Intraoperative Monitoring of Central Neurophysiology

2017 ◽  
Author(s):  
Alan D. Legatt ◽  
Marc R. Nuwer ◽  
Ronald G. Emerson
Keyword(s):  
Intraoperative Monitoring ◽  
Corticospinal Tract ◽  
Motor Evoked Potentials ◽  
Anesthetic Management ◽  
Depth Of Anesthesia ◽  
Central Nervous System Function ◽  
Anatomy And Physiology ◽  
Anesthetic Agents ◽  
Nervous System Function ◽  
Signal Changes

This chapter covers neurophysiological intraoperative monitoring (NIOM). It describes the relevant neurophysiological signals, their anatomical sources, the techniques used to record them, the manner in which they are assessed, and possible causes of intraoperative signal changes. Techniques used include electroencephalography (EEG), electromyography, and auditory, somatosensory, and motor evoked potentials. Some of these techniques can be used to localize and identify areas of cerebral cortex or the corticospinal tract. Recording of the electromyogram generated by reflex activity can be used to evaluate central nervous system function in some circumstances. EEG can be used to assess depth of anesthesia. Signals can be affected by anesthesia, and the chapter discusses various anesthetic agents, their effects on signals, and considerations for anesthetic management during NIOM. Personnel performing NIOM must be knowledgeable about the anatomy and physiology underlying the signals, the technology used to record them, and the factors (including anesthesia) that can affect them.

Intrapatient Reproducibility of the BISxp® Monitor

2006 ◽  
Vol 104 (2) ◽  
pp. 242-248 ◽  
Author(s):  
Dagmar J. Niedhart ◽  
Heiko A. Kaiser ◽  
Eric Jacobsohn ◽  
Charles B. Hantler ◽  
Alex S. Evers ◽  
...  
Keyword(s):  
Regression Coefficient ◽  
Anesthetic Management ◽  
Depth Of Anesthesia ◽  
Medical Systems ◽  
Limits Of Agreement ◽  
Zero Bias ◽  
Anesthetic Depth ◽  
Anesthetic Agents ◽  
Anesthesia Providers ◽  
Single Number

Background The Bispectral Index (BIS) reportedly reflects anesthetic depth. It is recommended that anesthetic agents should be titrated to maintain the BIS between 40 and 60 arbitrary BIS units during anesthesia. For anesthesia providers to follow this recommendation, the monitor should be predictably affected by different anesthetic agents and have good interpatient and intrapatient reproducibility. The authors hypothesized that when two BISxp devices (Aspect Medical Systems, Newton, MA) are placed concurrently on the same patient, their readings are concordant throughout the anesthetic period. Methods Simultaneous BIS recordings from two BISxp monitors were obtained during anesthesia at 5-s intervals from 12 participants. Results In total 22,860 concurrent paired BIS readings were obtained. For 10.7% of the time, there were sustained periods of 30 s or greater where the readings suggested a different depth of anesthesia. For 6% of the time, there were sustained periods of 30 s or greater where the readings differed by 10 or more arbitrary BIS units. The regression coefficient (R) for the two devices was 0.65 (range, 0.35-0.92). There was zero bias between the devices, and the 95% limits of agreement ranged between -18 and +17. Conclusion A conflicting anesthetic management was suggested by the simultaneous BIS readings 10.7% of the time. These results suggest that BISxp does not always provide a reproducible single number. Anesthesia providers should not rely exclusively on the BIS reading when assessing depth of anesthesia.

Ipsilateral Motor Innervation Discovered Incidentally on Intraoperative Monitoring: A Case Report

Neurosurgery ◽  
2017 ◽  
Vol 80 (3) ◽  
pp. E194-E200
Author(s):  
Jerry Ku ◽  
Daniel Mendelsohn ◽  
Jason Chew ◽  
Jason Shewchuk ◽  
Charles Dong ◽  
...  
Keyword(s):  
Intraoperative Monitoring ◽  
Corticospinal Tract ◽  
Diffusion Tensor ◽  
Motor Evoked Potentials ◽  
Motor Deficits ◽  
Motor Innervation ◽  
First Case ◽  
Technical Issues ◽  
Cautious Interpretation ◽  
Rare Anatomic Variant

Abstract BACKGROUND AND IMPORTANCE: Lesions in the corticospinal tract above the decussation at the medullary pyramids almost universally produce contralateral deficits. Rare cases of supratentorial lesions causing ipsilateral motor deficits have been reported previously, but only ever found secondary to stroke or congenital pyramidal tract malformations. CLINICAL PRESENTATION: Herein, we report a case of ipsilateral corticospinal tract innervation discovered incidentally with intraoperative monitoring during a microsurgical resection of a vestibular schwannoma. Intraoperative monitoring with electrical transcranial stimulation of the frontal scalp triggered motor-evoked potentials in the ipsilateral arms. The uncrossed pathways were later confirmed with MRI tractography using diffusion tensor imaging. CONCLUSION: To the best of our knowledge, this is the first case of isolated ipsilateral motor innervation of the corticospinal tract discovered incidentally during a neurosurgical procedure. Given the increasing use of intraoperative monitoring, this case underscores the importance of cautious interpretation of seemingly discordant neurophysiological findings. Once technical issues have been ruled out, ipsilateral motor innervation may be considered as a possible explanation and neurosurgeons should be aware of the existence of this rare anatomic variant.

