This course is self-paced and open to registration at any time. The course includes reading assignments and exams that are open book. The course has an additional week added to the end of the course to complete the final exam. The course is authored by Leisha Osburn, MEd, R EEG/EP T, CNIM, D ABNM. Course Instructor is Ryan Lau, BA, R EEG/EP T, CNIM, CLTM. Some of the articles for reading must be resourced by the participant but a link in included for locating and purchasing these articles online. Content is in the form of PDF downloads within the course. Some articles are also needed to complete reading assignments and if you do not have access to a library where you may be able to find or download the articles, a link to PUB-MED is provided where you can download the articles for a fee. If you have questions regarding the course, please contact Maggie at: firstname.lastname@example.org
This course is open for registration throughout the year. You will be given one year to complete the contents. If you follow the scheduled outline, you should complete your course in aprox. three months. This is an intermediate level course. This course is to introduce neuromonitoring professionals to transcranial electrical motor evoked potential monitoring, various methods, and a historical perspective. This course requires a basic knowledge of IONM practices and procedures. Professionals taking this course should have taken IONM 100-101 or have extensive experience in intraoperative neuromonitoring. 20 ACE credits are given for successful completion of this course.
Getting Started With TCeMEP
Leisha Osburn, MEd, R EEG/EP T, CNIM, CLTM, D ABNM
Instructor: Ryan Lau, MS, R EEG/EP T, CNIM, CLTM
Course Goal: This course will instruct the participant in the history and development of the current practices of TCeMEP, the usefulness in IONM, how TCeMEPs work, the basics of stimulating and recording, special considerations in anesthesia and patient safety, application of TCeMEP. The course also includes a review of case studies and problem solving exercises.
Lesson 1 Introduction to TCeMEP
Recognize why you should add TCeMEPs to your monitoring regime including:
- State what types of IONM monitor motor pathways in the spinal cord.
- Know the general locations (anterior, lateral, posterior) of SEP, ‘NMEP’, TCeMEP, and TCmMEP pathways.
- Explain orthodromic and antidromic, as applied to neural signals.
- State the direction of orthodromic voluntary motor pathways.
- State the direction of orthodromic somatosensory evoked potential pathways.
- Explain the direction a “NMEP” response travels.
- Know the primary blood supply for dorsal column pathways.
- Know the primary blood supply for voluntary motor pathways.
- Explain three ways that we know NMEPs do not monitor motor pathways.
- Explain how a magnetic field stimulates the motor cortex to produce TCmMEPs.
- Know the two most significant limitations of intraoperative TCmMEP monitoring.
- State the most significant limitation of SEP monitoring to predict post-operative motor function.
- Name two reasons that SEP responses can be present and unchanged, throughout a surgical procedure, despite the fact that motor pathways have sustained new damage.
- Discussion Question: 200-500 word summary of article from list:
- Chatrian G-E, Berger MS, Wirch AL. Discrepancy between intraoperative SSEP’s and Postoperative function. J Neurosurg 1988; 69: 450-54.
- Ginsberg HH, Shetter AG, Raudzens PA: Postoperative paraplegia with preserved intraoperative somatosensory evoked potentials: case report. J Neurosurg 1985; 63: 296-300.
- Kiers L, Cros D, Chiappa KH, et al: Variability of motor potentials evoked by transcranial magnetic stimulation. Electroencephalogr Clin Neurophysiol 89: 415-423, 1993.
- Machida M, Weinstein SL, Yamada T, Kimura J, Toriyama S. Dissociation of muscle action potentials and spinal somatosensory evoked potentials after ischemic damage of spinal cord. Spine 1988; 13: 1119-24.
- Minahan et al., Anterior spinal cord injury with preserved neuogenic ‘motor’ evoked potentials. Clinical Neurophysiology 112: 1442-1450, 2001.
- Toleikis JR, Skelly JP, Carlvin AO, et al: Spinally elicited peripheral nerve responses are sensory rather than motor. Clinical Neurophysiology 2000; 111: 736-742.
- Wiedemayer H, Sandalcioglu IE, Armbruster W, Regel J, Schaefer H, Stolke D. False negative findings in intraoperative SEP monitoring: analysis of 658 consecutive neurosurgical cases and review of published reports. J Neurol Neurosurg Psychiatry, 75: 280-286, 2004.
