Intraoperative Neuromonitoring

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Intraoperative Neuromonitoring
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Foreword
Preface
Contributors
Contents
General issues
Chapter 1: Overview of intraoperative neuromonitoring
History of Monitoring
Technologist Staffing and Supervision
Conclusions
References
Further reading
Chapter 2: Electroencephalography, electrocorticography, and cortical stimulation techniques
Electroencephalogram (EEG)
The electrophysiology of the EEG signals
Methodology
Interpretation
Clinical applications in the OR
Anesthesia considerations
Electrocorticography
Introduction
Physics and physiology
Methodology
Interpretation
Clinical applications
Epilepsy surgery
Temporal lobe epilepsy
Frontal cortical dysplasias
High-frequency oscillations (HFO)
Non-epilepsy surgery
Anesthesia considerations
Cortical Stimulation Techniques
Physics and physiology of electrical stimulation
Patient safety
Current density
Pulse features
Electrode material and geometry
Stimulation triggered after discharges and seizures
Stimulation methods
Constant voltage versus constant current stimulation
Stimulus polarity
Efficient depolarization of the alpha motor neurons
Type of stimulation
Monopolar cortical stimulation
Bipolar cortical stimulation
Types of stimulating electrodes
Stimulation paradigms used in clinical practice
Penfield or low-frequency paradigm (Fig. 2.8A)
Very low-frequency stimulation
The dual paradigm technique
Multipulse train method (Fig. 2.11)
References
Chapter 3: Intraoperative evoked potential techniques
Introduction
Basic Principles
Evoked potential generation
Averaging, reproducibility, and signal-to-noise ratio
Unaveraged evoked potentials
Stimulus properties
Electrodes
Cable management
Recording and technical parameters
Interpretation and Analysis
Somatosensory Evoked Potentials
Anatomical considerations
Anatomical controversies
Nondecussation
Stimulation technique
Anesthesia
Traditional SEP monitoring derivations
SEP optimization
Upper limbs
Lower limbs
Omitted and optional potentials
Benefits of SEP optimization
SEP warning criteria
SEP mapping
Cortical SEP mapping
Dorsal column SEP mapping
Motor Evoked Potentials
Anatomical considerations
Nondecussation
Physiologic basis
Stimulation technique
Current or voltage
Pulse duration
Strength–duration
Pulse number
Interstimulus interval
Facilitation
Anode and cathode selection
Anesthesia
D-wave recording
Muscle MEP recording
D-wave warning criteria
Muscle MEP warning criteria
MEP mapping
Cortical MEP mapping
Subcortical MEP mapping
Spinal cord MEP mapping
Brainstem Auditory Evoked Potentials
Anatomy and physiology
Stimulation technique
BAEP recording
Warning criteria and indications
Visual Evoked Potentials
Anatomy and physiology
Stimulation
Recording
Anesthesia
Warning criteria and interpretation
Conclusion
References
Chapter 4: EMG monitoring
Introduction
History
Physiology
Methodology
Facial Nerve Outcome Prediction and Traintime
Suprasegmentally Generated EMG Discharges (SEDs)
References
Chapter 5: Safety issues during surgical monitoring
Introduction
Electric Safety
Electric connections with the patient
Effects of electric currents
Electric shock
Functional physiologic activation
Cardiac failure
Conditions for electric activation of the heart muscle and nerve tissues
Physic effects of electric currents in general
Electric heating
Influence of electrode insertion
Heat drainage
Thermal toxicity
Protection against thermal injury
Specific effects from stimulation
Temperature effects
Effects of heat drainage
Accuracy of stimulators
Optimization of the pulse width
TES-induced parasitic current conduction along with physiologic amplifiers
Prevention of parasitic conduction
TES in skull defects and neonate anatomy
Direct cortical stimulation and excitotoxicity
Complications from TES muscle contractions
Bite injuries
Movement-induced injury
Seizures and after discharges
MEP and implanted devices
Invasive electrode complications
Equipment-Related Safety Issues
Leakage currents
Means of protection against electric shock
Single fault safe
Leakage current limits
Periodic inspection
Power cords and lead connectors
Conclusions
Acknowledgments
References
Intracranial surgery
Chapter 6: Neurophysiology during epilepsy surgery
Introduction
Epileptic Focus Mapping
