MEPs are now considered the gold standard for monitoring the motor pathways, SEPs continue to retain value as they provide specificity for assessing the integrity of the dorsal column. However, we believe SEPs should not be used exclusively--or as an alternative to motor evoked potentials--during spine surgery, but rather as a complementary method in combination with MEPs. For intramedullary spinal tumor resection, SEPs should not be used exclusively without MEPs.
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Affiliation(s)
- Vedran Deletis
- Institute for Neurology and Neurosurgery, Beth Israel Medical Center-Singer Division, 170 East End Avenue, Room 311, New York, NY 10128, USA.
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Tanaka S, Takanashi J, Fujii K, Ujiie H, Hori T. Motor evoked potential mapping and monitoring by direct brainstem stimulation. J Neurosurg 2007; 107:1053-7. [DOI: 10.3171/jns-07/11/1053] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
✓Motor evoked potentials (MEPs) by direct brainstem stimulation were generated during 12 neurosurgical operations performed in five posterior fossa tumors, six vertebrobasilar aneurysms, and an arachnoid cyst. The anterior aspect of the brainstem was exposed using a subtemporal approach (in six cases), a presigmoid approach (one case), or a lateral suboccipital approach (five cases). A train of five monopolar 5 to 25 mA pulses was then applied, and MEPs were recorded from the extremities. Motor evoked potentials were recorded in all patients (four mappings and seven monitorings) except in a 12-year-old child who underwent surgery for a posterior cerebral artery aneurysm. Although he experienced postoperative motor palsy, the aneurysm ruptured before electrodes could be placed. Two patients with postoperative motor palsy, one with a clival meningioma and one with a basilar trunk aneurysm, had shown significant decreases in MEP amplitude and even complete disappearance of MEPs during intraoperative brainstem stimulation. Motor evoked potentials elicited by direct brainstem stimulation seem to be an accurate neurophysiological monitoring method during operations around the anterior and lateral aspects of the brainstem.
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Affiliation(s)
- Satoshi Tanaka
- 1Department of Neurosurgery, Kawasaki Hospital, Hitachiohta
| | - Junko Takanashi
- 2Department of Clinical Laboratory, The Kitasato Institute Medical Center Hospital, Kitamoto
| | - Kiyotaka Fujii
- 3Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara; and
| | - Hiroshi Ujiie
- 4Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo, Japan
| | - Tomokatsu Hori
- 4Department of Neurosurgery, Neurological Institute, Tokyo Women's Medical University, Tokyo, Japan
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Pajewski TN, Arlet V, Phillips LH. Current approach on spinal cord monitoring: the point of view of the neurologist, the anesthesiologist and the spine surgeon. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2007; 16 Suppl 2:S115-29. [PMID: 17619913 PMCID: PMC2072895 DOI: 10.1007/s00586-007-0419-6] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 06/27/2007] [Indexed: 01/08/2023]
Abstract
Optimal outcome in spine surgery is dependent of the coordination of efforts by the surgeon, anesthesiologist, and neurophysiologist. This is perhaps best illustrated by the rising use of intraoperative spinal cord monitoring for complex spine surgery. The challenges presented by neurophysiologic monitoring, in particular the use of somatosensory and motor evoked potentials, requires an understanding by each member for the team of the proposed operative procedure as well as an ability to help differentiate clinically important signal changes from false positive changes. Surgical, anesthetic, and monitoring issues need to be addressed when relying on this form of monitoring to reduce the potential of negative outcomes in spine surgery. This article provides a practical overview from the perspective of the neurophysiologist, the anesthesiologist, and the surgeon on the requirements which must be understood by these participants in order to successfully contribute to a positive outcome when a patient is undergoing complex spine surgery.
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Affiliation(s)
- Thomas N. Pajewski
- Department of Anesthesiology, University of Virginia Health System, Charlottesville, VA USA
| | - Vincent Arlet
- Division of Scoliosis and Spine Surgery, Department of Orthopedic Surgery, University of Virginia Health System, P.O. Box 800710, Charlottesville, VA 22908-0710 USA
| | - Lawrence H. Phillips
- Department of Neurology, University of Virginia Health System, Charlottesville, VA USA
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Lo YL, Dan YF, Tan YE, Fook-Chong S, Tan SB, Tan CT, Raman S. Intraoperative monitoring study of ipsilateral motor evoked potentials in scoliosis surgery. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2006; 15 Suppl 5:656-60. [PMID: 16858594 PMCID: PMC1602201 DOI: 10.1007/s00586-006-0190-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 06/15/2006] [Accepted: 07/02/2006] [Indexed: 12/02/2022]
Abstract
Ipsilateral motor evoked potentials (MEPs) in spinal cord surgery intraoperative monitoring is not well studied. We show that ipsilateral MEPs have significantly larger amplitudes and were elicited with lower stimulation intensities than contralateral MEPs. The possible underlying mechanisms are discussed based on current knowledge of corticospinal pathways. Ipsilateral MEPs may provide additional information on the integrity of descending motor tracts during spinal surgery monitoring.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore, Singapore.
