352Generators neuralABR 68Glossopharyngeal nerve CN IX 178 343G - PDF document

352Generators, neural,ABR, 68Glossopharyngeal nerve (CN IX), 178, 343Gracile nucleus, 71Grounding (equipment), 288, 293, 296Guiding the surgeon in operations,basal ganglia for deep brain stimulation,265diagnosis of injured nerves, 251finding central sulcus, 247finding safe entry to brainstem, 245identification of specific tissue, 237making lesions in the brain, 264mapping,auditory-vestibular nerve, 241floor of the fourth ventricle, 245the spinal cord, 244peripheral motor nerves, 240sensory nerves, 240spinal cord, 245spinal dorsal roots, 242trigeminal nerve root, 241microvascular decompression (MVD) forhemifacial spasm, 256neuroma in continuity, 251placement of ABIs electrodes,267, 269HHazard, electrical, see electrical hazardHearing loss,auditory nerve, 115cochlear, 66, 87, 115conductive, 66, 87, 114Heat as a cause of injury,auditory nerve, 99, 105, 107facial nerve, 203Hemifacial spasm (MVD operations),abnormal muscle response, see abnormalmuscle responseidentification of compressing vessel,256monitoring of facial nerve, 205I…JInjured peripheral nerves, diagnosis, 251Interference,blood warmer, 290electrical, 287from power line, 286how to reduce effects, 291identification of source, 288infusion pumps, 290periodic, 287signature, 289spectrum, 289Interference, magnetic,how to reduce effects, 292identification of source, 289Interpretation of changes in sensory evokedpotentials,auditory evoked potentials, 105,relationship with hearing acuity, 113diagnosis of nerve injuries, 229measurement of nerve conduction, 229Ischemia, SSEP as indicator, 139Jendrassik maneuver, 176L…MLateral spinal tracts, anatomicalorganization, 164, 166Lateral spread response, see abnormalmuscle response, 257Light stimulat

ors, 42, 307Localizing cranial motor nerves, 237Localizing site of injury, 252motor nerves 237, 240peripheral nerves, 230Loudspeakers and audio amplifiers, 308Low-pass filters, see filters, low-passMAC,see Minimum alveolar concentrationMagnetic interference,identification of source, 287, 289how to reduce effects, 292Magnetic stimulation of nervous tissue, 43,179, 182Magnetic stimulators, 306Mapping central structures,central sulcus, 247 Wehave 12 cranial nerves; some are sensory nerves,some are motor nerves,and some are partof the autonomic nervous system.I.OlfactorySensory:SmellII.OpticSensory:VisionIII.OculomotorMotor: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 forIV.TrochlearMotor:Eye Movements:Innervates superior oblique muscle.V.TrigeminalSensory:Mediates cutaneous and proprioceptive sensations fromskin,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.AbducensMotor:Eye Movements:Innervates lateral rectus muscle.VII.FacialMotor:Innervates muscles of facial expression.Autonomic:Lacrimal and salivary glands.Sensory:Mediates taste and possible sensation from part of theface (behind the ear).Nervousintermedius:Pain around the ear; possibly taste.VIII. VestibulocochlearSensory:HearingEquilibrium,postural reflexes,orientation of the headIX.Glossopharyngeal Sensory:TasteInnervates taste buds in the posterior third of tongue.Sensory:Mediates visceral sensation from palate and posteriorInnervates the carotid body.Motor:Muscles in pos