The epileptogenic lesion
The epileptogenic zone
The seizure onset zone
The irritative zone
Intraoperative ECoG
Technique
Interpreter
Anesthesia
New approaches to intraoperative epileptic focus mapping
High-frequency oscillations
Single-pulse electric stimulation
Functional Mapping
Penfield technique
Penfield technique drawbacks
Evoked potential mapping
Somatosensory evoked potentials
Motor evoked potentials
Visual evoked potentials
Cortico–cortical evoked potentials
Long latency laryngeal muscle responses
Functional Monitoring
Somatosensory evoked potentials
Motor evoked potentials
Other evoked potentials
Conclusion
References
Chapter 7: Neurophysiology during movement disorder surgery
Introduction
Microelectrode Techniques
Local Field Potentials
General Stereotactic Technique
Internal Globus Pallidus Procedures
Subthalamic Nucleus Procedures
Data Analysis
Conclusion
References
Chapter 8: Intraoperative mapping and monitoring during brain tumor surgeries
Introduction and Neurooncologic Considerations
Technical Considerations, Methods, and Set-Up for Asleep and Awake Surgeries
Prerequisites for awake craniotomy
Preparation for direct cortical stimulation
Neurophysiologic methods
Motor evoked potentials
Direct cortical stimulation techniques
Somatosensory evoked potentials
Visual evoked potentials
Monitoring in Supratentorial Surgery
Surgical steps related to nonspecific evoked potential changes
Feasibility of SEP and MEP monitoring in glioma surgery
Critical surgical steps causing changes in evoked potentials
Correlation of MEP and SEP signal changes to neurologic outcome
MEP warning criteria
Cortical Mapping During Supratentorial Surgery Under General Anesthesia
Subcortical Mapping for the Corticospinal Tract During Surgery Under General Anesthesia
Sensory–Motor Integration and Praxis Circuits
Language and Cognitive Mapping During Awake Surgeries
Summary
References
Chapter 9: Mapping and monitoring of brainstem surgery
Introduction
Indication and Anesthetic Considerations
Mapping Techniques
Mapping of the facial colliculus and safe entry zone in the fourth ventricle floor
Stimulation set up
Recording technique
Illustrative case
Mapping of other cranial nerve nuclei
Mapping of the corticospinal tract
Limitations of mapping technique
Monitoring Techniques
Motor evoked potentials
Stimulation set up
Recording
Corticobulbar MEPs
Stimulation
Recording
Free-running electromyography
Brainstem auditory evoked potentials
Somatosensory evoked potentials
Intraoperative Monitoring Pitfalls
Optimal Response to Critical IONM Change
Remember ``TIPs´´
Conclusion
References
Chapter 10: Monitoring cerebellopontine angle and skull base surgeries
Introduction
Methods
Mapping intracranial part of CNs
Monitoring
Brainstem auditory evoked potentials (BAEP)
Somatosensory evoked potentials (SEPs)
Motor evoked potentials
Free running EMG for CNs monitoring
Corticobulbar MEPs (CoMEPs)
(a). Stimulation parameters
(b). Recording parameters
Facial nerve
Lower cranial motor nerves
Pitfalls in CBT monitoring
Brainstem reflexes
Blink reflex
Masseteric reflex
Laryngeal adductor reflex
Intraoperative Neuromonitoring During MVD for Hemifacial Spasm
Methodology for intraoperative monitoring the HFS
Auditory brainstem responses (ABR)
Lateral spread (LSR)
FCoMEPs
Blink reflex (BR)
Conclusion
References
Spinal surgery
Chapter 11: Monitoring scoliosis and other spinal deformity surgeries
Scoliosis and Kyphosis
Complications of Spinal Deformity Surgery
Cervical Myelopathy
Natural history
Clinical presentation
Surgery for Cervical Myelopathy
Basis for Intraoperative Neurophysiologic Monitoring During Cervical and Thoracic Spinal Surgery
Animal work
Patient experience
Techniques for Intraoperative Neurophysiologic Monitoring During Cervical and Thoracic Spinal Surgery
Somatosensory evoked potentials
Stimulation
Recording
Alarm criteria
Motor evoked potentials
Stimulation
Recording
Alarm criteria
Electromyography
IONM team
References
Further reading
Chapter 12: Intraoperative neuromonitoring during surgery for lumbar stenosis
Introduction
Pathoanatomic and Clinical Considerations in Lumbar Stenosis
Surgical Approaches and Associated Neural Risks
Evidence-Based Medicine and IONM in Lumbar Stenosis/Spine Surgery
Pedicle screw threshold testing: An update
Does MEP monitoring have a role in extradural lumbosacral surgery?