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Ulkatan S, Neuwirth M, Bitan F, Minardi C, Kokoszka A, Deletis V. Monitoring of scoliosis surgery with epidurally recorded motor evoked potentials (D wave) revealed false results. Clin Neurophysiol 2006; 117:2093-101. [PMID: 16844406 DOI: 10.1016/j.clinph.2006.05.021] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Revised: 05/16/2006] [Accepted: 05/22/2006] [Indexed: 01/19/2023]
Abstract
OBJECTIVE To elucidate the mechanism behind D wave amplitude changes after surgical correction of scoliosis. METHODS We collected D wave and muscle MEP data from 93 patients (78 female, 15 male, age range 4-19 years, mean age 15.9 years), who underwent surgical correction of scoliosis. D waves were recorded via a catheter electrode inserted epidurally through the flavectomy. Muscle MEPs from lower limb muscles were also recorded. Muscle MEPs/D wave were elicited by short trains/single transcranial electrical stimuli. SEPs were elicited through bilateral percutaneous stimulation of the tibial nerves at the ankle and an averaged response from 100 to 200 single sweeps were recorded over the scalp at Cz'/Fz. In addition, we analyzed intraoperatively obtained X-ray images of the spine in 9 patients and preoperative spinal MRI in two of those nine. RESULTS After surgical correction of scoliosis in 25 of 93 (27%) patients, the D wave amplitude changed by more than 20% of its baseline value. A decremental change occurred in 21 (84%) and an incremental change in 4 (16%) patients. D wave decrements of more than 50% were observed in 5 patients without significant SEP changes in any of these cases. In 9 patients, intraoperatively obtained X-rays of the spine (before and after correction of spine curvature) showed no catheter displacement. Muscle MEPs did not change and postoperative sensory-motor status was normal. In 2 patients, preoperative MRI revealed displacement of the spinal cord towards the concave side of the scoliotic curvature. CONCLUSIONS During scoliosis surgery, D wave amplitude changes should be interpreted cautiously until the definitive cause(s) of these changes are found. One possible mechanism to explain D wave changes during scoliosis correction could involve rotation of the spinal cord within the spinal canal, and the relative position of the epidural recording catheter (ERC). Rotation of the spinal cord after correction of scoliosis could introduce a new relationship between the ERC and the corticospinal tracts (CTs). Due to high incidence of false D wave amplitude changes we suggest that this methodology should not be used to assess the functional integrity of the CTs during scoliosis surgery. SIGNIFICANCE This study provides new insight into the methodology of D wave monitoring as well as strong evidence of a high incidence of false positive results using D wave monitoring during surgical correction of scoliosis.
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Affiliation(s)
- S Ulkatan
- Hyman-Newman Institute for Neurology and Neurosurgery, Beth Israel Medical Center, Singer Division, 170 East End Avenue, Room 311, New York, NY 10128, USA.
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Lo YL, Dan YF, Tan YE, Nurjannah S, Tan SB, Tan CT, Raman S. Intraoperative Motor-evoked Potential Monitoring in Scoliosis Surgery: Comparison of Desflurane/Nitrous Oxide With Propofol Total Intravenous Anesthetic Regimens. J Neurosurg Anesthesiol 2006; 18:211-4. [PMID: 16799350 DOI: 10.1097/01.ana.0000211007.94269.50] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
STUDY DESIGN A prospective, randomized study in a large general hospital setting. BACKGROUND During spinal surgery, monitoring motor-evoked potentials (MEPs) is a means of assessing the intraoperative integrity of corticospinal pathways. However, MEPs are known to be sensitive to the effects of anesthetic agents. OBJECTIVE To compare the use of desflurane or total intravenous anesthetic regimens (TIVA) with multipulse cortical stimulation for intraoperative monitoring (IOM). METHODS Twenty consecutive patients (10 in each arm) undergoing scoliosis correction surgery were randomly assigned to 2 equal groups receiving desflurane or TIVA. Inhalational anesthesia was maintained using 66% nitrous oxide in oxygen and a mean end-tidal desflurane concentration of 3.4%. For TIVA, continuous intravenous infusion of propofol was used. For analgesia, fentanyl and morphine were given when required for both groups. Cortical stimulation was achieved with 2 bipolar direct current stimulators connected in parallel by jumper cables. Five equivalent pulses 0.5 ms in duration at 4 ms intervals were delivered at C1C2 positions. MEP recordings were made in the abductor hallucis (AH) and tibialis anterior (TA) with needle electrodes. RESULTS Reproducible MEPs were obtained throughout the operation in all 20 cases, with up to 80 mA per stimulator. Before insertion of pedicle screws, mean MEP amplitudes (SD) obtained were 85 (19) and 21.7 (10.8) mV for AH and TA, respectively, using desflurane. With TIVA, amplitudes were 56.7 (28.4) and 59.1 (24.5) mV, respectively. Both muscle MEP amplitudes were significantly different using different anesthetic regimens (P < 0.05 for all). AH MEP amplitudes obtained with desflurane were significantly larger than TA amplitudes (P < 0.0001). No complications were reported intraoperatively and postoperatively. CONCLUSIONS This is the first study comparing the use of desflurane and TIVA showing that both anesthetic regimens allowed successful intraoperative monitoring useage throughout the procedures. For MEP recording, the AH was the preferred muscle with a desflurane anesthetic regimen.
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Affiliation(s)
- Yew-Long Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore.
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Fujiki M, Furukawa Y, Kamida T, Anan M, Inoue R, Abe T, Kobayashi H. Intraoperative corticomuscular motor evoked potentials for evaluation of motor function: a comparison with corticospinal D and I waves. J Neurosurg 2006; 104:85-92. [PMID: 16509151 DOI: 10.3171/jns.2006.104.1.85] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
The goal of this study was to compare motor evoked potentials recorded from muscles (muscle MEPs or corticomuscular MEPs) with corticospinal MEPs recorded from the cervical epidural space (spinal MEPs or corticospinal MEPs) to assess their efficacy in the intraoperative monitoring of motor function.
Methods
Muscle and spinal MEPs were simultaneously recorded during surgery in 80 patients harboring brain tumors. Each case was assigned to one of four groups according to final changes in the MEPs: 1) Group A, in which there was an increased amplitude in the muscle MEP with an increased I3 wave amplitude (12 cases); 2) Group B, in which there was no significant change in the MEP (43 cases); 3) Group C, in which there was a decreased muscle MEP amplitude (< 35% of the control) with a decreased I wave amplitude but an unchanged D wave (15 cases); or 4) Group D, in which there was an absent muscle MEP with a decreased D wave amplitude (10 cases). In patients in Group A, the increase in the amplitude of the muscle MEP (range of increase 128–280%, mean increase 188.75 ± 48.79%) was well correlated with the increase in the I3 wave in corticospinal MEPs. Most of these patterns were observed in patients harboring meningiomas (10 [83.3%] of 12 cases). Patients in Group B displayed no changes in muscle and corticospinal MEPs and no signs of postoperative neurological deterioration. Patients in Group C showed a substantial decrease in the amplitude of the muscle MEP (range of decrease 5.3–34.8% based on the control waveform, mean change 21.81 ± 10.93%) without deterioration in the corticospinal D wave, and exhibited severe immediate postoperative motor dysfunction. This indicates dysfunction of the cortical gray matter, including the motor cortices, which are supposed to generate I waves. Patients in Group D exhibited decreases in the corticospinal D wave (range of decrease 21.5–55%, mean decrease 39.75 ± 11.45%) and an immediate cessation of the muscle MEP as well as severe permanent motor paresis.
