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A. BMP-1
B. BMP-2
C. BMP-6
D. BMP-14.
Response (B) BMP-2 is the only BMP FDA approve d for
orthopedic applications such as ALIF. Currently, the
rh-BMP2 is marketed as Infuse for application in ALIF [16].
Question 39
Assessment of fusion is crucial to determining the success of
spinal fusion. Which of the following is the best option for
assessing successful fusion?
A. Assessment of flexion and/or extension at the site of
fusion
B. Plain film radiography
C. MRI
D. Axial CT with reconstruction.
Response (D) Newer instrumentation is often radiopaque
and makes fusion challenging to assess on plain radiogra-
phy. Assessment of range of motion may also be difficult as
instrumentation may provide rigid fixation. Therefore, axial
CT with reconstruction is the standard of evaluation [24].
Question 40
Which of the following graft material is osteoinductive but
lacks osteoconductive and osteogenic capabilities?
A. Platelet-rich plasma
B. Bone marrow aspirate
C. rhBMP
D. Demineralized bone matrix.
Response (A) Platelet-rich plasma is a highly concentrated
platelet formulation rich in various growth factors but lacks
structural support and osteogenic capabilities [16].
Question 41
Platelet-rich plasma is a formulation of concentrated platelets
formed from whole blood. Which of the following is false?
A. Platelet-rich plasma needs to be activated using calcium
chloride.
B. Platelet-rich plasma contains large concentrations of
growth factors.
C. There is strong evidence in the literature suggesting the
efficacy of platelet-rich plasma.
D. Once activated, it can be applied to a site of injury to
promote bone growth.
Response (C) While animal studies have shown benefit
from platelet-rich plasma, it has been inconclusive in human
fracture healing and shows little evidence in the setting of
fusion [16].
Question 42
Of the following BMPs, which has shown to have angio-
genic properties?
A. BMP-1
B. BMP-3
C. BMP-7
D. BMP-14.
Response (C) BMP-2 and BMP-7 have both been shown
to not only have osteogenic properties but are also highly
capable of local neovascularization [16].
Question 43
Platelet-rich plasma contains a wide variety of growth fac-
tors. Of the growth factors found in platelet-rich plasma,
which of the following promotes differentiation of mes-
enchymal stem cells (MSCs) into osteoblasts?
A. VEGF
B. BMP-7
C. PDGF
D. BMP-2.
Response (D) BMP-2 is the only BMP that has been shown
to differentiate MSCs to osteoblasts. VEGF plays a role in
angiogenesis. PDGF has a role in inflammation, cellular pro-
liferation, and angiogenesis. BMP-7 does not induce
osteoblastic differentiation of MSCs but is still osteogenic [16].
Question 44
A patient that had just undergone spinal fusion decide s to
take ibuprofen for postoperative pain. However, there is
concern that the medication may interfere with bone healing.
When in the healing process is the medication most likely to
affect healing?
A. 1 to 3 weeks
4 Bone Biology and Bone Substitutes 77
B. 4 to 5 weeks
C. 6 to 10 weeks
D. 12+ weeks.
Response (A) Callus formation, release of growth factors,
and inflammatory cytokines mediate the early phases of
bone healing. This occurs in the first 1–3 weeks of healing.
This inflammatory phase may be affected by the use of
NSAIDs such as ibuprofen. This can delay bone healing and
result in poorer outcomes [24].
Question 45
Demineralized bone matrix (DBMs) is formed from ground
cadaveric bone processed via acid extraction. Which of the
following is true regarding DBMs?
A. The efficacy of DBMs is variable as processing methods
are highly variable between various DBM products.
B. Disease transmission is not of concern with DBMs.
C. Demineralization processes retain BMP function in
final products.
D. Cellular components are intact in DBMs.
Response (A) Demineralizing is a highly proprietary pro-
cess, and as such, these processes are not typically pub-
lished. Thus, it isn’t easy to regulate these processes. DBMs
retain a high level of variability from one product to the next.
DBMs are formed from cadaveri c bone; so, still capable of
disease transmission. Demineralization can inactivate BMPs
in DBMs. DBMs are typically acellular [16].
Question 46
Which of the following grafts has a large supply of viable
cells, including osteocytes and osteoprogenitor cells that
confers osteogenic properties?
A. Cortical bone autograft
B. Vascularized bone autograft
C. Cancellous bone allograft
D. Demineralized bone matrix.
Response (B) Vascularized bone grafts retain large
amounts of viable cells in their structure that confer osteo-
genic properties. Cortical bone autografts still contain viable
cells; however, their supply is limited. Cancellous bone and
demineralized bone matrix lose cellularity in their processing
methods [16].