IONM in lumbosacral deformity and high-grade spondylolisthesis
IONM in TLIF and ALIF
IONM in LLIF and OLIF
IONM Methods during Lumbar Stenosis Surgery
Reflections on the IONM evidence base in extradural lumbosacral spine surgery
References
Chapter 13: Intraoperative neurophysiology in intramedullary spinal cord tumor surgery
Background
Why to Use Intraoperative Neurophysiology?
Clinical Presentation of ISCTs
Anesthesia for IONM
Intraoperative Neurophysiological Monitoring Techniques
Somatosensory evoked potentials
Muscle motor evoked potentials
D-wave
Intraoperative Neurophysiological Mapping Techniques
Dorsal column mapping
Mapping of the corticospinal tract
Neuromonitoring-Guided Surgery
Illustrative case
IONM and evidence-based medicine
Conclusions
References
Chapter 14: Monitoring spinal surgery for extramedullary tumors and fractures
Introduction
Indication for Monitoring
Clinical classification and presentation
Spine extramedullary tumor
Spine fracture
Indication for surgical treatment
Surgical treatment
Surgical treatment for extramedullary tumor
Surgical treatment for spine fracture
Risk of nervous system injury during surgery
Role of Intraoperative Neurophysiology
Preservation and prediction of spinal cord function
Mapping and monitoring spinal nerve root function
Monitoring modalities
Motor evoked potentials
Somatosensory evoked potentials
The bulbocavernosus reflex
Electromyography
Compound muscle action potentials
Anesthesiologic considerations
IONM and Outcomes for Spinal Extramedullary Tumors And Fractures
Conclusion
References
Chapter 15: Mapping and monitoring of tethered cord and cauda equina surgeries
Anatomy of the Pelvic Floor and Clinical Symptoms in Tethered Cord Syndrome
Mapping and Monitoring Techniques
Monitoring techniques
Somatosensory evoked potentials
Motor evoked potentials
Electromyography
Anal sphincter EMG
Bulbocavernosus reflex
Mapping techniques
Mapping of the cauda equina
Spinal cord stimulation
Limitations of Mapping and Monitoring Techniques in the Area of the Pelvic Floor
Complications and Clinical Outcomes After Tethered Cord Repair
Conclusion
References
Chapter 16: Dorsal root entry zone procedure and other surgeries for pain
Introduction
Anatomy of Pain
Classification of Surgeries for Pain
Ablative surgeries
Augmentative surgeries
NIOM for Pain Surgeries
DREZ procedure
Spinal cord DREZ procedure
Nucleus caudalis DREZ procedure
Trigeminal rhizotomy
Motor cortex stimulation
Spinal cord stimulation
Dorsal root ganglion stimulation
Other surgeries for pain
Future Directions
Conclusion
References
Peripheral nerve surgery
Chapter 17: Neurophysiology during peripheral nerve surgery
Introduction
Preoperative Evaluation
IONM Modalities
Nerve conduction studies
Somatosensory evoked potentials
Motor evoked potentials
Electromyography
IONM for Specific Disorders
Peripheral nerve tumors
Entrapment neuropathies
Selective fascicle biopsy
Peripheral nerve trauma and brachial plexus injury
Prevention of peripheral nerve injuries during surgical procedures
Technical/Interpretation Issues
Summary
References
Chapter 18: Monitoring surgery around the cranial nerves
Introduction
History
Monitoring Techniques
Spontaneous and triggered EMG
Recording electrodes
Recording techniques
EMG findings during IONM
Triggered EMG recordings
Anesthesia and EMG monitoring
Motor evoked potentials
Somatosensory evoked potentials
Brainstem auditory evoked potentials
Cranial nerve reflexes
Cranial Nerves
Monitoring of extraocular muscle function (CNs III, IV, and VI)
Function
EMG Recording and Stimulation Techniques
CN V (trigeminal nerve)
Functions and anatomy
Monitoring sensory function
CN VII (facial nerve)
Functions and anatomy
EMG monitoring
Facial nerve motor evoked potentials
IONM of facial nerve function using F waves
Lateral spread reflex
Facial nerve IONM acceptance and guidelines
CN VIII (vestibulocochlear nerve)
Functions and anatomy
BAEP monitoring applications
CN IX (glossopharyngeal nerve)
Functions and anatomy
IONM of CN IX
CN X (vagus nerve)
Functions and anatomy
EMG monitoring of CN X
Other techniques for monitoring CN X
CN XI (accessory nerve)