Conclusions
These results indicate that, during surgery, monitoring of corticomuscular MEPs (which are related to I waves) is a much more sensitive method for the detection of immediate motor cortical damage than monitoring of corticospinal MEPs (D wave).
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Affiliation(s)
- Minoru Fujiki
- Department of Neurosurgery, School of Medicine, Oita University, Oita, Japan.
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DiCindio S, Schwartz DM. Anesthetic Management for Pediatric Spinal Fusion: Implications of Advances in Spinal Cord Monitoring. ACTA ACUST UNITED AC 2005; 23:765-87, x. [PMID: 16310663 DOI: 10.1016/j.atc.2005.08.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Currently, the detection of emerging injury through intraoperative neurologic monitoring is the best way to prevent neurologic injury. This requires a team approach that includes the anesthesiologist, neurophysiologist, and surgeon. The monitoring modalities available for the patient must be considered in planning the anesthetic management. In addition, intraoperative care for the patient requires an ongoing attention to how the anesthetic drugs affect spinal cord monitoring.
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Affiliation(s)
- Sabina DiCindio
- Department of Anesthesiology, Alfred I. duPont Hospital for Children, Wilmington, DE 19899, USA.
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28
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Tanaka S, Kobayashi I, Sagiuchi T, Takanashi J, Iwamoto K, Sato S, Fujii K. Compensation of Intraoperative Transcranial Motor-Evoked Potential Monitoring by Compound Muscle Action Potential After Peripheral Nerve Stimulation. J Clin Neurophysiol 2005; 22:271-4. [PMID: 16093899 DOI: 10.1097/01.wnp.0000166169.25564.f4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
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.
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Affiliation(s)
- Satoshi Tanaka
- Department of Neurosurgery and Clinical Laboratory, The Kitasato Institute Medical Center Hospital, Kitamoto, and Department of Neurosurgery, Kitasato University School of Medicine, Sagamihara, Japan
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Wilkinson MF, Kaufmann AM. Monitoring of facial muscle motor evoked potentials during microvascular decompression for hemifacial spasm: evidence of changes in motor neuron excitability. J Neurosurg 2005; 103:64-9. [PMID: 16121975 DOI: 10.3171/jns.2005.103.1.0064] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Hemifacial spasm (HFS) is thought to be due to a hyperactive facial motor nucleus consequent to chronic neurovascular contact. The lateral spread (LS) response is presumed to reflect changes in facial motor neuron excitability. Facial muscle motor evoked potentials (MEPs) use the same efferent pathway as LS, therefore the authors speculated that these potentials should reflect differences consistent with changes at the facial motor nucleus level. METHODS Monitoring of LS and bilateral facial MEP was performed in 10 consecutive patients undergoing MVD for HFS. Ipsilateral facial MEPs were monitored in 17 patients undergoing MVD for trigeminal neuralgia (TN). Latency, amplitude, and duration of the MEPs were compared before and after MVD. Following MVD the duration of ipsilateral MEPs decreased from 17.6 +/- 1.2 to 7.6 +/- 0.7 msec and their amplitude decreased from 269.9 +/- 66.3 to 76.5 +/- 26.2 microV (p < or = 0.01). These changes were consequent to the abolition of LS in eight of 10 patients and an approximately 50% reduction in two patients. The relationship between the reduction in MEPs and changes in LS was significant (p < 0.01). Control facial muscle MEPs (nonspastic side in patients with HFS and in those with TN) did not change significantly during the MVD procedure. Spasms were alleviated in nine of 10 patients, and there was no indication of facial nerve damage intraoperatively or postoperatively. CONCLUSIONS Facial muscle MEPs represent a novel tool for studying the neurophysiological mechanisms of HFS in particular and monitoring the facial nerve in general. Data in this study support the hypothesis that the development of HFS and its alleviation with MVD are related to changes in facial motor nucleus activity.
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Affiliation(s)
- Marshall F Wilkinson
- Centre for Cranial Nerve Disorders, Division of Neurosurgery, University of Manitoba, Winnipeg, Manitoba, Canada.
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Ilić TV, Petković S. [Principles and application of transcranial magnetic stimulation]. VOJNOSANIT PREGL 2005; 62:389-402. [PMID: 15913044 DOI: 10.2298/vsp0505389i] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Tihomir V Ilić
- Vojnomedicinska akademija, Klinika za neurologiju, Crnotravska, Beograd, Srbija i Crna Gora. tihoilic@EUnet
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Tanaka S, Kobayashi I, Utsuki S, Iwamoto K, Takanashi J. Biopsy of brain stem glioma using motor-evoked potential mapping by direct peduncular stimulation and individual adjuvant therapy. Case report. Neurol Med Chir (Tokyo) 2005; 45:49-55. [PMID: 15699622 DOI: 10.2176/nmc.45.49] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A 23-year-old man presented with a brain stem glioma manifesting as a 6-month history of right hemiparesis and diplopia. Serial magnetic resonance imaging showed an intrinsic diffuse brain stem glioma that gradually localized to the left cerebral peduncle after initial adjuvant therapy. Surgery was performed through a left subtemporal transtentorial approach under motor-evoked potential (MEP) mapping by direct peduncular stimulation. The lateral aspect of the midbrain was exposed, a train of five bipolar 25 mA pulses was applied, and MEPs recorded from the extremities. MEPs were only recorded from the left extremities even with left cerebral peduncular stimulation. Partial resection of the tumor was safely performed, with slight temporary neurological worsening. The histological diagnosis was anaplastic astrocytoma. Individual adjuvant therapy based on the results of real-time reverse transcription-polymerase chain reaction of O6-methylguanine-deoxyribonucleic acid methyltransferase achieved an almost complete tumor response. Surgery under pyramidal tract mapping and intensive postoperative adjuvant therapy resulted in a good outcome despite the presence of a generally intractable intrinsic brain stem glioma.
