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Vedran Deletis - One of the best experts on this subject based on the ideXlab platform.

  • the value of intraoperative Motor Evoked Potential monitoring during surgical intervention for thoracic idiopathic spinal cord herniation
    Journal of Neurosurgery, 2012
    Co-Authors: Klaus Novak, Georg Widhalm, Adauri Bueno De Camargo, Noel I Perin, George I Jallo, Engelbert Knosp, Vedran Deletis
    Abstract:

    Object Thoracic idiopathic spinal cord herniation (TISCH) is a rare neurological disorder characterized by an incarceration of the spinal cord at the site of a ventral dural defect. The disorder is associated with clinical signs of progressive thoracic myelopathy. Surgery can withhold the natural clinical course, but surgical repair of the dural defect bears a significant risk of additional postoperative Motor deficits, including permanent paraplegia. Intraoperative online information about the functional integrity of the spinal cord and warning signs about acute functional impairment of Motor pathways could contribute to a lower risk of permanent postoperative Motor deficit. Motor Evoked Potential (MEP) monitoring can instantly and reliably detect dysfunction of Motor pathways in the spinal cord. The authors have applied MEPs during intraoperative neurophysiological monitoring (IOM) for surgical repair of TISCH and have correlated the results of IOM with its influence on the surgical procedure and with t...

  • transcranial electric stimulation for intraoperative Motor Evoked Potential monitoring stimulation parameters and electrode montages
    Clinical Neurophysiology, 2007
    Co-Authors: Andrea Szelenyi, Karl F Kothbauer, Vedran Deletis
    Abstract:

    Abstract Objective To evaluate the efficacy of constant current transcranial electric stimulation (TES) parameters for eliciting muscle Motor Evoked Potentials (MEPs) in the abductor pollicis brevis muscles (APB) and the tibialis anterior muscles (TA). The following parameters were tested intraoperatively: interstimulus interval (ISI), individual stimulation pulse duration within a train of five stimuli. Different montages of stimulating electrodes were assessed for effectiveness and focality. Further, reference values for APB and TA Motor thresholds in neurosurgical patients with normal Motor status under total intravenous anesthesia were determined. Methods Motor thresholds of contralateral muscle MEPs were determined at 0.1, 0.2, 0.4, and 0.5 ms pulse duration and ISIs of 2, 3, 4, and 5 ms using a train of five monophasic constant current pulses with C3/C4 (27 patients). The stimulating electrodes were positioned at C1, C2, C3, C4, Cz, and Cz+6 cm. Different montages were used to determine the most effective and the most focal stimulation montages for the APB and TA muscles (30 patients). Eighty-six patients with clinically normal Motor function were studied for Motor threshold reference values. Results The prolongation of the pulse duration has the strongest effect to decrease the Motor threshold, which proportionally increases the delivered charge. The lowest stimulation threshold to elicit muscle MEPs in the APB and TA muscles is achieved with a train of stimuli consisting of an individual stimulus pulse duration of 0.5 ms. An ISI of 4 ms gave the lowest Motor thresholds, but did not reach statistical significance compared to 3 ms. The stimulating electrode montage C3/C4 (C4/C3) allows for the lowest stimulation thresholds, but the vigorous muscle contractions it has is a disadvantage. The most focal stimulating electrode montages for the contralateral APB muscles are C3/Cz and C4/Cz, respectively, and for the TA muscles Cz/Cz+6 cm. Conclusions In adult neurosurgical patients with a normal Motor status under total intravenous anesthesia, an individual pulse duration of 0.5 ms and an ISI of 4 ms provide the lowest Motor thresholds. Pragmatically, C1/C2, resp., C2/C1 montage provides monitorable responses in both APB and TA muscles at reasonable stimulation thresholds without inducing movements disturbing surgery and especially microdissection. If the most focal hemispheric stimulation for the distal upper extremity muscles is required, the use of C3 or C4 referenced to Cz is recommended. Significance The stimulation parameters within a train of five pulses with an individual pulse duration of 0.5 ms and an ISI of 4 ms provide the lowest Motor threshold. These data confirm not only studies for D wave recovery but also provide optimal stimulation parameters for intraoperative near threshold stimulation.