terior throat (stylopharyngeal muscle).Autonomic:Parotid gland.X.VagusSensory:Mediates visceral sensation from the pharynx,larynx,thorax,and abdomen.Innervates the skin in the ear canal and taste buds in theAutonomic: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,XI.Spinal accessoryMotor:Innervates the trapezius and sternocleidomastoidXII.HypoglossalMotor:Innervates intrinsic muscles of the tongue. Cranial Nerves: Anatomy and Physiology IndexDigital filters, for evoked potentials, 97,101, 320Display units, 308Dorsal column nuclei, 71Dorsal column system, anatomy, 71Dorsal horn of the spinal cord, anatomy,166Dorsal root, neurectomy, 242Eanatomy, 55physiology, 57Earphones, 41, 307ECoG,see electrocochleographic potentialsEfficacy of monitoring, 336Electrical interference,different kinds, 47how to reach monitoring equipment, 291how to reduce effects, 292identification of source, 286, 287Electrical safety, 294Electrical stimulators,constant current, 188, 304constant voltage, 202, 208, 304maximal output, 305Electrocoagulation (electrocautery),interference, 294, 312hazards, 294Electrocochleographic (ECoG) potentials,recording, 104Electromyographic potentials (EMG),extraocular muscles, 207facial muscles, 199skeletal muscles, 183, 186, 188Erbs point, 128Evoked potentials,auditory, 85somatosensory, 125, 280visual, 145Extraocular muscles,anatomy, 177, 207recording EMG potentials, 207Evaluating benefits of intraoperativemonitoring,cost benefit analysis, 333promotion of better operating methods,335reduction of postoperative deficits, 331shorten operating time,

335Evaluation of postoperative deficits, 333Extraocular muscles, monitoring, 207FFacial muscles,recording EMG, 199, 238, 240, 257other indications of contractions, 199Facial nerve, location of injury ofintracranial portion, 204Facial nerve monitoring,extracranial portion, 206intracranial portion, 197False negative responses, 329, 336False positive responses, 329, 336Far field potentials, see also ABR, SSEP,and VEP,characteristics, 34display of results, 46optimal recording, 45recording, 45selection of stimulus and recordingparameters, 46, 299, 308Filtering,analog (electronic) filters, 92, 319digital filters, 92, 320electronic low- and high-pass, inamplifiers, 302Filters,band-pass, 302, 320Bessel filters, 303digital, 92, 320weighting function, 322zero-phase finite impulse response,320Wiener filters, 325electronic, 92, 302, 319high-pass, 302intelligentŽ filters, 325notch, 303Floor of fourth ventricle, mapping, 245 recording from a nerve, 28, 309, 328, 328 Index Abducens nerve (CN VI), 177, 207, 343Abnormal muscle response, 256Acoustic tumor operations, see vestibularschwannomaAction potentials, nerve fibers, 22, 230, 268Aliasing, how to avoid, 315common mode rejection, 301filters, 302maximal output, 301Anatomy,auditory pathways, 61basal ganglia, 155, 158, 159cerebellum, 162cerebral cortex, 62, 65, 71, 81, 82, 157,160, 173ear, 55motor pathways, 157somatosensory system, 70spinal cord, 70, 157, 164, 167visual pathways, 82Anatomical location of nerve injuries,assessment, 230Anesthesia requirements,ABR, 124cortical evoked somatosensorypotentials, 142guidance for implantation of electrodesfor deep brain stimulation, 271identification of central sulcus, 249monitoring motor systems, 189, 279monitor