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Affiliation(s)
- Satoshi Tanaka
- Department of Neurosurgery, The Kitasato Institute Medical Center Hospital, Kitamoto, Saitama, Japan.
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Skinner SA, Nagib M, Bergman TA, Maxwell RE, Msangi G. The Initial Use of Free-running Electromyography to Detect Early Motor Tract Injury during Resection of Intramedullary Spinal Cord Lesions. Oper Neurosurg (Hagerstown) 2005; 56:299-314; discussion 299-314. [PMID: 15794827 DOI: 10.1227/01.neu.0000156545.33814.8d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Accepted: 09/20/2004] [Indexed: 11/19/2022] Open
Abstract
Abstract
OBJECTIVE:
The resection of intramedullary spinal cord lesions (ISCLs) can be complicated by neurological deficits. Neuromonitoring has been used to reduce intraoperative risk. We have used somatosensory evoked potentials (SEPs) and muscle-derived transcranial electrical motor evoked potentials (myogenic TCE-MEPs) to monitor ISCL removal. We report our retrospective experience with the addition of free-running electromyography (EMG).
METHODS:
Thirteen patients underwent 14 monitored ISCL excisions. Anesthesia was maintained with minimal inhalant to reduce motoneuron suppression and enhance the myogenic TCE-MEPs. Free-running EMG was examined in the four limbs for evidence of abnormal bursts, prolonged tonic discharge, or sudden electrical silence. Warning of an electromyographic abnormality or myogenic TCE-MEP loss prompted interventions, including blood pressure elevation, a pause in surgery, a wake-up test, or termination of surgery. Pre- and postoperative neurological examinations determined the incidence of new deficits.
RESULTS:
The combined use of free-running EMG and myogenic TCE-MEPs detected all eight patients with a new motor deficit after surgery; there was one false-positive report. In three of the eight true-positive cases, an electromyographic abnormality immediately anticipated loss of the myogenic TCE-MEPs. Two patients with abnormal EMGs but unchanged myogenic TCE-MEPs experienced mild postoperative worsening of motor deficits; myogenic TCE-MEPs alone would have generated false-negative reports in these cases.
CONCLUSION:
During resection of ISCLs, free-running EMG can supplement motor tract monitoring by TCE-MEPs. Segmental and suprasegmental elicitation of neurotonic discharges can be observed in four-limb EMG. Abnormal electromyographic bursts, tonic discharge, or abrupt electromyographic silence may anticipate myogenic TCE-MEP loss and predict a postoperative motor deficit.
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Affiliation(s)
- Stanley A Skinner
- Department of Intraoperative Monitoring, Abbott Northwestern Hospital, Minneapolis, Minnesota 55407-3799, USA.
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Scheufler KM, Reinacher PC, Blumrich W, Zentner J, Priebe HJ. The Modifying Effects of Stimulation Pattern and Propofol Plasma Concentration on Motor-Evoked Potentials. Anesth Analg 2005; 100:440-447. [PMID: 15673873 DOI: 10.1213/01.ane.0000141678.04200.86] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The quality of intraoperative motor-evoked potentials (MEPs) largely depends on the stimulation pattern and anesthetic technique. Further improvement in intraoperative MEP recording requires exact knowledge of the modifying effects of each of these factors. Accordingly, we designed this study to characterize the modifying effect of different stimulation patterns during different propofol target plasma concentrations (PTPCs) on intraoperatively recorded transcranial electrical MEPs. In 12 patients undergoing craniotomy, stimulation patterns (300-500 V; 100-1000 Hz; 1-5 stimuli) were varied randomly at different PTPCs (2, 4, and 6 microg/mL). Remifentanil was administered unchanged at 0.2 microg . kg(-1) . min(-1). MEPs were recorded from the thenar and hypothenar muscles. Analysis of MEPs was blinded to the PTPC. Three-way analysis of variance revealed significant main effects of increasing stimulation intensity, frequency, and number of stimuli on MEP amplitude (P < 0.05). Maximum MEP amplitudes and recording success rates were observed with three or more stimuli delivered at 1000 Hz and > or =150 V. A significant main effect of PTPC (2 vs 4 and 6 microg/mL) on MEP amplitude was observed at the thenar recording site only (P < 0.05). An amplitude ratio calculated from corresponding MEPs evoked by double and quadruple stimulation proved to be insensitive to changes in PTPC. In conclusion, MEP characteristics varied significantly in response to changes in stimulation pattern and less to changes in PTPC.
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Affiliation(s)
- Kai M Scheufler
- *Department of Neurosurgery, University Hospital, Freiburg, Germany; †Department of Neurosurgery, University Hospital, Aachen, Germany; and ‡Department of Anesthesiology, University Hospital, Freiburg, Germany
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Calancie B, Molano MR, Broton JG. Tendon reflexes for predicting movement recovery after acute spinal cord injury in humans. Clin Neurophysiol 2004; 115:2350-63. [PMID: 15351378 DOI: 10.1016/j.clinph.2004.04.028] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2004] [Indexed: 10/26/2022]
Abstract
OBJECTIVE Use the tendon reflex to examine spinal cord excitability after acute spinal cord injury (SCI), relating excitability findings to prognosis. METHODS We conducted repeated measures of reflex responses to mechanical taps at the patellar and Achilles tendons of the lower limbs, and the wrist flexor tendons of the upper limbs in persons with acute SCI, beginning as early as the day of injury. The single largest EMG response (peak-to-peak) for each site was recorded. Subjects were compared based on level of injury and final neurologic status of lower limb motor function (i.e. absence of any voluntary recruitment in a lower limb muscle: motor-complete; voluntary recruitment in 1 or more lower-limb muscles: motor-incomplete). RESULTS We studied 229 subjects with acute SCI. Persons with injury to the cervical or thoracic spinal cord and who were (or became) motor-incomplete showed large tendon responses, even at the time of initial evaluation. In combination with larger tendon response amplitudes, the presence of the 'crossed-adductor' response to patellar tendon taps at the acute stage was highly predictive of functional motor recovery following SCI. In marked contrast, tendon responses were small (e.g. < 0.1 mV) or absent in persons with acute, motor-complete injury (and which remained motor-complete), and the crossed-adductor response was never seen. Reflex amplitudes and the incidence of the crossed-adductor response increased somewhat over time in persons with motor-complete SCI, but did not approach the values seen in motor-incomplete subjects. CONCLUSIONS Taken together, tendon response amplitude and reflex spread were sensitive and specific indicators of preserved supraspinal control over lower limb musculature in subjects with acute SCI. A simple algorithm using these outcome measures predicted a 'motor-complete' status with 100% accuracy, and a motor-incomplete status with accuracy exceeding 91%.
