Koht, Sloan, Toleikis's Monitoring the Nervous System for Anesthesiologists and Other Health Care Professionals

Preface Acknowledgments Contents Contributors Part I: Monitoring Techniques 1: Somatosensory-Evoked Potentials Introduction Anatomy and Vascular Supply Methods Stimulation Recording Intraoperative Variables Affecting SSEPS: Pharmacology and Physiology Inhalational Anesthetics Intravenous Anesthetics Temperature Tissue Perfusion Oxygenation/Ventilation Intracranial Pressure Other Physiologic Variables Criteria for Intervention During Intraoperative SSEP Monitoring Dorsal Column Mapping Other Intraoperative Applications for SSEPs References 2: Transcranial Motor-Evoked Potentials Introduction Anatomy of the MEP Response Technical Aspects of MEP Monitoring Optimizing Compound Muscle Action Potential Patient Characteristics Contributing to Outcomes Effect of Anesthesia Management Outcomes Conclusion References 3: Auditory-Evoked Potentials Anatomy of the Auditory System Conduction of Auditory Signals from Ear to Cochlea Neural Components of the Auditory System and Electrical Generators Along the Auditory Pathway Cochlea: Electrocochleogram Auditory Pathway from Cochlear Nerve to Midbrain Auditory Brainstem-Evoked Responses and Cochlear Nerve Compound Action Potential Primary Auditory Cortex: Mid-Latency Auditory-Evoked Potentials Vascular Supply of Auditory Pathway Structures Techniques for Recording Auditory-Evoked Potentials Stimulation Electrocochleogram Compound Nerve Action Potentials from the Cochlear Nerve Brainstem Auditory-Evoked Potentials MLAEPs Anesthetic and Physiologic Considerations for Monitoring of Auditory Brainstem Responses ABR Alarm Criteria References 4: Visual-Evoked Potentials Introduction Flash Electroretinogram (F-ERG) Flash Visual-Evoked Potentials (F-VEPs) Introduction of the Intraoperative Monitoring of the Visual System: Orbital Surgeries Identified Sources of Intraoperative Variations in F-VEPs Recognition of a Reliable Monitoring of Vision Anatomy and Physiology of the Visual System Realization of Intraoperative Electroretinogram (ERG) and Flash Visual-Evoked Potentials (F-VEPs) Intraoperative ERG Intraoperative F-VEP Devices for Flash Stimulation Characteristics of Stimulation Light ERG Recordings and Analyses F-VEP Recordings and Analyses Warning Criteria Warning Criteria for ERGs Warning Criteria for F-VEPs Other Intraoperative Applications with ERG and F-VEP: Cardiovascular Surgeries, Deep Brain Stimulation Direct Electrical Stimulation of Visual Pathway Effects of Temperature Effects of Anesthesia on ERGs Effects of Anesthesia on F-VEPs Conclusion References 5: Deep Brain Stimulation Introduction Surgery Microelectrode Recording (MER) Complications Asleep vs. Awake Surgery The MER Procedure Target Structures for the Case Examples Cases and Disorders Case 1: Routine DBS of the STN in Parkinson’s Disease Clinical Symptoms of PD Parkinson’s Disease Procedure and Decisions Case 2: Noncomplex (PD-STN, Asleep) Preoperative Evaluation Procedure and Decisions Case 3: Complex Dystonia Procedure and Decisions Case 4: Complex Status Dystonicus Procedure and Decisions Conclusion References 6: Intraoperative Electromyography General Principles of EMG Anatomy of the Lower Motor Neuron System Motor Unit Neuromuscular Junction Anesthesia Considerations for EMG Neuromuscular Blocking Agents Local Anesthetic Agents Anesthesia for Other Myogenic Modalities Train-of-Four Technique Common Troubleshooting Issues in Train-of-Four Clipping Misinterpretation of Train-of-Four Data and Stimulus Artifact Spontaneous EMG—Fundamental Principles Neuronal Axons Respond to Mechanical Stimuli Neuronal Axons Respond to Thermal Stimuli Recording Electrode Considerations Electrode Type