Emg & ncs ِAdnan AL BANNA

The Neuromonitoring Studies
Who? What? When? Where? Why? How?

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

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

What?
Iatrogenic injury
Iatrogenic i·at·ro·gen·ic (ī-āt'rə-jěn'ĭk)
Induced in a patient by a physician's
adj.
activity, manner, or therapy.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mif ompany. Published by Mifflin Company.flin C Houghton

What?
Iatrogenic neurological injury in spine surgery
can be caused by:
Surgical
Distraction, compression or blunt trauma
Ischemia of neural structures
Thrombotic events
Anesthetic or Systemic Problems
Ischemia,
hypoxia
hypothermia
cervical extension duri ubation
Positioning
Direct compression
Compromised blood supply
Neck and shoulder positioning
ng int

What?
What is the incidence of iatrogenic
injury
in elective spine
surgery?
Iatrogenic neurological injuries in elective spinal surgery
without neurophysiological monitoring:
Anterior cervical discectomy – 0.46%
Scoliosis correction - .23-3.2%
Intramedullary tumor resection - >23.8%
Vauzelle C, Stagnara P, Jouvinroux P al monitoring of s y during spinal surgery.
Clin Orthop Relat Res 1973;93:173-8
. Function pinal cord activit
0

Why?
Why avoid iatrogenic injury?
To improve or maintain quality of life.
(WHO - HRQOL)
People with spinal cord injury (SCI):
report lower sense of well-being
score lower on physical, mental, and social health
domains
Dijkers, M: Quality of life of individuals
measurement, and research findings. J.
3, May/June 2005, Pages 87-110. Retriev
of conceptualization,
ab Res ent Number 1, Volume 42 Number
http://www.rehab.research.va.gov/jour/05/ uppl1/dijkers.html42/3s
with
Reh
ed 9/
spinal
11/12
cord
& De
from
injury
v, Sup
: A re
plem
view

Why?
To improve or maintain quality of life. (WHO – HRQOL)
“Life expectancies for persons with SCI continue to
increase, but are still somewhat below life expectancies
for those with no SCI.”
National Spinal Cord Injury Statistical Center, Birmingham, A Facts and Figures at a
Glance, February 2012, retrieved 9/11/12 at
https://www.nscisc.uab.edu/PublicDocuments/fact_figures_docs/Facts%202012%20Feb%20Final.pdf
labama, Spinal Cord Injury

Why?
Reduce the costs associated with iatrogenic injury.
The average yearly health care and living expenses directly
attributable to SCI was $69,204 in February 2012 dollars.
These figures do not include any in ch as losses
in wages, fringe benefits and produ vity.
National Spinal Cord Injury Statistical Center, Birmingham, Alabama, Figures at a Glance,
February 2012, retrieved Sept. 11, 20112 at https://www.nscisc.uab.edu/PublicDocuments/fact_figures_docs/Facts
%202012%20Feb%20Final.pdf
dir
cti
Spina
ect
l Cord
co
Injur
sts
y Fac
su
ts and

How?
How can we avoid iatrogenic injury?
Timely detection of changes in
neurologic status allows
therapeutic action to ameliorate
or avoid neurologic eficits.d

How?
How can we detect changes in
neurologic status?
Functional vs. Structural Assessment
Structural Assessment
Radiography
Sonography
Visualization

The Role of Intraoperative Neuromonitoring
How?
How can we detect changes in
neurologic status?
Function Assessment
Using provocative and non-provocative
techniques.
Intraoperative Neurophys logic Monitoring
(IONM)
io

How?
How is IONM performed?
Electrophysiologic Assessments
Non-Provocative
Spontaneous electromyography
Electroencephalography (EEG)
Provocative
(sEMG)
Triggered electromy rap EMG)
Electroencephalo aph EEG)
Evoked Potentials (EP)
Somatosensory (SSEP)
Motor (MEP)
Nerve Conduction Study (NCS)
gr
og
y (
hy (t

How?
How effective is IONM?
Efficacy of IONM in Cervical Spine
SurgerySomatosensory evoked potentials
sensitivity - 52% (+ correctly ID'd)
specificity - 100% (- correctly ID'd)
PPV - 100% (true +/+calls)
NPV -
Motor evoked
97% (true -/- calls)
potentials
sensitivity -
specificity -
100%
96%
PPV -
NPV - %
Electromyography
sensitivity - 46%
specificity - 73%
PPV -
NPV -
3%
97%
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.
96
10
%
0

How?
Efficacy of IONM in Thorocolumbar
Spine Surgery (nerve
SSEPs
root emphasis)
sensitivity
specificity
sEMG
sensitivity %
specificity %- 23.7
-
-
-
29
95
10
%
%
0