ing sensory systems, 279recording of EMG, 191recording of EMG potentials, 282visual evoked potentials, 147Anesthesia,basic principles, 279effect on neuroelectric potentials, 281inhalation, 279intravenous, 280muscle relaxants, 281total intravenous (TIVA), 280Anteriorlateral (somatosensory) system, 72nature, 301, 303, 312, 315, 328Ascending auditory pathways,classical, 61electrical potentials, 65non-classical, 62Ascending somatosensory pathways,anteriorlateral system, 72dorsal column system, 70Ascending visual pathways, 82Audio amplifiers and loudspeakers, 308Auditory brainstem implants (ABI),monitoring placement ofelectrodes, 267Auditory brainstem responses (ABR),as indicator of brainstem manipulations, 118display, 93electrode placement, 90farfield potentials (ABR), 86interpretation, 105monitoring, 85neural generators, 68optimal filtering, 300optimal stimulation, 87processing, 67, 303, 308, 313stimulus artifact, 301, 303wave form, 66Auditory evoked potentials (near field),interpretation, 105recording from auditory nerve, 93recording from cochlear nucleus, 94Auditory nerve,as generator of peak I and II of ABR, 69conduction block, 106conduction velocity, 69recording compound action potentialsfrom, 93, 103 STN:Subthalamic nucleusTC-MEPs:Transcranial motor evoked TES:Transcranial electrical stimulationTGN:Trigeminal neuralgiaTIVA:Total intravenous anesthesiaTN:Trigeminal neuralgia V:VoltsVAS:Ventral acoustic striaVEP:Visual evoked potentialsVim:Intermediary nucleus of the thalamusS:MicrosecondV:MicrovoltA:Microamps348Intraoperative Neurophysiological Monitoring 356CAP from auditory nerve, 93CAP from cochlear nucleus, 94electrocochleographic (ECoG)potentials, 104facial nerve, 198Visual evoked p

otentials,indicator of optic nerve injury, 145monitoring, 145,neural generators, 84Visual system,ascending visual pathways, 82cortex (striate), 82evoked potentials, 83eye, 82Weighting function, seedigital filtersWick electrode, 93, 94Wiener filtering, see digital filtersZero phase digital filters, see digital filters S:Microseconds AAF:Anterior auditory field ABI:Auditory brainstem implantsABR:Auditory brainstem responseAI:Primary auditory cortex AICA:Anterior inferior cerebellar artery AII:Secondary cortex AP:Action potentials AVCN:Anterior ventral cochlear nucleusCAP:Compound action potentials CCT:Central conduction time cm:CentimeterCM:Cochlear microphonicsCMAP:Compound muscle action potentialCMN:Centromedian nucleusCN I-XII:Cranial nerves I-XIICN:Cochlear nucleusCNAP:Compound nerve action potentialsCNS:Central nervous systemCPA:Cerebellopontine angleCPG:Central pattern generatorCSF:Cerebrospinal fluidCT:Corticospinal tractDAS:Dorsal acoustic striadB:DecibelDBS:Deep brain stimulation DC:Direct electric current DCN:Dorsal cochlear nucleusDPV:Disabling positional vertigoDRG:Dorsal root gangliaECoG:ElectrocochleographicEEG:Electroencephalographic EKG:Electrocardiogram (or EMG:Electromyographic (potentials)EPSP:Excitatory postsynaptic potentialGPe:Globus pallidus external partCPG:Central pattern generator GPi:Globus pallidus internal partGPN:Glosso-pharyngeal neuralgiaHD:Huntingtons diseaseHFS:Hemifacial spasm HL:Hearing levelHz:Hertz,cycles per secondIPL:Interpeak latencyISI:Inter stimulus interval kHz:KilohertzkOhm:KiloohmLED:Light-emitting diodesLGN:Lateral geniculate nucleus LL:Lateral lemniscusmA:Milliamperema:MilliampereMAC:Minimal end-alveolar concentrationMCA:Middle cerebral arte

