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Yu C, Owens RK, Crawford CH, Djurasovic M, Gum JL, Brown M, Carreon LY. Cost-Effectiveness of Intraoperative Electromyography to Determine Adequate Screw Position. Global Spine J 2024; 14:407-410. [PMID: 35950238 PMCID: PMC10802540 DOI: 10.1177/21925682221107652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
STUDY DESIGN Prospective observational cohort. OBJECTIVES To examine the cost-effectiveness of IntraOperative ElectroMyeloGraphy (IO-EMG) by evaluating how often an abnormal IO-EMG signal changed the surgeon's surgical plan, or replaced a pedicle screw either intra-operatively or as a second unplanned surgery. METHODS Patients undergoing instrumented posterolateral lumbar fusion were monitored with intraoperative triggered EMG's. Pedicle screws were placed freehand from L1 to S1 by attending physicians and fellows. Concern for pedicle breach was a screw stimulation<10 mA. RESULTS There were 145 cases with a total of 725 pedicle screws placed. Mean age was 57.8 ± 14.2 yrs, OR time was 238 ± 95 minutes, EBL was 426.8 ± 354.3cc. Mean number of surgical levels fused was 2.7 ± 1.1. 686 (95%) screws stimulated at >10 mA and 39 (5%) screws stimulated at <10 mA. All 39 screws were removed and pedicles re-examined. Intraoperative screw repositioning was necessary in 8 of 145 cases (6%). No patient required a return to the OR for screw repositioning. As a worst case cost analysis, assuming the 8 patients requiring intraoperative screw positioning would have returned to the OR at a cost of $11,798 per readmission, the per patient cost is $651 which is less than the ION per patient cost of $750. CONCLUSIONS Only 1% of the 725 lumbar pedicle screws placed in 8 of 145 cases required repositioning. Due to the infrequency of pedicle wall breaches and the cost of ION, the utility of this modality in straightforward lumbar fusions should be critically evaluated.
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Affiliation(s)
- Charles Yu
- Norton Leatherman Spine Center, Louisville, KY, USA
| | | | | | | | | | - Morgan Brown
- Norton Leatherman Spine Center, Louisville, KY, USA
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Ran G, Chen K, Huang Y, Hu C, Shen X. Electromyographic Response of Facial Nerve Stimulation Under Partial Neuromuscular Blockade During Resection of Vestibular Schwannoma. World Neurosurg 2019; 132:e28-e33. [PMID: 31521756 DOI: 10.1016/j.wneu.2019.09.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 09/03/2019] [Accepted: 09/05/2019] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To evaluate whether use of partial nondepolarizing neuromuscular blocking agents, at a train-of-four level 1, compromise facial nerve monitoring during vestibular schwannoma (VS) resection. METHODS Sixty consecutive patients undergoing VS resection were enrolled into a partial peripheral neuromuscular blockade group or free of neuromuscular blockade group. Stimulation threshold to elicit an electromyographic response amplitude of at least 100 μV was recorded at the proximal and distal facial nerve after VS removal. The proximal-to-distal ratio of amplitude of the orbicularis oculi and oris muscles was calculated. RESULTS All patients successfully passed the electromyography monitoring test. Mean electrical stimulation thresholds were higher in the peripheral neuromuscular blockade group than in the free of neuromuscular blockade group (0.12 mA vs. 0.06 mA at proximal site, P = 0.001; 0.08 mA vs. 0.03 mA at distal site, P = 0.0002). The differences in median proximal-to-distal amplitude ratios were not statistically significant in both groups. There was a trend toward more patients needing phenylephrine. Recovery profiles were comparable in the 2 groups. CONCLUSIONS Although mean stimulation threshold to elicit a response amplitude was higher in the peripheral neuromuscular blockade group than in the free of neuromuscular blockade group at the proximal site, the stimulation thresholds in both groups were sufficient for facial nerve monitoring in VS surgery, indicating no clinical difference in both groups.
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Affiliation(s)
- Guo Ran
- Department of Anesthesiology, The Eye, Ear, Nose and Throat Hospital of Fudan University, Shanghai Medical College of Fudan University, Shanghai, China
| | - Kaizheng Chen
- Department of Anesthesiology, The Eye, Ear, Nose and Throat Hospital of Fudan University, Shanghai Medical College of Fudan University, Shanghai, China
| | - Yanzhe Huang
- Department of Anesthesiology, The Eye, Ear, Nose and Throat Hospital of Fudan University, Shanghai Medical College of Fudan University, Shanghai, China
| | - Chunbo Hu
- Department of Anesthesiology, The Eye, Ear, Nose and Throat Hospital of Fudan University, Shanghai Medical College of Fudan University, Shanghai, China
| | - Xia Shen
- Department of Anesthesiology, The Eye, Ear, Nose and Throat Hospital of Fudan University, Shanghai Medical College of Fudan University, Shanghai, China.
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Lieberman JA, Lyon R, Jasiukaitis P, Berven SH, Burch S, Feiner J. The reliability of motor evoked potentials to predict dorsiflexion injuries during lumbosacral deformity surgery: importance of multiple myotomal monitoring. Spine J 2019; 19:377-385. [PMID: 30025994 DOI: 10.1016/j.spinee.2018.07.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 07/08/2018] [Accepted: 07/09/2018] [Indexed: 02/03/2023]
Abstract
STUDY DESIGN Case-control analysis of transcranial motor evoked potential (MEP) responses and clinical outcome. OBJECTIVE To determine the sensitivity and specificity of MEPs to predict isolated nerve root injury causing dorsiflexion weakness in selected patients having complex lumbar spine surgery. SUMMARY OF BACKGROUND DATA The surgical correction of distal lumbar spine deformity involves significant risk for damage to neural structures that control muscles of ankle and toe dorsiflexion. Procedures often include vertebral translation, interbody fusion, and posterior-based osteotomies. The benefit of using MEP monitoring to predict dorsiflexion weakness has not been well-established. The purpose of this paper is to describe the relationship between neural complications from lumbar surgery and intraoperative MEP changes. METHODS Included were 542 neurologically intact patients who underwent posterior spinal fusion for the correction of distal lumbar deformity. Two myotomes, including tibialis anterior (TA) and extensor hallucis longus (EHL), were monitored. MEP and free-running electromyography data were assessed in each patient. Cases of new dorsiflexion weakness noted postoperatively were identified. Data in case and control patients were compared. There was no direct funding for this work. The Department of Anesthesiology and Perioperative Care provides salary support for authors one and six. Authors two and three report employment in the field of intraoperative neurophysiological monitoring as a study-specific conflict of interest. RESULTS Twenty-five patients (cases) developed dorsiflexion weakness. MEP amplitude decreased in the injured myotomes by an average of 65 ± 21% (TA) and 60±26% (EHL), which was significantly greater than the contralateral uninjured side or for control subjects. (p < .01) Receiver operator characteristic (ROC) curves showed high sensitivity, specificity, and predictive value for changes in MEP amplitude using either the TA or EHL. Analysis of MEP changes to either TA or EHL yielded a superior ROC curve. Net reclassification improvement analysis showed assessing MEP changes to both TA and EHL improved the predictability of injury. CONCLUSIONS The use of MEP amplitude change is highly sensitive and specific to predict a new postoperative dorsiflexion injury. Monitoring two myotomes (both TA and EHL) is superior to relying on MEP changes from a single myotome. Electromyography activity was less accurate but compliments MEP use. Additional studies are needed to define optimal intraoperative MEP warning thresholds.
