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.

Monitoring of Spinal Cord Stimulation Evoked Potentials during Thoracoabdominal Aneurysm Surgery

Neurosurgery ◽  
1991 ◽  
Vol 28 (2) ◽  
pp. 325-330 ◽  
Author(s):  
Richard B. North ◽  
Benjamin Drenger ◽  
Charles Beattie ◽  
Robert W. McPherson ◽  
Stephen Parker ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Evoked Potential ◽  
Conduction Block ◽  
Significant Risk ◽  
Thoracoabdominal Aneurysm ◽  
Direct Stimulation ◽  
Lower Extremity Ischemia ◽  
Extremity Ischemia ◽  
Stimulation Of

Abstract Repair of a thoracoabdominal aneurysm involves a significant risk of ischemic injury to the spinal cord. Standard monitoring of somatosensory evoked potentials, which relies upon peripheral nerve stimulation, becomes nonspecific and insensitive during this surgery when aortic cross-clamping produces lower extremity ischemia causing a peripheral conduction block. Techniques for the insertion of percutaneous epidural electrodes, developed originally for pain management, have been adapted to this setting to permit direct stimulation of the spinal cord for intraoperative monitoring of evoked potentials. The clinical outcome in patients monitored by this technique has been consistent with evoked potential findings.

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.

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

Neurosurgery ◽  
1984 ◽  
Vol 15 (2) ◽  
pp. 214-227 ◽  
Author(s):  
Walter J. Levy ◽  
Michael McCaffrey ◽  
Donald H. York ◽  
Fred Tanzer
Keyword(s):  
Motor Cortex ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Transcranial Stimulation ◽  
Stimulation Of

Motor evoked potentials from transcranial stimulation of the motor cortex in humans

Neurosurgery ◽  
1984 ◽  
Vol 15 (3) ◽  
pp. 287???302 ◽  
Author(s):  
W J Levy ◽  
D H York ◽  
M McCaffrey ◽  
F Tanzer
Keyword(s):  
Motor Cortex ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Transcranial Stimulation ◽  
Stimulation Of

Motor evoked potentials from transcranial stimulation of the motor cortex in cats

Neurosurgery ◽  
1984 ◽  
Vol 15 (2) ◽  
pp. 214???27
Author(s):  
W J Levy ◽  
M McCaffrey ◽  
D H York ◽  
F Tanzer
Keyword(s):  
Motor Cortex ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Transcranial Stimulation ◽  
Stimulation Of

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.

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