Question 47
The surgeon decided to utilize calcium phosphate cement in
the intervertebral space during spinal surgery to augment the
fusion. Which of the following is not a property of calcium
phosphate?
A. Slow biodegradation
B. Osteointegration capability
C. Ability to withstand tensile and shear forces
D. Good compressive strength.
Response (C) Ceramic cement is typically very brittle
under tensile and shear forces. While they can withstand
compressive forces in vitro, they may fail when subjected to
these other forces in vivo. These properties are crucial to
why calcium phosphate materials are not popular amongst
surgeons [16 ].
Question 48
Which of the following BMPs has shown no osteoinductive
properties?
A. BMP-2
B. BMP-3
C. BMP-4
D. BMP-7.
Response (B) BMP-3 has no demonstrated osteoinductive
activity and, as such, is not implicated in osteogenesis.
Specifically, BMP-2, -4, -6, -7, -9, and -14 have significant
osteogenic properties [16].
Question 49
Endochondral ossification is crucial in the process of bone
formation. This requires neovascularization of hyaline car-
tilage. Which of the following growth factors plays a role in
inducing vascular invasion of cartilage?
A. PDGF
B. BMP-1
C. VEGF
D. PTH.
Response
(C) Vascular endothelial growth factor is
released by platelets and chondrocytes in calluses to promote
angiogenesis to vascularize hyaline cartilage [16].
78 A. Khan et al.
Question 50
Recombinant human parathyroid hormone (rhPTH) can be
used to increase bone mineral density and reduce overall
fracture risk. Which of the following is true regarding the
cellular action of PTH?
A. PTH has a direct effect on osteoblasts and indirect on
osteoclasts.
B. PTH has an indirect effect on both osteoblasts and
osteoclasts.
C. PTH has a direct effect on osteoclasts and osteoblasts.
D. PTH has a direct effect on osteoclasts and indirect on
osteoblasts.
Response (A) PTH has a direct effect on osteoblasts,
increasing their activity through PTH receptors on osteo-
blasts. Increased osteoblast activity will, in turn, activate
osteoclast activity through cell-to-cell interactions, specifi-
cally pathways involving RANKL and osteoprotegerin [29].
Question 51
Which of the following factors could affect spinal fusion:
A. Type of graft material, e.g., autograft or synthetic
biomaterials
B. Patient age
C. NSAIDs
D. Smoking status
E. All of the above.
Response (E) All of the following are factors that can
contribute to the healing process of bone graft. These factors
can each contribute to fusion failure or pseudoarthrosis.
Each must be taken into account when counseling patients
on expectations and post-operative procedures [30–33].
Question 52
Which of the following factors could affect spinal fusion:
A. Method of preparation of the graft recipient site
B. Mechanical stability of the spine segment
C. Spinal region
D. A and B
E. All of the above.
Response (E) The cervical region is considered a more
favorable envir onment for fusion versus the thoracic or
lumbar regions. Proper curettage of the endplate and proper
stabilization of the spine after placement of the graft also
affect the spinal fusion [30–33].
Question 53
Which of the following is the most abundant protein in the
organic matrix of bone?
A. Type I collagen
B. Type II collagen
C. Type III collagen
D. Type IV collagen
E. Type V collagen.
Response (A) Type I collagen is a fibrillar type collagen. It
forms 90% of the organic mass of bone and tendon and is the
major collagen of skin, ligaments, cornea, and many interstitial
connective tissues. Type II collagen is the main collagenous
component of cartilage. Type III collagen forms reticulate,
commonly found alongside type I collagen. Type IV collagen
forms the basal lamina, and type V collagen is found within the
dermal/epidermal junction and the placental tissues [34].
Question 54
Regarding Demineralized Bone Matrix (DBM), all of the
following statements are true, EXCEPT:
A. It is an allograft bone that underwent the process of acid
extraction.
B. It lacks osteoinductive properties.
C. It is devoid of bone minerals.
D. It contains collagen and non-collagenous proteins.
Response (B) Allograft bone may undergo processing by
acid extraction to remove bone minerals while retaining
collagen and non-collagenous proteins. The end product is
DBM, an allograft form with osteoinductive activity. It is
important to note that osteoinductive properties are highly
dependent on the preparation method of the material so not
all DBMs are equal in osteoinductive properties [35–37].