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Affiliation(s)
- Jeremy A Lieberman
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA 94143, USA.
| | - Russ Lyon
- Division of Operating Room Services, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Paul Jasiukaitis
- Division of Operating Room Services, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Sigurd H Berven
- Department of Orthopedic Surgery, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Shane Burch
- Department of Orthopedic Surgery, University of California, San Francisco, San Francisco, CA 94143, USA
| | - John Feiner
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA 94143, USA
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Ansó J, Scheidegger O, Wimmer W, Gavaghan K, Gerber N, Schneider D, Hermann J, Rathgeb C, Dür C, Rösler KM, Mantokoudis G, Caversaccio M, Weber S. Neuromonitoring During Robotic Cochlear Implantation: Initial Clinical Experience. Ann Biomed Eng 2018; 46:1568-1581. [PMID: 30051248 DOI: 10.1007/s10439-018-2094-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 07/11/2018] [Indexed: 10/28/2022]
Abstract
During robotic cochlear implantation a drill trajectory often passes at submillimeter distances from the facial nerve due to close lying critical anatomy of the temporal bone. Additional intraoperative safety mechanisms are thus required to ensure preservation of this vital structure in case of unexpected navigation system error. Electromyography based nerve monitoring is widely used to aid surgeons in localizing vital nerve structures at risk of injury during surgery. However, state of the art neuromonitoring systems, are unable to discriminate facial nerve proximity within submillimeter ranges. Previous work demonstrated the feasibility of utilizing combinations of monopolar and bipolar stimulation threshold measurements to discretize facial nerve proximity with greater sensitivity and specificity, enabling discrimination between safe (> 0.4 mm) and unsafe (< 0.1 mm) trajectories during robotic cochlear implantation (in vivo animal model). Herein, initial clinical validation of the determined stimulation protocol and nerve proximity analysis integrated into an image guided system for safety measurement is presented. Stimulation thresholds and corresponding nerve proximity values previously determined from an animal model have been validated in a first-in-man clinical trial of robotic cochlear implantation. Measurements performed automatically at preoperatively defined distances from the facial nerve were used to determine safety of the drill trajectory intraoperatively. The presented system and automated analysis correctly determined sufficient safety distance margins (> 0.4 mm) to the facial nerve in all cases.
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Affiliation(s)
- Juan Ansó
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland
| | | | - Wilhelm Wimmer
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland. .,Department of Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland.
| | - Kate Gavaghan
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland
| | - Nicolas Gerber
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland
| | - Daniel Schneider
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland
| | - Jan Hermann
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland
| | - Christoph Rathgeb
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland
| | - Cilgia Dür
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland.,Department of Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland
| | - Kai Michael Rösler
- Department of Neurology, Inselspital, University of Bern, Bern, Switzerland
| | - Georgios Mantokoudis
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland.,Department of Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland
| | - Marco Caversaccio
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland.,Department of Head and Neck Surgery, Inselspital, University of Bern, Bern, Switzerland
| | - Stefan Weber
- ARTORG Center for Biomedical Engineering, University of Bern, Murtenstrasse 50, 3008, Bern, Switzerland
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Woo EJ, DiCuccio MN. Clinically significant pedicle screw malposition is an underestimated cause of radiculopathy. Spine J 2018; 18:1166-1171. [PMID: 29221759 DOI: 10.1016/j.spinee.2017.11.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Revised: 10/13/2017] [Accepted: 11/02/2017] [Indexed: 02/03/2023]
Affiliation(s)
- Emily Jane Woo
- Center for Biologics Evaluation and Research, US Food and Drug Administration, 10903 New Hampshire Ave, Silver Spring, MD 20993, USA.
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Utility of Intraoperative Neuromonitoring for Lumbar Pedicle Screw Placement Is Questionable: A Review of 9957 Cases. Spine (Phila Pa 1976) 2017; 42:1006-1010. [PMID: 27851660 PMCID: PMC5552371 DOI: 10.1097/brs.0000000000001980] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A retrospective database study. OBJECTIVE The goal of this study was to (1) evaluate the trends in the use of electromyography (EMG) for instrumented posterolateral lumbar fusions (PLFs) in the United States and (2) assess the risk of neurological injury following PLFs with and without EMG. SUMMARY OF BACKGROUND DATA Neurologic injuries from iatrogenic pedicle wall breaches during screw placement are known complications of PLFs. The routine use of intraoperative neuromonitoring (ION) such as EMG during PLF to improve the accuracy and safety of pedicle screw implantation remains controversial. METHODS A retrospective review was performed using the PearlDiver Database to identify patients who had PLF surgery with and without EMG for lumbar disorders from years 2007 to 2015. Patients undergoing concomitant interbody fusions or spinal deformity surgery were excluded. Demographic trends and risk of neurological injuries were assessed. RESULTS During the study period, 2007 to 2015, 9957 patients underwent PLFs. Overall, EMG was used in 2495 (25.1%) of these patients. There was a steady increase in the use of EMG from 14.9% in 2007 to 28.7% in 2009, followed by a steady decrease to 21.9% in 2015 (P < 0.0001). The risk of postoperative neurological injuries following PLFs was 1.35% (134/9957) with a risk of 1.36% (34/2495) with EMG and 1.34% (100/7462) without EMG (P = 0.932). EMG is used most commonly for PLFs in the Southern part of the United States. CONCLUSION In this retrospective national database review, we found that there was a steady increase in the routine use of EMG for PLFs followed by a steady decline. Regional differences were observed in the utility of EMG for PLFs. The risk of neurological complications following PLF in the absence of spinal deformity is low and the routine use of EMG for PLF may not decrease the risk. LEVEL OF EVIDENCE 4.
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Pearlman RC, Isley MR, Ganley JC. Electrical Artifact During Intraoperative Electromyographic Neuromonitoring. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/1086508x.2008.11079668] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Ronald C. Pearlman
- Department of Communication Sciences and Disorders Howard University Washington, D. C
| | - Michael R. Isley
- Intraoperative Neuromonitoring Department Orlando Regional Medical Center Orlando, Florida
| | - Jason C. Ganley
- Department of Chemical Engineering Howard University Washington, D. C
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8
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Isley MR, Pearlman RC, Wadsworth JS. Recent Advances in Intraoperative Neuromonitoring of Spinal Cord Function: Pedicle Screw Stimulation Techniques. ACTA ACUST UNITED AC 2015. [DOI: 10.1080/1086508x.1997.11079176] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Michael R. Isley
- Intraoperative Neuromonitoring Department Orlando Regional Medical Center Orlando, Florida
| | | | - James S. Wadsworth
- Intraoperative Neuromonitoring Department Orlando Regional Medical Center Orlando, Florida
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Abstract
Both remote monitoring and nearby/available care models depend on waveform telemetry (a limited form of telemedicine) during intraoperative neurophysiological monitoring (IONM). These dominant models neither mandate preoperative patient contact nor assume co-practitioner collegiality. This review and commentary argues in favor of a routine, normative relationship between the patient and the IONM physician/professional (IONM-P). Similarly, normal collegial relations should be established and maintained over time between the IONM-P and fellow co-practitioners (the proceduralist and the anesthesiologist). This professional practice "upgrade" places the IONM-P in a much stronger bioethical position among peers (and third party reviewers of the field and its practices). This "upgrade" also improves the likelihood that correct context-driven decisions will be made by the co-practitioners (IONM-P, proceduralist, and anesthesiologist) during complex multimodality monitoring. Most current models of IONM can be accommodated by readily available telemedicine-mediated videoconferencing. Several lines of argument are used to support this "patient-centered care model" of IONM.
