APPENDIX

C ra n i a l N e rve s : A n a t o m y a n d P hy s i o l o g y
We have 12 cranial nerves; some are sensory nerves, some are motor nerves, and some are part
of the autonomic nervous system.

I. Olfactory Sensory: Smell

II. Optic Sensory: Vision
III. Oculomotor Motor: Eye Movements: Innervates all extraocular muscles,
except the superior oblique and lateral rectus mus-
cles. Innervates the striated muscle of the eyelid.
Autonomic: Mediates pupillary constriction and accommodation for
near vision.
IV. Trochlear Motor: Eye Movements: Innervates superior oblique muscle.
V. Trigeminal Sensory: Mediates cutaneous and proprioceptive sensations from
skin, muscles, and joints in the face and mouth, includ-
ing the teeth and the anterior two-thirds of the tongue.
Motor: Innervates muscles of mastication.
VI. Abducens Motor: Eye Movements: Innervates lateral rectus muscle.
VII. Facial Motor: Innervates muscles of facial expression.
Autonomic: Lacrimal and salivary glands.
Sensory: Mediates taste and possible sensation from part of the
face (behind the ear).
Nervous
intermedius: Pain around the ear; possibly taste.
VIII. Vestibulocochlear Sensory: Hearing
Equilibrium, postural reflexes, orientation of the head
in space.
IX. Glossopharyngeal Sensory: Taste
Innervates taste buds in the posterior third of tongue.
Sensory: Mediates visceral sensation from palate and posterior
third of the tongue.
Innervates the carotid body.
Motor: Muscles in posterior throat (stylopharyngeal muscle).
Autonomic: Parotid gland.
X. Vagus Sensory: Mediates visceral sensation from the pharynx, larynx,
thorax, and abdomen.
Innervates the skin in the ear canal and taste buds in the
epiglottis.
Autonomic: Contains autonomic fibers that innervate smooth mus-
cle in heart, blood vessels, trachea, bronchi, esopha-
gus, stomach, and intestine.
Motor: Innervates striated muscles in the soft palate, pharynx,
and the larynx.
XI. Spinal accessory Motor: Innervates the trapezius and sternocleidomastoid
muscles.
XII. Hypoglossal Motor: Innervates intrinsic muscles of the tongue.

343
344 Intraoperative Neurophysiological Monitoring

CN VI. Abducens nerve: Controls eye

FUNCTIONS OF THE CRANIAL
movements from the midline toward the side.
NERVES
Lesion to CN VI prevents movements of the
eye from the midline and outward.
CN I. Olfactory nerve: Communicates
chemical airborne messages to the brain.
CN VII. Facial nerve: Controls the face.
CN II. Optic nerve: Communicates optic CN VII is often monitored intraoperatively
information. Variations in contrast are the most because it is at risk in all operations to
powerful stimulations of the visual system. remove acoustic tumors and it is involved in
diseases such as hemifacial spasm. The auto-
CN III. Oculomotor nerve: Controls all of nomic fibers of CN VII control both tear
the extraocular eye muscles, except the glands and salivary glands. A loss of facial
trochlearis and the lateral rectus muscles; thus, function is cosmetically important and makes
it innervates the superior, the inferior, the it difficult to eat, and the lack of tears and the
medial rectus, and the inferior oblique muscles. inability to close the eye might result in
This muscle moves the eye in all directions; injures to the cornea.
therefore lesions to CN III affect essentially all Nervus intermedius: Perhaps taste. Deep
eye movements and cause the eye to be devi- ear pain (geniculate neuralgia).
ated downward and outward. It also innervates
the eyelid and makes it possible to close the eye CN VIII. Vestibulocochlear nerve: The
when lying down. Lesions to CN III cause pto- two parts of this nerve communicate auditory
sis (partial closure of the eyelid). CN III con- information and information about head move-
tains autonomic fibers that control the size of ments. Whereas the covering of the nerve fibers
the pupil and stretches the lens to achieve of most of the brainstem cranial nerves changes
accommodation. Lesions to the CN III essen- from peripheral myelin to central myelin a few
tially make the eye useless. millimeters from the brainstem, the transitional
zone for CN VIII is in the internal auditory
CN IV. Trochlearis nerve: Controls the meatus, which means that CN VIII throughout
trochlear muscle, and contraction of this mus- its entire intracranial course is covered with
cle causes the eye to move downward when it central myelin and it has no epineurium. This
is in a position medial to the midline. Lesions means that CN VIII has mechanical properties
of CN IV affect downward and inward move- similar to those of the brain, making it more
ments of the eye. fragile than other cranial nerves.
The vestibular portion of CN VIII communi-
CN V. Trigeminal nerve: This nerve’s sen- cates to the brain information gathered by the
sory portion — the portio major — innervates the inner ear about the position of the head. In fact,
skin of the face and the cornea. This portion of we can do quite well without the vestibular por-
CN V thereby communicates sensory informa- tion of CN VIII, but if it is injured on one side
tion about touch and pain from the face and the only, severe balance disturbances can result;
mouth. CN V is the nerve that causes toothache however, one can adapt to such dysequilibrium
and the severe pain of trigeminal neuralgia. depending on one’s age (better when younger
Lesions to the sensory portion of CN V cause a than when older).
loss of sensation of the face. Loss of corneal sen-
sation could result in corneal bruises. CN IX. Glossopharyngeal nerve: Com-
The motor potion of CN V –– the portio municates sensory information from the throat
minor –– controls the muscles of mastication. to the brain and information about blood pres-
Lesions to the motor portion of CN V cause sure to the cardiovascular centers. The motor
atrophy of the mastication muscles. portion of CN IX controls the stylopharyngeal
Appendix Cranial Nerves: Anatomy and Physiology 345

