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.

Effects of Isoflurane and Desflurane on Neurogenic Motor- and Somatosensory-evoked Potential Monitoring for Scoliosis Surgery

1996 ◽  
Vol 85 (5) ◽  
pp. 1013-1019 ◽  
Author(s):  
Jean-Marc Bernard ◽  
Yann Pereon ◽  
Guillemette Fayet ◽  
Pierre Guiheneuc
Keyword(s):  
Spinal Cord ◽  
Nitrous Oxide ◽  
Evoked Potentials ◽  
Stimulus Intensity ◽  
Somatosensory Evoked Potentials ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Volatile Anesthetic ◽  
Anesthetic Agents ◽  
Oxygen Nitrous Oxide

Background Most techniques used to monitor spinal cord tracts are sensitive to the effects of anesthesia, particularly to volatile anesthetic agents. The aim of this prospective study was to show that evoked potentials recorded from the peripheral nerves after spinal cord stimulation, so-called neurogenic motor evoked potentials, are resistant to clinical concentrations of isoflurane or desflurane, compared with somatosensory-evoked potentials. Methods Twenty-three patients were studied during surgery to correct scoliosis. The background anesthetic consisted of a continuous infusion of propofol. Isoflurane (n = 12) or desflurane (n = 11) were then introduced to achieve 0.5 and 1.0 end-tidal minimum alveolar concentrations (MAC), both in 50% oxygen-nitrous oxide and in 100% oxygen. Somatosensory-evoked potentials were elicited and recorded using a standard method, defining cortical P40 and subcortical P29. Neurogenic motor-evoked potentials were elicited by electric stimulation of the spinal cord via needle electrodes placed by the surgeon in the rostral part of the surgical field. Responses were recorded from needle electrodes inserted in the right and left popliteal spaces close to the sciatic nerve. Stimulus intensity was adjusted to produce a supramaximal response; that is, an unchanged response in amplitude with subsequent increases in stimulus intensity. Measurements were obtained before introducing volatile agents and 20 min after obtaining a stable level of each concentration. Results Isoflurane and desflurane in both 50% oxygen-nitrous oxide and 100% oxygen were associated with a significant decrease in the amplitude and an increase in the latency of the cortical P40, whereas subcortical P29 latency did not vary significantly. Typical neurogenic motor-evoked potentials were obtained in all patients without volatile anesthetic agents, consisting of a biphasic wave, occurring 15 to 18 ms after stimulation, with an amplitude ranging from 1.3 to 4.1 microV. Latency or peak-to-peak amplitude of this wave was not significantly altered with isoflurane and desflurane, either in the presence or in the absence of nitrous oxide. Conclusions Compared with cortical somatosensory-evoked potentials, neurogenic motor-evoked potential signals are well preserved in patients undergoing surgery to correct scoliosis under general anesthesia supplemented with isoflurane or desflurane in concentrations as great as 1 MAC.

Motor Evoked Potentials from Transcranial Stimulation of the Motor Cortex in Humans

Neurosurgery ◽  
1984 ◽  
Vol 15 (3) ◽  
pp. 287-302 ◽  
Author(s):  
Walter J. Levy ◽  
Donald H. York ◽  
Michael McCaffrey ◽  
Fred Tanzer
Keyword(s):  
Spinal Cord ◽  
Motor Cortex ◽  
Evoked Potentials ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Sensory Modality ◽  
Motor Evoked Potential ◽  
Transcranial Stimulation ◽  
Direct Stimulation ◽  
Stimulation Of

Abstract Electrical monitoring of the motor system offers the potential for the detection of injury, the diagnosis of disease, the evaluation of treatment, and the prediction of recovery from damage. Existing evoked potentials monitor one or another sensory modality, but no generally usable motor monitor exists. We have reported a motor evoked potential using direct stimulation of the spinal cord over the motor tracts in cats and in humans. To achieve a less invasive monitor, we used transcranial stimulation over the motor cortex in the cat, thus stimulating the motor cortex. We report here the initial application of this method to humans. A plate electrode over the motor cortex on the scalp and a second electrode on the palate direct a mild current through the motor cortex which will activate the motor pathways. This signal can be recorded over the spinal cord. It can elicit contralateral peripheral nerve and electromyographic signals in the limbs or movements when the appropriate stimulation parameters are used. In clinical use to date, this has been more reliable than the somatosensory evoked potential in predicting motor function in patients where the two tests differed. It offers a number of possibilities for the development of valuable brain and spinal cord monitoring techinques, but requires further animal studies and clinical experience. Studies to date have not demonstrated adverse effects, but evaluation is continuing.