The refractory period of fast conducting corticospinal tract axons in man and its implications for intraoperative monitoring of motor evoked potentials

2004 ◽  
Vol 115 (8) ◽  
pp. 1931-1941 ◽  
Author(s):  
Klaus Novak ◽  
Adauri Bueno de Camargo ◽  
Michael Neuwirth ◽  
Karl Kothbauer ◽  
Vahe E. Amassian ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Refractory Period ◽  
Intraoperative Monitoring ◽  
Corticospinal Tract ◽  
Motor Evoked Potentials

Acute Loss of Intraoperative Evoked Potential Signals

2017 ◽  
Author(s):  
Leslie Jameson
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Nerve Injury ◽  
Patient Outcomes ◽  
Peripheral Nerve Injury ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Anesthetic Management ◽  
Standard Of Care ◽  
Anesthetic Agents

Monitoring of somatosensory and motor evoked potentials has become the standard of care for a large proportion of spine surgeons. Understanding how anesthetic management may affect these evoked potentials is critical to optimizing the ability to detect impending spinal cord or peripheral nerve injury. Similarly, once a nerve injury is detected, knowledge of the various anesthetic and surgical maneuvers possible to avoid permanent injury is essential for the best patient outcomes. This chapter discusses the effects of various anesthetic agents on somatosensory and motor evoked potentials and potential critical interventions that can be made when a nerve injury is identified by this monitoring.

Anesthesia for rabbits submitted to experimental surgeries: Report of a series of eight anesthesias

2020 ◽  
pp. 151-158
Author(s):  
Rafael Antonio Caldart Bedin ◽  
Maisa Schultz ◽  
Antonio Bedin
Keyword(s):  
Muscle Relaxation ◽  
Anesthetic Management ◽  
Laboratory Animals ◽  
Average Weight ◽  
Anesthetic Induction ◽  
Anesthetic Agents ◽  
Reasonable Degree ◽  
Bioethical Debate ◽  
Precordial Stethoscope

Anesthesia for laboratory animals is a matter of biomedical concern and one of the most present dilemmas in the current bioethical debate. The use of anesthetic agents in experimental surgery aims at analgesia and restraining the animal, in order to achieve a reasonable degree of muscle relaxation and to produce sufficient analgesia. This practice requires the use of protocols for the administration of safe and efficient doses. Eight New Zealand rabbits were submitted to laparotomies demonstrating the surgical technique discipline of the local medical course. For pre-anesthetic medication, acepromazine 1 mg.kg-1 associated with ketamine 15 mg.kg-1 was used subcutaneously. Anesthesia was maintained with isoflurane and oxygen under a laryngeal mask in a Mapleson D anesthesia system and under spontaneous breathing. Hydration was performed with 10 ml.kg-1 saline every hour. A thermal mattress was used. Precordial stethoscope, pulse oximetry and clinical parameters were used for monitoring. For euthanasia, ketamine 10 mg.kg-1 associated with potassium chloride 19.1% 1 ml.kg-1 was used intravenously. The average weight of the rabbits was 2721.25 ± 275.01 grams and the duration of the anesthetic procedure was 120 ± 87 minutes. Discussion. In long-term anesthesia, such as laparotomies, the use of pre-anesthetic medication and then anesthetic induction by the combination of agents is recommended. However, anesthetic management requires monitoring to prevent insufficient or excessive doses from occurring.

scholarly journals General anesthesia with remimazolam in a patient with mitochondrial encephalomyopathy: a case report

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yuji Suzuki ◽  
Matsuyuki Doi ◽  
Yoshiki Nakajima
Keyword(s):  
Lactic Acidosis ◽  
General Anesthesia ◽  
Mitochondrial Disease ◽  
Muscle Relaxation ◽  
Anesthetic Management ◽  
Perioperative Period ◽  
Mitochondrial Encephalomyopathy ◽  
Anesthesia Induction ◽  
General Anesthetic ◽  
Anesthetic Agents