Question 55
Regarding Bone Morphogenetic Proteins (BMPs), all of the
following statements are true, EXCEPT:
A. They are osteo-conductive proteins.
B. They are soluble proteins.
4 Bone Biology and Bone Substitutes 79
C. They are members of the transforming growth
factor-beta (TGF-b) superfamily of growth factors.
D. The use of a carrier is a must to maintain an effective
local concentration and prevent their diffusion away
from the operative site.
Response (A) BMPs are osteoinductive proteins. The other
statements are all true [38–40].
Question 56
Regarding the properties of the graft material, which one of
the foll owing is true:
A. Allografts have osteoconductive properties and lacks
osteogenic properties.
B. Ceramics lack osteoinductive and osteogenic properties.
C. Composite grafts have both osteoinductive and osteo-
conductive properties.
D. Autograft have osteoconductive, osteoinductive and
osteogenic properties.
E. A and C.
F. All of the above.
Response (F) Osteoinduction takes advantage of endocrine
and paracrine signaling pathways for cell recruitment and
differentiation to promote bone formation. In this way, they
can promote bone formation in soft tissue as well. Osteogen-
esis implies the presence of cells that form bone or bony
precursors in the graft material. Osteoconduction is the pres-
ence of scaffold material that can support bone growth and
angiogenesis. Allografts will provide structure but do not
typically contain cells within the material to provide osteo-
genic properties. Ceramics are only structural and have no
growth factors or cells. Composite grafts may provide a variety
of osteoinductive and osteoconductive properties based on the
composition of the composite. Autografts provide all crucial
properties for bone growth and are the most effective [12–15].
Question 57
Which one of the following statements regarding the clas-
sification of graft materials according to the intention of their
use?
A. Extender is a type of graft material used in combination
with autograft bone.
B. Enhancer is a type of graft material used in conjunction
with autograft bone to increase the rate of successful
arthrodesis above the rate of fusion achieved using
autograft alone.
C. Substitute is a type of graft material used as an alter-
native to autograft bone and is intended to provide
equivalent or superior fusion success compared with
autograft bone.
D. All of the above.
Response (D) Extender is a type of graft material used in
combination with autograft bone. Enhancer is a type of graft
material used in conjunction with autograft bone to increase
the rate of successful arthrodesis above the rate of fusion
achieved using autograft alone. Substitute is a type of graft
material used as an alternative to autograft bone and is
intended to provide equivalent or superior fusion success
compared with autograft bone [12–15].
Question 58
Regarding the difference between nonstructural grafts and
structural grafts, which one of the following is false?
A. Nonstructural grafts are also termed morselized grafts.
B. Structural grafts consist of particles of bone, e.g., can-
cellous bone from the iliac crest.
C. Nonstructural grafts do not provide structural stability
when used by themselves, and spinal instrumentation is
used to facilitate bony union.
D. Structural grafts provide mechanical support during the
process of fusion consolidation.
Response (B) Nonstructural grafts consist of particles of
bone, e.g., cancellous bone from the iliac crest [41–43].
Question 59
Regarding anterior column structural grafts, which one of
the foll owing is true:
A. Strut grafts reconstruct the anterior spinal column fol-
lowing discectomy.
B. Interbody grafts reconstruct the anterior spinal column
after corpectomy.
C. Trans-vertebral grafts are not across an intervening disc
space.
D. None of the above.
Response (D) Strut grafts reconstruct the anterior spinal
column following corpectomy. Interbody grafts reconstruct
the anterior spinal column following discectomy;
Trans-vertebral grafts are used to stabilize adjacent vertebrae
and achieve fusion across an intervening disc space [44
–47].
80 A. Khan et al.
Question 60
Which of the following complications has been reported
following the use of recombinant bone morphogenic
protein-2 (rhBMP-2) during spinal fusion procedures?
A. Ectopic bone formation
B. Postoperative radiculitis
C. Increased rates of cage migration
D. Increased rates of postoperative seroma formation
E. All of the above.
Response (E) Although the FDA initially approved
rhBMP-2 for use in anterior lumbar interbody fusion, it has
seen much off-label use. Given its extensive use, there have
been concerns regarding potential complications of its use.
These complications are known to include: ectopic bone
formation with compression of nearby structures, inflam-
mation of the nerve roots due to local inflammatory reac-
tions, increased rates of cage migration due to early
osteolytic changes, and seroma formation [48].
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82 A. Khan et al.