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10
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van der Heide B, Bourgoin C, Eils G, Garnevall B, Blackmore M. Test-Retest Reliability and Face Validity of a Modified Neural Tissue Provocation Test in Patients with Cervicobrachial Pain Syndrome. J Man Manip Ther 2013. [DOI: 10.1179/106698106790820863] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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11
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Muscle relaxant use during intraoperative neurophysiologic monitoring. J Clin Monit Comput 2012; 27:35-46. [DOI: 10.1007/s10877-012-9399-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 09/15/2012] [Indexed: 12/17/2022]
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12
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García PC, Pérez MH, Lorensu PP, Rodríguez BD, Hernández PS, Rodrigo ÁA. Valor predictivo de la estimulación eléctrica de los tornillos pediculares torácicos en la mal posición medial de los mismos en la instrumentación de cirugía de columna. COLUNA/COLUMNA 2012. [DOI: 10.1590/s1808-18512012000200018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJETIVO: Demostrar si la técnica de estimulación eléctrica permite la detección de la mal posición medial de los tornillos pediculares torácicos. RESULTADOS: Se analizaron 421 tornillos torácicos. Tuvimos alertas a la estimulación en 25 (5,93%) de los casos. A todos los pacientes se les realizó radiografía posoperatoria demostrando 22 tornillos (5,2%) medializados. Realizamos TAC en 17 pacientes (37%), con ningún tornillo en posición 1 y 10 tornillos en posición 2 (8,5%). Se consideraron tornillos medializados los que tenían respuesta positiva a estimulación inferior a 6 mA. CONCLUSIONES: la estimulación eléctrica nos ha permitido reducir el riesgo de posición medial de los tornillos torácicos, minimizando además el uso de radiografía intraoperatoria.
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13
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Bevevino AJ, Lehman RA. Commentary: Electromyographic thresholds for stimulated thoracic pedicle screws are influenced by multiple factors. Spine J 2012; 12:133-5. [PMID: 22405615 DOI: 10.1016/j.spinee.2012.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 01/05/2012] [Indexed: 02/03/2023]
Affiliation(s)
- Adam J Bevevino
- Integrated Department of Orthopaedic Surgery and Rehabilitation, Walter Reed National Military Medical Center, 8901 Wisconsin Ave. NW, Bethesda, MD 20889, USA
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Samdani AF, Tantorski M, Cahill PJ, Ranade A, Koch S, Clements DH, Betz RR, Asghar J. Triggered electromyography for placement of thoracic pedicle screws: is it reliable? 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 2010; 20:869-74. [PMID: 21170665 DOI: 10.1007/s00586-010-1653-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 09/03/2010] [Accepted: 12/05/2010] [Indexed: 11/28/2022]
Abstract
Reliable electromyography (EMG) thresholds for detecting medial breaches in the thoracic spine are lacking, and there is a paucity of reports evaluating this modality in patients with adolescent idiopathic scoliosis (AIS). This retrospective analysis evaluates the ability of triggered EMG to detect medial breaches with thoracic pedicle screws in patients with AIS. We reviewed 50 patients (937 pedicle screws) undergoing posterior spinal fusion (PSF) with intraoperative EMG testing. Postoperative CT scans were used for breach identification, and EMG values were analyzed. There were 47 medial breaches noted with a mean threshold stimulus of 10.2 mA (milliamperes). Only 8/47 breaches stimulated at 2-6 mA. Thirteen of the forty-seven screws tested at an EMG value ≤6 mA and/or a decrease of ≥65% compared with intraosseously placed screws. The sensitivity and positive predictive value for EMG was 0.28 and 0.21. A subanalysis of T10-T12 screws identified six of seven medial breaches. Using guidelines from the current literature, EMG does not appear to be reliable in detecting medial breaches from T2 to T9 but may have some utility from T10 to T12.
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Affiliation(s)
- Amer F Samdani
- Shriners Hospitals for Children, 3551 N Broad Street, Philadelphia, PA 19140, USA.
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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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Wang MY, Pineiro G, Mummaneni PV. Stimulus-evoked electromyography testing of percutaneous pedicle screws for the detection of pedicle breaches: a clinical study of 409 screws in 93 patients. J Neurosurg Spine 2010; 13:600-5. [DOI: 10.3171/2010.5.spine09536] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Percutaneous pedicle screws have recently become popularized for lumbar spinal fixation. However, successful anatomical hardware placement is highly dependent on intraoperative imaging. In traditional open surgery, stimulus-evoked electromyography (EMG) responses can be useful for detecting pedicle screw breaches. The use of insulated sleeves for percutaneous screws has allowed for EMG testing in minimally invasive surgery; however, no reports on the reliability of this testing modality have been published.
Methods
A total of 409 lumbar percutaneous pedicle screws were placed in 93 patients. Levels of instrumentation included L-1 (in 12 patients), L-2 (in 34), L-3 (in 44), L-4 (in 120), L-5 (in 142), and S-1 (in 57 patients). Intraoperative EMG stimulation thresholds were obtained using insulating sleeves over a metallic tap prior to final screw placement. Data were compared with postoperative fine-cut CT scans to assess pedicle screw placement. Data were collected prospectively and analyzed retrospectively.
Results
There were 5 pedicle breaches (3 medial and 2 lateral; 3 Grade 1 and 2 Grade 2 breaches) visualized on postoperative CT scans (1.2%). Two of these breaches were symptomatic. In 2 instances, intraoperative thresholds were the sole basis for screw trajectory readjustment, which resulted in proper placement on postoperative imaging. Thirty-five screw trajectories were associated with a threshold of less than 12 mA. However, all breaches were associated with thresholds of greater than 12 mA. Using thresholds below 12 mA as the indicator of a screw breach, this resulted in a sensitivity of 0.0, specificity of 90.3, positive predictive value of 0.0, and negative predictive value of 0.98. Utilizing a threshold of any decreased stimulus (< 20 mA) would have detected 60% of breaches, with a mean threshold of 16.25 mA.
Conclusions
While these data are limited by the low number of radiographic breaches, it appears that tap stimulation with an insulating sleeve may not be reliable for detecting low-grade radiographically breached pedicles using typical stimulation thresholds (< 12 mA). Imaging-based modalities remain more reliable for assessing percutaneous pedicle screw trajectories until more robust and sensitive electrophysiological testing methods can be devised.