ryMEP:Motor evoked potentialsMGB:Medial geniculate bodyMGP:Medial segment of globus pallidusMI:Primary motor cortexmm:MillimeterMOhm:Megaohmms:MillisecondMSO:Medial superior olivary nucleus mv:MillivoltsMVD:Microvascular decompression NF2:Neurofibromatosis type 2NIHL:Noise induced hearing lossNMEP:Neurogenic motor evoked potentialsNTB:Nucleus of the trapezoidal bodyPAF:Posterior auditory field PD:Parkinsons diseasePeak equivalent sound pressure levelPICA:Posterior inferior cerebellar arteryPMC:Premotor cortical (areas)pps:Pulses per secondPVCN:Posterior ventral cochlear nucleusREZ:Root exit zone (or root entry zone)RMS:Root mean squareSI:Primary somatosensory cortex SMA:Supplementary motor areaSNc:Substantia nigra pars compactaSNR:Signal-to-noise ratioSNr:Substantia nigra is the pars reticulataSOC:Superior olivary complexSP:Summating potentialSSEP:Somatosensory evoked potentialsAbbreviations IndexSomatosensory system,ascending pathways, anatomy,dorsal column system, 70anterior lateral system, 72electrical potentials from, seesomatosensory evoked potentialsreceptors, 70Sound generators, 307Spinal cord monitoring,motor system, 179SSEP, 125, 188Spinal cord monitoring, motor evokedpotentials (MEP),electrical stimulation of exposed cerebralcortex, 183electrical stimulation of spinal cord, 180recording from spinal cord, 183recording, 180, 184stimulation of spinal cord, 187transcranial electrical stimulation (TES),24, 172, 180, 212transcranial magnetic stimulation (TMS),172, 182Spinal cord tumor operations, 188corticospinal tract, 164reticulospinal tract, 164rubrospinal tract, 164tectospinal tract, 164vestibulospinal tract, 164Spinal medial system, see medial spinaltractsSpinal lateral system,

see lateral spinaltractsSpinal reflexes, 168Spinal roots, stimulation, 189Stimulating electrodes, 41, 199, 202, 209, 211,238, 242, 247, 249, 253, 256, 307Stimulation, electrical,bipolar, 202, 256, 309monopolar, 201, 309tripolar, 253, 256Stimulation of spinal roots, 189electrical, 303constant current and constantvoltage, 304output limitations, 306light, 307magnetic, 304, 306sound (earphones), 307Stimulus artifacts, reduction,auditory evoked potentials, 301, 303computer programs, 327electrical stimulation, 304magnetic stimulation, 184overloading amplifiers, 183Stimulus-dependent latency, 24Sunderland, grades of neural injury, 224Suppression of evoked potentials,from anesthesia, 141, 142Suppression of motor responses,from anesthesia, 192from lack of attention, 177TTemporal dispersion of action potentials,effects, 26Ten-twenty system, 129Thalamus, in motor systems, 162Total intravenous anesthesia (TIVA), 280Transcranial electrical stimulation (TES),24, 172, 180, 212Transcranial magnetic stimulation (TMS),172, 182Trigeminal nerve (CN V),anatomy, 73, 343mapping trigeminal nerve root, 241monitoring motor portion, 207Trigeminal evoked potentials, 142Trigeminal system, anatomicalorganization, 73Trochlear nerve (CN IV), 177, 207, 343U…ZUnit responses,basal ganglia and thalamus, 265nerve fibers, 22Upper limb SSEP, see somatosensoryevoked potentialsVestibular Schwannoma operations,monitoring,ABR, 101, 209brainstem manipulations, 118 gag reflex on the affected side and a risk ofchoking on food. Lesions on one side will likelyhave little effect on cardiovascular function,buta loss of CN IX on both sides is fatal. CN X. Vagus nerve:This nerves namemeans the vagabonderingŽnerve,descriptive inthat it tr

avels around in a large portion of thebody. This nerve conveys parasympathetic inputto the entire chest and abdomen. The vagus nervealso controls the vocal cords,the heart,and thediaphragm. The most noticeable effect of unilat-eral lesions to CN X is hoarseness,because thevocal cord on the affected side cannot close.the heart,unilateral lesions to CN X have littleeffect on the cardiovascular system,but the effectof bilateral severance of the vagal nerve is severe.The vagus nerve might carry more complex sen-sory information from the lower body. CN XI. Spinal accessory nerve:XI cause atrophy of the muscles that are inner-vated by that nerve. CN XII. Hypoglossal nerve:movements of the tongue. Unilateral lesions toCN XII cause deviation of the tongue and atro-phy of the tongue on the affected side. Bilaterallesions make it almost impossible to speak andswallowing is impaired.AppendixCranial Nerves: Anatomy and Physiology345 354Optic nerve (CN II), 82, 145, 343Optic tract, 82, 145, 343Output limitations,amplifiers, 301stimulators, 306Parkinsons disease, 161Pathology of peripheral nerves,classification, 224diagnosis, 251Pedicle screw,cost-benefit analysis, 334Periodic interference, see interferencePeripheral nerves,anatomy and physiology, 221classification, 221conduction velocity, 222diagnosis of injury, 251localizing site of injury, 252measurements of conduction, 229neuroma in continuity, 251pathology, 225regeneration of injured nerves, 226response to electrical stimulation, 24responses to natural stimulation, 24stimulus and recording parameters, 254Post-operative deficits, estimation, 329,331, 332Power line interference, see interference,electrical and magneticExcitatory postsynaptic potent

