The Role of Intraoperative Neuromonitoring (IONM)

Comprehensive Care of Spine Pathologies, October 13, 2012Comprehensive Care of Spine Pathologies, October 13, 2012

The Role of Intraoperative NeuromonitoringThe Role of Intraoperative NeuromonitoringDavid Barnkow, AuD, DABNM, CNIMDavid Barnkow, AuD, DABNM, CNIM

Who? What? When? Where? Why? How?Who? What? When? Where? Why? How?

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Image Retrieved 9/11/2012 from: http://computingforsustainability.files.wordpress.com/2011/04/trolley-Image Retrieved 9/11/2012 from: http://computingforsustainability.files.wordpress.com/2011/04/trolley-problem.jpg, modified without permission.problem.jpg, modified without permission.

What?What?What’s the problem?What’s the problem?




Image Retrieved 9/11/2012 from: http://computingforsustainability.files.wordpress.com/2011/04/trolley-problem.jpg, Image Retrieved 9/11/2012 from: http://computingforsustainability.files.wordpress.com/2011/04/trolley-problem.jpg, modified without permission.modified without permission.




Iatrogenic injuryIatrogenic injury

Iatrogenic i·at·ro·gen·ic (ī-āt'r -jěn'ĭk) adj. əIatrogenic i·at·ro·gen·ic (ī-āt'r -jěn'ĭk) adj. əInduced in a patient by a physician's Induced in a patient by a physician's activity, manner, or therapy.activity, manner, or therapy.

The American Heritage® Stedman's Medical DictionaryThe American Heritage® Stedman's Medical DictionaryCopyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.




Iatrogenic neurological injury in spine surgery Iatrogenic neurological injury in spine surgery can be caused by:can be caused by:

SurgicalSurgicalDistraction, compression or blunt traumaDistraction, compression or blunt traumaIschemia of neural structuresIschemia of neural structuresThrombotic eventsThrombotic events

Anesthetic or Systemic ProblemsAnesthetic or Systemic ProblemsIschemia, Ischemia, hypoxiahypoxiahypothermiahypothermiacervical extension during intubationcervical extension during intubation

PositioningPositioningDirect compressionDirect compressionCompromised blood supplyCompromised blood supplyNeck and shoulder positioningNeck and shoulder positioning




What is the incidence of iatrogenic injury in elective spine What is the incidence of iatrogenic injury in elective spine surgery?surgery?

Iatrogenic neurological injuries in elective spinal surgery Iatrogenic neurological injuries in elective spinal surgery without neurophysiological monitoring:without neurophysiological monitoring:

Anterior cervical discectomy – 0.46%Anterior cervical discectomy – 0.46%Scoliosis correction - 0.23-3.2%Scoliosis correction - 0.23-3.2%Intramedullary tumor resection - >23.8%Intramedullary tumor resection - >23.8%

Vauzelle C, Stagnara P, Jouvinroux P. Functional monitoring of spinal cord activity during spinal surgery. Vauzelle C, Stagnara P, Jouvinroux P. Functional monitoring of spinal cord activity during spinal surgery.

Clin Orthop Relat Res 1973;93:173-8Clin Orthop Relat Res 1973;93:173-8



Why?Why?Why avoid iatrogenic injury?Why avoid iatrogenic injury?

To improve or maintain quality of life. To improve or maintain quality of life. (WHO - HRQOL)(WHO - HRQOL)

People with spinal cord injury (SCI):People with spinal cord injury (SCI):report lower sense of well-beingreport lower sense of well-beingscore lower on physical, mental, and social health score lower on physical, mental, and social health domainsdomains

Dijkers, M: Quality of life of individuals with spinal cord injury: A review of conceptualization, Dijkers, M: Quality of life of individuals with spinal cord injury: A review of conceptualization, measurement, and research findings. J. Rehab Res & Dev, Supplement Number 1, Volume 42 Number measurement, and research findings. J. Rehab Res & Dev, Supplement Number 1, Volume 42 Number 3, May/June 2005, Pages 87-110. Retrieved 9/11/12 from 3, May/June 2005, Pages 87-110. Retrieved 9/11/12 from

http://www.rehab.research.va.gov/jour/05/42/3suppl1/dijkers.htmlhttp://www.rehab.research.va.gov/jour/05/42/3suppl1/dijkers.html




To improve or maintain quality of life. (WHO – HRQOL)To improve or maintain quality of life. (WHO – HRQOL)

““Life expectancies for persons with SCI continue to Life expectancies for persons with SCI continue to increase, but are still somewhat below life expectancies increase, but are still somewhat below life expectancies for those with no SCI.”for those with no SCI.”