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Affiliation(s)
- Michael Y. Wang
- 1Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida; and
| | - Guillermo Pineiro
- 1Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida; and
| | - Praveen V. Mummaneni
- 2Department of Neurological Surgery, University of California, San Francisco, California
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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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18
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Skinner SA, Transfeldt EE, Savik K. Surface Electrodes Are Not Sufficient To Detect Neurotonic Discharges: Observations In A Porcine Model And Clinical Review Of Deltoid Electromyographic Monitoring Using Multiple Electrodes. J Clin Monit Comput 2008; 22:131-9. [DOI: 10.1007/s10877-008-9114-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2007] [Accepted: 02/27/2008] [Indexed: 01/02/2023]
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Chappuis JL, Johnson G. Using intraoperative electrophysiologic monitoring as a diagnostic tool for determining levels to decompress in the cervical spine: a case report. ACTA ACUST UNITED AC 2007; 20:403-7. [PMID: 17607108 DOI: 10.1097/bsd.0b013e31803755d5] [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: 11/25/2022]
Abstract
OBJECTIVE This report describes the clinical usefulness of using intraoperative electrophysiologic monitoring as a diagnostic tool for determining levels to decompress in the cervical spine. METHODS A 59-year-old man was experiencing intractable neck and left upper extremity pain after sustaining a second spinal injury. (The patient had previously undergone an anterior cervical discectomy and fusion at C5-C6 with plating to treat injuries from a motor vehicle accident.) On examination, he had no motor changes but did have pain in his left upper extremity and numbness of the left thumb and index finger. A myelogram and postmyelogram computed tomography scan revealed a disc herniation at C4-C5 with severe neural foraminal disease on the left side of C4-C5 and residual posterior osteophytes with questionable neuroforaminal stenosis on the left side of C5-C6. Routine electrophysiologic studies showed mild irritation of the left biceps (left C5-C6 nerve root), indicating radiculopathy. The patient was admitted with plans to undergo plate removal, exploration of the fusion at C5-C6, and an anterior cervical discectomy with foraminotomies and fusion at C4-C5. Continuous free-running electromyography was recorded during the surgical procedures. RESULTS The surgery was performed as planned; however, the irritation observed at C5-C6 did not subside. Relying on this information, as an extension of the patient's history and physical examination, a decision was made to remove the previous fusion at C5-C6 and to explore the left C6 root. A very tight neural foramen was found at this level. After decompression and foraminotomy, no electrophysiologic activity above baseline was recorded at C5-C6. The patient was then fused and plated from C4 to C6, and awoke with no left upper extremity pain. Neurologic examination was normal immediately after surgery and at 3 months follow-up. CONCLUSIONS Intraoperative, continuous free-running electromyography proved clinically effective in determining the course of surgery.
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Affiliation(s)
- James L Chappuis
- Orthopaedic and Spine Surgery of Atlanta LLC, Atlanta, GA 30327, USA.
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Magit DP, Hilibrand AS, Kirk J, Rechtine G, Albert TJ, Vaccaro AR, Simpson AK, Grauer JN. Questionnaire Study of Neuromonitoring Availability and Usage for Spine Surgery. ACTA ACUST UNITED AC 2007; 20:282-9. [PMID: 17538352 DOI: 10.1097/01.bsd.0000211286.98895.ea] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
STUDY DESIGN Questionnaire study presented to practicing spine surgeons. OBJECTIVE To evaluate surgeon preference and availability of selected electrophysiologic neuromonitoring for different spine surgeries. SUMMARY OF BACKGROUND DATA Maximizing the safety of spinal procedures and limiting potential iatrogenic neurologic injury has made intraoperative neuromonitoring an attractive option. METHODS We distributed a questionnaire to 180 orthopedic spine surgeons and neurosurgeons at a clinically oriented spine meeting asking surgeon preference and availability of various types of intraoperative neuromonitoring modalities for different types of surgical procedures. Demographic data were also gathered. RESULTS Somatosensory evoked potentials (SSEPs) were the most available neuromonitoring modality, followed by electromyographies and motor-evoked potentials. In both anterior and posterior cervical surgery, SSEPs were the most preferred modality. MEPs were frequently preferred in myelopathic cervical cases. Almost 70% preferred some neuromonitoring for anterior thoracic/thoracolumbar cases and 55% for posterior thoracic/thoracolumbar cases. Surgeon satisfaction was related to the number of available neuromonitoring modalities. No significant differences were found between orthopedist and neurosurgeon preferences. Fellowship-trained surgeons were more likely to use neuromonitoring for specific indications. CONCLUSIONS SSEPs remains the most widely available and preferred type of neuromonitoring for spine surgeons. The type of case and neurologic status of patient (eg, presence of myelopathy) affects these choices. Surgeons were more satisfied with greater neuromonitoring availability, and were more likely to use neuromonitoring if they had a fellowship background.
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Affiliation(s)
- David P Magit
- Department of Orthopaedics and Rehabilitation, Yale University School of Medicine, PO Box 208071, New Haven, CT 065120-8071, USA
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21
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Yamazaki T, Matsudaira K. Diathermy testing: a novel method with electric knife stimulation to avoid nerve injuries during lumbar pedicle screw placement. J Neurosurg Spine 2007; 6:479-84. [PMID: 17542518 DOI: 10.3171/spi.2007.6.5.479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
✓ The purpose of this retrospective study was to demonstrate the utility of diathermy in avoiding nerve injuries due to misplacement of lumbar pedicle screws (PSs).
The authors used diathermy to assess whether a screw deviated from the pedicle by observing synchronous leg movements caused by intermittently touching an electric knife to the pedicular instrument. Diathermy was performed in 259 cases in which 1301 PSs had been placed. Leg movements were observed in 36 cases, and the sensitivity of diathermy was 85.7%, with a specificity of 99.5%. No neurological complications associated with the placement of PSs were observed after adding diathermy testing to conventional methods.
Diathermy testing may be a way to avoid nerve injuries during lumbar PS placement.
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Affiliation(s)
- Takashi Yamazaki
- Department of Orthopedics, Musashino Red Cross Hospital, Tokyo, Japan.
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22
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Bindal RK, Ghosh S. Intraoperative electromyography monitoring in minimally invasive transforaminal lumbar interbody fusion. J Neurosurg Spine 2007; 6:126-32. [PMID: 17330579 DOI: 10.3171/spi.2007.6.2.126] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Minimally invasive transforaminal lumbar interbody fusion (TLIF) is an increasingly popular method for achieving lumbar decompression and fusion. The procedure is technically more demanding than open fusion, with correspondingly more theoretical risk of complication. The authors describe the use of intraoperative electromyography (EMG) as an adjunct to surgery to reduce the risk of complications.
Methods
Between August 2005 and April 2006, 25 consecutive patients underwent minimally invasive TLIF in which a total of 105 pedicle screws were placed. Intraoperative EMG was performed and included passive recordings during decompression and interbody graft placement, as well as active recording during the placement of the pedicle access needle and testing of the pedicle tap. A uniform protocol for active monitoring was used, with the pedicle access needle set at 7 mA. To assess hardware placement, all patients underwent postoperative radiography and 20 underwent postoperative computed tomography (CT) scanning.
In no patient did the authors observe significant EMG activation during decompression. In five cases, intermittent nerve root firing was noted after the interbody graft was placed, but this did not correlate with any postoperative deficits. Using the active stimulation protocol, 76.2% of screw placements required one or more changes to the trajectory of the pedicle access needle. With successful placement of the pedicle access needle, in all 105 screws, the pedicle tap nerve root stimulation threshold was greater than 15 mA. Postoperative radiography was performed in all patients and CT scanning was performed in 20 patients (with 85 screws being placed). Postoperative imaging revealed only three cases of pedicle breach. In all cases, the breach was at the lateral wall of the pedicle and not thought to be clinically relevant.