scholarly journals Effect of Two Anesthetic Regimes with Dexmedetomidine as Adjuvant on Transcranial Electrical Motor Evoked Potentials during Spine Surgery

2020 ◽  
Vol 07 (02) ◽  
pp. 084-090
Author(s):  
Rajeeb K. Mishra ◽  
Hemanshu Prabhakar ◽  
Indu Kapoor ◽  
Dinu S. Chandran ◽  
Arvind Chaturvedi
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Spine Surgery ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Spinal Column ◽  
Motor Evoked Potential ◽  
Standard Group ◽  
Time Points ◽  
Group D

Abstract Background Transcranial motor evoked potential (TcMEP) recording during spinal cord/spinal column surgery is a reliable and valid diagnostic adjunct to assess spinal cord integrity and is recommended if utilized for this purpose. Electrophysiologic monitoring in terms of TcMEP has been proven to be a useful tool in detecting spinal cord dysfunction at the earliest and allows corrective action to be taken before permanent neuronal dysfunction sets in. The quality of intraoperative neuromonitoring is influenced by various factors. Most anesthetics used in clinical practice suppress the evoked potentials. Thus, selecting an appropriate technique is always a challenging task. Materials and Methods Thirty ASA I and II patients scheduled for elective dorsolumbar spine surgery with TcMEP monitoring were recruited in the study. Patients were randomized into three groups: (1) Propofol (group P) 100 to 150 µg/kg/min with dexmedetomidine 0.6 µg/kg/hr and fentanyl 1 µg/kg/hr, (2) desflurane (group D) (<0.5 MAC) with dexmedetomidine 0.6 µg/kg/hr and fentanyl 1 µg/kg/hr, and (3)standard group (group S) patients received propofol 100 to 150 µg/kg/min, fentanyl 1 µg/kg/hr along with equal volume of saline (placebo). TcMEP amplitudes were recorded bilaterally from electrodes placed at least in one set of muscles with motor origin rostral and one set of muscle caudal to the spinal level of lesion at different time points. Results Three patients were excluded after allocation; 27 out of 30 patients were analyzed. The demographic and surgical characteristics of patients were comparable. The stimulation voltage needed to elicit the responses in all the three groups was comparable. No difference was observed in brachioradialis muscle amplitudes between the groups at different time points. However, in the right brachioradialis muscle, we found reduced amplitudes at baseline in group D and at 120 minutes in group P. We noticed reduced amplitudes of bilateral brachioradialis muscle in group P at 60 minutes and 90 minutes with respect to the baseline. For lower extremity, we measured amplitudes of TcMEP in tibialis anterior (TA) and did not find any difference in amplitudes between the groups at different time points. Conclusion We observed that the desflurane–dexmedetomidine combination did not hinder TcMEP as compared with both standard and propofol–dexmedetomidine groups. Thus, this combined regime could be used in surgeries requiring motor evoked potential monitoring.

Incidence of peripheral nerve injury during shoulder arthroplasty when motor evoked potentials are monitored

2017 ◽  
Vol 32 (5) ◽  
pp. 897-906 ◽  
Author(s):  
Alexander W. Aleem ◽  
W. Bryan Wilent ◽  
Alexa C. Narzikul ◽  
Andrew F. Kuntz ◽  
Edward S. Chang ◽  
...  
Keyword(s):  
Peripheral Nerve ◽  
Evoked Potentials ◽  
Nerve Injury ◽  
Shoulder Arthroplasty ◽  
Peripheral Nerve Injury ◽  
Motor Evoked Potentials

Motor Evoked Potentials

2016 ◽  
pp. 592-605
Author(s):  
Jeffrey A. Strommen ◽  
Andrea J. Boon
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Magnetic Stimulation ◽  
Motor Evoked Potentials ◽  
Standard Of Care ◽  
Transcranial Electrical Stimulation ◽  
Pharmacological Agents ◽  
Physiological Variables ◽  
Stimulation Parameters ◽  
Cord Injury

Motor evoked potentials (MEP) may be used in the diagnosis of central and peripheral neurological disorders and have become the standard of care in many operative procedures as a means to monitor the motor pathways.In the awake patient, transcranial magnetic stimulation (TMS) can be utilized with surface or subcutaneous muscle recordings to identify central conduction abnormalities, as well as assist with prognosis, in conditions such as multiple sclerosis, stroke, spinal cord injury, Parkinson’s disease, hereditary spastic paraplegia, or ALS. In the operating theater, transcranial electrical stimulation with recording from the spinal cord, root, peripheral nerve, or muscle can be used to prevent spinal cord damage, determine continuity of roots or peripheral nerves, and assist with surgical planning. MEP are significantly affected by many physiological variables and pharmacological agents. Various techniques in regards to simulation sites, stimulation parameters, and recording techniques and sites need to be modified to enhance the reproducibility and reliability of these responses.