National Spinal Cord Injury Statistical Center, Birmingham, Alabama, Spinal Cord Injury Facts and Figures at a National Spinal Cord Injury Statistical Center, Birmingham, Alabama, Spinal Cord Injury Facts and Figures at a Glance, February 2012, retrieved 9/11/12 at Glance, February 2012, retrieved 9/11/12 at https://www.nscisc.uab.edu/PublicDocuments/fact_figures_docs/Facts%202012%20Feb%20Final.pdfhttps://www.nscisc.uab.edu/PublicDocuments/fact_figures_docs/Facts%202012%20Feb%20Final.pdf




Reduce the costs associated with iatrogenic injury.Reduce the costs associated with iatrogenic injury.

The average yearly health care and living expenses directly The average yearly health care and living expenses directly attributable to SCI was $69,204 in February 2012 dollars. attributable to SCI was $69,204 in February 2012 dollars. These figures do not include any indirect costs such as losses These figures do not include any indirect costs such as losses in wages, fringe benefits and productivity. in wages, fringe benefits and productivity.

National Spinal Cord Injury Statistical Center, Birmingham, Alabama, Spinal Cord Injury Facts and Figures at a Glance, National Spinal Cord Injury Statistical Center, Birmingham, Alabama, Spinal Cord Injury Facts and Figures at a Glance, February 2012, retrieved Sept. 11, 20112 at https://www.nscisc.uab.edu/PublicDocuments/fact_figures_docs/FactsFebruary 2012, retrieved Sept. 11, 20112 at https://www.nscisc.uab.edu/PublicDocuments/fact_figures_docs/Facts%202012%20Feb%20Final.pdf%202012%20Feb%20Final.pdf



How?How?How can we avoid iatrogenic injury?How can we avoid iatrogenic injury?

Timely detection of changes in Timely detection of changes in neurologic status allows neurologic status allows

therapeutic actiontherapeutic action to ameliorate to ameliorate or avoid neurologic deficitsor avoid neurologic deficits.



How?How?How can we detect changes in How can we detect changes in neurologic status?neurologic status?

Functional vs. Structural AssessmentFunctional vs. Structural AssessmentStructural AssessmentStructural Assessment

RadiographyRadiographySonographySonographyVisualizationVisualization



How?How?How can we detect changes in How can we detect changes in neurologic status?neurologic status?

Function AssessmentFunction Assessment Using provocative and non-provocative Using provocative and non-provocative techniques.techniques.

Intraoperative Neurophysiologic Monitoring Intraoperative Neurophysiologic Monitoring (IONM)(IONM)



How?How?How is IONM performed?How is IONM performed?

Electrophysiologic AssessmentsElectrophysiologic AssessmentsNon-ProvocativeNon-Provocative

Spontaneous electromyography (sEMG)Spontaneous electromyography (sEMG)Electroencephalography (EEG)Electroencephalography (EEG)

ProvocativeProvocativeTriggered electromyography (tEMG)Triggered electromyography (tEMG)Electroencephalography (EEG)Electroencephalography (EEG)Evoked Potentials (EP)Evoked Potentials (EP)Somatosensory (SSEP)Somatosensory (SSEP)Motor (MEP)Motor (MEP)Nerve Conduction Study (NCS)Nerve Conduction Study (NCS)



How?How?How effective is IONM?How effective is IONM?