Conclusions
A continuous stimulation pedicle access needle alerts the surgeon to incorrect medial trajectories and may lead to safer pedicle cannulation. As a result of electrophysiological feedback, the pedicle access needle trajectory was altered in 76.2% of the reported cases. The use of the authors’ protocol resulted in a 0% incidence of clinically relevant malpositioned hardware and a low overall neurological complication rate. Intraoperative nerve root monitoring is a useful adjunct to minimally invasive TLIF.
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Affiliation(s)
- Rajesh K Bindal
- Department of Neurosurgery, Baylor College of Medicine, Houston, Texas 77478, USA.
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Leppanen RE. Intraoperative Monitoring of Segmental Spinal Nerve Root Function with Free-Run and Electrically-Triggered Electromyography and Spinal Cord Function with Reflexes and F-Responses. J Clin Monit Comput 2006; 19:437-61. [PMID: 16437295 DOI: 10.1007/s10877-005-0086-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2005] [Revised: 06/14/2005] [Accepted: 06/16/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND CONTEXT Orthodromic ascending somatosensory evoked potentials and antidromic descending neurogenic somatosensory evoked potentials monitor spinal cord sensory function. Transcranial motor stimulation monitors spinal cord motor function but only activates 4-5% of the motor units innervating a muscle. Therefore, 95-96% of the motor spinal cord systems activating the motor units are not monitored. To provide more comprehensive monitoring, 11 techniques have been developed to monitor motor nerve root and spinal cord motor function. These techniques include: 1. neuromuscular junction monitoring, 2. recording free-run electromyography (EMG) for monitoring segmental spinal nerve root function, 3. electrical stimulation to help determine the correct placement of pedicle screws, 4. electrical impedance testing to help determine the correct placement of pedicle screws, 5. electrical stimulation of motor spinal nerve roots, 6. electrical stimulation to help determine the correct placement of iliosacral screws, 7. recording H-reflexes, 8. recording F-responses, 9. recording the sacral reflex, 10. recording intralimb and interlimb reflexes and 11. recording monosynaptic and polysynaptic reflexes during dorsal root rhizotomy. OBJECTIVE This paper is the position statement of the American Society of Neurophysiological Monitoring. It is the practice guideline for the intraoperative use of these 11 techniques. METHODS This statement is based on information presented at scientific meetings, published in the current scientific and clinical literature, and presented in previously-published guidelines and position statements of various clinical societies. RESULTS These 11 techniques when used in conjunction with somatosensory and transcranial motor evoked potentials provide a multiple-systems approach to spinal cord and nerve root monitoring. CONCLUSIONS The techniques reviewed in this paper may be helpful to those wishing to incorporate these techniques into their monitoring program.
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Affiliation(s)
- Ronald E Leppanen
- Knoxville Neurology Clinic, 939 Emerald Avenue, Suite 907, Knoxville, Tennessee 37917, USA.
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Resnick DK, Choudhri TF, Dailey AT, Groff MW, Khoo L, Matz PG, Mummaneni P, Watters WC, Wang J, Walters BC, Hadley MN. Guidelines for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 15: electrophysiological monitoring and lumbar fusion. J Neurosurg Spine 2005; 2:725-32. [PMID: 16028743 DOI: 10.3171/spi.2005.2.6.0725] [Citation(s) in RCA: 34] [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
Based on the medical evidence provided by the literature reviewed, there does not appear to be support for the hypothesis that any form of intraoperative monitoring improves patient outcomes following lumbar decompression or fusion procedures for degenerative spinal disease. Evidence does indicate that a normal evoked EMG response is predictive for intrapedicular screw placement (high NPV for breakout). The presence of an abnormal EMG response does not, however, exclude intrapedicular screw placement (low PPV). The majority of clinically apparent postoperative nerve injuries are associated with intraoperative changes in SSEP and/or DSEP monitoring. For this reason, changes in DSEP/SSEP monitoring appear to be sensitive to nerve root injury. There is a high-false positive rate, however, and changes in DSEP and SSEP recordings are frequently not related to nerve injury. A normal study has been shown to correlate with the lack of a significant postoperative nerve injury. There is no substantial evidence to indicate that the use of intraoperative monitoring of any kind provides useful information to the surgeon in terms of assessing the adequacy of nerve root decompression at the time of surgery.
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Affiliation(s)
- Daniel K Resnick
- Department of Neurosurgery, University of Wisconsin Medical School, Madison, Wisconsin 53792, USA.
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Krassioukov AV, Sarjeant R, Arkia H, Fehlings MG. Multimodality intraoperative monitoring during complex lumbosacral procedures: indications, techniques, and long-term follow-up review of 61 consecutive cases. J Neurosurg Spine 2004; 1:243-53. [PMID: 15478361 DOI: 10.3171/spi.2004.1.3.0243] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The purpose of this study was to examine the neurological outcomes after complex lumbosacral surgery in patients undergoing multimodality neurophysiological monitoring. METHODS Sixty-one patients were consecutively enrolled in this study. These patients underwent complex intra- and extradural lumbosacral procedures with concomitant intraoperative electromyography (EMG) monitoring of the lower-limb muscles, external anal and urethral sphincters (EAS and EUS), and lower-limb somatosensory evoked potentials (SSEPs). Long-term (minimum 2-year) clinical follow-up data were obtained in all cases. Most patients were treated for spinal/spinal cord tumors (61%) or adult tethered cord syndrome (25%). Recordable lower-extremity SSEPs were reported in 54 patients (89%). New postoperative neurological deficits occurred in only three patients (4.9%), and remained persistent in only one patient (1.6%) at long-term follow-up examination. In only one of these cases was a significant decrease in SSEP amplitude detected. Spontaneous EMG activity was observed in the lower-extremity muscles and/or EAS and EUS in 51 cases (84%). Intraoperatively, EMG demonstrated activity only in the EUS in 5% of patients and only in the EAS in 28%. In seven patients (11%) spontaneous intraoperative EMG activity was observed in both the EAS and the EUS; however, in only three of these cases was EMG activity recorded in both sphincters simultaneously. In addition to spontaneously recorded EMG activity, electrically evoked EMG activity was also used as an intraoperative adjunct. A bipolar stimulating electrode was used to identify functional neural tissue before undertaking microsurgical dissection in 58 individuals (95%). In the majority of these patients, evoked EMG activity occurred either in one (33%) or in two muscles (9%) simultaneously. The presence of electrically evoked EMG activity in structures encountered during microdissection altered the plan of treatment in 24 cases (42%). CONCLUSIONS The authors conclude that the combined SSEP and EMG monitoring of lower-limb muscles, EAS, and EUS is a practical and reliable method for obtaining optimal electrophysiological feedback during complex neurosurgical procedures involving the conus medullaris and cauda equina. Analysis of the results indicates that these intraoperative adjunctive modalities positively influence decision making with regard to microsurgery and reduce the risk of perioperative neurological complications. Validation of the clinical value of these approaches, however, will require further assessment in a larger prospective cohort of patients.