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Affiliation(s)
- Blair Calancie
- Department of Neurosurgery, SUNY's Upstate Medical University, Syracuse, New York, USA.
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Othman Z, Lenke LG, Bolon SM, Padberg A. Hypotension-induced loss of intraoperative monitoring data during surgical correction of scheuermann kyphosis: a case report. Spine (Phila Pa 1976) 2004; 29:E258-65. [PMID: 15187651 DOI: 10.1097/01.brs.0000127193.89438.b7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Presentation of a case report of Scheuermann kyphosis surgical correction. OBJECTIVE To describe a scenario where both neurogenic mixed evoked potentials and somatosensory-evoked potentials were lost due solely to hypotension before any correction of a kyphotic spinal deformity was performed. SUMMARY OF BACKGROUND DATA Multimodality intraoperative neurophysiologic monitoring of the spinal cord has become widely utilized during surgical correction of scoliotic and kyphotic deformities. Most spinal surgeries also benefit from a state of hypotension to minimize blood loss, but unchecked and persistent hypotension may lead to inadequate perfusion to the spinal cord, resulting in spinal cord dysfunction noted by diminution of neuromonitoring data. METHODS An 18-year-old boy with a 95 degrees Scheuermann kyphosis underwent a posterior spinal fusion for correction of his deformity. Intraoperative neurophysiologic monitoring consisting of neurogenic mixed evoked potentials and somatosensory-evoked potentials were performed throughout surgery. RESULTS After placement of segmental pedicle screw fixation points and multiple osteotomies, before any instrumented correction of the deformity, all lower extremity neuromonitoring data were acutely lost. The surgeon was immediately warned of the data loss, with the mean arterial pressure noted to be 50 mm Hg. The mean arterial pressure was raised with the use of epinephrine bolus and dopamine infusion. Subsequently, all lower extremity neuromonitoring data returned. A Stagnara wake-up test was performed, which the patient passed, and the surgical correction was performed with his pressure maintained on a dopamine infusion. He awakened without neurologic deficits and had an uneventful recovery. CONCLUSIONS Although a state of mild hypotension may be beneficial to limit blood loss during spinal deformity corrective surgery, acute and/or prolonged hypotension may jeopardize spinal cord vascularity and should be avoided especially during surgical treatment of high-risk deformities such as kyphosis. Early warning by multimodality physiologic neuromonitoring appears to be a useful method to alert surgeons of the potentially devastating problem of hypotension-induced spinal cord dysfunction and allows immediate corrective actions.
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Affiliation(s)
- Zanariah Othman
- Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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Lo YL, Dan YF, Tan YE, Nurjannah S, Tan SB, Tan CT, Raman S. Intra-operative monitoring in scoliosis surgery with multi-pulse cortical stimuli and desflurane anesthesia. Spinal Cord 2004; 42:342-5. [PMID: 15007378 DOI: 10.1038/sj.sc.3101605] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
STUDY DESIGN Prospective, observational study. SETTING Country General Hospital, Singapore. OBJECTIVE Intraoperative monitoring (IOM) with motor-evoked potentials (MEPs) assesses the integrity of cortical spinal tracts during scoliosis surgery. MEPs are sensitive to the effects of inhalational anesthetic agents. We evaluate the use of desflurane in combination with multipulse cortical stimulation in this study. METHODS In all, 10 consecutive neurologically normal subjects underwent scoliosis surgery with desflurane anesthesia (0.5 maximum alveolar concentration) and five pulse cortical stimulation (250 Hz) from two stimulators in parallel configuration, delivering a maximum intensity of 160 mA. RESULTS Consistent MEPs were obtained from the abductor hallucis and tibialis anterior in nine of ten and five of five of subjects, respectively. Baseline coefficients of variations were below 16% for both muscles. CONCLUSION This combination of anesthetic and stimulation protocols is efficacious for IOM during spinal cord surgery. Our findings support the use of desflurane for successful acquisition of MEPs during scoliois surgery as an alternative anesthetic regime.
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Affiliation(s)
- Y L Lo
- Department of Neurology, National Neuroscience Institute, Singapore General Hospital
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Abstract
The advent of equipment capable of performing SEPs, MEPs, and EMG in a multiplexed manner and in a timely fashion brings a new level of monitoring that far exceeds the previous basic monitoring done with SEPs only. Whether this more comprehensive monitoring will result in greater protection of the nervous system awaits future analysis. In any event, monitoring of the spinal cord with SEPs is an accepted standard of care for cases that place the spinal cord at risk. Likewise, nerve root monitoring with EMG is a widely practiced form of monitoring and shows great benefit. MEPs and reflex monitoring, which address the descending pathways and the interneuronal connections, is efficacious in detecting abnormalities that may be missed by SEPs.
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Affiliation(s)
- Jefferson C Slimp
- Department of Rehabilitation Medicine, University of Washington School of Medicine, Box 356490, Seattle, WA 98195, USA.