Efficacy of IONM in Cervical Spine SurgeryEfficacy of IONM in Cervical Spine SurgerySomatosensory evoked potentialsSomatosensory evoked potentials

sensitivity - sensitivity - 52% (+ correctly ID'd)52% (+ correctly ID'd)specificity - specificity - 100% (- correctly ID'd)100% (- correctly ID'd)PPV - PPV - 100% (true +/+calls)100% (true +/+calls)NPV - NPV - 97% (true -/- calls)97% (true -/- calls)

Motor evoked potentialsMotor evoked potentialssensitivity - sensitivity - 100%100%specificity - specificity - 96%96%PPV - PPV - 96%96%NPV -NPV - 100%100%

ElectromyographyElectromyographysensitivity -sensitivity - 46%46%specificity - specificity - 73%73%PPV - PPV - 3%3%NPV -NPV - 97%97%

Kelleher MO, Tan G, Sarjeant R, Fehlings MG: Predictive value of intraoperative neurophysiological monitoring during cervical spine surgery: a prospective analysis Kelleher MO, Tan G, Sarjeant R, Fehlings MG: Predictive value of intraoperative neurophysiological monitoring during cervical spine surgery: a prospective analysis of 1055 consecutive patients. J Neurosurg Spine. 2008 Mar;8(3):215-21.of 1055 consecutive patients. J Neurosurg Spine. 2008 Mar;8(3):215-21.




Efficacy of IONM in Thorocolumbar Efficacy of IONM in Thorocolumbar Spine Surgery (nerve root emphasis)Spine Surgery (nerve root emphasis)

SSEPsSSEPssensitivity - sensitivity - 29%29%specificity - specificity - 95%95%

sEMGsEMGsensitivity - sensitivity - 100%100%specificity -specificity - 23.7%23.7%




Multimodal IONM reduces the relative risk of post-Multimodal IONM reduces the relative risk of post-operative neurological complications in spine surgery by an operative neurological complications in spine surgery by an estimated 49.4% at a mean cost of $63,387 per neurological estimated 49.4% at a mean cost of $63,387 per neurological deficit averted.deficit averted.

Ney JP, Van der Goes DN, Watanabe JH: Cost-effectiveness of intraoperative neurophysiological monitoring for spinal Ney JP, Van der Goes DN, Watanabe JH: Cost-effectiveness of intraoperative neurophysiological monitoring for spinal

surgeries: Beginning steps, Clinical Neurophysiology, Volume 123, Issue 9, Pages 1705-1707, September 2012surgeries: Beginning steps, Clinical Neurophysiology, Volume 123, Issue 9, Pages 1705-1707, September 2012



When?When?When is IONM appropriate?When is IONM appropriate?

Identify iatrogenic nervous system compromise in a Identify iatrogenic nervous system compromise in a timely fashion.timely fashion.

Ongoing monitoringOngoing monitoring

Identify neural structures through specific testing Identify neural structures through specific testing procedures.procedures.

Time-Specific assessmentTime-Specific assessment

Identify when iatrogenic injury occurred in Identify when iatrogenic injury occurred in experimental procedures.experimental procedures.

Ongoing monitoringOngoing monitoring



Where?Where?Where can IONM be performed?Where can IONM be performed?

On the hospital floorsOn the hospital floorsIn Pre-Op HoldingIn Pre-Op HoldingIn the Operating RoomIn the Operating Room



Who?Who?Who provides IONM?Who provides IONM?

Technologists – Technical ComponentTechnologists – Technical Component•Associate and Bachelor Degrees.Associate and Bachelor Degrees.•Trained in the technical aspects of data collection. Trained in the technical aspects of data collection. •Lack training and knowledge to provide Lack training and knowledge to provide interpretation, diagnosis and treatmentinterpretation, diagnosis and treatment

Credentials:Credentials:•ABRET - American Board of Registration of ABRET - American Board of Registration of Electroencephalographic and Evoked Potential Electroencephalographic and Evoked Potential Technologists Technologists •CNIM - Certificate in Neurophysiologic CNIM - Certificate in Neurophysiologic Intraoperative MonitoringIntraoperative Monitoring



Who?Who?

Who provides IONM?Who provides IONM?