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Abstract
The rapid advances in the technology of, and accumulation of pertinent data in, electrophysiological testing has increased exponentially in the past decade. This is attributable to continued advances in computer technology, biomedical engineering, and now the coregistration of the electrophysiological data with neuroimaging results. Knowledge of normal function and electrophysiological response at rest or on stimulation of the central and peripheral nervous systems is important to the neurosurgeon. Only by a basic understanding of normal and abnormal recordings may diagnoses and localizations be achieved. Intraspinal and intracranial surgical procedures are predicated on nontrauma to the neuraxis. This can be accomplished by performing electrophysiological testing to monitor the function of the spinal and cranial nerves, spinal cord, brainstem, basal ganglia, and cerebrum. If the surgeon cannot delineate critical cortex or pathways, he or she will be unable to avoid these areas in the patient.
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Affiliation(s)
- Richard M Lehman
- Department of Surgery, Division of Neurosurgery, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Brunswick, New Jersey 08901, USA.
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27
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Gunnarsson T, Krassioukov AV, Sarjeant R, Fehlings MG. Real-time continuous intraoperative electromyographic and somatosensory evoked potential recordings in spinal surgery: correlation of clinical and electrophysiologic findings in a prospective, consecutive series of 213 cases. Spine (Phila Pa 1976) 2004; 29:677-84. [PMID: 15014279 DOI: 10.1097/01.brs.0000115144.30607.e9] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Retrospective analysis of a prospectively accrued series of 213 consecutive patients who underwent intraoperative neurophysiologic monitoring with electromyography and somatosensory-evoked potentials during thoracolumbar spine surgery. OBJECTIVES To study the incidence of significant intraoperative electrophysiologic changes and new postoperative neurologic deficits. SUMMARY OF BACKGROUND DATA Continuous intraoperative electromyography and somatosensory-evoked potentials are frequently used in spinal surgery to prevent neural injury. However, only limited data are available on the sensitivity, specificity, and predictive values of intraoperative electrophysiologic changes with regard to the occurrence of new postoperative neurologic deficits. METHODS We examined data on patients who underwent intraoperative monitoring with continuous lower limb electromyography and somatosensory-evoked potentials. The analysis focused on the correlation of intraoperative electrophysiologic changes with the development of new neurologic deficits. RESULTS A total of 213 patients underwent surgery on a total of 378 levels; 32.4% underwent an instrumented fusion. Significant electromyograph activation was observed in 77.5% of the patients and significant somatosensory-evoked potential changes in 6.6%. Fourteen patients (6.6%) had new postoperative neurologic symptoms. Of those, all had significant electromyograph activation, but only 4 had significant somatosensory-evoked potential changes. Intraoperative electromyograph activation had a sensitivity of 100% and a specificity of 23.7% for the detection of a new postoperative neurologic deficit. Somatosensory-evoked potentials had a sensitivity of 28.6% and specificity of 94.7%. CONCLUSIONS Intraoperative electromyographic activation has a high sensitivity for the detection of a newpostoperative neurologic deficit but a low specificity. In contrast, somatosensory-evoked potentials have low sensitivity but high specificity. Combined intraoperative neurophysiologic monitoring with electromyography and somatosensory-evoked potentials is helpful for predicting and possibly preventing neurologic injury during thoracolumbar spine surgery.
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Affiliation(s)
- Thorsteinn Gunnarsson
- Division of Neurosurgery, University of Toronto, Krembil Neuroscience Center, Toronto Western Hospital, Canada
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28
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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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29
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Jou IM, Hsu CC, Chern TC, Chen WY, Dau YC. Spinal somatosensory evoked potential evaluation of acute nerve-root injury associated with pedicle-screw placement procedures: an experimental study. J Orthop Res 2003; 21:365-72. [PMID: 12568971 DOI: 10.1016/s0736-0266(02)00135-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Pedicle screws for spinal fixation risk neural damage because of the proximity between screw and nerve root. We assessed whether spinal somatosensory evoked potential (SSEP) could selectively detect pedicle-screw-related acute isolated nerve injury. Because pedicle screws are too large for a rat's spine, we inserted a K-wire close to the pedicle in 32 rats, intending not to injure the nerve root in eight (controls), and to injure the L4 or L5 root in 24. We used sciatic-nerve-elicited SSEP pre- and postinsertion. Radiologic, histologic, and postmortem observations confirmed the level and degree of root injury. Sciatic (SFI), tibial (TFI), and peroneal function indices (PFI) were calculated and correlated with changes in potential. Although not specific for injuries to different roots, amplitude reduction immediately postinsertion was significant in the experimental groups. Animals with the offending wire left in place for one hour showed a further non-significant deterioration of amplitude. Electrophysiologic changes correlated with SFI and histologic findings in all groups. SSEP monitoring provided reliable, useful diagnostic and intraoperative information about the functional integrity of single nerve-root injury. These findings are clinically relevant to acute nerve-root injury and pedicle-screw insertion. If a nerve-root irritant remains in place, a considerable neurologic deficit will occur.
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Affiliation(s)
- I-Ming Jou
- Department of Orthopaedics, College of Medicine, National Cheng Kung University Hospital, 138 Sheng-Li Road, Tainan 704, Taiwan, ROC.
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30
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Abstract
Intraoperative electromyography (EMG) provides useful diagnostic and prognostic information during spine and peripheral nerve surgeries. The basic techniques include free-running EMG, stimulus-triggered EMG, and intraoperative nerve conduction studies. These techniques can be used to monitor nerve roots during spine surgeries, the facial nerve during cerebellopontine angle surgeries, and peripheral nerves during brachial plexus exploration and repair. However, there are a number of technical limitations that can cause false-positive or false-negative results, and these must be recognized and avoided when possible. The author reviews these basic electrophysiologic techniques, how they are applied to specific surgical situations, and their limitations.
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31
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Pring ME, Trousdale RT, Cabanela ME, Harper CM. Intraoperative electromyographic monitoring during periacetabular osteotomy. Clin Orthop Relat Res 2002:158-64. [PMID: 12072758 DOI: 10.1097/00003086-200207000-00020] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Periacetabular osteotomy has become the procedure of choice in many centers for the treatment of symptomatic hip dysplasia. Intraoperative real-time nerve monitoring has been advocated during acetabular fracture repair and complex total hip arthroplasties to prevent iatrogenic sciatic nerve injury. To the authors' knowledge there is no information concerning the use of intraoperative electromyographic monitoring during periacetabular osteotomy. The purpose of the current study was to investigate the use of intraoperative continuous electromyographic monitoring during periacetabular osteotomy in a relatively large consecutive series of patients as a mechanism to prevent nerve injury during surgery and as a prognostic indicator of neurologic function after periacetabular osteotomy. From September 1992 to July 1999, 140 consecutive periacetabular osteotomies were done in 127 patients at the authors' institution. There were 96 females and 31 males, with an average age of 32 years at the time of surgery. All patients had intraoperative electromyographic monitoring of femoral and sciatic innervated muscles. All patients were followed up for a minimum of 1 year, until complete resolution of neurologic deficits, or both. Thirty-six patients (26%) had abnormal electromyographic activity recorded during surgery. Seven patients (5%) had peroneal nerve deficits postoperatively including extensor hallucis longus and tibialis anterior weakness with loss of sensation in the first web space. Abnormal electromyographic activity was observed intraoperatively in five of the seven patients with postoperative deficits. Six of the seven injuries resolved completely. One patient with intraoperative electromyographic activity (0.7%) had a postoperative foot drop that persisted for greater than 1 year. There were no femoral, tibial, or obturator nerve deficits observed. Electromyographic monitoring appears to provide prediction of postoperative neurologic deficit.