ial (EPSP), 24Pre-and postoperative tests,ABR, 40, 86facial function, 332hearing threshold and speechdiscrimination, 40, 86, 114, 332SSEP, 40, 136,Preparing the patient for monitoring, 41Q…RQuality control,evoked potentials, 308, 313microelectrode recordings, 267Recording and stimulating electrodes, 41Rejection filters, see notch filtersRolandic fissure, see central sulcusRecording techniques,bipolar and monopolar recordings, 309far field evoked potentials, 309Reliability of monitoring, 48SSafety, electrical,operating room personnel, 297patients, 295Scoliosis operations, monitoring, 188Segmental pathways, spinal cord, 167Sensory systems, anatomy and physiology,55Signal processing,artifact rejection, 311optimizing signal averaging, 312reducing effect of amplifier blockage,312signal averaging, 310Signature of interference, 289Skull base operations, monitoring,ABR as indicator of brainstemmanipulations, 85, 118extraocular muscles, 206facial nerve, 198, 205lower cranial nerves, 211motor portion of CN V, 206Slowly varying evoked potentials, signalaveraging, 313Somatosensory cortex,anatomical organization, 71recording, 247Somatosensory evoked potentials (SSEP),interpretation of responses, 136lower limb, 127, 128, 134,142indicators of cerebral ischemia, 125, 137,139monitoring of peripheral nerves, 131monitoring of spinal cord, 125,neural generator,upper limb SSEP, 79lower limb SSEP, 78recording from spinal cord, 137recording of short latency potentials,127stimulation, 127, 132upper limb, 75,125, 127, 133, 136, 142 FUNCTIONS OF THE CRANIAL NERVESCN I. Olfactory nerve:CN II. Optic nerve:information. Variations in contrast are the mostpowerful stimulations of the visual system. CN III. Oculomotor n

erve:the extraocular eye muscles,except theit innervates the superior,the inferior,themedial rectus,and the inferior oblique muscles.This muscle moves the eye in all directions;therefore lesions to CN III affect essentially alleye movements and cause the eye to be devi-ated downward and outward. It also innervatesthe eyelid and makes it possible to close the eyewhen lying down. Lesions to CN III cause pto-sis (partial closure of the eyelid). CN III con-tains autonomic fibers that control the size ofthe pupil and stretches the lens to achievetially make the eye useless.CN IV. Trochlearis nerve:trochlear muscle,and contraction of this mus-cle causes the eye to move downward when itof CN IV affect downward and inward move-ments of the eye.CN V. Trigeminal nerve:This nerves sen-sory portion „ the portio major „ innervates theskin of the face and the cornea. This portion ofCN V thereby communicates sensory informa-tion about touch and pain from the face and themouth. CN V is the nerve that causes toothacheand the severe pain of trigeminal neuralgia.Lesions to the sensory portion of CN V cause aloss of sensation of the face. Loss of corneal sen-The motor potion of CN V …… the portioLesions to the motor portion of CN V causeatrophy of the mastication muscles.CN VI. Abducens nerve:Controls eyemovements from the midline toward the side.Lesion to CN VI prevents movements of theeye from the midline and outward.CN VII. Facial nerve:Controls the face.CN VII is often monitored intraoperativelyremove acoustic tumors and it is involved indiseases such as hemifacial spasm. The auto-nomic fibers of CN VII control both tearglands and salivary glands. A loss of facialfunction is cosmetically important and m