How?
Multimodal IONM reduces the relative risk of post-
operative neurological complications in spine surgery by an
estimated 49.4% at a mean cost of $63,387 perneurological
deficit averted.
Ney JP, Van der Goes DN, Watanabe JH: Cost-effectiveness of intraoperati uroph ological monitoring for spinal
surgeries: Beginning steps, Clinical Neurophysiology, Volume 123, Is mber 2012sue 9,
ve ne
Pages 1705
ysi
-1707, Septe

When?
When is IONM appropriate?
Identify iatrogenic nervous system compromise in a
timely fashion.
Ongoing monitoring
Identify neural structures through specific testing
procedures.
Time-Specific assessm
Identify when iatrogenic i jury cur d in
experimental procedures.
Ongoing monitoring
n
ent
oc re

Where?
Where can IONM be performed?
On the hospital floors
In Pre-Op Holding
In the Operating Room

Who?
Who provides IONM?
Technologists – Technical Component
•Associate and Bachelor Degrees.
•Trained in the technical aspects of data collection.
•Lack training and knowledge to provide
interpretation, diagnosis and treatment
Credentials:
•ABRET - American Boar Registrati of
Electroencephalograph and E ked Potential
Technologists
•CNIM - Certificate in Neurophysiologic
Intraoperative Monitoring
ic
d of
vo
on

Who?
Who provides IONM?
Non-Physician Surgical Neurophysiologist – Professional
Component
•Non-MD providers with Doctorate Degrees.
•Technical Support for CNIMs.
•Technical Component
•Site-specific credentials may allow:
Supervision duties
Interpretation with tr ent ggestions to
surgical team M.D.s.
Credentials:
•ABNM – American Board of Neurophysiologic
Monitoring
•Diplomat – D.ABNM
eatm su

Who?
Who provides IONM?
Clinical Neurophysiologist – Medical Component
Medical Doctors – M.D. and D.O. With specific
certification.
Interpretation
Diagnosis
Treatment
Credentials: Certification from
ABPN - American Board of sychiatr nd Neurology
ABCN - American Board of al Neurophysiology
ABEM - American Board of mergency
ABNM – American Board of Neurophysiologic
Monitoring
E Medicine
; P
Cli
nic
y a

Anatomy Review
Sensory Input
Posterior Dorsal Column-
Lemniscal Tract
Conveys touch, vibration
and proprioception
information to the brain.
Retrieved on 9/12/12 from; http://en.wikipedia.org/wiki/File:Gray759.png

Anatomy Review
Corticospinal Tract
Voluntary skilled
activity
Pre-central gyrus of
cortex to spinal cord
without interruption
Retrieved on 9/12/12 from:http://en.wikipedia.org/wiki/File:Gray764.png

Anatomy Review
Spinal Cord Anatomy
Blood supply of dorsal
1/3
of spinal cord via the
two
posterior spinal arteries.Blood supply of the
anterior 2/3 of spinal
cordvia the single anterior
spinal artery.
Retrieved on 9/12/2012 from; http://en.wikipedia.org/wiki/File:Medulla_spinalis_-_tracts_-
_English.svg

Anatomy Review
Anterior Spinal Artery
Spinal cord blood
supply and
regions
watershed
Nuwer MR, Handbook of Clinical Neurophysiology Volume 8; Intraoperative
Monitoring of Neural Function.(2008). Elsevier, Daube and Mauguiere Eds. Pg 58

Anatomy Review
Nerve Roots
Retrieved on 9/12/2012 from http://en.wikipedia.org/wiki/File:Spinal_nerve.svg

Anatomy Review
Intervertebral
Foramen
Retrieved on 9/12/12 from
http://upload.wikimedia.org/wikipedia/commons/a/ad/Foraminaintervertebr
alia.png

Electrophysiological Techniques in IONM
Motor (MEP)
Electromyography
Spontaneous EMG (sEMG)
Triggered EMG (tEMG)
low r ance spine surgeryNerve Conduction Study (NCS
low relevance to spine surgeryElectroencephalography (EEG)
elev to

Electrophysiological
Techniques in IONM
Stimulation:
electrical, peripheral mixed nerve.
Recording:
neurogenic. peripheral,
subcortical, cortical.
Use:
monitor dorsal spinal cord
(afferent) and afferent peripheral
nerves

David Barnkow, AuD, DABNM, CNIM
Techniques in IONM
Stimulation:
electrical, peripheral
mixed nerve
Recording:
neurogenic.
peripheral,
subcortical, cortical
Retrieved on 9/12/12 from; http://en.wikipedia.org/wiki/File:Gray759.png

Techniques in IONM
Motor (MEP)
Stimulation:
Electrical or
Magnetic
Recording:
Neurogenic - Spinal
Cord
Myogenic - Muscles
of Interest
Use:
Monitor anterior
spinal cord and
efferent peripheral
nerves
Retrieved on 9/12/12 from:http://en.wikipedia.org/wiki/File:Gray764.png