muscle. Lesions of CN IX will cause a loss of effect on the cardiovascular system, but the effect
gag reflex on the affected side and a risk of of bilateral severance of the vagal nerve is severe.
choking on food. Lesions on one side will likely The vagus nerve might carry more complex sen-
have little effect on cardiovascular function, but sory information from the lower body.
a loss of CN IX on both sides is fatal.
CN XI. Spinal accessory nerve: Controls
CN X. Vagus nerve: This nerve’s name muscles in the neck and shoulder (sternocleido-
means the “vagabondering” nerve, descriptive in mastoid and trapezoid muscles). Lesions of CN
that it travels around in a large portion of the XI cause atrophy of the muscles that are inner-
body. This nerve conveys parasympathetic input vated by that nerve.
to the entire chest and abdomen. The vagus nerve
also controls the vocal cords, the heart, and the CN XII. Hypoglossal nerve: Controls
diaphragm. The most noticeable effect of unilat- movements of the tongue. Unilateral lesions to
eral lesions to CN X is hoarseness, because the CN XII cause deviation of the tongue and atro-
vocal cord on the affected side cannot close. phy of the tongue on the affected side. Bilateral
Although CN X carries information to and from lesions make it almost impossible to speak and
the heart, unilateral lesions to CN X have little swallowing is impaired.
Abbreviations
μS: Microseconds ICC: Central nucleus of the inferior
AAF: Anterior auditory field colliculus
ABI: Auditory brainstem implants IPL: Interpeak latency
ABR: Auditory brainstem response ISI: Inter stimulus interval
AI: Primary auditory cortex kHz: Kilohertz
AICA: Anterior inferior cerebellar artery kOhm: Kiloohm
AII: Secondary cortex LED: Light-emitting diodes
AP: Action potentials LGN: Lateral geniculate nucleus
AVCN: Anterior ventral cochlear nucleus LL: Lateral lemniscus
CAP: Compound action potentials mA: Milliampere
CCT: Central conduction time ma: Milliampere
cm: Centimeter MAC: Minimal end-alveolar concentration
CM: Cochlear microphonics MCA: Middle cerebral artery
CMAP: Compound muscle action potential MEP: Motor evoked potentials
CMN: Centromedian nucleus MGB: Medial geniculate body
CN I-XII: Cranial nerves I-XII MGP: Medial segment of globus pallidus
CN: Cochlear nucleus MI: Primary motor cortex
CNAP: Compound nerve action potentials mm: Millimeter
CNS: Central nervous system MOhm: Megaohm
CPA: Cerebellopontine angle ms: Millisecond
CPG: Central pattern generator MSO: Medial superior olivary nucleus
CSF: Cerebrospinal fluid mv: Millivolts
CT: Corticospinal tract MVD: Microvascular decompression
DAS: Dorsal acoustic stria (operations)
dB: Decibel NF2: Neurofibromatosis type 2
DBS: Deep brain stimulation NIHL: Noise induced hearing loss
DC: Direct electric current NMEP: Neurogenic motor evoked potentials
DCN: Dorsal cochlear nucleus NTB: Nucleus of the trapezoidal body
DPV: Disabling positional vertigo PAF: Posterior auditory field
DRG: Dorsal root ganglia PD: Parkinson’s disease
ECoG: Electrocochleographic PeSPL: Peak equivalent sound pressure level
EEG: Electroencephalographic PICA: Posterior inferior cerebellar artery
(potentials) PMC: Premotor cortical (areas)
EKG: Electrocardiogram (or pps: Pulses per second
electrocardiographic) PVCN: Posterior ventral cochlear nucleus
EMG: Electromyographic (potentials) REZ: Root exit zone (or root entry zone)
EPSP: Excitatory postsynaptic potential RMS: Root mean square
GPe: Globus pallidus external part SI: Primary somatosensory cortex
CPG: Central pattern generator SMA: Supplementary motor area
GPi: Globus pallidus internal part SNc: Substantia nigra pars compacta
GPN: Glosso-pharyngeal neuralgia SNR: Signal-to-noise ratio
HD: Huntington’s disease SNr: Substantia nigra is the pars reticulata
HFS: Hemifacial spasm SOC: Superior olivary complex
HL: Hearing level SP: Summating potential
Hz: Hertz, cycles per second SSEP: Somatosensory evoked potentials