Location and Spacing Electrode Configuration EMG Recording Parameters Recording Sweep (Time Base) Filters Sensitivity Use of Audio Feedback Audio Feedback Audio Squelch or Muting Patterns of Iatrogenic EMG Activity Differential Diagnosis for EMG Activity “Light” Anesthesia Patient Positioning Thermal Induced EMG from Irrigation Artifact and Electrical Noise Triggered EMG—Fundamental Principles Stimulus Configurations: Monopolar Versus Bipolar Stimulus Artifact in Triggered EMG EMG Application and Technique for Cranial Nerves Electrode Placement for Cranial Nerves Cranial Nerves III, IV, and VI Cranial Nerves V and VII Cranial Nerves IX, X, XI, and XII Glossopharyngeal Nerve—CNIX Vagus Nerve—CNX Spinal Accessory Nerve—CNXI Hypoglossal Nerve—CN XII Stimulus and Recording Parameters and Technique for Triggered Cranial Nerve EMG Stimulus Intensity for Cranial Nerves Intracranial Cranial Nerve Stimulation Extracranial Cranial Nerve Stimulation Stimulating Dissectors Safety Issues with Cranial Nerve Stimulation Cranial Nerve Identification with Triggered EMG Using Triggered EMG to Evaluate Facial Nerve Function After Acoustic Neuroma Surgery Mapping the Floor of the Fourth Ventricle Mapping Technique Triggered EMG Application in Thyroid Surgery Factors Causing Amplitude and/or Latency Changes in Vagus Nerve CMAP EMG Applications and Technique in Spinal Procedures Recommended Recording and Stimulating Parameters for Spinal EMG Electrode and Montage Considerations for Spinal EMG EMG Electrode Placements According to Vertebral Levels Involved in the Surgery Assessing Nerve Root Function and Pedicle Screw Placement Description of Pedicle Screw Stimulation Technique Stimulus Setup Stimulation Automated Thresholding Sources of False-Negative Screw Thresholds Summary of Factors that May Falsely Increase Thresholds Sources of False Positive Screw Thresholds Minimally Invasive Lateral Transpsoas Approach to the Spine Technique for Triggered EMG during the Lateral Transpsoas Approach Cauda Equina Surgery Selective Dorsal Rhizotomy Suprasegmentally Generated EMG Discharges (SEDs) References 7: The Use of Spinal Reflex Responses for IOM Introduction Anatomy and Neurophysiology Spinal Cord Pathophysiology Spinal Nerve Root Pathophysiology Late Responses F-Responses F-Response Facilitation—Interaction Technique A-Waves H-Reflexes: Monosynaptic, Oligosynaptic Neurophysiologic Basis of H-Reflexes Gastrocnemius H-Reflex Gastrocnemius H-Reflex Normal Parameters Gastrocnemius H-Reflex Stimulation and Recording Techniques Flexor Carpi Radialis H-Reflex Flexor Carpi Radialis H-Reflex Background and Normal Parameters Flexor Carpi Radialis H-Reflex Stimulation and Recording Techniques Anesthetic Effects on Spinal Cord CPGs Clinical Correlation of H-Reflexes and F-Responses Clinical Correlation Summary H-Reflex Facilitation—Interaction Techniques Polysynaptic Reflexes Sacral Reflex Intraoperative Application of BCRs Monosynaptic and Polysynaptic Reflexes: Selective Dorsal and Ventral Root Rhizotomy Background Technical Summary Lower Extremity Intralimb and Interlimb Polysynaptic Reflexes Conclusion References 8: Brainstem Reflexes Under General Anesthesia Introduction Effects of General Anesthesia on Brainstem Centers Anatomy and Physiology of Specific Brainstem Reflexes Under General Anesthesia Blink Reflex H-Masseter Laryngeal Adductor Reflex (LAR) Methodologies for Eliciting Brainstem Reflexes Under General Anesthesia Blink Reflex H-Masseter Laryngeal Adductor Reflex (LAR) Contribution of Anesthesiology to Successfully Monitor Brainstem Reflexes Correlation of Brainstem Reflexes Monitoring with Postoperative Outcome Conclusion References 9: Brain Mapping: Asleep and Awake Introduction Planning Presurgical Mapping Planning