Non-Physician Surgical Neurophysiologist – Professional Non-Physician Surgical Neurophysiologist – Professional ComponentComponent

•Non-MD providers with Doctorate Degrees.Non-MD providers with Doctorate Degrees.•Technical Support for CNIMs.Technical Support for CNIMs.•Technical ComponentTechnical Component•Site-specific credentials may allow:Site-specific credentials may allow:

Supervision dutiesSupervision dutiesInterpretation with treatment suggestions to Interpretation with treatment suggestions to surgical team M.D.s.surgical team M.D.s.

Credentials:Credentials:•ABNM – American Board of Neurophysiologic ABNM – American Board of Neurophysiologic Monitoring Monitoring •Diplomat – D.ABNMDiplomat – D.ABNM



Who?Who?Who provides IONM?Who provides IONM?

Clinical Neurophysiologist – Medical ComponentClinical Neurophysiologist – Medical ComponentMedical Doctors – M.D. and D.O. With specific Medical Doctors – M.D. and D.O. With specific certification.certification.

InterpretationInterpretationDiagnosisDiagnosisTreatmentTreatment

Credentials: Certification from;Credentials: Certification from;ABPN - ABPN - American Board of Psychiatry and NeurologyAmerican Board of Psychiatry and Neurology ABCN - ABCN - American Board of Clinical NeurophysiologyAmerican Board of Clinical Neurophysiology ABEM - ABEM - American Board of Emergency MedicineAmerican Board of Emergency Medicine ABNM – ABNM – American Board of Neurophysiologic American Board of Neurophysiologic

Monitoring Monitoring



Retrieved on 9/12/12 from; http://en.wikipedia.org/wiki/File:Gray759.png

Anatomy ReviewAnatomy ReviewSensory InputSensory Input

Posterior Dorsal Column-Posterior Dorsal Column-Lemniscal TractLemniscal Tract

Conveys touch, vibration Conveys touch, vibration and proprioception and proprioception information to the brain.information to the brain.



Anatomy ReviewAnatomy Review

Corticospinal TractCorticospinal Tract

Voluntary skilled Voluntary skilled activityactivity

Pre-central gyrus of Pre-central gyrus of cortex to spinal cord cortex to spinal cord without interruptionwithout interruption

Retrieved on 9/12/12 from:http://en.wikipedia.org/wiki/File:Gray764.pngRetrieved on 9/12/12 from:http://en.wikipedia.org/wiki/File:Gray764.png



Retrieved on 9/12/2012 from; http://en.wikipedia.org/wiki/File:Medulla_spinalis_-_tracts_-Retrieved on 9/12/2012 from; http://en.wikipedia.org/wiki/File:Medulla_spinalis_-_tracts_-_English.svg_English.svg

Anatomy ReviewAnatomy ReviewSpinal Cord AnatomySpinal Cord Anatomy

Blood supply of dorsal 1/3 Blood supply of dorsal 1/3 of spinal cord via the two of spinal cord via the two posterior spinal arteries.posterior spinal arteries.

Blood supply of the Blood supply of the anterior 2/3 of spinal cord anterior 2/3 of spinal cord via the single anterior via the single anterior spinal artery.spinal artery.



Anatomy ReviewAnatomy ReviewAnterior Spinal ArteryAnterior Spinal Artery

Spinal cord blood Spinal cord blood supply and watershed supply and watershed regionsregions

Nuwer MR, Handbook of Clinical Neurophysiology Volume 8; Intraoperative Nuwer MR, Handbook of Clinical Neurophysiology Volume 8; Intraoperative Monitoring of Neural Function.(2008). Elsevier, Daube and Mauguiere Eds. Pg 58Monitoring of Neural Function.(2008). Elsevier, Daube and Mauguiere Eds. Pg 58



Anatomy ReviewAnatomy ReviewNerve RootsNerve Roots

Retrieved on 9/12/2012 from http://en.wikipedia.org/wiki/File:Spinal_nerve.svgRetrieved on 9/12/2012 from http://en.wikipedia.org/wiki/File:Spinal_nerve.svg



Retrieved on 9/12/12 from Retrieved on 9/12/12 from http://upload.wikimedia.org/wikipedia/commons/a/ad/Foraminaintervertebrhttp://upload.wikimedia.org/wikipedia/commons/a/ad/Foraminaintervertebralia.pngalia.png