Abstract Background Systemic anesthetic management of patients with mitochondrial disease requires careful preoperative preparation to administer adequate anesthesia and address potential disease-related complications. The appropriate general anesthetic agents to use in these patients remain controversial. Case presentation A 54-year-old woman (height, 145 cm; weight, 43 kg) diagnosed with mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes underwent elective cochlear implantation. Infusions of intravenous remimazolam and remifentanil guided by patient state index monitoring were used for anesthesia induction and maintenance. Neither lactic acidosis nor prolonged muscle relaxation occurred in the perioperative period. At the end of surgery, flumazenil was administered to antagonize sedation, which rapidly resulted in consciousness. Conclusions Remimazolam administration and reversal with flumazenil were successfully used for general anesthesia in a patient with mitochondrial disease.

scholarly journals Long-term motor deficit in brain tumour surgery with preserved intra-operative motor-evoked potentials

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Davide Giampiccolo ◽  
Cristiano Parisi ◽  
Pietro Meneghelli ◽  
Vincenzo Tramontano ◽  
Federica Basaldella ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Brain Tumour ◽  
Evoked Potential ◽  
Corticospinal Tract ◽  
Motor Evoked Potentials ◽  
Motor Evoked Potential ◽  
Motor Deficit ◽  
Motor Deficits ◽  
Brain Tumour Surgery

Abstract Muscle motor-evoked potentials are commonly monitored during brain tumour surgery in motor areas, as these are assumed to reflect the integrity of descending motor pathways, including the corticospinal tract. However, while the loss of muscle motor-evoked potentials at the end of surgery is associated with long-term motor deficits (muscle motor-evoked potential-related deficits), there is increasing evidence that motor deficit can occur despite no change in muscle motor-evoked potentials (muscle motor-evoked potential-unrelated deficits), particularly after surgery of non-primary regions involved in motor control. In this study, we aimed to investigate the incidence of muscle motor-evoked potential-unrelated deficits and to identify the associated brain regions. We retrospectively reviewed 125 consecutive patients who underwent surgery for peri-Rolandic lesions using intra-operative neurophysiological monitoring. Intraoperative changes in muscle motor-evoked potentials were correlated with motor outcome, assessed by the Medical Research Council scale. We performed voxel–lesion–symptom mapping to identify which resected regions were associated with short- and long-term muscle motor-evoked potential-associated motor deficits. Muscle motor-evoked potentials reductions significantly predicted long-term motor deficits. However, in more than half of the patients who experienced long-term deficits (12/22 patients), no muscle motor-evoked potential reduction was reported during surgery. Lesion analysis showed that muscle motor-evoked potential-related long-term motor deficits were associated with direct or ischaemic damage to the corticospinal tract, whereas muscle motor-evoked potential-unrelated deficits occurred when supplementary motor areas were resected in conjunction with dorsal premotor regions and the anterior cingulate. Our results indicate that long-term motor deficits unrelated to the corticospinal tract can occur more often than currently reported. As these deficits cannot be predicted by muscle motor-evoked potentials, a combination of awake and/or novel asleep techniques other than muscle motor-evoked potentials monitoring should be implemented.

Increased corticospinal excitability prior to arm cycling is due to enhanced supraspinal but not spinal motoneurone excitability

2013 ◽  
Vol 38 (11) ◽  
pp. 1154-1161 ◽  
Author(s):  
Kevin E. Power ◽  
David B. Copithorne
Keyword(s):  
Magnetic Stimulation ◽  
Corticospinal Tract ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Corticospinal Excitability ◽  
Quiescent State ◽  
M Wave ◽  
Arm Cycling ◽  
Intention To Move ◽  
Stimulation Of

Human studies have not assessed supraspinal or spinal motoneurone excitability in the quiescent state prior to a rhythmic and alternating cyclical motor output. The purpose of the current study was to determine whether supraspinal and (or) spinal motoneurone excitability was modulated in humans prior to arm cycling when compared with rest with no intention to move. We hypothesized that corticospinal excitability would be enhanced prior to arm cycling due, in part, to increased spinal motoneurone excitability. Supraspinal and spinal motoneurone excitability were assessed via transcranial magnetic stimulation (TMS) of the motor cortex and transmastoid stimulation of the corticospinal tract, respectively. Surface electromyography recordings of TMS motor evoked potentials (MEPs) and cervicomedullary MEPs (CMEPs) were made from the relaxed biceps brachii muscle prior to rhythmic arm cycling and at rest with no intention to move. The amplitude of the MEPs was greater (mean increase: +9.8% of maximal M wave; p = 0.006) and their onset latencies were shorter (mean decrease: –1.5 ms; p < 0.05) prior to cycling when compared with rest. The amplitudes of the CMEPs at any of 3 stimulation intensities were not different between conditions. We conclude that premovement enhancement of corticospinal excitability is greater prior to arm cycling than at rest because of increases in supraspinal but not spinal motoneurone excitability.

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