of the Intraoperative Mapping Procedure Language and Parietal Mapping and Monitoring During Awake Craniotomies Establishing Baselines The Mapping Strategy Continuous Monitoring of Language or Parietal Functions Subcortical Mapping Ictal Events Location of the Central Sulcus by Median SSEP Phase Reversal Technique Motor Mapping via Electrical Stimulation with the Penfield Paradigm Motor Mapping and Monitoring via Electrical Stimulation with the Multipulse Train Paradigm Subcortical Motor Mapping Protection of the Thalamocortical Input to the Peri-Rolandic Region Electrocorticography (ECoG) in Functional Mapping Conclusions References 10: Intraoperative Monitoring of EEG and Processed EEG Introduction The Genesis of the EEG Cytoarchitecture Control of Rhythm and Anesthesia-Induced Sedation and Loss of Consciousness EEG Signal Time-Domain Method Frequency-Domain Methods Raw and Processed EEG Anesthetic Drugs Impact on EEG Propofol and Barbiturates Benzodiazepines Ketamine Dexmedetomidine Opioids Volatile Agents Nitrous Oxide Muscle Relaxants Clinical Utility of Raw and Processed EEG Future Directions of EEG Monitoring Conclusion References 11: Central Nervous System Near-Infrared Spectroscopic Monitoring: Technique and Clinical Application Introduction Instrumentation Transcranial NIRS Technology Regional Cerebral Oxygen Saturation Measurement Safety Considerations Limitations of Cerebral Oximetry Environmental Factors Patient Factors Technical Limitations Rationale for Cerebral NIRS Monitoring Physiology Factors Affecting NIRS Monitoring Basics of Oxygen Demand and Delivery Patient Factors Systemic Arterial Pressure Systemic Oxygen Delivery Systemic Arterial PaCO2 and pH Cerebral Blood Inflow and Outflow Obstruction Cerebral Oxygen Consumption Supplemental Cerebral Perfusion Differential Diagnosis of Cerebral Oxygen Desaturation and Treatment Algorithm Clinical Uses for Cerebral Oximetry Applications in Neonatology rScO2 Measurement in Neonates with HIE Measurement of Cerebral Autoregulation in Infants with HIE Measurement of Mitochondrial Redox State Measurement of CBF Measurement of CMRO2 Hybrid and Emerging Technologies in Neonatology Applications in Vascular Surgery Applications in Cardiac Surgery Overview of rScO2 Monitoring in Cardiac Surgery Effects of CPB on rScO2 rScO2, Neurologic Outcomes, and Organ System Dysfunction After Cardiac Surgery rScO2 as a Monitor of Cardiac Output and Hematocrit After Cardiac Surgery Conclusions on Cerebral Oximetry Monitoring in Cardiac Surgery Applications in Neurologic Critical Care Overview of the Role of Cerebral Oximetry in Neurologic Critical Care Adequacy of Cerebral Oxygenation Cerebral Autoregulation Cerebral Blood Flow Seizures Intracranial Bleeding Intracranial Pressure Future Directions for NIRS Research Conclusions References 12: Intracranial Pressure Monitoring Introduction The ICP Waveforms and Pressure Reactivity Index Indications of ICP Monitoring ICP Monitoring Techniques Intraparenchymal ICP Monitor/Micro Transducer Subarachnoid ICP Monitor Epidural Monitor Intraventricular Monitor Noninvasive ICP Monitoring Optic Nerve Sheath Diameter (ONSD) Transcranial Doppler (TCD) Other Methods of ICP Monitoring ICP-Guided Therapy Summary References 13: Monitoring Cerebral Blood Flow Physiology Mechanisms of CBF Regulation Autoregulation and Altered Humoral Responses Cerebrovascular Reserve CBF Measurement and Clinical Applications of Specific Techniques Perioperatively Stable Xenon CTCBF (XeCTCBF) Xe133 CBF Jugular Bulb AVO2 Difference Thermodilution rCBF Transcranial Doppler Vasospasm Cerebrovascular Reserve Intracranial Pressure Brain Death Vessel Patency Emboli Hyperemia Noninvasive, Spectroscopy-Based Monitors of CBF Imaging-Based Modalities Blood