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Affiliation(s)
- Maya E Pring
- Mayo Clinic and Foundation, 200 First Street SW, Rochester, MN 55905, 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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Abstract
The author describes application of intraoperative neurophysiologic monitoring to surgical treatment of lumbar stenosis. Benefits of somatosensory and motor evoked potential studies during surgical correction of spinal deformity are well known and documented. Free-running and evoked electromyographic studies during pedicle screw implantation is an accepted practice at many institutions. However, the functional integrity of spinal cord, cauda equina, and nerve roots should be monitored throughout every stage of surgery including exposure and decompression. Somatosensory evoked potentials monitor overall spinal cord function. Intraoperative electromyography provides continuous assessment of motor root function in response to direct and indirect surgical manipulation. Electromyographic activities observed during exposure and decompression of the lumbosacral spine included complex patterns of bursting and neurotonic discharge. In addition, electromyographic activities at distal musculature were elicited by impacting a surgical instrument or graft plug against bony elements of the spine. All electromyographic events provided direct feedback to the surgical team and were regarded as a cause for concern. Simultaneously monitored evoked potential and electromyographic studies protect spinal cord and nerve roots during seemingly low-risk phases of a surgical procedure when neurologic injury may occur and the patient is placed at risk for postoperative myelopathy or radiculopathy.
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Affiliation(s)
- D S Weiss
- Department of Orthopedics, Lenox Hill Hospital, New York, NY, USA
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34
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Minahan RE, Riley LH, Lukaczyk T, Cohen DB, Kostuik JP. The effect of neuromuscular blockade on pedicle screw stimulation thresholds. Spine (Phila Pa 1976) 2000; 25:2526-30. [PMID: 11013506 DOI: 10.1097/00007632-200010010-00016] [Citation(s) in RCA: 31] [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 Nerve root stimulation thresholds were studied relative to the level of neuromuscular blockade in patients undergoing lumbar decompression surgery. OBJECTIVES To determine what levels of intraoperative neuromuscular blockade can be used during pedicle screw stimulation. BACKGROUND DATA Previous studies of intraoperative pedicle screw stimulation thresholds have failed to determine the effect of neuromuscular blockade on the stimulation threshold. METHODS Twenty-one roots in 10 patients undergoing lumbar decompression surgery were studied at different levels of neuromuscular blockade. Ninety-five nerve root thresholds were determined relative to level of blockade. RESULTS Neuromuscular blockade below 80% provides nerve root thresholds similar to thresholds without blockade. CONCLUSIONS Neuromuscular blockade should be less than 80% when using pedicle screw electrical stimulation testing.
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Affiliation(s)
- R E Minahan
- Department of Neurology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, USA
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35
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Obi T, Mochizuki M, Isobe K, Mizoguchi K, Takatsu M, Nishimura Y. Mechanically elicited nerve root discharge: mechanical irritation and waveform. Acta Neurol Scand 1999; 100:185-8. [PMID: 10478583 DOI: 10.1111/j.1600-0404.1999.tb00736.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Intraoperative monitoring is very important for protecting nerve roots during lumbar surgery for spinal degeneration. Our objective was to evaluate the correlation between the type of mechanical irritation and waveform by mechanically elicited EMGs during the surgery. METHOD Mechanically elicited EMGs were recorded bilaterally on muscle groups innervated by the lumbar nerve roots in the area of surgery in 24 consecutive patients with lumbar spinal degenerative disease. RESULTS It was confirmed that surgical irritation produced 3 types of waveforms as discharges from nerve roots; short, waning and continuous discharges. Each waveform was easily elicited mechanically and was sensitively related to the type and strength of mechanical stimulation. CONCLUSION It was indicated that the mechanical irritation on the root could elicit the nerve root discharge with no post-operative nerve root deficit. It may be useful to monitor the mechanically elicited EMGs during the surgery for spinal degeneration.
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Affiliation(s)
- T Obi
- Department of Neurology, National Shizuoka Hospital, Japan
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36
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Abstract
The intraoperative application of evoked potential and electromyographic (EMG) monitoring has increased significantly over the last 2 decades. Cranial nerve monitoring is widely accepted and used by otologists, neurologic surgeons, and ophthalmologists. Direct and indirect techniques for assessing the peripheral nervous system are used by plastic and orthopedic surgeons when performing intraoperative nerve grafting. Myriad techniques and applications for monitoring the spinal cord and peripheral nervous system have been developed, evaluated, and used by orthopedic and neurologic surgeons involved in spinal surgery.
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Affiliation(s)
- A M Padberg
- Electrophysiologic Monitoring Services, BJC Health Care System, Department of Orthopaedic Surgery, Washington University Medical Center, St. Louis, Missouri 63110, USA
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37
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Abstract
Intraoperative electromyography can provide useful information regarding lumbosacral nerve root function during thoracolumbar spinal surgery. Free-running electromyography provides continuous feedback regarding the location and potential for surgical injury to the lumbosacral nerve roots within the operative field. Stimulus-evoked electromyography can confirm that transpedicular instrumentation has been positioned correctly within the bony cortex. However, electromyography has a number of potential limitations, which are discussed in this article along with improved methods to increase the overall efficacy of intraoperative electromyography, including: 1) Electromyography is sensitive to blunt lumbosacral nerve root irritation or injury, but may provide misleading results with "clean" nerve root transection. 2) Electromyography must be recorded from muscles belonging to myotomes appropriate for the nerve roots considered at risk from surgery. 3) Electromyography can be effective only with careful monitoring and titration of pharmacologic neuromuscular junction blockade. 4) When transpedicular instrumentation is stimulated, an exposed nerve root should be stimulated directly as a positive control whenever possible. 5) Pedicle holes and screws should be stimulated with single shocks at low-stimulus intensities when pharmacologic neuromuscular blockade is excessive. 6) Chronically compressed nerve roots that have undergone axonotmesis (wallerian degeneration) have higher thresholds for activation from electrical and mechanical stimulation. 7) Hence, whenever axonotmetic nerve root injury is suspected, the stimulus thresholds for transpedicular holes and screws must be specifically compared with those required for the direct activation of the adjacent nerve root (and not published guideline threshold values).