5
Intraoperative Neuromonitoring
Asham Khan, Moleca M. Ghannam, Ryan M. Hess, Slah Khan,
Alexander O. Aguirre, Cathleen C. Kuo, Ali Y. Elkady, Ahmed H. Omar,
Mohammad Elbaroody, and Mohamed A. R. Soliman
Question 1
Motor evoked potentials (MEPs) during spinal deform ity
surgery is a sensitive monitor of:
A. Corticospinal tract
B. Dorsal column
C. Medial lemniscus
D. Lateral spinothalamic tract.
Response (A) MEPs directly monitor the function of the
motor pathways in the anterior/central portions of the spinal
cord and the nerve roots. These are very sensitive indicators
of corticospinal tract injury and have proven to be very
sensitive indicators of spinal cord ischemia during spinal
deformity correction. Spinal cord motor function monitoring
is based on muscle responses to intermittent stimulation of
the motor cortex in real-time [1].
Question 2
Which of the following anesthesia agents can be used during
motor evoked potentials (MEPs) intraoperative monitoring?
A. Halothane.
B. Sevoflurane.
C. Isoflurane.
D. Propofol.
Response (D) MEPs have high sensitivity (75–100%) and
specificity (84–100%), but they require avoidance of halo-
genated anesthetics (halothane, sevoflurane, isoflurane, etc.)
and neuromuscular blockades (vecuronium, rocuronium,
etc.). Ketamine-based anesthesia allows for appropriate MEP
recordings, but total intravenous anesthesia (TIVA) with
propofol is the anesthetic of choice [1].
Question 3
The use of EMG during surgery is to monitor:
A. The nerve root function during surgery
B. The muscle tone during surgery
C. The muscle movement during surgery
D. The presence of impulses in muscles during surgery.
Response (A) EMG is a type of ‘real-time’ neuromoni-
toring modality, mostly employed in detecting nerve root
injuries [2 ].
A. Khan M. M. Ghannam R. M. Hess S. Khan
A. O. Aguirre C. C. Kuo M. A. R. Soliman (&)
Neurosurgery Department, University at Buffalo,
Buffalo, NY, United States
e-mail: msolim8@uwo.ca
A. Khan
e-mail: akhan@ubns.com
M. M. Ghannam
e-mail: mghannam@ubns.com
R. M. Hess
e-mail: rhess@ubns.com
S. Khan
e-mail: slahkhan@buffalo.edu
A. O. Aguirre
e-mail: aa284@buffalo.edu
C. C. Kuo
e-mail: ckuo9@buffalo.edu
A. Y. Elkady A. H. Omar M. Elbaroody M. A. R. Soliman
Neurosurgery Department, Cairo University, Cairo, Egypt
e-mail: ayousri54@gmail.com
A. H. Omar
e-mail: a.hussein.omar1990@gmail.com
M. Elbaroody
e-mail: mohammad.elbaroody@kasralainy.edu.eg
© The Author(s), under exclusive license to Springer Nature Switzerland AG 2024
C. Gragnaniello et al. (eds.), MCQs in Spine Surgery,
https://doi.org/10.1007/978-3-031-69332-8_5
83
Question 4
The nerve impulses are actually:
A. ATP
B. Action potentials
C. Repolarization of nerves
D. Perception.
Response (B) Depolarization of the nerve cell leads to
action potential formation, which propagates through the
nerve body and axon to reach the target muscle [3].
Question 5
Regarding intraoperative somatosensory evoked potentials
(SEPs) monitoring, all of the following is correct EXCEPT:
A. SEPs are more sensitive than motor evoked potentials
(MEPs) to reduced blood flow secondary to vascular
insult or hypotension.
B. SEPs were developed to monitor the posterior columns
of the spinal cord.
C. SEPs monitoring does not provide any information on
the descending corticospinal tract or spinal cord grey
matter.
D. There is no difference between the SEPs monitoring
between adults and infants.
Response (A) MEPs monitoring during spine surgery is
both efficacious and safe. MEPs are more sensitive to
reduced blood flow secondary to hypotension or vascular
insult, compared to SEPs. Furthermore, MEPs change earlier
than the SEPs signal, which facilitates quicker diagnosis of
impending spinal cord injury [4].
Question 6
Which of the following is correct regarding somatosensory
evoked potentials (SEPs) and motor evoked potentials
(MEPs)?
A. SEPs are more sensitive to reduced blood flow sec-
ondary to vascular insult or hypotension.