Oxygenation Level-Dependent (BOLD) MRI Arterial Spin Labeling (ASL) Computed Tomography Perfusion Intraoperative Cerebral Blood Flow Monitoring Indocyanine Green (ICG) Videoangiography Laser Speckle Contrast Imaging Monitors of Autoregulation TCD-Based autoregulation (Mx) Pressure-Reactivity Index (PRx) Cerebral Oximetry Index (COx) Summary References 14: Transcranial Doppler Ultrasonography Introduction Technology Practical Cerebrovascular Anatomy Examination Technique Interpreting TCD Ultrasonography Interpretation of CBFV Cerebrovascular Reactivity to Carbon Dioxide (Vasomotor Reactivity) Cerebral Autoregulation Testing Microemboli Monitoring Noninvasive Estimation of Intracranial Pressure (ICP) Clinical Applications of TCD Ultrasonography Diagnosing and Monitoring of Cerebral Vasospasm Monitoring During Carotid Artery Interventions Assessment of Patterns and Extent of Collateral Circulation in Patients with Cerebrovascular Stenosis or Occlusion, Including Moyamoya Disease Detection of Right-to-Left Shunts and Assessment for Patent Foramen Ovale (PFO)/Paradoxical Embolism Detecting Microemboli Following Stroke or Transient Ischemic Attack Monitoring Cerebral Thrombolysis in Acute Ischemic Stroke Assessment of Stroke Risk in Children with Sickle Cell Disease Monitoring Coronary Artery Bypass Surgery and Prosthetic Cardiac Valves [54] TBI Diagnosis of Cerebral Circulatory Arrest Limitations Conclusion References Part II: From Techniques to the Operating Room: General Considerations 15: IOM Instrumentation Layout and Electrical Interference Introduction Basic Electronics and Definitions Definition 1 Definition 2 Definition 3 Definition 4 Definition 5 Pathway 1: The Skin of the Patient Cskin Pathway 2: Ambient Sources of Electrical Noise Vnoise The Basic IOM Recording Circuit Tissue Physiologic Generator (Vtissue) Circuit Component: Tissue Between Generator and Electrode (Ztissue) Circuit Component: Electrode Connection to the Patient and Electrode Components (Zelectrode) Circuit Component: The Wire Between the Electrode Patient End and Connector End (Zleadwire) Circuit Component: Leadwire Connection to Safety Connector and Electrode to Amplifier Connection (Zpin) Circuit Component: Amplifier Impedance (Za) Circuit Component: Amplifier Iso-ground Basic Circuit Summary Points Understanding Sources of Electrical Interference Practical Tips Specifically for the Anesthesiologist For the IOM Professional During Patient Setup When Troubleshooting Electrical Noise Technical Note: Modern IOM Equipment and Grounding Recording Pathway: Input Switching Recording Pathway: Amplifiers Recording Pathway: Anti-aliasing Filters Recording Pathway: A/D Convertors Recording Pathway: Digital Signal and Computer Processing Conclusion References 16: Signal Optimization in Intraoperative Neuromonitoring Introduction Patient-Related Issues Somatosensory-Evoked Potentials Peripheral Nerve Disorders Central Nervous System Dysfunction Motor-Evoked Potentials Peripheral Nervous System Disorders Central Nervous System Dysfunction Electromyography and Nerve Conduction Studies Electroencephalography Anesthetic and Systemic Effects Somatosensory-Evoked Potentials Motor-Evoked Potentials Electromyography Electroencephalography Technical Issues Increased Electrical Noise Electrical Noise: 60 Hz Electrical Noise: High Frequency Electrical Noise: Low Frequency or Intermittent Electrical Noise: General Strategies Poor Signal Amplitudes Recording Technique Stimulation Technique Errors of Signal Acquisition Electrode Plug-In Errors System Errors General Principles Timing of Optimization Prioritization Conclusion References 17: Optimization of Intraoperative Neurophysiological Monitoring Through Anesthetic Management Introduction