  • Motor Evoked Potential monitoring improves outcome after surgery for intramedullary spinal cord tumors a historical control study
    Neurosurgery, 2006
    Co-Authors: Francesco Sala, Vedran Deletis, Giorgio Palandri, Elisabetta Basso, P Lanteri, F Faccioli, Albino Bricolo
    Abstract:

    OBJECTIVE: The value of intraoperative neurophysiological monitoring (INM) during intramedullary spinal cord tumor surgery remains debated. This historical control study tests the hypothesis that INM monitoring improves neurological outcome. METHODS: In 50 patients operated on after September 2000, we monitored somatosensory Evoked Potentials and transcranially elicited epidural (D-wave) and muscle Motor Evoked Potentials (INM group). The historical control group consisted of 50 patients selected from among 301 patients who underwent intramedullary spinal cord tumor surgery, previously operated on by the same team without INM. Matching by preoperative neurological status (McCormick scale), histological findings, tumor location, and extent of removal were blind to outcome. A more than 50% somatosensory Evoked Potential amplitude decrement influenced only myelotomy. Muscle Motor Evoked Potential disappearance modified surgery, but more than 50% D-wave amplitude decrement was the major indication to stop surgery. The postoperative to preoperative McCormick grade variation at discharge and at a follow-up of at least 3 months was compared between the two groups (Student's t tests). RESULTS: Follow-up McCormick grade variation in the INM group (mean, +0.28) was significantly better (P = 0.0016) than that of the historical control group (mean, -0.16). At discharge, there was a trend (P = 0.1224) toward better McCormick grade variation in the INM group (mean, -0.26) than in the historical control group (mean, -0.5). CONCLUSION: The applied Motor Evoked Potential methods seem to improve long-term Motor outcome significantly. Early Motor outcome is similar because of transient Motor deficits in the INM group, which can be predicted at the end of surgery by the neurophysiological profile of patients.

  • Motor Evoked Potential monitoring for intramedullary spinal cord tumor surgery correlation of clinical and neurophysiological data in a series of 100 consecutive procedures
    Neurosurgical Focus, 1998
    Co-Authors: Karl F Kothbauer, Vedran Deletis, Fred Epstein
    Abstract:

    Resection of intramedullary spinal cord tumors carries a high risk for surgical damage to the Motor pathways. This surgery is therefore optimal for testing the performance of intraoperative Motor Evoked Potential (MEP) monitoring. This report attempts to provide evidence for the accurate representation of patients' pre- and postoperative Motor status by combined epidural and muscle MEP monitoring during intramedullary surgery. The authors used transcranial electrical Motor cortex stimulation to elicit MEPs, which were recorded from the spinal cord (with an epidural electrode) and from limb target muscles (thenar, anterior tibial) with needle electrodes. The amplitude of the epidural MEPs and the presence or absence of muscle MEPs were the parameters for MEP interpretation. A retrospective analysis was performed on data from the resection of 100 consecutive intramedullary tumors and MEP data were compared with the pre- and postoperative Motor status. Intraoperative monitoring was feasible in all patients without severe preoperative Motor deficits. Preoperatively paraplegic patients had no recordable MEPs. The sensitivity of muscle MEPs to detect postoperative Motor deficits was 100% and its specificity was 91%. There was no instance in which a patient with stable MEPs developed a Motor deficit postoperatively. Intraoperative MEPs adequately represented the Motor status of patients undergoing surgery for intramedullary tumors. Because deterioration of the Motor status was transient in all cases, it can be considered that impairment of the functional integrity of the Motor pathways was detected before permanent deficits occurred.