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Neuloh G, Schramm J. Motor Evoked Potential Monitoring for the Surgery of Brain Tumours and Vascular Malformations. Adv Tech Stand Neurosurg 2004; 29:171-228. [PMID: 15035339 DOI: 10.1007/978-3-7091-0558-0_5] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Brain surgery incurs a significant risk of a new motor deficit in lesions within or adjacent to the motor areas and pathways which, for the patient, presents one of the most disabling complications of such operations. It is a major concern of intracranial procedures to delineate and monitor motor regions in order to preserve their structural and functional integrity, while still achieving maximal cytoreduction. The technique of motor evoked potential recording has had to be adapted to intraoperative recording conditions under general anaesthesia, but has been available for clinical use now for almost ten years. This contribution summarizes the current technique and related methods, as well as our clinical experience in some 400 cases of MEP monitoring in supratentorial tumors, lesions in and around the brainstem, and aneurysm surgery. Intraoperative MEP recordings have been shown to reliably reflect an impending new motor deficit. Irreversible MEP deterioration heralds new paresis, and unaltered recordings predict preserved motor function. This is also true in aneurysm surgery where conventional SEP monitoring may yield false-negative results with regard to development of a new motor deficit. Moreover, if MEP deterioration can be reversed, or halted by early surgical intervention, the presence of only a transient motor deficit, or even the lack of a new postoperative deficit, indicates the success of the MEP monitoring method in the prevention of a significant motor impairment. Certain complicated lesions can only be operated on at all because MEP monitoring is available. In conclusion, intraoperative MEP monitoring is a useful aid in brain surgery with which to avoid a new motor deficit without compromise to the surgical result. Controlled prospective studies will be required to verify the clinical value of the method.
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Affiliation(s)
- G Neuloh
- Department of Neurosurgery, University of Bonn, Germany
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MacDonald DB, Al Zayed Z, Khoudeir I, Stigsby B. Monitoring scoliosis surgery with combined multiple pulse transcranial electric motor and cortical somatosensory-evoked potentials from the lower and upper extremities. Spine (Phila Pa 1976) 2003; 28:194-203. [PMID: 12544939 DOI: 10.1097/00007632-200301150-00018] [Citation(s) in RCA: 139] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A retrospective case review was performed. OBJECTIVE To assess the value, rapidity, and safety of combined multiple-pulse transcranial electric stimulation motor-evoked potential and somatosensory-evoked potential monitoring during scoliosis surgery. SUMMARY OF BACKGROUND DATA Leg somatosensory-evoked potentials can miss motor deficits, and a 50% amplitude warning criterion can produce false alarms. METHODS For this study, 33 scoliosis surgeries in neurologically normal patients under propofol/fentanyl anesthesia omitting neuromuscular blockade were monitored with four-extremity multiple-pulse transcranial electric stimulation muscle motor-evoked potentials and cortical somatosensory-evoked potentials. Instead of amplitude criteria, parallel (same-direction) change was used to identify systemic alteration and nonparallel (one- or two-limb) deterioration to identify focal neurologic compromise. Clinical observation and intraoperative electroencephalography were used to assess adverse effects. RESULTS Instantaneous motor-evoked potentials and rapidly reproducible cortical somatosensory-evoked potentials provided comprehensive feedback every 0.8 to 6.7 minutes (median, 2.4 minutes) without adverse effects. Parallel (systemic) changes without alarm or deficit included motor-evoked potential fading or temporary loss and leg somatosensory-evoked potential amplitudes below 50% of initial, maximum, or median intraoperative values in 10% to 37% of the cases. Three nonparallel changes occurred: 1) abrupt bilateral leg somatosensory-evoked potential 20% to 30% reduction without motor-evoked potential change during instrumentation resolving spontaneously over 30 minutes, with transient postoperative sensory symptoms; 2) right-arm somatosensory-evoked potential and motor-evoked potential reduction during hyperabduction restored after repositioning, without deficit; 3) abrupt bilateral leg motor-evoked potential loss preceding 30% to 60% somatosensory-evoked potential reduction during derotation rapidly restored after instrumentation release, without deficit. CONCLUSIONS In neurologically normal patients, the combined methods are safe and rapid, and could improve the sensitivity and specificity of scoliosis monitoring. Arm controls facilitate differentiation between systemic alterations and focal neurologic compromise.
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Affiliation(s)
- David B MacDonald
- Section of Clinical Neurophysiology, Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.
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MacDonald DB. Safety of intraoperative transcranial electrical stimulation motor evoked potential monitoring. J Clin Neurophysiol 2002; 19:416-29. [PMID: 12477987 DOI: 10.1097/00004691-200210000-00005] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
This article reviews intraoperative transcranial electrical stimulation (TES) motor evoked potential (MEP) monitoring safety based on comparison with other clinical and experimental brain stimulation methods and clinical experience in more than 15000 cases. Comparative analysis indicates that brain damage and kindling are highly unlikely. There have been remarkably few adverse events. Pulse train TES-induced or coincidental seizures (n = 5) are rare, probably because of very brief (<0.03 second) stimuli, anesthesia, and the general absence of predisposing cerebral conditions. Soft bite blocks may prevent tongue or lip laceration (n = 29) or mandibular fracture (n = 1). Rare cardiac arrhythmia (n = 5) and intraoperative awareness (n = 1) may be coincidental. Minor scalp burns (n = 2) are rare. Although possible, no spinal epidural recording electrode complications or injuries resulting from TES-induced movement were found. There have been no recognized adverse neuropsychological effects, headaches, or endocrine disturbances. Comprehensive relative contraindications include epilepsy, cortical lesions, convexity skull defects, raised intracranial pressure, cardiac disease, proconvulsant medications or anesthetics, intracranial electrodes, vascular clips or shunts, and cardiac pacemakers or other implanted biomedical devices. Otherwise unexplained intraoperative seizures and possibly arrhythmias are indications to abort TES. With appropriate precautions in expert hands, the well-established benefits of TES MEP monitoring decidedly outweigh the associated risks.
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Affiliation(s)
- David B MacDonald
- Department of Neurosciences, King Faisal Specialist Hospital & Research Center, Riyadh, Saudi Arabia.
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Abstract
Transcranial magnetic stimulation (TMS) has been used increasingly to probe the physiology of the human cortex. Besides measuring directly the cortical excitability in motor and visual systems, this noninvasive method can be used to study short- and long-term cortical plasticity. One possible method to examine basic mechanisms underlying cortical excitability and plasticity in humans is the combination of TMS and pharmacologic interventions. In this review the author describes TMS paradigms used to study mechanisms of plasticity in the intact human motor system and its excitability using pharmacologic methods.