- Zornow et al., (Preservation of evoked potentials in a case of anterior spinal artery syndrome. Electroencephalogr Clin Neurophysiol 77: 137-39, 1990.
Lesson 2 Spinal Anatomy
- Identify the number of cervical, thoracic, lumbar, sacral vertebra and coccyx
- Identify the anatomical parts of the human spine including:
- Spinous processes
- Vertebral body
- Vertebral canal
- Transverse processes
- Intervertebral foramen
- Cervical Vertebra
- Odontoid process
- Transverse foramen
- Thoracic Vertebra/Verbrae
- Lumbar Vertebra/Verbrae
- Vertebral canal
- Cerebrospinal fluid (CSF)
- Subarachnoid space
- Gray Matter
- White Matter
- Sensory and Motor Pathways
- Spinal Nerve Rood
- Dorsal and Ventral roots
- Posterior/Dorsal Columns
- Position sense or Proprioception
- Vibration sense
- Fasciculus Gracilis
- Fasciculus Cuneatus
- Ipsilateral and Contralateral
- Cervicomedullary junction
- Corticospinal tract
- Anterior and Posterior horns
- Conus Medullaris
- Filum Terminale
Lesson 3 Sensory and Motor Pathways
- Draw a detailed, labeled diagram showing the initiation and termination of the voluntary motor pathway that is monitored by TCeMEPs
- List the point(s) of decussation of this pathway
- Describe the anatomical arrangement of information carried in each portion of the pathway
- Compare and contrast the anatomical relationships between pathways monitored with TCeMEPs versus somatosensory evoked potentials (SEPs) versus electromyographic (EMG) monitoring
- Analyze the significance, as related to the monitoring, of the differences in the anatomical relationships between pathways monitored with TCeMEPs versus SEP versus EMG monitoring
Lesson 4 How do TCeMEPs Work?
- State the most common stimulating electrode placement for TCeMEPs.
- Name anatomical region initiates the signal after the TCeMEP stimulus is given.
- State is the polarity of the electrode that activates this anatomical region.
- Recite the path that the TCeMEP signal takes from its initiation to the production of the compound muscle action potential (CMAP).
- List all of the synapses along the pathway described above.
- State the composition of the signal that is initiated to single pulse stimulation of the motor cortex in the awake patient.
- Cite a specific effect that anesthetics have on this signal.
- Explain why the cited effect is significant to the successful recording of myogenic TCeMEPs.
- Explain why multi-pulse Transcranial stimulation can be successful in producing CMAPs even in anesthetized patients.
- Describe the type of signal recorded by epidural spinal recording electrodes after TCeMEP stimulation.
- Describe the type of signal recorded by recording electrodes placed in muscles of the extremities after TCeMEP stimulation.
- Compare and contrast the advantages and disadvantages of each.
Lesson 5 History of TCeMEP by Donald York, PhD
- Recognize the contributions throughout history that brought us to the use of TCeMEP in IONM including:
- 1874 Dr Bartholow - Stimulation to exposed cortex
- 1937 Penfield and Bouldery - Stimulation of exposed cortex to define of motor homunculus
- 1954 Gualtierotti and Paterson - Baboons contraction of facial muscles and neck
- 1970’s Milner and Brown et al. - Precentral stimulation in man, and refinements in baboon corticospinal neuron properties by Phillips and Porter
- 1980’s Many Advances - Digitimer, Queens Square Montage, etc.
- 1984 - Levy, York, McCaffrey and Tanzer - Transcranial stimulation of anesthetized humans
- 1985 - Machida, et al. - Epidural spinal stimulation
- 1988 - Jeff Owen MEP by spinal cord stimulation
- 1990’s - Edmonds et al., and Dvorak, Herdmann, et al. Magnetic stimulation
- 1991 - Sloan and Levin and in 1992 Kalkman, Drummond, et al. achieved good reproducible MEPs using propofol and etomidate ranter than gass anesthetics
- Recognize the use of spinal stimulation in Neurogenic Motor Evoked Potentials - NMEP, and that this is not an evoked potential
- Recognize that reliable TCeMEPs require no use of neuromuscular blockade
Lesson 6 Stimulation and Recording Protocols
- State common and modified positions for TCeMEP stimulating electrodes.
- Explain reasons for using these different stimulating positions and describe scenarios for using one derivation versus another.
- Specify which stimulating electrode is “active” for the production of the TCeMEP response.