  • Motor Evoked Potential monitoring for intramedullary spinal cord tumor surgery correlation of clinical and neurophysiological data in a series of 100 consecutive procedures
    Neurosurgical Focus, 1998
    Co-Authors: Karl F Kothbauer, Vedran Deletis, Fred J Epstein
    Abstract:

    Resection of intramedullary spinal cord tumors carries a high risk for surgical damage to the Motor pathways. This surgery is therefore optimal for testing the performance of intraoperative Motor Evoked Potential (MEP) monitoring. This report attempts to provide evidence for the accurate representation of patients' pre- and postoperative Motor status by combined epidural and muscle MEP monitoring during intramedullary surgery. The authors used transcranial electrical Motor cortex stimulation to elicit MEPs, which were recorded from the spinal cord (with an epidural electrode) and from limb target muscles (thenar, anterior tibial) with needle electrodes. The amplitude of the epidural MEPs and the presence or absence of muscle MEPs were the parameters for MEP interpretation. A retrospective analysis was performed on data from the resection of 100 consecutive intramedullary tumors and MEP data were compared with the pre- and postoperative Motor status. Intraoperative monitoring was feasible in all patients w...

David B Macdonald - One of the best experts on this subject based on the ideXlab platform.

  • Safety of intraoperative transcranial electrical stimulation Motor Evoked Potential monitoring
    2014
    Co-Authors: David B Macdonald
    Abstract:

    Motor Evoked Potential (MEP) monitoring safety based on comparison with other clinical and experimental brain stimulation methods and clinical experience in more than 15,000 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 othe

  • intraoperative Motor Evoked Potential monitoring a position statement by the american society of neurophysiological monitoring
    Clinical Neurophysiology, 2013
    Co-Authors: David B Macdonald, Stanley A Skinner, Jay L Shils, Charles D Yingling
    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.

  • four limb muscle Motor Evoked Potential and optimized somatosensory Evoked Potential monitoring with decussation assessment results in 206 thoracolumbar spine surgeries
    European Spine Journal, 2007
    Co-Authors: David B Macdonald, Zayed Al Zayed, Abdulmoneam Al Saddigi
    Abstract:

    The objective of this study was to improve upon leg somatosensory-Evoked Potential (SEP) monitoring that halves paraplegia risk but can be slow, miss or falsely imply Motor injury and omits arm and decussation assessment. We applied four-limb transcranial muscle Motor-Evoked Potential (MEP) and optimized peripheral/cortical SEP monitoring with decussation assessment in 206 thoracolumbar spine surgeries under propofol/opioid anesthesia. SEPs were optimized to minimal averaging time that determined feedback intervals between MEP/SEP sets. Generalized changes defined systemic alterations. Focal decrements (MEP disappearance and/or clear SEP reduction) defined neural compromise and prompted intervention. They were transient (quickly resolved) or protracted (>40 min). Arm and leg MEP/SEP monitorability was 100% and 98/97% (due to neurological pathology). Decussation assessment disclosed sensoriMotor non-decussation requiring ipsilateral monitoring in six scoliosis surgeries (2.9%). Feedback intervals were 1–3 min. Systemic changes never produced injury regardless of degree. They were gradual, commonly included MEP/SEP fade and sometimes required large stimulus increments to maintain MEPs or produced >50% SEP reductions. Focal decrements were abrupt; their positive predictive value for injury was 100% when protracted and 13% when transient. Six transient arm decrements predicted one temporary radial nerve injury; five suggested arm neural injury prevention (2.4%). There were 15 leg decrements: six MEP-only, four MEP before SEP, three simultaneous and two SEP-only. Five were protracted, predicting four temporary cord injuries (three Motor, one Brown–Sequard) and one temporary radiculopathy. Ten were transient, predicting one temporary sensory cord injury; nine suggested cord injury prevention (4.4%). Two radiculopathies and one temporary delayed paraparesis were unpredicted. The methods are reliable, provide technical/systemic control, adapt to non-decussation and improve spinal cord and arm neural protection. SEP optimization speeds feedback and MEPs should further reduce paraplegia risk. Radiculopathy and delayed paraparesis can evade prediction.