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Affiliation(s)
- N R Holland
- Department of Neurology, University of Oklahoma Health Sciences Center, Oklahoma City, USA
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38
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Jou IM, Lai KA. Neuromonitoring of an experimental model of clip compression on the spinal nerve root to characterize acute nerve root injury. Spine (Phila Pa 1976) 1998; 23:932-9; discussion 939-40. [PMID: 9580962 DOI: 10.1097/00007632-199804150-00017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES To evaluate the sensitivity of an electro-monitoring method in acute nerve root injury, and to determine a proposed criterion for irreversible electrophysiologic degradation. STUDY DESIGN Acute nerve root injury was induced by a clip compression model in rabbits, mimicking nerve root injury by a transpedicular screw. A common neuromonitoring technique, spinal somatosensory-evoked potential, was used to study the electrophysiologic change during the procedure. SUMMARY OF BACKGROUND DATA With the advent of the transpedicular screw system, increased risk of injury to the spinal root because of the passage of screws is not unexpected. Although both an experimental model and a clinical application in intraoperative neuromonitoring of spinal cord function have been established, the value of neuromonitoring of an acute spinal root injury remains obscure. Several neurophysiologic surveillance techniques have been used successfully to monitor the potential injury to the spinal cord during orthopedic procedures around the spinal cord and spinal column. Spinal somatosensory-evoked potential, which has the advantages of high amplitude and quick recording time, is used to detect nerve root impairment during the insertion of transpedicular screws. METHODS Experimental acute nerve root injury was induced in rabbits by direct hemostatic clip compression on the nerve root (S1) during different time intervals. Spinal somatosensory-evoked potential elicited by stimulating the sciatic nerve and recorded from a needle electrode at the L6-L7 interspinous ligament was monitored immediately before and after compression. RESULTS Spinal somatosensory-evoked potential is sensitive enough to detect the compromise of a single nerve root and that a decrease in the amplitude is the most reliable and sensitive sign. With this model, there was a statistically significant correlation between the compression time and reduction of amplitude and delay of latency. The criterion for irreversible electrophysiologic change was an amplitude loss of more than 20% and a delay in latency immediately after nerve root compression. CONCLUSIONS It was concluded that spinal somatosensory-evoked potential can provide immediate feedback of nerve root injury and should be considered for use during the dynamic phase of transpedicular screw insertion.
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Affiliation(s)
- I M Jou
- Department of Orthopedics, National Cheng-Kung University Hospital, Tainan, Taiwan, Republic of China
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39
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Darden BV, Owen JH, Hatley MK, Kostuik J, Tooke SM. A comparison of impedance and electromyogram measurements in detecting the presence of pedicle wall breakthrough. Spine (Phila Pa 1976) 1998; 23:256-62. [PMID: 9474735 DOI: 10.1097/00007632-199801150-00022] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
STUDY DESIGN A prospective comparison of impedance measurements, electrically elicited electromyograms, and mechanically elicited electromyograms to detect pedicle wall breakthrough. OBJECTIVE To determine whether impedance measurements are as sensitive as electromyogram measurements in evaluating pedicle wall breakthrough. SUMMARY OF BACKGROUND DATA In a previous animal study, impedance values in pedicle screw placement were tested, to determine a baseline value for an intact pedicle. If pedicle wall breakthrough occurred, it was thought that the impedance values should be significantly lower. METHODS Impedance measurements, electrically elicited electromyograms and mechanically elicited electromyograms were recorded in 20 patients undergoing surgery for spinal degeneration, using previously described standard protocol. Analysis of variance statistics were used to evaluate the data. RESULTS Impedance values for the pedicle holes varied from 500 ohms to 31,000 ohms. There was no correlation between these values and those of the two pedicles in which breaches were detected on visual inspection. Electrically elicited electromyograms detected the breakthroughs in both pedicles, whereas mechanically elicited electromyograms detected one of the breakthroughs. CONCLUSIONS Electrically elicited electromyograms were more sensitive in detecting pedicle wall breakthrough than were impedance measurements. This may be because of the inability to ascribe absolute impedance values to human pedicle bone caused by the wide variability in bone quality.
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Affiliation(s)
- B V Darden
- Charlotte Spine Center, North Carolina, USA
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40
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Holland NR, Kostuik JP. Continuous electromyographic monitoring to detect nerve root injury during thoracolumbar scoliosis surgery. Spine (Phila Pa 1976) 1997; 22:2547-50. [PMID: 9383863 DOI: 10.1097/00007632-199711010-00016] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
STUDY DESIGN The results of intraoperative monitoring during a case of nerve root injury sustained from scoliosis surgery to the thoracolumbar spine are described. OBJECTIVES To improve the efficacy of intraoperative monitoring in preventing nerve root injury during scoliosis surgery. SUMMARY OF BACKGROUND DATA Posterior tibial nerve somatosensory-evoked potentials are the electrophysiologic modality most commonly used for spinal cord monitoring during thoracolumbar spine surgery. Although radiculopathy is a more frequent postoperative complication than myelopathy, monitoring of mixed-nerve, somatosensory-evoked potentials may not detect injuries to individual nerve roots. METHODS The patient described in this report developed left L5 radiculopathy after scoliosis surgery to the thoracolumbar spine. During surgery, intraoperative electromyographic monitoring identified frequent trains of neurotonic discharges in the left anterior tibial muscle. Bilateral, posterior, tibial nerve, somatosensory-evoked potentials remained normal. The left L5 nerve root was explored 9 days after the original surgery and was found to be compressed by bony structures. Electrophysiologic testing showed that the nerve root had undergone significant Wallerian degeneration, but remained in partial continuity. RESULTS Nerve root injury was detected by neurotonic discharges identified during intraoperative electromyographic monitoring, but not by somatosensory-evoked potentials, which remained normal. When the injured nerve root was explored, a simple electromyographic technique was used to characterize the extent and type of injury. CONCLUSIONS The authors of this study recommend electromyographic monitoring of appropriate lumbosacral myotomes in addition to somatosensory-evoked potentials during this type of procedure.
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Affiliation(s)
- N R Holland
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland, USA
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Clements DH, Morledge DE, Martin WH, Betz RR. Evoked and spontaneous electromyography to evaluate lumbosacral pedicle screw placement. Spine (Phila Pa 1976) 1996; 21:600-4. [PMID: 8852316 DOI: 10.1097/00007632-199603010-00013] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
STUDY DESIGN A prospective study was performed to evaluate the effectiveness of evoked and spontaneous electromyography in predicting pedicle wall breakthrough and subsequent lumbar radiculopathy occurring after placement of pedicle screw instrumentation of the lumbar spine. OBJECTIVES To correlate cortical breakthrough of the pedicle wall with an electrically evoked electromyography threshold of stimulation, to assess the sensitivity of mechanically evoked electromyography for nerve root irritation, and to correlate postoperative nerve root irritation with intraoperative findings. SUMMARY OF BACKGROUND DATA Pedicle wall breakthrough has been evaluated by radiographic means and found to be difficult to evaluate. Methods to perform both electrically evoked and mechanically evoked electromyography have been developed more sensitive tests for breakthrough. METHODS Twenty-five patients receiving 112 pedicle screws were evaluated. RESULTS Cortical breakthrough was associated with electrically evoked electromyography threshold of less than 11 milliAmps. Not all screws that had broken through the pedicle wall caused a postoperative radiculopathy. Electromyographic activity was sensitive to nerve root stimulation. CONCLUSIONS Measuring the electrically evoked electromyography threshold of stimulation helps to assess pedicle screw placement. Mechanically evoked electromyography indicates intraoperative nerve root displacement. Postoperative radiculopathy correlated with pedicle wall breakthrough, but did not occur in every case.
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Affiliation(s)
- D H Clements
- Department of Orthopaedic Surgery, Temple University Hospital, Philadelphia, Pennsylvania, USA
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