347
348 Intraoperative Neurophysiological Monitoring

STN: Subthalamic nucleus V: Volts

TC-MEPs: Transcranial motor evoked VAS: Ventral acoustic stria
potentials VEP: Visual evoked potentials
TES: Transcranial electrical stimulation Vim: Intermediary nucleus of the thalamus
TGN: Trigeminal neuralgia μS: Microsecond
TIVA: Total intravenous anesthesia μV: Microvolt
TN: Trigeminal neuralgia μA: Microamps
Index 349

Index
A
Abducens nerve (CN VI), 177, 207, 343 muscle relaxants, 281
Abnormal muscle response, 256 total intravenous (TIVA), 280
Acoustic tumor operations, see vestibular Anteriorlateral (somatosensory) system, 72
schwannoma Artifacts, stimulus,
Action potentials, nerve fibers, 22, 230, 268 nature, 301, 303, 312, 315, 328
Aliasing, how to avoid, 315 reducing, 304, 307, 320, 327, 328
Alpha motoneurons, 157,168, 185, 187, 193 Ascending auditory pathways,
Amplifiers, classical, 61
common mode rejection, 301 electrical potentials, 65
filters, 302 non-classical, 62
maximal output, 301 Ascending somatosensory pathways,
Anatomy, anteriorlateral system, 72
auditory pathways, 61 dorsal column system, 70
basal ganglia, 155, 158, 159 Ascending visual pathways, 82
cerebellum, 162 Audio amplifiers and loudspeakers, 308
cerebral cortex, 62, 65, 71, 81, 82, 157, Auditory brainstem implants (ABI),
160, 173 monitoring placement of
ear, 55 electrodes, 267
motor pathways, 157 Auditory brainstem responses (ABR),
somatosensory system, 70 as indicator of brainstem manipulations, 118
spinal cord, 70, 157, 164, 167 display, 93
visual pathways, 82 electrode placement, 90
Anatomical location of nerve injuries, farfield potentials (ABR), 86
assessment, 230 interpretation, 105
Anesthesia requirements, monitoring, 85
ABR, 124 neural generators, 68
cortical evoked somatosensory optimal filtering, 300
potentials, 142 optimal stimulation, 87
guidance for implantation of electrodes processing, 67, 303, 308, 313
for deep brain stimulation, 271 stimulus artifact, 301, 303
identification of central sulcus, 249 wave form, 66
monitoring motor systems, 189, 279 Auditory evoked potentials (near field),
monitoring sensory systems, 279 interpretation, 105
recording of EMG, 191 recording from auditory nerve, 93
recording of EMG potentials, 282 recording from cochlear nucleus, 94
visual evoked potentials, 147 Auditory nerve,
Anesthesia, as generator of peak I and II of ABR, 69
basic principles, 279 conduction block, 106
effect on neuroelectric potentials, 281 conduction velocity, 69
inhalation, 279 recording compound action potentials
intravenous, 280 from, 93, 103