  • intraoperative facial Motor Evoked Potential monitoring with transcranial electrical stimulation during skull base surgery
    Clinical Neurophysiology, 2005
    Co-Authors: Charles Dong, David B Macdonald, Brian D Westerberg, Ryojo Akagami, Ahmed Alkhani, Imad Kanaan, Maher Hassounah
    Abstract:

    Abstract Objective : To address the limitations of standard electromyography (EMG) facial nerve monitoring techniques by exploring the novel application of multi-pulse transcranial electrical stimulation (mpTES) to myogenic facial Motor Evoked Potential (MEP) monitoring. Methods : In 76 patients undergoing skull base surgery, mpTES was delivered through electrodes 1cm anterior to C1 and C2 (M1–M2), C3 and C4 (M3–M4) or C3 or C4 and Cz (M3/M4–Mz), with the anode contralateral to the operative side. Facial MEPs were monitored from the orbicularis oris muscle on the operative side. Distal facial nerve excitation was excluded by the absence of single pulse responses and by onset latency consistent with a central origin. Results : M3/M4–Mz mpTES ( n =50) reliably produced facial MEPs while M1–M2 ( n =18) or M3–M4 ( n =8) stimulation produced 6 technical failures. Facial MEPs could be successfully monitored in 21 of 22 patients whose proximal facial nerves were inaccessible to direct stimulation. Using 50, 35 and 0% of baseline amplitude criteria, significant facial deficits were predicted with a sensitivity/specificity of 1.00/0.88, 0.91/0.97 and 0.64/1.00, respectively. Conclusions : Facial MEPs can provide an ongoing surgeon-independent assessment of facial nerve function and predict facial nerve outcome with sufficiently useful accuracy. Significance : This method substantially improves facial nerve monitoring during skull base surgery.

  • safety of intraoperative transcranial electrical stimulation Motor Evoked Potential monitoring
    Journal of Clinical Neurophysiology, 2002
    Co-Authors: David B Macdonald
    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 15,000 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.

Michael C Ridding - One of the best experts on this subject based on the ideXlab platform.

  • examining Motor Evoked Potential amplitude and short interval intracortical inhibition on the up going and down going phases of a transcranial alternating current stimulation tacs imposed alpha oscillation
    European Journal of Neuroscience, 2021
    Co-Authors: Annmaree Vallence, John C. Rothwell, Kathryn Dansie, Mitchell R Goldsworthy, Suzanne M Mcallister, Ruiting Yang, Michael C Ridding
    Abstract:

    Many brain regions exhibit rhythmical activity thought to reflect the summed behaviour of large populations of neurons. The endogenous alpha rhythm has been associated with phase-dependent modulation of corticospinal excitability. However, whether exogenous alpha rhythm, induced using transcranial alternating current stimulation (tACS) also has a phase-dependent effect on corticospinal excitability remains unknown. Here, we triggered transcranial magnetic stimuli (TMS) on the up- or down-going phase of a tACS-imposed alpha oscillation and measured Motor Evoked Potential (MEP) amplitude and short-interval intracortical inhibition (SICI). There was no significant difference in MEP amplitude or SICI when TMS was triggered on the up- or down-going phase of the tACS-imposed alpha oscillation. The current study provides no evidence of differences in corticospinal excitability or GABAergic inhibition when targeting the up-going (peak) and down-going (trough) phase of the tACS-imposed oscillation.

Yukihiko Fujii - One of the best experts on this subject based on the ideXlab platform.

  • p158 usefulness of cranial nerve Motor Evoked Potential monitoring during skull base surgery
    Clinical Neurophysiology, 2014
    Co-Authors: Masafumi Fukuda, Tetsuro Takao, T Hiraishi, Yukihiko Fujii
    Abstract:

    s of Poster Presentations / Clinical Neurophysiology 125, Supplement 1 (2014) S1–S339 S89 P158 Usefulness of cranial nerve Motor Evoked Potential monitoring during skull base surgery M. Fukuda, T. Takao, T. Hiraishi, Y. Fujii Brain Research Institute, University of Niigata, Department of Neurosurgery,

  • monitoring of abnormal muscle response and facial Motor Evoked Potential during microvascular decompression for hemifacial spasm
    Surgical Neurology International, 2012
    Co-Authors: Masafumi Fukuda, Makoto Oishi, Tetsuro Takao, Tetsuya Hiraishi, Yosuke Sato, Yukihiko Fujii
    Abstract:

    BACKGROUND To determine whether the monitoring of abnormal muscle response (AMR) and facial Motor Evoked Potential (FMEP) during microvascular decompression (MVD) for hemifacial spasm (HFS) might be useful for predicting the postoperative clinical course and final outcomes. METHODS We analyzed 45 HFS patients who underwent both AMR and FMEP monitoring during MVD. Patients were divided into two groups on the basis of post-MVD disappearance (group AMR-A) or persistence (group AMR-B) of AMR. With regard to FMEPs, patients were classified into one of the two groups according to the ratio of the final to baseline FMEP amplitudes recorded for the orbicularis oculi muscle: one group with a ratio of <50% (group FMEP-A), and the other with a ratio of ≥50% (group FMEP-B). RESULTS Twenty-one of the 26 (81%) patients in group AMR-A were assigned to group FMEP-A, whereas 9 of the 17 (53%) patients in group AMR-B were assigned to FMEP-B (P < 0.05). In 38 of the 40 (95%) patients in whom the AMRs disappeared or persisted at amplitudes <50% that at the baseline, HFS had subsided at the final follow-up. Forty of the 42 (95%) patients whose FMEP amplitude ratios indicated reduction in the amplitudes from the baseline, had complete relief of the symptoms. Nineteen of the 20 (95%) patients whose AMRs disappeared after MVD experienced immediate relief of their symptoms after the operation. With regard to 14 of the 20 (70%) patients whose AMRs persisted at the final recordings, the symptoms of HFS improved over time and eventually subsided (P < 0.001). CONCLUSIONS Intraoperative monitoring of both AMR and FMEP during MVD may be useful in predicting the postoperative outcomes in HFS patients. The AMR-related findings may help to predict whether HFS disappears immediately after surgery or some time later.

  • facial nerve Motor Evoked Potential monitoring during skull base surgery predicts facial nerve outcome
    Journal of Neurology Neurosurgery and Psychiatry, 2008
    Co-Authors: Masafumi Fukuda, Makoto Oishi, Tetsuro Takao, Akihiko Saito, Yukihiko Fujii
    Abstract:

    Objective: To determine whether monitoring facial nerve Motor-Evoked Potentials (FNMEPs) elicited by transcranial electrical stimulation during skull base tumour surgery is useful for predicting facial nerve outcome. Methods: This study analysed FNMEP findings in 26 patients with skull base tumours. Corkscrew electrodes positioned at C3 or C4 and Cz were used to deliver supramaximal stimuli (180–550 V). FNMEPs were recorded from the orbicularis oculi and oris muscles. The correlation between the final-to-baseline FNMEP ratio and postoperative facial nerve function was examined. Results: Postoperative facial nerve function correlated significantly with the FNMEP ratios in the orbicularis oculi (p = 0.004) and orbicularis oris (p 50%. Conclusions: Intraoperative FNMEP monitoring can be useful for predicting facial nerve function after skull base surgery. This new method is a valuable adjunct to conventional facial nerve monitoring.

Daniel M. Schwartz - One of the best experts on this subject based on the ideXlab platform.

  • transcranial electric Motor Evoked Potential monitoring during spine surgery is it safe
    Spine, 2011
    Co-Authors: Daniel M. Schwartz, A.s. Hilibrand, Alexander R Vaccaro, William C. Welch, Anthony K Sestokas, John P Dormans, John M Flynn, Mark P Li, Suken A Shah, Denis S Drummond
    Abstract:

    Study Design. Retrospective review. Objective. To report on the safety of repetitive transcranial electric stimulation (RTES) for eliciting Motor-Evoked Potentials during spine surgery. Summary of Background Data. Theoretical concerns over the safety of RTES have hindered broader acceptance of transcranial electric Motor-Evoked Potentials (tceMEP), despite successful implementation of spinal cord monitoring with tceMEPs in many large spine centers, as well as their apparent superiority over mixed-nerve somatosensory-Evoked Potentials (SSEP) for detection of spinal cord injury. Methods. The records of 18,862 consecutive patients who met inclusion criteria and underwent spine surgery with tceMEP monitoring were reviewed for RTES-related complications. Results. This large retrospective review identified only 26 (0.14%) cases with RTES-related complications; all but one of these were tongue lacerations, most of which were self-limiting. Conclusions. The results demonstrate that RTES is a highly safe modality for monitoring spinal cord Motor tract function intraoperatively.