CN XII (hypoglossal nerve)
Summary
References
Vascular surgery
Chapter 19: Monitoring in carotid endarterectomy
Introduction
Anatomic, Physiologic, Clinical, and Surgical Considerations
Collateral cerebral blood supply and cerebral autoregulation
Predictors of intraoperative cerebral ischemia and the risk of perioperative stroke
Carotid endarterectomy—Surgical techniques
Critical steps of the procedure
Intraoperative Neurophysiologic Monitoring for Detection of Cerebral Ischemia in Carotid Endarterectomy
Electroencephalogram
Methodology
Alarm criteria for raw EEG analysis
Quantitative EEG analysis
Somatosensory evoked potentials
Pros and cons of multimodality CEA monitoring
Combined EEG and SEP monitoring
Adding transcranial motor evoked potentials
Anesthesia considerations
EEG monitoring
SEP/tcMEP monitoring
Other Monitoring Techniques for Detecting Cerebral Ischemia
TCD
Stump pressure
Cerebral oximetry
Conclusion
References
Chapter 20: Surgery and intraoperative neurophysiologic monitoring for aneurysm clipping
Introduction to Cerebrovascular Surgery
History
The neurophysiologist's view on aneurysm surgery
The neurosurgical view on aneurysm surgery
Unruptured aneurysms
Aneurysm rupture rate
Morbidity and mortality of unruptured aneurysms
Treatment options and preferred treatment
Neurophysiologic Methods
Brainstem auditory evoked potentials
Somatosensory evoked potentials
Motor evoked potentials
Visual evoked potentials
Technical Considerations for IONM in Cerebral Aneurysm Procedures—Set-up in the Operating Room
Anesthesia
General considerations
Interaction between participating teams in aneurysm surgery
Vascular Territories and Recommended Recordings
Anterior circulation aneurysms
Posterior circulation aneurysms
Specific Surgical Steps in Aneurysm Surgery
Temporary clipping
Surgical reaction on IOM alteration and duration of monitoring
Comparison to other methods
Signal deterioration and neurologic outcome
Socioeconomic aspects and evidence
Conclusion
References
Chapter 21: Monitoring cardiac and ascending aortic procedures
Introduction
Monitoring During Cardiac Operations
Pathophysiology of neurologic injury
On-pump procedures
Off-pump procedures
Critical events during cardiac operations
Specific monitoring modalities
Possible interventions
Monitoring During Ascending Aortic/Aortic Arch Procedures
Basic anatomy and pathophysiology
Circulation management strategies and IONM
Deep hypothermic circulatory arrest
Selective antegrade cerebral perfusion
Retrograde cerebral perfusion
Methods of cardiopulmonary bypass
Critical events during aortic arch repair
Arrival
Initiation of anesthesia to the initiation of CPB
Initiation of CPB to the beginning of the aortic repair
During the period of aortic repair
After the repair
Specific monitoring modalities
Conclusions
References
Chapter 22: Neuromonitoring during descending aorta procedures
Introduction
The Vascularization of the Spinal Cord: Anatomy and Hemodynamics of the Spinal Cord Arterial Network
Preoperative Planning
Assessment of the vascular anatomy
Choosing an operative approach: Open vs endovascular TAA repair
Open TAA Repair
Open TAA repair via the clamp-and-sew technique
Cerebrospinal fluid drainage
Regional spinal cord hypothermia
Open TAA repair with distal aortic perfusion and neurophysiologic monitoring
Maintaining adequate distal aortic perfusion
Sequential clamping of the aorta and prevention of the steal phenomena
Multimodality neurophysiologic monitoring
Neurophysiologic changes in SCI
SEPs vs MEPs
Differences in blood supply: gray vs white matter
Amplitude alarm criteria for MEPs
Neurophysiologic changes in limb ischemia
Neurophysiologic changes in cerebral ischemia
Key points in neurophysiologic monitoring
Obtaining reliable baselines
Choice of anesthetics
Safety of MEPs
After exposure and before the start of DAP
Proximal aortic cross-clamping
Distal aortic cross-clamping, below the origin of the segmental arteries
Clamping distal to the origin of the pelvic visceral arteries
Closing and postoperative course
Delayed Paraplegia
Conclusions
References
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