349
350 Index

Auditory prostheses, placement of cochlear Communication,

nucleus stimulating electrodes, 267 importance, 287
Auditory system, anatomy and physiology, 55 in the operating room, 48
Axonotmesis, 224 Compound action potentials,
auditory nerve, 103
B long nerve, 25
Basal ganglia, peripheral nerves, 226, 230, 256
guide of electrode placement for deep Compound muscle action potentials
brain stimulation, 264 (CMAPs), 31, 191
organization, 159 Computer systems, 308
Bipolar, Conduction block, peripheral nerve, 37, 225
recording from a nerve, 28, 309, 328, 328 Conduction velocity,
vs monopolar recording in localizing mixed nerves, 27, 221
nerves, 239, 309 peripheral nerves, 222
stimulation, 202, 209, 309 sign of injury, 226
Blood supply, Constant voltage or constant current
cerebrum, 140 stimulators,
to spinal cord, 126, 169 monitoring extraocular muscles, 208
Brainstem manipulations, ABR as indicator, 118 monitoring facial nerve, 202, 239
pedicle screw monitoring, 188
C Corticospinal system,
CAP, see compound action potentials anatomical organization, 164
Cause of injury to the auditory nerve, interpretation of recorded responses, 184
heating, 106 monitoring, 172,179, 181, 183
stretching, 106 recording from (D and I waves), 172,
unknown, 116 181, 183
Central conduction time (CCT), 78, 139, Cotton wick electrode, 93, 94
141, 144 Cranial motor nerves,
Central control of muscle tone and anatomical organization, 177, 343
excitability, 176 localizing, 237
Central sulcus, identification, 247 monitoring, 197, 237
Cerebellum, 162 Cranial nerves,
Cerebral perfusion, anatomy and physiology, 343
compared with measurement of blood Cunate nucleus, 71
flow, 141 Cut end response, 37
SSEP as indicator, 139
Choice of operations to be monitored, 335 D
Cochlea, D and I waves, 172, 181, 183
anatomy, 55 Data analysis, 309
electrical potentials, 60 Dermatomes,
implants, 267 monitoring of SSEP, 127, 131
Cochlear nerve, see auditory nerve organization, 128
Cochlear nucleus, Descending pathways,
anatomy, 61, 69 auditory, 65
implants (ABIs), 267 motor, 164
placement of stimulating electrodes, 267 Diagnosis of injury to peripheral nerves, 251
recording, 94, 103 Differential amplifiers, see Amplifiers
Index 351

Digital filters, for evoked potentials, 97, cost benefit analysis, 333
101, 320 promotion of better operating methods,
Display units, 308 335
Dorsal column nuclei, 71 reduction of postoperative deficits, 331
Dorsal column system, anatomy, 71 research in the operating room, 337
Dorsal horn of the spinal cord, anatomy, shorten operating time, 335
166 Evaluation of postoperative deficits, 333
Dorsal root, neurectomy, 242 Extraocular muscles, monitoring, 207