Electromyography
Recording and interpretation of muscle activityin
real time.
Spontaneous EMG (sEMG)
Stimulation:
None
Recording:
Continuous recording of uscles
innervated by nerve roots at risk
Surface or needle electrodes
Use:
Detect mechanical nerve root irritation
m

Electromyography
Recording and interpretation of muscle activity in real
time
Triggered EMG (tEMG)
Stimulation:
electrical
Recording:
Brief, time-locked uscle activity
Use:
Differentiate sue
Compute nerve conduction velocity
(NCV)
Assess pedicle screw integrity
tis
m

Let us look at IONM in:
Spinal Deformity Surgery
Spinal Decompression Surgery
Anterior Cervical Discectomy Fu onand si

IONM in
Times of Risk:
Induction: Low unless spinal instability
Positioning: Low unless symptoms easily provoked
Surgical: Significant dur g deformity correction
pedicle screw implantation
in

IONM in
Structures at Risk:
Primary:
Spinal cord
Mechanism: Cord distraction and compression,
ischemia
Nerve Roots
Mechanism: Trauma, compre on, ardware
Secondary:
Peripheral nerves and brachial plexus
Mechanism: Stretch and compression
ssi h

IONM in
Modalities Monitored:
SSEP – dorsal spinal cord and peripheral nerves
MEP – ventral spinal cord and peripheral nerves
sEMG, tEMG – nerve roots

IONM in
63 year old female with 20 year history of C5-6 tetraplegia with
partial zone preservation to left C7 myotome, and post traumatic
tethered spinal cord due to MVA.
Planned procedure: cervical laminectomy, spinal c d
untethering, expansion duraplasty.
Spoiler Alert: These data suggested the possibil ansient
changes in the left side sensory and motor neurological status
during this procedure.
ity
or
of tr

IONM in Spinal Deformity Surgery
63 year old female with 20 year history of C5-6 tetraplegia
Prepositioning Data – Ulnar and Tibial SSEP

Prepositioning Data - MEP

9:20 - Post-positioning Data – Ulnar SSEP
9:29 – Reposition left arm
9:39 – No Ulnar SSEP Cortical Response. Neck repositioned
9:49 – Left Ulnar stimulation moved to elbow.
9:59 – Patient returned to bed.
10:30 – Prone on OR table.
10:33 – Median Stimulation in Ulnar Test
11:02 – Surgery aborted.

Post-positioning Data – MEP
9:20 - Post-positioning Data – Ulnar SSEP
9:29 – Reposition left arm
9:39 – No Ulnar SSEP Cortical Response. Neck repositioned.
9:49 – Left Ulnar stimulation moved to elbow.
10:30 – Prone on OR table.
11:02 – Surgery aborted.

63 year old female with 20 year history of C5-6
tetraplegia
Surgery was aborted.
Clinical exam in post-op recovery demonstrated
no new neurolog al deficits.ic

IONM in
Times of Risk:
Induction: Low
Positioning: Moderate for mechanical irritation of
nerve
root
Surgical: Significant during decompre on.ssi

IONM in
Structures at Risk:
Primary:
Nerve roots
Mechanism: Trauma, stretching
Secondary:
Spinal cord
Mechanism: Ischemia
Peripheral nerves and brachial ple s
Mechanism: Compression, stretching
xu

IONM in
sEMG – nerve roots
SSEP – spinal cord and peripheral nerves
tEMG, MEP (optional)

IONM in
68 year old female with L4-5 DDD, spondylolisthesis, spinal stenosis, radiculopathy
Procedure: PSF, PLIF L4-5
Laminectomy in progress.

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

IONM in
68 year old female with L4-5 DDD, spondylolisthesis, spinal
stenosis, radiculopathy
Triggered EMG – Pedicle Screw Stimulation Thresholds
Acceptable Limits > 8 mA.
Site Left ght
L4 screw
L5 screw
L5 nerve
8 mA (2nd, 15 mA) mA
36 mA mA
A
Ri
30
33
0.2 m

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

IONM in
Anterior Cervical Discectomy and Fusion
Times of Risk:
Induction: Possibly Significant
Positioning: Possibly Signifi ant
Surgical: Signific tan
c

IONM in
Structures at Risk:
Primary:
Spinal Cord, Cervical Nerve Roots
Secondary:
Recurrent Laryngeal erve, Brachial PlexusN

IONM in
MEP
SSEP
Recurrent Laryng erve sEMG
sEMG
eal (CN X) N

IONM in
59 year old male
Dx: DDD C5-6
Procedure: Artificial Disc C5-6

IONM in
Artificial Disc C5-6

Emg & ncs ِAdnan AL BANNA

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