Sciatic nerve injury model in the axolotl: functional, electrophysiological, and radiographic outcomes

2010 ◽  
Vol 112 (4) ◽  
pp. 880-889 ◽  
Author(s):  
Nina Kropf ◽  
Kartik Krishnan ◽  
Moses Chao ◽  
Mark Schweitzer ◽  
Zehava Rosenberg ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Mr Imaging ◽  
Peripheral Nerve ◽  
Evoked Potentials ◽  
Nerve Regeneration ◽  
Nerve Injury ◽  
Outcome Measures ◽  
Peripheral Nerve Injury ◽  
Motor Evoked Potentials ◽  
Muscle Denervation

Object The 2 aims of this study were as follows: 1) to establish outcome measures of nerve regeneration in an axolotl model of peripheral nerve injury; and 2) to define the timing and completeness of reinnervation in the axolotl following different types of sciatic nerve injury. Methods The sciatic nerves in 36 axolotls were exposed bilaterally in 3 groups containing 12 animals each: Group 1, left side sham, right side crush; Group 2, left side sham, right side nerve resected and proximal stump buried; and Group 3 left side cut and sutured, right side cut and sutured with tibial and peroneal divisions reversed. Outcome measures included the following: 1) an axolotl sciatic functional index (ASFI) derived from video swim analysis; 2) motor latencies; and 3) MR imaging evaluation of nerve and muscle edema. Results For crush injuries, the ASFI returned to baseline by 2 weeks, as did MR imaging parameters and motor latencies. For buried nerves, the ASFI returned to 20% below baseline by 8 weeks, with motor evoked potentials present. On MR imaging, nerve edema peaked at 3 days postintervention and gradually normalized over 12 weeks, whereas muscle denervation was present until a gradual decrease was seen between 4 and 12 weeks. For cut nerves, the ASFI returned to 20% below baseline by Week 4, where it plateaued. Motor evoked potentials were observed at 2–4 weeks, but with an increased latency until Week 6, and MR imaging analysis revealed muscle denervation for 4 weeks. Conclusions Multiple outcome measures in which an axolotl model of peripheral nerve injury is used have been established. Based on historical controls, recovery after nerve injury appears to occur earlier and is more complete than in rodents. Further investigation using this model as a successful “blueprint” for nerve regeneration in humans is warranted.

Transplantation Strategies for Spinal Cord Injury Based on Microenvironment Modulation

2020 ◽  
Vol 15 (6) ◽  
pp. 522-530
Author(s):  
Jiawei Shu ◽  
Feng Cheng ◽  
Zhe Gong ◽  
Liwei Ying ◽  
Chenggui Wang ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Peripheral Nerve ◽  
Nerve Injury ◽  
Autonomic Dysfunction ◽  
Peripheral Nerve Injury ◽  
Therapeutic Effects ◽  
Permanent Damage ◽  
Cord Injury ◽  
Severe Motor

Spinal cord injury (SCI) is different from peripheral nerve injury; it results in devastating and permanent damage to the spine, leading to severe motor, sensory and autonomic dysfunction. SCI produces a complex microenvironment that can result in hemorrhage, inflammation and scar formation. Not only does it significantly limit regeneration, but it also challenges a multitude of transplantation strategies. In order to promote regeneration, researchers have recently begun to focus their attention on strategies that manipulate the complicated microenvironment produced by SCI. And some have achieved great therapeutic effects. Hence, reconstructing an appropriate microenvironment after transplantation could be a potential therapeutic solution for SCI. In this review, first, we aim to summarize the influential compositions of the microenvironment and their different effects on regeneration. Second, we highlight recent research that used various transplantation strategies to modulate different microenvironments produced by SCI in order to improve regeneration. Finally, we discuss future transplantation strategies regarding SCI.

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.

Sign in / Sign up

Export Citation Format

Share Document