E F
Ear, Facial muscles,
anatomy, 55 recording EMG, 199, 238, 240, 257
physiology, 57 other indications of contractions, 199
Earphones, 41, 307 Facial nerve, location of injury of
ECoG, see electrocochleographic potentials intracranial portion, 204
Efficacy of monitoring, 336 Facial nerve monitoring,
Electrical interference, extracranial portion, 206
different kinds, 47 intracranial portion, 197
how to reach monitoring equipment, 291 False negative responses, 329, 336
how to reduce effects, 292 False positive responses, 329, 336
identification of source, 286, 287 Far field potentials, see also ABR, SSEP,
Electrical safety, 294 and VEP,
Electrical stimulators, characteristics, 34
constant current, 188, 304 display of results, 46
constant voltage, 202, 208, 304 optimal recording, 45
maximal output, 305 recording, 45
Electrocoagulation (electrocautery), selection of stimulus and recording
interference, 294, 312 parameters, 46, 299, 308
hazards, 294 Filtering,
Electrocochleographic (ECoG) potentials, analog (electronic) filters, 92, 319
recording, 104 digital filters, 92, 320
Electromyographic potentials (EMG), electronic low- and high-pass, in
extraocular muscles, 207 amplifiers, 302
facial muscles, 199 Filters,
recording, 282, 283 band-pass, 302, 320
skeletal muscles, 183, 186, 188 Bessel filters, 303
Erb’s point, 128 digital, 92, 320
Evoked potentials, weighting function, 322
auditory, 85 zero-phase finite impulse response,
recording, 281, 283, 285, 292, 294 320
somatosensory, 125, 280 Wiener filters, 325
visual, 145 electronic, 92, 302, 319
Extraocular muscles, high-pass, 302
anatomy, 177, 207 “intelligent” filters, 325
recording EMG potentials, 207 low-pass, 301, 302
Evaluating benefits of intraoperative notch, 303
monitoring, Floor of fourth ventricle, mapping, 245
352 Index

G I–J
Generators, neural, Injured peripheral nerves, diagnosis, 251
ABR, 68 Interference,
SSEP, 77 blood warmer, 290
Glossopharyngeal nerve (CN IX), 178, 343 electrical, 287
Gracile nucleus, 71 from power line, 286
Grounding (equipment), 288, 293, 296 how to reduce effects, 291
Guiding the surgeon in operations, identification of source, 288
basal ganglia for deep brain stimulation, infusion pumps, 290
265 periodic, 287
diagnosis of injured nerves, 251 signature, 289
finding central sulcus, 247 spectrum, 289
finding safe entry to brainstem, 245 Interference, magnetic,
identification of specific tissue, 237 how to reduce effects, 292
localizing motor nerves, 237 identification of source, 289
making lesions in the brain, 264 Interpretation of changes in sensory evoked
mapping, potentials,
auditory-vestibular nerve, 241 auditory evoked potentials, 105,
floor of the fourth ventricle, 245 relationship with hearing acuity, 113
the spinal cord, 244 Intraoperative,
peripheral motor nerves, 240 diagnosis of nerve injuries, 229
sensory nerves, 240 measurement of nerve conduction, 229
spinal cord, 245 Ischemia, SSEP as indicator, 139
spinal dorsal roots, 242 Jendrassik maneuver, 176
trigeminal nerve root, 241
microvascular decompression (MVD) for L–M
hemifacial spasm, 256 Lateral spinal tracts, anatomical
neuroma in continuity, 251 organization, 164, 166
placement of ABIs electrodes, Lateral spread response, see abnormal
267, 269 muscle response, 257
Light stimulators, 42, 307
H Localizing cranial motor nerves, 237
Hazard, electrical, see electrical hazard Localizing site of injury, 252
Hearing loss, motor nerves 237, 240
auditory nerve, 115 peripheral nerves, 230
cochlear, 66, 87, 115 Loudspeakers and audio amplifiers, 308
conductive, 66, 87, 114 Low-pass filters, see filters, low-pass
Heat as a cause of injury, MAC, see Minimum alveolar concentration
auditory nerve, 99, 105, 107 Magnetic interference,
facial nerve, 203 identification of source, 287, 289
Hemifacial spasm (MVD operations), how reach recording equipment, 292
abnormal muscle response, see abnormal how to reduce effects, 292
muscle response Magnetic stimulation of nervous tissue, 43,
identification of compressing vessel, 179, 182
256 Magnetic stimulators, 306
monitoring of auditory nerve, 264 Mapping central structures,
monitoring of facial nerve, 205 central sulcus, 247
Index 353