Interaction Between IONM Modality and Anesthetic Technique Impact of Patient-Related Factors on IONM Mechanism of Drug Action Anesthetic Effects on EEG Effects on Neuronal Metabolism Mechanisms of Consciousness and Unconsciousness Natural Sleep Versus General Anesthesia Anesthetic-Induced Unconsciousness Propofol Etomidate Barbiturates Ketamine Dexmedetomidine Benzodiazepines Opioids Halogenated Agents Nitrous Oxide EEG and Depth of Anesthesia Monitoring EEG During Emergence from Anesthesia Anesthesia Selection and EEG Monitoring Anesthetic Effects on Evoked Potentials Effect Based on Location of Synapses Effect Based on Anesthesia Goals Amnesia Unconsciousness Immobility Antinociception Effects of Specific Anesthetic Agents on Evoked Responses Halogenated Inhalational Agents Nitrous Oxide Propofol Etomidate Benzodiazepines Dexmedetomidine Barbiturates Opioids Ketamine Lidocaine, Magnesium, and Regional Anesthesia NMBA NMB and MEP NMB and Facial Nerve Monitoring NMB and Recurrent Laryngeal Nerve Monitoring Peripheral Nerve Monitoring and Pedicle Screw Testing Optimization of the Anesthetic Approach Physiological Considerations in Anesthesia Management Conclusion References 18: Basic Evaluation and Effective Communication of IOM Signal Changes Troubleshooting IOM Changes Anesthetic IOM Changes Physiologic IOM Changes Positioning and IOM Changes Technical IOM Changes Communication Around IOM and IOM Changes References Part III: Clinical Applications 19: Anesthesia for Awake Neurosurgery Introduction Anesthesia for Awake Craniotomy Patient Selection and Preparation Intraoperative Period Patient Positioning Awake Brain Mapping and Monitoring Electrocorticography (ECOG) Intraoperative Adverse Events Comparison of Techniques Patient Experience Benefits of Awake Craniotomy Awake Placement of Electrodes for Deep Brain Stimulation Awake Carotid Endarterectomy Anesthesia for Awake MRI-Guided Intracranial Laser Interstitial Thermal Therapy Awake Spine Surgery Summary References 20: Intraoperative Neurophysiologic Monitoring and Mapping of the Motor System During Surgery for Supratentorial Lesions Under General Anesthesia Introduction Case: Resection of an Insular Glioma Risks of Surgery for Insular Tumors and Other Supratentorial Mass Lesions Preservation of Nonmotor Function Using Mapping and Monitoring Techniques Motor Mapping and Monitoring Monitoring Results and Surgical Intervention Possible Causes of the MEP Change and the Role of the Surgical Interventions The Role of Subcortical Mapping to Identify the CST During Brain Tumor Removal Why Is Neurophysiologic Monitoring Useful? Conclusion References 21: Intraoperative Neurophysiological Monitoring for Intracranial Aneurysm Surgery Introduction Case Presentation 1: MCA Aneurysm Which Monitors Should You Consider for the Aneurysm Clipping? What Do We Expect the Selected Neuromonitoring Modalities to Monitor During This Surgery? What Are Some Drawbacks of Each of the Above Modalities in Relation to This Surgery? What Is the Interpretation of These Neurophysiologic Monitoring Waveforms? What Is the Cause of This Change? What Is the Cause of These Changes? Case Presentation 2: ICA/Ophthalmic Aneurysm Should Only Upper Extremity SSEPs and TCMEPs, Only Lower Extremity SSEPs and TCMEPs, or Both Upper and Lower Extremity SSEPs and TCMEPs Be Monitored for This Surgery? Case Presentation 3: Basilar Apex Aneurysm How Does This Aneurysm Location Influence the Choice of Neurophysiologic Monitoring Modalities to Be Used? What Are the Most Likely Etiologies for This Signal Change? References 22: Intracranial Arteriovenous Malformation Surgery Introduction Case Presentation What Management Could Be Considered to Potentially Decrease Blood Loss Prior to Surgical Resection