Anatomy ReviewAnatomy Review

Intervertebral Intervertebral ForamenForamen



Electrophysiological Techniques in IONMElectrophysiological Techniques in IONM

Evoked Potentials (EP)Evoked Potentials (EP)Somatosensory (SSEP)Somatosensory (SSEP)Motor (MEP)Motor (MEP)

ElectromyographyElectromyographySpontaneous EMG (sEMG)Spontaneous EMG (sEMG)Triggered EMG (tEMG)Triggered EMG (tEMG)

Nerve Conduction Study (NCS) Nerve Conduction Study (NCS) low relevance to spine surgerylow relevance to spine surgery

Electroencephalography (EEG) Electroencephalography (EEG) low relevance to spine surgerylow relevance to spine surgery



Electrophysiological Electrophysiological Techniques in IONMTechniques in IONM

Evoked Potentials (EP)Evoked Potentials (EP)

Somatosensory (SSEP)Somatosensory (SSEP)Stimulation: Stimulation:

electrical, peripheral mixed nerve.electrical, peripheral mixed nerve.Recording:Recording:

neurogenic. peripheral, neurogenic. peripheral, subcortical, cortical.subcortical, cortical.

Use:Use:monitor dorsal spinal cord monitor dorsal spinal cord (afferent) and afferent peripheral (afferent) and afferent peripheral nervesnerves



Retrieved on 9/12/12 from; http://en.wikipedia.org/wiki/File:Gray759.pngRetrieved on 9/12/12 from; http://en.wikipedia.org/wiki/File:Gray759.png


Evoked Potentials (EP)Evoked Potentials (EP)

Somatosensory (SSEP)Somatosensory (SSEP)Stimulation: Stimulation:

electrical, peripheral electrical, peripheral mixed nervemixed nerve

Recording: Recording: neurogenic. neurogenic. peripheral, peripheral, subcortical, corticalsubcortical, cortical




Evoked Potentials (EP)Evoked Potentials (EP)Motor (MEP)Motor (MEP)

Stimulation: Stimulation: Electrical or Electrical or MagneticMagnetic

Recording: Recording: Neurogenic - Spinal Neurogenic - Spinal CordCordMyogenic - Muscles Myogenic - Muscles of Interestof Interest

Use:Use:Monitor anterior Monitor anterior spinal cord and spinal cord and efferent peripheral efferent peripheral nervesnerves

Retrieved on 9/12/12 from:http://en.wikipedia.org/wiki/File:Gray764.pngRetrieved on 9/12/12 from:http://en.wikipedia.org/wiki/File:Gray764.png



Electrophysiological Techniques in IONMElectrophysiological Techniques in IONMElectromyographyElectromyography

Recording and interpretation of muscle activity in Recording and interpretation of muscle activity in real time.real time.

Spontaneous EMG (sEMG)Spontaneous EMG (sEMG)Stimulation: Stimulation:

NoneNoneRecording: Recording:

Continuous recording of muscles Continuous recording of muscles innervated by nerve roots at riskinnervated by nerve roots at risk

Surface or needle electrodesSurface or needle electrodesUse: Use:

Detect mechanical nerve root irritationDetect mechanical nerve root irritation



Electrophysiological Techniques in IONMElectrophysiological Techniques in IONMElectromyographyElectromyography

Recording and interpretation of muscle activity in real Recording and interpretation of muscle activity in real timetime

Triggered EMG (tEMG)Triggered EMG (tEMG)Stimulation: Stimulation:

electricalelectricalRecording: Recording:

Brief, time-locked muscle activityBrief, time-locked muscle activityUse:Use:

Differentiate tissueDifferentiate tissueCompute nerve conduction velocity Compute nerve conduction velocity

(NCV)(NCV)Assess pedicle screw integrityAssess pedicle screw integrity



Let us look at IONM in:Let us look at IONM in:

Spinal Deformity SurgerySpinal Deformity Surgery

Spinal Decompression SurgerySpinal Decompression Surgery

Anterior Cervical Discectomy and FusionAnterior Cervical Discectomy and Fusion



IONM inIONM inSpinal Deformity SurgerySpinal Deformity Surgery

Times of Risk:Times of Risk:Induction: Low unless spinal instabilityInduction: Low unless spinal instability

Positioning: Low unless symptoms easily provokedPositioning: Low unless symptoms easily provoked

Surgical: Significant during deformity correctionSurgical: Significant during deformity correctionpedicle screw implantationpedicle screw implantation




Structures at Risk:Structures at Risk:Primary: Primary:

Spinal cordSpinal cordMechanism: Cord distraction and compression, Mechanism: Cord distraction and compression, ischemiaischemia

Nerve RootsNerve RootsMechanism: Trauma, compression, hardwareMechanism: Trauma, compression, hardware

Secondary: Secondary: Peripheral nerves and brachial plexusPeripheral nerves and brachial plexus

Mechanism: Stretch and compressionMechanism: Stretch and compression




Modalities Monitored:Modalities Monitored:SSEP – dorsal spinal cord and peripheral nervesSSEP – dorsal spinal cord and peripheral nervesMEP – ventral spinal cord and peripheral nervesMEP – ventral spinal cord and peripheral nervessEMG, tEMG – nerve rootssEMG, tEMG – nerve roots




63 year old female with 20 year history of C5-6 tetraplegia with 63 year old female with 20 year history of C5-6 tetraplegia with partial zone preservation to left C7 myotome, and post traumatic partial zone preservation to left C7 myotome, and post traumatic tethered spinal cord due to MVA.tethered spinal cord due to MVA.

Planned procedure: cervical laminectomy, spinal cord Planned procedure: cervical laminectomy, spinal cord untethering, expansion duraplasty.untethering, expansion duraplasty.

Spoiler Alert: These data suggested the possibility of transient Spoiler Alert: These data suggested the possibility of transient changes in the left side sensory and motor neurological status changes in the left side sensory and motor neurological status during this procedure.during this procedure.



IONM in Spinal Deformity SurgeryIONM in Spinal Deformity Surgery63 year old female with 20 year history of C5-6 tetraplegia63 year old female with 20 year history of C5-6 tetraplegiaPrepositioning Data – Ulnar and Tibial SSEPPrepositioning Data – Ulnar and Tibial SSEP



IONM in Spinal Deformity SurgeryIONM in Spinal Deformity Surgery63 year old female with 20 year history of C5-6 tetraplegia63 year old female with 20 year history of C5-6 tetraplegiaPrepositioning Data - MEPPrepositioning Data - MEP



IONM in Spinal Deformity SurgeryIONM in Spinal Deformity Surgery63 year old female with 20 year history of C5-6 tetraplegia63 year old female with 20 year history of C5-6 tetraplegia9:20 - Post-positioning Data – Ulnar SSEP9:20 - Post-positioning Data – Ulnar SSEP9:29 – Reposition left arm9:29 – Reposition left arm9:39 – No Ulnar SSEP Cortical Response. Neck repositioned9:39 – No Ulnar SSEP Cortical Response. Neck repositioned9:49 – Left Ulnar stimulation moved to elbow.9:49 – Left Ulnar stimulation moved to elbow.9:59 – Patient returned to bed.9:59 – Patient returned to bed.10:30 – Prone on OR table.10:30 – Prone on OR table.10:33 – Median Stimulation in Ulnar Test10:33 – Median Stimulation in Ulnar Test10:46 – Patient returned to bed.10:46 – Patient returned to bed.11:02 – Surgery aborted.11:02 – Surgery aborted.



IONM in Spinal Deformity SurgeryIONM in Spinal Deformity Surgery63 year old female with 20 year history of C5-6 tetraplegia63 year old female with 20 year history of C5-6 tetraplegiaPost-positioning Data – MEPPost-positioning Data – MEP9:20 - Post-positioning Data – Ulnar SSEP9:20 - Post-positioning Data – Ulnar SSEP9:29 – Reposition left arm9:29 – Reposition left arm9:39 – No Ulnar SSEP Cortical Response. Neck repositioned.9:39 – No Ulnar SSEP Cortical Response. Neck repositioned.9:49 – Left Ulnar stimulation moved to elbow.9:49 – Left Ulnar stimulation moved to elbow.9:59 – Patient returned to bed.9:59 – Patient returned to bed.10:30 – Prone on OR table.10:30 – Prone on OR table.10:46 – Patient returned to bed.10:46 – Patient returned to bed.11:02 – Surgery aborted.11:02 – Surgery aborted.