B. SEPs change earlier than the MEPs signal, which facil-
itates quicker diagnosis of impending spinal cord injury.
C. There is no difference in monitoring MEPs between
adults and infants.
D. The MEPs is elicited using a high-voltage
short-duration stimulus applied to the scalp overlying
the primary motor cortex.
Response (D) MEPs achieve motor specificity without the
need for signal averaging. The MEPs is elicited using a
high-voltage short-duration stimulus applied to the scalp
overlying the primary motor cortex. The transcranial impulse
generates multiple electrical waves that propagate down the
spinal cord and synapse of the neuromuscular junction,
leading to depolarization and muscle contraction. Monitor-
ing the amplitude, latency, and morphology of the resultant
compound muscle action potential assesses the motor path-
way. Unlike SEPs, MEPs in pediatrics has some differences
compared to adult patients. They require a greater charge
delivered to obtain MEPs compared to adolescents, with
decreased reliability in patients aged <6 years [4].
Question 7
A recording electrode was placed over the vastus lateralis
muscle for EMG monitoring during a lumbar fusion surgery.
Which root value corresponds to vastus lateralis?
A. L4-L5
B. L3-L4
C. S1-S2
D. T11-12.
Response (B) The vastus lateralis is supplied by muscular
branches of the femoral nerve which is formed by contri-
butions from L2, L3, and L4 [5].
Question 8
During thoraco-lumbar scoliosis correction surgery, the
electrodes for intraoperative monitoring should be placed in
all the following EXCEPT:
A. Intercostal
B. Rectus abdominus
C. Adductor pollicis
D. Vastus lateralis.
Response (C) Adductor pollicis is for C8-T1 root moni-
toring which is innervated proximal to the thoracolumbar
levels involved in the surgery [6].
Question 9
All of the following decrease the amplitude of intraoperative
somatosensory evoked potentials (SEPs) EXCEPT:
A. Propofol
B. Isoflurane
84 A. Khan et al.
C. Nitrous oxide
D. Sevoflurane.
Response (A) All halogenated inhalational agents produce a
dose-dependent decrease in amplitude and increase in latency
for SEPs with cortical responses affected to a larger degree than
subcortical and peripheral nerve responses. Nitrous oxide
(N2O) causes a profound reduction in amplitude with increased
latency in all neurophysiologic monitoring with suppression of
cortical responses that mimic halogenated agents [7].
Question 10
During intraoperative scoliosis correction, the surgeon notes
a decrease of >50% in the amplitude. According to the
intraoperative neuromonitoring (IONM) checklist, which of
the foll owing should be considered?
A. Stop current manipulation.
B. Administration of steroids.
C. Check the depth of anesthesia.
D. All of the above.
Response (D) Decrease in the ampl itude >50% means an
affection to the neuronal tissue. All the above answers are
actions done to avoid permanent neuronal injury [7].
Question 11
Intraoperative monitoring is highly recommended to be
utilized in which of the following spinal procedures:
A. Correction of spinal deformities (e.g., scoliosis,
kyphosis)
B. Insertion of spinal fixation devices (e.g., pedicle screw
placement)
C. Decompression at the level of the spinal cord
D. Surgical treatment of spinal cord tumors
E. All of the above.
Response (E) In performing all of these spinal surgeries,
intraoperative monitoring is highly recommended [8, 9].
Question 12
What is the most common mechanism responsible for neu-
rologic injury during scoliosis surgery?
A. Direct injury due to surgical trauma (placement of
spinal implants)
B. Traction and/or compression affecting neural structures
(Spinal realignment and deformity correction)
C. Ischemia resulting in decreased perfusion of the spinal
cord and/or nerve
D. Compressive neuropathy.
Response (C) Mechanisms that can cause neurologic
injury during deformity surgeries are: (a) compression
and/or traction of the neural structures, that could have
occurred during spinal deformity correction and realignment
using instrumentation or due to an epidural hematoma after
corpectomy procedure; (b) iatrogenic direct neural injury,
especially during spinal implant placement or neural
decompression; (c) compressive neuropathy due to patient
positioning before or during surgery (e.g. brachial plexus
injury); (d) ischemia resulting in reduced perfusion of the
neural structures, causing an ischemic injury to the spinal
cord and/or nerve roots (e.g. following critical segmental
vessels ligation that supplies the spinal cord or after sus-
tained hypotension). Ischemia is the most common mecha-
nism responsible for neurologic injury during scoliosis
surgery [10 , 11].