  • transcranial electric Motor Evoked Potential detection of compressional peroneal nerve injury in the lateral decubitus position
    Journal of Clinical Monitoring and Computing, 2008
    Co-Authors: Vidya M Bhalodia, Anthony K Sestokas, Patrick R Tomak, Daniel M. Schwartz
    Abstract:

    The peroneal nerve is susceptible to injury due to compression at the fibular head for patients placed in the lithotomy, hemilithotomy or lateral decubitus positions during surgery. Upper extremity somatosensory and transcranial electric Motor Evoked Potential monitoring has proven efficacious for identifying impending positional brachial plexopathy or upper extremity peripheral neuropathy in adult and pediatric patients undergoing spine surgery. We report on two cases to illustrate the usefulness of monitoring transcranial electric Motor Evoked Potentials recorded from tibialis anterior muscle to identify emerging peroneal nerve compression secondary to lateral decubitus positioning.

  • comparison of transcranial electric Motor and somatosensory Evoked Potential monitoring during cervical spine surgery
    Journal of Bone and Joint Surgery American Volume, 2004
    Co-Authors: A.s. Hilibrand, Venkat Sethuraman, Daniel M. Schwartz, Alexander R Vaccaro, Todd J Albert
    Abstract:

    Background: There has been little enthusiasm for somatosensory Evoked Potential monitoring in cervical spine surgery as a result, in part, of the increased risk of Motor tract injury at this level, to which somatosensory monitoring may be insensitive. Transcranial electric Motor Evoked Potential monitoring allows assessment of the Motor tracts; therefore, we compared transcranial electric Motor Evoked Potential and somatosensory Evoked Potential monitoring during cervical spine surgery to determine the temporal relationship between the changes in the Potentials demonstrated by each type of monitoring and neurological sequelae and to identify patient-related and surgical factors associated with intraoperative neurophysiological changes. Methods: Somatosensory Evoked Potential and transcranial electric Motor Evoked Potential data recorded for 427 patients undergoing anterior or posterior cervical spine surgery between January 1999 and March 2001 were analyzed. All patients who showed substantial (at least 60%) or complete unilateral or bilateral amplitude loss, for at least ten minutes, during the transcranial electric Motor Evoked Potential and/or somatosensory Evoked Potential monitoring were identified. Results: Twelve of the 427 patients demonstrated substantial or complete loss of amplitude of the transcranial electric Motor Evoked Potentials. Ten of those patients had complete reversal of the loss following prompt intraoperative intervention, whereas two awoke with a new Motor deficit. Somatosensory Evoked Potential monitoring failed to identify any change in one of the two patients, and the change in the somatosensory Evoked Potentials lagged behind the change in the transcranial electric Motor Evoked Potentials by thirty-three minutes in the other. No patient showed loss of amplitude of the somatosensory Evoked Potentials in the absence of changes in the transcranial electric Motor Evoked Potentials. Transcranial electric Motor Evoked Potential monitoring was 100% sensitive and 100% specific, whereas somatosensory Evoked Potential monitoring was only 25% sensitive; it was, however, 100% specific. Conclusions: Transcranial electric Motor Evoked Potential monitoring appears to be superior to conventional somatosensory Evoked Potential monitoring for identifying evolving Motor tract injury during cervical spine surgery. Surgeons should strongly consider using this modality when operating on patients with cervical spondylotic myelopathy in general and on those with ossification of the posterior longitudinal ligament in particular. Level of Evidence: Diagnostic study, Level I-1 (testing of previously developed diagnostic criteria in series of consecutive patients [with universally applied reference “gold” standard]). See Instructions to Authors for a complete description of levels of evidence.