of the AVM? Which Monitors Should You Consider for the Surgical Resection? What Are Potential Benefits of Combining SSEP and MEP Monitoring? Although the Majority of AVMS Are Suptratentorial in Location, What Additional Neuromonitoring Would Be Helpful If the AVM Involved the Posterior Fossa/Vertebrobasilar Circulation? When Should Neuromonitoring Be Performed During the Case? Transcranial MEP Stimulation Can Cause Movement of the Patient. What Can Be Done to Minimize This Movement? After Initial Baseline MEP Recordings Are Obtained, You Note Detectable Signals From Bilateral Upper and Lower Extremities. However, You Notice That Both Contralateral and Ipsilateral Waveforms Are Obtained With Stimulation of One Hemisphere. What Is The Stimulation Intensity Is Decreased to the Point Where Only Contralateral Extremity Waveforms Are Obtained. However, Now There Is No Signal From One Foot. Surgery Has Not Yet Begun. What Can Be Done to Improve the Signal Knowing That Increasing the What Nonradiographic Intraoperative Method Could Be Used to Help Delineate the Vasculature While the Surgeons Are Dissecting Around the AVM? The Electrophysiologist Reports to the Surgery and Anesthesia Teams That the Amplitude of the MEP Response From One Lower Extremity Has Decreased Significantly. The Surgeons State That They Are Not Working in the Territory of the Anterior Cerebral Art What Affects the Speed With Which MEPs Can Detect Potential Ischemia? During AVM Resection, EEG Slowing Is noted, Then a Global Decrease in MEP Amplitude Occurs, and Then This Is Followed by a Global Increase in SSEP Latency of Greater Than 10%. The Surgeons Are Notified of These Changes. What Do You Expect Is the Cause MEPs, As Utilized in the Case Above, Give Real-Time Assessment of Primary Motor System Integrity. What Additional Monitoring Could Be Utilized If the AVM Was Located Within or in Very Close Proximity to the Primary Motor Cortex and/or the Corticospina What Would an Alternative Anesthetic Technique Be for a Patient With an AVM Located in or Very Near the Motor and/or Language Cortex? Postoperatively, If the Patient’s Mental Status Deteriorated, What Cause Particular to AVM Obliteration Should Be Considered? What Type of Neurological Monitor Might You Consider at This Point? What Precautions Should Be Taken to Avoid NPPB? Would the Management of an AVM Differ If the Patient Was Pregnant, and What Additional Monitoring Should You Consider? References 23: Microvascular Decompression for Cranial Nerve Disorders Introduction Cranial Nerve Disorders from Vascular Compression Trigeminal Neuralgia Pathophysiology of Classical TN Presentation of Clinical Scenarios Case 1 What Was the Cause of This Change? Was It Surgical, Pharmacologic, Physiologic, Positional, or Technical? Case 2 What Could Be the Cause? Case 3 Is This a Significant Change? What Is the Cause of This Change? Case 4 What Happened? Is This Related to the Remifentanil Infusion, a Cardiac Incident, Brainstem Manipulation, or Something Else? Case 5 What Is the Problem and What Should Be Done? Case 6 Hemifacial Spasm Electrophysiology and Pathophysiology of HFS Anatomy of the Facial Nerve and Etiology of HFS Imaging in HFS Operative Technique of Microvascular Decompression of the Facial Nerve Anesthetic Considerations During MVD for HFS Principles of Intraoperative Neuromonitoring for HFS Monitoring for Complications Case Illustrations Case 1: Understanding the AMR During MVD of the Facial Nerve Case 2: “Frozen Shoulder” or Adhesive Capsulitis of the Glenohumeral Joint After MVD in the Contralateral Decubitus Position Case 3: Hearing Loss as a Result of MVD for HFS Case 4: Anesthesia and the AMR Case 5: Stroke During MVD for HFS Case 6: Facial Weakness and MVD for HFS