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Suihko V. Modelling the response of scalp sensory receptors to transcranial electrical stimulation. Med Biol Eng Comput 2002; 40:395-401. [PMID: 12227625 DOI: 10.1007/bf02345071] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Transcranial electrical stimulation of the brain causes considerable discomfort to the patient. The purpose of the study was to find out whether this could be affected by the choice of stimulation parameters. A spherical volume conductor model of the head and active compartmental models of a pyramidal motor nerve and scalp nociceptor were used in combination to simulate the scalp nociception to transcranial electrical stimulation. Scalp nociceptors were excited at distances of several centimetres from the electrodes. The size of the excited scalp area correlated with the length of the stimulation pulse. The area was 12.3, 20.4 and 26.0 cm2, for a 10 micros, 100 micros and 1 ms constant current pulse, respectively. With a 100 micros constant current pulse, the threshold for motor excitation was 205mA and, for nociception, it was 51 mA. There was no significant difference between constant current and capacitor discharge pulses or between electrodes of different sizes. The results imply that the use of very short stimulation pulses can reduce the pain. If a topical anaesthesia is used to reduce the pain, it has to be applied on a large area around the electrodes.
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Affiliation(s)
- V Suihko
- Department of Clinical Neurophysiology, Tampere University Hospital, Finland.
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Abstract
Since 1985, when the technique of transcranial magnetic stimulation (TMS) was first developed, a wide range of applications in healthy and diseased subjects has been described. Comprehension of the physiological basis of motor control and cortical function has been improved. Modifications of the basic technique of measuring central motor conduction time (CMCT) have included measurement of the cortical silent period, paired stimulation in a conditioning test paradigm, repetitive transcranial magnetic stimulation (rTMS), and peristimulus time histograms (PSTH). These methods allow dissection of central motor excitatory versus inhibitory interplay on the cortical motor neuron and its presynaptic connections at the spinal cord, and have proven to be powerful investigational techniques. TMS can be used to assess upper and lower motor neuron dysfunction, monitor the effects of many pharmacological agents, predict stroke outcome, document the plasticity of the motor system, and assess its maturation and the effects of aging, as well as perform intraoperative monitoring. The recent use of rTMS in the treatment of depression and movement disorders is novel, and opens the way for other potential therapeutic applications.
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Affiliation(s)
- Markus Weber
- Department of Neurology, Kantonsspital, CH-9007 St. Gallen, Switzerland
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Bartley K, Woodforth IJ, Stephen JPH, Burke D. Corticospinal volleys and compound muscle action potentials produced by repetitive transcranial stimulation during spinal surgery. Clin Neurophysiol 2002; 113:78-90. [PMID: 11801428 DOI: 10.1016/s1388-2457(01)00711-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
OBJECTIVES To report our experience with neurophysiological monitoring of corticospinal function using compound muscle action potentials (CMAPs) produced by repetitive transcranial electrical stimulation in a large series of patients, after defining optimal stimulus parameters in a small group of patients. METHODS In 100 patients undergoing spinal surgery, corticospinal volleys were recorded using epidural electrodes, or CMAPs were recorded from innervated muscles, or both techniques were used to monitor spinal cord function. In subsets of patients, stimulus parameters were varied to determine the optimal parameters for CMAP recordings, using the corticospinal volleys to guide the initial choice. RESULTS Recordings of corticospinal volleys indicated that less energy was delivered to the cortex if the duration of each stimulus in the stimulus train was brief (e.g. 50 micros) and that there was attenuation of D and I waves in the corticospinal volley when the interstimulus interval in the train was <5 ms. An interstimulus interval of 5 ms proved significantly more effective than an interstimulus interval of 2 ms in evoking CMAPs, but resulted in a more complex, dispersed electromyographic (EMG) potential. The superiority of the 5 ms interval did not depend on stimulus intensity or the existence of pre-existing neurological deficit. Using trains of 5 pulses of duration 50 micros, interstimulus interval 5 ms and intensity 500 V, satisfactory CMAPs could be recorded in 55 of 82 patients, significantly less often in neurologically impaired patients than in neurologically normal subjects. Epidural recordings of the corticospinal volley were obtained in 61 of 69 patients, again more often in neurologically normal subjects. CONCLUSIONS When epidural recordings can be made, direct recordings of corticospinal activity are probably more reliable than recordings of CMAPs. However, epidural recordings are not suitable under all circumstances, and the ability to record CMAPs reliably represents an advance in intraoperative monitoring. Under the anaesthetic conditions used in the present study, the optimal stimulus parameters consist of a train of 5 stimuli of 50 micros duration at an interstimulus interval of 5 ms and an intensity of 500 V.
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Affiliation(s)
- Kathleen Bartley
- Department of Clinical Neurophysiology, Prince of Wales and Sydney Children's Hospitals, Sydney, Australia
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Calancie B, Harris W, Brindle GF, Green BA, Landy HJ. Threshold-level repetitive transcranial electrical stimulation for intraoperative monitoring of central motor conduction. J Neurosurg 2001; 95:161-8. [PMID: 11599831 DOI: 10.3171/spi.2001.95.2.0161] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The authors conducted a study to evaluate repetitive transcranial electrical stimulation (TES) to assess spinal cord motor tract function in individuals undergoing spine surgery, with emphasis on safety and efficacy. METHODS Somatosensory evoked potentials (SSEPs) were elicited using standard technique. Muscle electromyographic values were measured in response to a three- or four-pulse train of stimulation delivered to the motor cortex via subdermal electrodes. They also evaluated whether changes in the minimum stimulus intensity (that is, threshold level) needed to elicit a response from a given muscle predict motor status immediately postoperatively, as well as whether changes in SSEP response amplitude and latency predict sensory status immediately postoperatively. Anesthesia was routinely induced with intravenous propofol and remifentanil, supplemented with inhaled nitrous oxide. Use of neuromuscular block was avoided after intubation. Satisfactory monitoring of muscle response to threshold-level repetitive TES was achieved in all but nine of the 194 patients studied. In contrast, cortical SSEP responses could not be elicited in 42 of 194 individuals. In cases in which responses were present, TES-based evoked responses proved to be extremely accurate for predicting postoperative motor status. Somatosensory evoked potential monitoring was nearly as accurate for predicting postoperative sensory status. There were frequent instances of postoperative motor or sensory deficit that were not predicted by SSEP- and TES-based monitoring, respectively. There were no adverse events attributable to TES-based monitoring, although since this study ended we have had a single adverse event attributable to threshold-level repetitive TES. CONCLUSIONS Intraoperative threshold-level repetitive TES-based monitoring of central motor conduction has proven to be a simple, safe, and highly accurate technique for the prevention or minimization of inadvertent motor deficit during surgery involving the spine or spinal cord.