IONM in Spinal Deformity SurgeryIONM in Spinal Deformity Surgery63 year old female with 20 year history of C5-6 63 year old female with 20 year history of C5-6

tetraplegiatetraplegia

Surgery was aborted.Surgery was aborted.

Clinical exam in post-op recovery demonstrated Clinical exam in post-op recovery demonstrated no new neurological deficits.no new neurological deficits.



IONM inIONM inSpinal Decompression SurgerySpinal Decompression Surgery

Times of Risk:Times of Risk:Induction: LowInduction: Low

Positioning: Moderate for mechanical irritation of nerve rootPositioning: Moderate for mechanical irritation of nerve root

Surgical: Significant during decompression.Surgical: Significant during decompression.





Nerve rootsNerve rootsMechanism: Trauma, stretchingMechanism: Trauma, stretching

Secondary: Secondary: Spinal cordSpinal cord

Mechanism: IschemiaMechanism: IschemiaPeripheral nerves and brachial plexusPeripheral nerves and brachial plexus

Mechanism: Compression, stretchingMechanism: Compression, stretching




Modalities Monitored:Modalities Monitored:sEMG – nerve rootssEMG – nerve rootsSSEP – spinal cord and peripheral nervesSSEP – spinal cord and peripheral nervestEMG, MEP (optional)tEMG, MEP (optional)




68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathy68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathy

Procedure: PSF, PLIF L4-5Procedure: PSF, PLIF L4-5

Laminectomy in progress.Laminectomy in progress.



IONM inIONM inSpinal Decompression SurgerySpinal Decompression Surgery68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathy68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathy


Rasp on End-plate prior to cage implantation.Rasp on End-plate prior to cage implantation.




68 year old female with L4-5 DDD, spondylolisthesis, spinal 68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathystenosis, radiculopathy


Triggered EMG – Pedicle Screw Stimulation ThresholdsTriggered EMG – Pedicle Screw Stimulation ThresholdsAcceptable Limits Acceptable Limits >> 8 mA. 8 mA.SiteSite Left Left Right Right L4 screw L4 screw 8 mA (2nd, 15 mA) 8 mA (2nd, 15 mA) 30 mA30 mAL5 screw L5 screw 36 mA 36 mA 33 mA33 mAL5 nerve L5 nerve 0.2 mA0.2 mA



IONM inIONM inSpinal Decompression SurgerySpinal Decompression Surgery68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathy68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathy


Examine left L4 pedicle due to low screw threshold.Examine left L4 pedicle due to low screw threshold.



IONM inIONM in


Times of Risk:Times of Risk:Induction: Possibly SignificantInduction: Possibly SignificantPositioning: Possibly SignificantPositioning: Possibly SignificantSurgical: SignificantSurgical: Significant



IONM inIONM in



Spinal Cord, Cervical Nerve RootsSpinal Cord, Cervical Nerve RootsSecondary: Secondary:

Recurrent Laryngeal Nerve, Brachial PlexusRecurrent Laryngeal Nerve, Brachial Plexus



IONM inIONM in


Modalities Monitored:Modalities Monitored:MEPMEPSSEPSSEPRecurrent Laryngeal (CN X) Nerve sEMGRecurrent Laryngeal (CN X) Nerve sEMGsEMGsEMG



IONM inIONM in


59 year old male59 year old male

Dx: DDD C5-6Dx: DDD C5-6

Procedure: Artificial Disc C5-6Procedure: Artificial Disc C5-6



IONM inIONM inAnterior Cervical Discectomy and FusionAnterior Cervical Discectomy and FusionArtificial Disc C5-6Artificial Disc C5-6



The EndThe End

Healthcare

The Role of Intraoperative Neuromonitoring (IONM)