floor of the fourth ventricle, 245 Muscle relaxants (paralysis),

peripheral motor nerves, 240 component of anesthesia, 281
sensory nerves, 240 monitoring of facial nerve, 258
spinal cord, 244, 245 monitoring of spinal motor system, 184,
Mapping nerves, 185, 190, 193
auditory-vestibular nerve, 241 recording of abnormal muscle response,
branches of the trigeminal nerve, 241 258, 271
central motor nerves, 237 testing, 291
peripheral motor nerves, 240 MVD, see Microvascular decompression
sensory nerves, 240 operations
spinal dorsal roots, 243 N
Masking of auditory evoked potentials by
drilling, 116 Near field potentials, general, 23, 24
Mechanically induced facial nerve activity, Near field potentials, recorded from,
in operations for vestibular cerebral cortex, 45, 247
schwannoma, 202 cord, 181, 182, 183, 187
Medial spinal tracts, fiber tracts, 44
anatomical organization, 164, 167 muscles (EMG), 43, 183, 185, 187, 190,
Median nerve, stimulation, 125, 127 199, 201, 252, 257, 263
nuclei, 45, 94
Microelectrodes,
peripheral nerves, 11, 27, 45, 230, 252
equipment for recording with, 266
Nerves,
properties, 265
conduction velocity, 11, 23, 27, 37, 44,
use in recording unit potentials, 265
69, 221, 229
use in recordings from basal ganglia, 265
cranial, 85, 93, 197, 343
Microvascular decompression (MVD)
long, 27
operations, identification of
peripheral, 229,
compressing vessel in hemifacial
signs of injury, 37, 224, 226, 230
spasm, 256
Neural generators,
Middle ear, 55
ABR, 66, 68
Minimum alveolar concentration (MAC),
SSEP, 77, 79
279
VEP, 84
Mistakes, how to reduce, 284
Neurapraxia, 224
Monopolar recording,
Neurogenic evoked potentials from spinal
auditory nerve, 93, 103,105
cord, 139
cochlear nucleus, 94
Neuroma in continuity, 251
from a long nerve, 25, 230
Non-classical sensory pathways, 61, 62, 73, 82
Motor cortex,
Nonspecific descending motor system, 167
direct electrical stimulation, 172, 182
Non-surgical factors,
localization, 247
irrigation, 114, 116
transcranial electrical stimulation (TES),
temperature, 127
24, 172, 180, 212
Notch filters, 303
transcranial magnetic stimulation (TMS), Nucleus Z, 71
172, 182 Nyquist frequency, 315
Motor evoked potentials (MEP), recording,
180, 185 O–P
Motor pathways, anatomy and physiology, 157 Obersteiner-Redlich zone, 112
Multiunit recordings, 265 Oculomotor nerve (CN III), 177, 207, 209, 343
354 Index

Optic nerve (CN II), 82, 145, 343 Recording techniques,

Optic tract, 82, 145, 343 bipolar and monopolar recordings, 309
Otoacoustic emission, 60 far field evoked potentials, 309
Output limitations, Reliability of monitoring, 48
amplifiers, 301
stimulators, 306 S
Parkinson’s disease, 161 Safety, electrical,
Pathology of peripheral nerves, operating room personnel, 297
classification, 224 patients, 295
diagnosis, 251 Scoliosis operations, monitoring, 188
Pedicle screw, Segmental pathways, spinal cord, 167
cost-benefit analysis, 334 Sensory systems, anatomy and physiology,
monitoring, 132,188 55
Periodic interference, see interference Signal processing,
Peripheral nerves, artifact rejection, 311
anatomy and physiology, 221 optimizing signal averaging, 312
classification, 221 reducing effect of amplifier blockage,
conduction velocity, 222 312
diagnosis of injury, 251 signal averaging, 310
localizing site of injury, 252 Signature of interference, 289
measurements of conduction, 229 Skull base operations, monitoring,
neuroma in continuity, 251 ABR as indicator of brainstem
pathology, 225 manipulations, 85, 118
regeneration of injured nerves, 226 extraocular muscles, 206
response to electrical stimulation, 24 facial nerve, 198, 205
responses to natural stimulation, 24 lower cranial nerves, 211
stimulus and recording parameters, 254 motor portion of CN V, 206
Post-operative deficits, estimation, 329, Slowly varying evoked potentials, signal
331, 332 averaging, 313
Power line interference, see interference, Somatosensory cortex,
electrical and magnetic anatomical organization, 71
Excitatory postsynaptic potential (EPSP), 24 recording, 247
Pre-and postoperative tests, Somatosensory evoked potentials (SSEP),
ABR, 40, 86 interpretation of responses, 136
facial function, 332 lower limb, 127, 128, 134,142
hearing threshold and speech indicators of cerebral ischemia, 125, 137,
discrimination, 40, 86, 114, 332 139
SSEP, 40, 136, monitoring of peripheral nerves, 131
Preparing the patient for monitoring, 41 monitoring of spinal cord, 125,
neural generator,
Q–R upper limb SSEP, 79
Quality control, lower limb SSEP, 78
evoked potentials, 308, 313 recording from spinal cord, 137
microelectrode recordings, 267 recording of short latency potentials,
Recording and stimulating electrodes, 41 127
Rejection filters, see notch filters stimulation, 127, 132
Rolandic fissure, see central sulcus upper limb, 75,125, 127, 133, 136, 142
Index 355