Question 13
Which one of the following statements regarding
somatosensory evoked potentials (SEPs) is incorrect?
A. They are a modification of the basic EEG in which a
cortical or subcortical response to repetitive stimulation
of a peripheral mixed nerve is recorded at sites cephalad
and caudad to the operative field.
B. They provide direct information about the status of the
ascending spinal cord sensory tracts.
C. They can provide an indirect information about the
status of the spinal cord motor tracts.
D. SEPs data provide real-time data regarding the intra-
operative neurologic funct ion.
Response (D) SEPs do not provide real-time data regard-
ing neurologic function because there is a slight delay
(usually, 1 min). The SEPs response is averaged for
extraction from background noise [12–15].
Question 14
Which one of the following changes of somatosensory
evoked potentials (SEPs) is incorrect?
A. A unilateral complete loss of amplitude mandates
stopping of surgery.
5 Intraoperative Neuromonitoring 85
B. A bilateral loss of amplitude 50% or greater relative to
baseline amplitude mandates stopping of surgery.
C. Spinal cord injury is more likely to occur if the
amplitude is unchanged.
D. Changes in latency are common and less significant.
Response (C) Spinal cord injury is unlikely if the ampli-
tude is unchanged [12–15].
Question 15
Which of the following statements regarding the transcranial
electric motor evoked potentials (tceMEPs) is false?
A. tceMEPs are neuroelectric impulses elicited by tran-
scranial application of a high-voltage stimulus to elec-
trodes placed over specific scalp regions to excite
specific areas of the motor cortex.
B. tceMEPs can provide information about the functional
integrity of the spinal cord motor tracts that cannot be
obtained using somatosensory evoked potentials (SEPs).
C. tceMEPs are extremely sensitive to spinal cord blood
flow alterations resulting from intraoperative hypoten-
sion or evolving vascular injury.
D. When evolving intraoperative injury occurs, the chan-
ges in tceMEPs appear delayed compared to SEPs
changes.
Response (D) Alterations in tceMEPs present earlier than
changes in SEPs in patients with evolving neurologic injury,
which permits earlier initiation of corrective action to pre-
vent permanent neurologic compromise. tceMEPs are not a
replacement for SEPs but are used in combination with SEPs
to directly measure both spinal cord sensory and motor tract
function, thereby increasing the efficacy of spinal monitoring
[16–18].
Question 16
Which of the following techniques are used for monitoring
spinal cord function?
A. Stagnara wake-up test
B. Ankle clonus test
C. Somatosensory evoked potentials (SEPs)
D. Transcranial electric motor-evoked potentials (tceMEPs)
E. All of the above.
Response (E) Stagnara wake-up test, ankle clonus test,
somatosensory-evoked potentials (SEPs), and transcranial
electric motor-evoked potentials (tceMEPs) are all
neuromonitoring techniques that can be used to assess the
spinal cord function during spine surgery [19–20].
Question 17
Which one of the following regarding electromyographic
monitoring during spinal procedures is false?
A. Electromyography (EMG) is used to assess the func-
tional integrity of individual nerve roots.
B. Mechanically elicited electromyograms are used during
the dynamic phases of surgery, such as pedicle screw
insertion.
C. Mechanically elicited EMGs are termed stimulus-
evoked EMG or triggered EMG.
D. Electrically elicited EMGs should be used during the
static phases of surgery, such as immediately before or
after pedicle screw placement.
Response (C) Mechanically elicited EMGs are termed spon-
taneous, or free-running EMGs. An electrically elicited EMG is
termed a stimulus-evoked or triggered EMG [14, 21, 22].
Question 18
Regarding the effect of the anesthetic agents on neuro-
physiologic signals, all of the following statements are true,
EXCEPT:
A. Inhalational agents depress signal amplitude, increase
signal variability, and increase interpretative error.
B. All depolarizing and non-depolarizing paralytic agents
should be avoided throughout the operation.
C. Inhalational agents should be avoided after induction
and intubation.
D. A total intravenous anesthesia regimen (TIVA) is
optimal when transcranial electric motor and
somatosensory evoked potentials are recorded.
Response (B) All depolarizing and non-depolarizing par-
alytic agents should be avoided, except at the beginning of
the procedure during spinal exposure, because these agents
block neuromuscular junction transmission and preclude
muscle contraction. Muscle relaxation allows for easier
exposure and retraction [23–25].
Question 19
Which one of the following factors has an adverse effect on
somatosensory evoked potentials (SEPs) recordings?
86 A. Khan et al.