Case 7: Vestibular Nerve Dysfunction (After MVD for HFS) Case 8: Dysphagia/Hoarseness Following MVD for HFS Glossopharyngeal Neuralgia References 24: Surgery for Extra-axial Infratentorial Mass and IOM Introduction Clinical Presentation of Tumors Located in the Infratentorial Compartment Pathologies in Extra-Axial Surgery Adult Patients Pediatric Patients Surgery and Workflow Interdisciplinary Communication Surgery and Surgical Approaches for Infratentorial Mass Positioning Surgical Approach Anesthesia Considerations for Surgeries Within the Infratentorial Compartment Intraoperative Neurophysiology for the Tumors Within the Infratentorial Compartment Monitoring of Motor Cranial Nerves Monitoring of Sensory Fibers of Cranial Nerves Monitoring of the Auditory Nerves Monitoring of the Somatosensory and Motor Pathways Case 1. Resection of a Meningioma in the Right Cerebellopontine Angle Which IOM modalities should you consider for this suboccipital surgery in the sitting position? Anesthesia Type of Anesthesia Anesthesia for Brain Surgery in the Sitting Position Neuromonitoring Effects of the Surgical Resection Postoperative Course Surgical Positioning of the Patient in the Sitting Position Tumor Resection Stimulation of the Facial Nerve Case 2. Effect of Neuromuscular Blockade on EMG and DNS Recordings Case 3 What should be considered for IOM in this case? Intraoperative Neuromonitoring Course Case 4 Intraoperative Neuromonitoring Course Conclusions References 25: Intraoperative Neurophysiology Monitoring for Intra-axial Posterior Fossa Surgery Introduction Anesthesia Surgery of the Midbrain Mapping Corticospinal Tract Identification at the Level of the Cerebral Peduncle Monitoring Motor-Evoked Potentials Brainstem Auditory-Evoked Potentials Surgery of the Pons Mapping of the Facial Colliculus on the Floor of the Fourth Ventricle Facial Nerve Monitoring: Free-Running Electromyography Facial Motor-Evoked Potentials Surgery of the Medulla Oblongata Mapping IX/X, XI, and XII Cranial Nerve Nuclei Lower Cranial Nerve Monitoring Lower Cranial Corticobulbar-Evoked Potentials Brainstem Reflexes and Other Monitoring Techniques Conclusion References 26: Endoscopic Skull Base Surgery Introduction Perioperative Considerations Goals of IOM During Skull Base Surgery Modes of Neuromonitoring Electromyography Evoked Potentials (SSEP, MEP, VEP, ABR) Case 1 Differential Diagnosis of ABR Findings Case Progression Case 2 Differential Diagnosis of SSEP Findings Case Progression Conclusion References 27: IOM for Surgery Near the Extracranial Facial Nerve Introduction Anatomy of Facial Nerve Methodology of CMAP Monitoring/Mapping Recording Electrode Setup Preoperative Mapping Continuous CMAP Monitoring Intraoperative Mapping Warning Criteria and Correlation with Outcome Comparison of Results for Various FN Monitoring Methods Conclusions References 28: The Techniques and Rationale of Intraoperative Monitoring for Perilaryngeal Surgeries Introduction Surgical Anatomy Techniques of IONM Anesthesia Spontaneous Electromyography Triggered Electromyography Localization Continuity Viability Prediction of Nonrecurrence Continuous IONM Automatic Periodic Stimulation Laryngeal Adductor Reflex Rationale of IONM Inference of Protection Systematic Procedures Training for Health Professionals Conclusions References 29: Carotid Surgery Introduction Why Monitor During Carotid Surgery? Monitors of Cerebral Ischemia During Carotid Surgery Awake Patient EEG SSEP MEP Transcranial Doppler Preoperative Considerations Case 1 Case 2 Evaluation of Changes in Monitoring Management of Changes Postoperative Complications/Outcomes Conclusions References 30: Cervical Spine Surgery Introduction Case Presentations Case 1 What Are the Possible Causes for