akesit difficult to eat,and the lack of tears and theinability to close the eye might result inNervus intermedius:CN VIII. Vestibulocochlear nerve:two parts of this nerve communicate auditoryinformation and information about head move-ments. Whereas the covering of the nerve fibersof most of the brainstem cranial nerves changesfrom peripheral myelin to central myelin a fewmillimeters from the brainstem,the transitionalzone for CN VIII is in the internal auditorymeatus,which means that CN VIII throughoutits entire intracranial course is covered withcentral myelin and it has no epineurium. Thismeans that CN VIII has mechanical propertiessimilar to those of the brain,making it morefragile than other cranial nerves. The vestibular portion of CN VIII communi-cates to the brain information gathered by theinner ear about the position of the head. In fact,we can do quite well without the vestibular por-tion of CN VIII,but if it is injured on one sideonly,severe balance disturbances can result;however,one can adapt to such dysequilibriumdepending on ones age (better when youngerCN IX. Glossopharyngeal nerve:sure to the cardiovascular centers. The motor344Intraoperative Neurophysiological Monitoring Indexfloor of the fourth ventricle, 245peripheral motor nerves, 240sensory nerves, 240spinal cord, 244, 245Mapping nerves,auditory-vestibular nerve, 241branches of the trigeminal nerve, 241central motor nerves, 237sensory nerves, 240spinal dorsal roots, 243Masking of auditory evoked potentials bydrilling, 116Mechanically induced facial nerve activity,in operations for vestibularschwannoma, 202Medial spinal tracts,anatomical organization, 164, 167Median nerve, stimulation, 125, 127equipment for recordin

g with, 266properties, 265use in recording unit potentials, 265use in recordings from basal ganglia, 265Microvascular decompression (MVD)operations, identification ofcompressing vessel in hemifacialspasm, 256Middle ear, 55Minimum alveolar concentration (MAC),279Mistakes, how to reduce, 284Monopolar recording,auditory nerve, 93, 103,105cochlear nucleus, 94from a long nerve, 25, 230Motor cortex,direct electrical stimulation, 172, 182localization, 247transcranial electrical stimulation (TES),24, 172, 180, 212transcranial magnetic stimulation (TMS),172, 182Motor evoked potentials (MEP), recording,180, 185Motor pathways, anatomy and physiology, 157Multiunit recordings, 265Muscle relaxants (paralysis),component of anesthesia, 281monitoring of facial nerve, 258monitoring of spinal motor system, 184,185, 190, 193recording of abnormal muscle response,258, 271testing, 291MVD,see Microvascular decompressionoperationsNear field potentials, general, 23, 24Near field potentials, recorded from,cerebral cortex, 45, 247cord, 181, 182, 183, 187fiber tracts, 44muscles (EMG), 43, 183, 185, 187, 190,199, 201, 252, 257, 263nuclei, 45, 94peripheral nerves, 11, 27, 45, 230, 252Nerves,conduction velocity, 11, 23, 27, 37, 44,69, 221, 229cranial, 85, 93, 197, 343long, 27peripheral, 229,signs of injury, 37, 224, 226, 230Neural generators,ABR, 66, 68SSEP, 77, 79VEP, 84Neurapraxia, 224Neurogenic evoked potentials from spinalcord, 139Neuroma in continuity, 251Non-classical sensory pathways, 61, 62, 73, 82Nonspecific descending motor system, 167Non-surgical factors,irrigation, 114, 116temperature, 127Notch filters, 303Nucleus Z, 71Nyquist frequency, 315O…PObersteiner-Redlich zone, 112Oculomotor nerve (CN III), 177, 207,