Somatosensory system, output limitations, 306

ascending pathways, anatomy, light, 307
dorsal column system, 70 magnetic, 304, 306
anterior lateral system, 72 sound (earphones), 307
electrical potentials from, see Stimulus artifacts, reduction,
somatosensory evoked potentials auditory evoked potentials, 301, 303
receptors, 70 computer programs, 327
Sound generators, 307 electrical stimulation, 304
Spinal cord monitoring, magnetic stimulation, 184
motor system, 179 overloading amplifiers, 183
SSEP, 125, 188 Stimulus-dependent latency, 24
Spinal cord monitoring, motor evoked Sunderland, grades of neural injury, 224
potentials (MEP), Suppression of evoked potentials,
electrical stimulation of exposed cerebral from anesthesia, 141, 142
cortex, 183 Suppression of motor responses,
electrical stimulation of spinal cord, 180 from anesthesia, 192
recording from spinal cord, 183 from lack of attention, 177
recording, 180, 184
stimulation of spinal cord, 187 T
transcranial electrical stimulation (TES), Temporal dispersion of action potentials,
24, 172, 180, 212 effects, 26
transcranial magnetic stimulation (TMS), Ten-twenty system, 129
172, 182 Thalamus, in motor systems, 162
Spinal cord tumor operations, 188 Total intravenous anesthesia (TIVA), 280
Spinal motor pathways, organization, Transcranial electrical stimulation (TES),
corticospinal tract, 164 24, 172, 180, 212
reticulospinal tract, 164 Transcranial magnetic stimulation (TMS),
rubrospinal tract, 164 172, 182
tectospinal tract, 164 Trigeminal nerve (CN V),
vestibulospinal tract, 164 anatomy, 73, 343
Spinal medial system, see medial spinal mapping trigeminal nerve root, 241
tracts monitoring motor portion, 207
Spinal lateral system, see lateral spinal Trigeminal evoked potentials, 142
tracts Trigeminal system, anatomical
Spinal reflexes, 168 organization, 73
Spinal roots, stimulation, 189 Trochlear nerve (CN IV), 177, 207, 343
Stimulating electrodes, 41, 199, 202, 209, 211,
238, 242, 247, 249, 253, 256, 307 U–Z
Stimulation, electrical, Unit responses,
bipolar, 202, 256, 309 basal ganglia and thalamus, 265
monopolar, 201, 309 nerve fibers, 22
tripolar, 253, 256 Upper limb SSEP, see somatosensory
Stimulation of spinal roots, 189 evoked potentials
Stimulators, Vestibular Schwannoma operations,
electrical, 303 monitoring,
constant current and constant ABR, 101, 209
voltage, 304 brainstem manipulations, 118
356 Index

CAP from auditory nerve, 93 Visual system,

CAP from cochlear nucleus, 94 ascending visual pathways, 82
electrocochleographic (ECoG) cortex (striate), 82
potentials, 104 evoked potentials, 83
facial nerve, 198 eye, 82
Visual evoked potentials, Weighting function, see digital filters
indicator of optic nerve injury, 145 Wick electrode, 93, 94
monitoring, 145, Wiener filtering, see digital filters
neural generators, 84 Zero phase digital filters, see digital filters