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Affiliation(s)
- B Calancie
- The Miami Project to Cure Paralysis, University of Miami School of Medicine, Florida, USA.
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Luk KD, Hu Y, Wong YW, Cheung KM. Evaluation of various evoked potential techniques for spinal cord monitoring during scoliosis surgery. Spine (Phila Pa 1976) 2001; 26:1772-7. [PMID: 11493849 DOI: 10.1097/00007632-200108150-00008] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN This prospective study compared the outcomes of different evoked potential (EP) techniques for intraoperative spinal cord monitoring. OBJECTIVES To evaluate the reliability of different EP techniques administered during scoliosis surgery. SUMMARY OF BACKGROUND DATA A number of different methods of intraoperative spinal cord monitoring are available. Because each has its own advantages and limitations, multimodal spinal cord monitoring has been proposed to improve monitoring reliability. MATERIALS AND METHODS Cortical somatosensory-evoked potential (CSEP), cortical motor-evoked potential (CMEP), spinal somatosensory-evoked potential (SSEP), and spinal cord-evoked potential (SCEP) were applied simultaneously to 30 patients undergoing surgical correction for spinal deformity. The presence of the EP waveforms and their reproducibilities over separate tests were compared. In addition, the monitoring outcomes were evaluated with the clinical results. RESULTS Of the 30 patients, CSEP waveforms were successfully recorded in 28 cases (93%), SCEP in 25 cases (83%), CMEP in 24 cases (80%), and SSEP in 21 cases (70%). Latencies of each EP technique showed no significant variability. However, amplitudes showed significant differences between different techniques. SCEP and CMEP showed clearer waveforms of greater amplitude that could be detected faster than CSEP and SSEP waveforms. SCEP and SSEP waveforms were more easily influenced by the surgical procedure. CONCLUSION CSEP and CMEP are recommended for routine monitoring, so that both ascending and descending tracts are monitored. If adequate signals for either of these proposed monitoring methods cannot be easily obtained, SSEP can substitute for CSEP, whereas SCEP can substitute for CMEP.
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Affiliation(s)
- K D Luk
- Department of Orthopaedic Surgery, Duchess of Kent Children's Hospital, University of Hong Kong, Hong Kong
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Lin VW, Nino-Murcia M, Frost F, Wolfe V, Hsiao I, Perkash I. Functional magnetic stimulation of the colon in persons with spinal cord injury. Arch Phys Med Rehabil 2001; 82:167-73. [PMID: 11239306 DOI: 10.1053/apmr.2001.18215] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To evaluate the usefulness of functional magnetic stimulation (FMS) as a noninvasive method to stimulate the colon in individuals with spinal cord injury (SCI). DESIGN A prospective before-after trial consisting of 2 protocols. SETTING FMS laboratories of 2 SCI centers. PARTICIPANTS Two able-bodied men and 13 men with SCI levels ranging from C3 to L1. Protocol 1 consisted of 9 subjects, 2 of whom were excluded from the analysis. Protocol 2 consisted of 4 subjects. INTERVENTION Commercially available magnetic stimulators with round magnetic coils (MCs) were used. Protocol 1 measured the effects of FMS on rectal pressure by placing the MC on the transabdominal and lumbosacral regions. Protocol 2 consisted of a 5-week stimulation period to investigate the effects of FMS on total and segmental colonic transit times (CTTs). MAIN OUTCOME MEASURE An increase in rectal pressure and a decrease in CTT by magnetic stimulation. RESULTS Data were averaged and the standard error of the mean was calculated. Statistically significant changes in rectal pressure and CTT were also measured. Rectal pressures increased from 26.7 +/- 7.44cmH(2)O to 48.0 +/- 9.91cmH(2)O, p =.0037, with lumbosacral stimulation, and from 30.0 +/- 6.35cmH(2)O to 42.7 +/- 7.95cmH(2)O, p =.0015, with transabdominal stimulation. With FMS, the mean CTT decreased from 105.2 to 89.4 hours, p =.02. CONCLUSION FMS is able to stimulate the colon and reduce CTT. FMS is a noninvasive, technological advancement for managing neurogenic bowel in patients with SCI.
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Affiliation(s)
- V W Lin
- Functional Magnetic Stimulation Laboratory, Spinal Cord Injury/Disorder Health Care Group, VA Long Beach Health Care System, Long Beach, CA 9022, USA
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Nebelung W, Wissel H, Awiszus F. On the applicability of two different stimulation techniques for intra-operative peroneal nerve conduction testing. J Orthop Res 2001; 19:160-5. [PMID: 11332614 DOI: 10.1016/s0736-0266(00)00016-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Dysfunction of the peroneal nerve is an important complication of knee surgery. We compared two monitoring procedures of peroneal nerve function during a standardized operation, a closing wedge high tibial osteotomy. For two types of stimulation the evoked compound motor unit action potentials (CMAPs) were recorded on the tibialis anterior muscle. We used direct perineural electrical stimulation of the common peroneal nerve distal to the cuff (dCMAPs) after nerve identification in the surgical field. Additionally, magnetic stimulation of the sacral plexus proximal to the cuff (pCMAPs) was performed. It was found that dCMAPs were recorded during almost one hour of tourniquet time whereas the pCMAPs were blocked after 25-30 min in 9 out of 11 cases. On the other hand, the CMAP obtained after proximal stimulation exhibited a latency shift with tourniquet yielding an indicator of ischaemic changes present beneath and distal to the tourniquet cuff. In conclusion, different applicabilities of both stimulation techniques under tourniquet conditions were demonstrated.
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Affiliation(s)
- W Nebelung
- Neuromuscular Research Group, Otto-von Guericke-University Magdeburg, Clinic for Orthopedic Surgery, Germany.
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