the Diminished Baseline SSEP and MEP Signals in This Patient? What Are the Possible Causes for the Diminished Left-Sided SSEP and MEP Signals at This Point in Time? Case 2 What Could Be the Cause of This EMG Change? MEPs Were Acquired and Revealed No Changes. SSEP Responses Were also Stable. How Should We Proceed? Case 3 How Should the Airway Be Secured in This Patient? Should an Awake or Asleep Technique Be Used? Would Neuromonitoring, After Induction but Prior to Intubation, Be of any Value in This Case? What Neuromonitoring Modalities Should Be Used for This Case? What Could Be the Cause of These Right Arm SSEP Changes? What Should Be Done to Correct These Changes and Avoid Injury? What Could Be the Cause of This Global Change in Cortical SSEPs Alone? What Might Be the Cause of This Type of Change in SSEPs? Case 4 What Might Be the Cause of This Type of Change in SSEPs? Conclusion References 31: Surgery for Scoliosis Introduction IONM Modalities Case Study Summary and Conclusion References 32: Surgery for Adult Deformity Correction Introduction Background and Pathogenesis Identification and Classification Surgical Goals and Approaches Approaches to Instrumentation and Intraoperative Neuromonitoring Anterior Approaches Lateral Approaches Posterior Approaches Checklists and Protocols Gain Control of the Room Anesthetic/Systemic Technical/Neurophysiologic Surgical Ongoing Considerations Best Practice Guideline for IONM Practices Case 1 Case 2 Discussion Conclusions References 33: IONM During Lumbosacral Spinal Fusion Procedures Introduction Basic Anatomy Relevant Diagnoses and Procedure Specifics Pedicle Screw and Nerve Root Testing: Interpreting Threshold Values Modality-Specific Considerations SSEP and MEP Alert Criteria Considerations Therapeutic Impact Considerations Anesthesia Considerations Fusion Procedures Posterior Lumbar Interbody Fusion (PLIF) Transforaminal Lumbar Interbody Fusion (TLIF) Anterior Lumbar Interbody Fusion (ALIF) Lateral Lumbar Interbody Fusion (LLIF) Oblique Lumbar Interbody Fusion (OLIF) Conclusion References 34: Intraoperative Neurophysiology During Intramedullary Spinal Cord Tumor Surgery Preoperative Considerations Clinical Picture Tumor Features Monitoring and Mapping Techniques Monitoring Techniques D Wave Mapping Techniques Patient Positioning and Baseline Determination Surgical Technique IONM Changes: Contributing Factors, Warning Criteria, and Reaction Strategies Contributing Factors Warning Criteria Reaction Strategies References 35: Surgery in the Peripheral Nervous System Peripheral Nerve Anatomy and Injury Types Electrodiagnostics and Peripheral Nerve Surgery Anesthetic Considerations Limitations of Electrodiagnostics Conclusions References 36: Aortic Intervention: A Practical Guide to Monitoring, Preventing, and Treating Spinal Cord Injury Aortic Aneurysms Management of Descending Thoracic and Thoracoabdominal Aortic Disease and Outcomes Incidence and Risk Factors for Spinal Cord Ischemia Spinal Cord Blood Supply Pathophysiology of Spinal Cord Injury Prevention of Spinal Cord Injury Open Repair Endovascular Repair Cerebrospinal Fluid Drainage (CSFD) Oxygen Delivery and Blood Pressure Management Neuromonitoring Motor- and Somatosensory-Evoked Potentials Near-Infrared Spectroscopy Liverpool Heart and Chest Hospital Spinal Cord Protection Approach CSFD Insertion Intraoperative CSFD Management Postoperative Instructions Analgesia Response to Postoperative Spinal Cord Deficit Acetazolamide Intraoperative Spinal Cord Monitoring Electrode Placement Settings Used for Transcranial Motor-Evoked Potential Baselines and Measuring Change Tailoring Anesthetic Techniques Interventional Approach and Motor-Evoked Potential Protocols Intraoperative Algorithm Open Thoracoabd