- Describe 2 types of stimulating electrodes.
- Compare and contrast reasons for using one type of stimulating electrode versus another.
- Describe clinical conditions that may cause difficulty in delivering adequate stimulus to motor cortex to produce TCeMEPs.
- List common stimulus parameters used to produce TCeMEPs.
- Detail a plan for modifying stimulus parameters when initial parameters fail to produce myogenic TCeMEP responses in all extremities.
- Describe the “double train” stimulation technique and explain two scenarios when this technique may be beneficial in eliciting a response.
- List the category of muscles which have been found to be most optimal for recording reliable myogenic TCeMEP responses.
- Discuss the clinical evidence leading to the conclusion that this category of muscles is most optimal for myogenic TCeMEP monitoring.
- Recognize standard stimulus and recording parameters for common types of monitoring equipment.
- List common methods and electrode types for recording myogenic TCeMEPs.
- Detail montages for recording essential muscle groups for multiple types of surgical procedures.
Lesson 7 Special Consideration in TCeMEP
- List anesthetics and other drugs commonly used during surgical procedures
- For each type of anesthetic or drug, identify the effect it has on TCeMEP monitoring
- Formulate and defend the optimal anesthetic regime for TCeMEP monitoring
Lesson 8 Special Considerations Part II: The Safety of TCeMEP Monitoring
- List the risk factors involved in the performance of TCeMEPs
- Discuss the details of each risk factor
- Using your knowledge and currently published literature, discuss the potential harm to the patient for each risk factor
- List the special considerations involved in the performance of TCeMEPs
- Discuss the details of each special consideration
- Using your knowledge and currently published literature discuss the potential harm to the patient or affect upon the monitoring for each special consideration
- Detail a plan to take specific actions to deal with each of the special considerations and risk factors involved in the performance of TCeMEPs
- Defend that plan against other suggested methods of dealing with these issues.
Lesson 9 Application of TCeMEP and Alarm Criteria
- Give examples of the current schools of thought regarding the significance of various changes seen in TCeMEP waveforms
- Compare and contrast these differing schools of thought, citing the pros and cons of each
- For each school of thought, critically analyze the potential for harm, if that school of thought is followed, and turns out to be wrong. Illustrate this in terms of false positive and false negative TCeMEP findings
Lesson 10: Examine Case Studies
Lesson 11 TCeMEP Problem Based Learning Exercises
Lesson 12 Motor Evoked Potentials in IONM by Alan Legatt
Identify the purpose of MEP monitoring including:
- Limitations of SEP monitoring
Recognize the physiology of electrical brain stimulation including:
- Fiber tracts of the spinal cord
- Blood supply to the spinal cord
- Vascular territories within the spinal cord
Discuss the need to use multiple-pulse transcranial stimulation
Compare M-waves and D-waves
Identify recording techniques for Transcranial Motor Evoked Potentials including:
- Stimulation techniques
- Neurons and projections from the cerebral cortex
- Anodal vs Cathodal stimulation
- Current flows and Membrane Voltage
- Electrical Stimulation of Nerve Fibers
- Electrical Stimulation of Cortical Pyramidal Neuron
- TCMS largely elicits tangential currents in the brain
- Synapses within the Motor Pathways
- Cerebral Cortex
- Anterior Horn Cell
- Neuromuscular Junction
- Temporal summation of subthreshold EPSPs
- Identify the MEPs that can be monitored following TCES
- Stimulus trains
Recognize significant changes and alarm criteria for TCeMEP
- Run to run variability of Myogenic MEPs
- Interpretation of MEPs
- Dorsal column somatosensory system
Identify anesthetic considerations in TCeMEP
- Anesthetic management of TCeMEPs
- Effects of anesthetic agents
- Halogenated inhalational agents
- Nitrous oxide
- Neuromuscular Blockade
- Partial Neuromuscular Blockade
Recognize safety considerations during TCeMEP
- Tongue and lip injury
- Scalp burns
- Other complications
Identify reasons for the concurrent use of both sensory and motor evoked potentials
- SEPs and MEPs both stable 90%
- Adverse changes in both MEPs and SEPs 4.2%
- Adverse MEP changes and SEP stable 4.1%
- Adverse SEP but MEP stable 1.5%
- Ryan Lau, BA, R. EEG/EP T., CNIM, CLTM: Ryan Lau