The Role of Motor Evoked Potentials during Surgery for Intramedullary Spinal Cord Tumors

Neurosurgery ◽  
1997 ◽  
Vol 41 (6) ◽  
pp. 1327-1336 ◽  
Author(s):  
Nobu Morota ◽  
Vedran Deletis ◽  
Shlomi Constantini ◽  
Markus Kofler ◽  
Henry Cohen ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Spinal Cord Tumors ◽  
Intramedullary Spinal Cord

Use of Intraoperative Transcranial Motor Evoked Potentials to Predict Outcome after Resection of Pediatric Intramedullary Spinal Cord Tumors

Neurosurgery ◽  
2005 ◽  
Vol 57 (2) ◽  
pp. 436-436
Author(s):  
Kurtis Auguste ◽  
Alfredo Quiñones-Hinojosa ◽  
Russ Lyon ◽  
Peter P. Sun ◽  
Victor L. Perry ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Spinal Cord Tumors ◽  
Intramedullary Spinal Cord ◽  
Transcranial Motor Evoked Potentials

scholarly journals Neuromodulation of motor-evoked potentials during stepping in spinal rats

2013 ◽  
Vol 110 (6) ◽  
pp. 1311-1322 ◽  
Author(s):  
Parag Gad ◽  
Igor Lavrov ◽  
Prithvi Shah ◽  
Hui Zhong ◽  
Roland R. Roy ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Motor Task ◽  
Hindlimb Muscles ◽  
Epidural Spinal Cord Stimulation ◽  
Highly Correlated ◽  
Muscle Responses

The rat spinal cord isolated from supraspinal control via a complete low- to midthoracic spinal cord transection produces locomotor-like patterns in the hindlimbs when facilitated pharmacologically and/or by epidural electrical stimulation. To evaluate the role of epidural electrical stimulation in enabling motor control (eEmc) for locomotion and posture, we recorded potentials evoked by epidural spinal cord stimulation in selected hindlimb muscles during stepping and standing in adult spinal rats. We hypothesized that the temporal details of the phase-dependent modulation of these evoked potentials in selected hindlimb muscles while performing a motor task in the unanesthetized state would be predictive of the potential of the spinal circuitries to generate stepping. To test this hypothesis, we characterized soleus and tibialis anterior (TA) muscle responses as middle response (MR; 4–6 ms) or late responses (LRs; >7 ms) during stepping with eEmc. We then compared these responses to the stepping parameters with and without a serotoninergic agonist (quipazine) or a glycinergic blocker (strychnine). Quipazine inhibited the MRs induced by eEmc during nonweight-bearing standing but facilitated locomotion and increased the amplitude and number of LRs induced by eEmc during stepping. Strychnine facilitated stepping and reorganized the LRs pattern in the soleus. The LRs in the TA remained relatively stable at varying loads and speeds during locomotion, whereas the LRs in the soleus were strongly modulated by both of these variables. These data suggest that LRs facilitated electrically and/or pharmacologically are not time-locked to the stimulation pulse but are highly correlated to the stepping patterns of spinal rats.

Factors predicting the feasibility of monitoring lower-limb muscle motor evoked potentials in patients undergoing excision of spinal cord tumors

2011 ◽  
Vol 14 (6) ◽  
pp. 748-753 ◽  
Author(s):  
Vedantam Rajshekhar ◽  
Parthiban Velayutham ◽  
Mathew Joseph ◽  
K. Srinivasa Babu
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Success Rate ◽  
Lower Limb ◽  
Tibialis Anterior ◽  
Muscle Power ◽  
Motor Evoked Potentials ◽  
Tibialis Anterior Muscle ◽  
Spinal Cord Tumors ◽  
Motor Outcome

Object This prospective study on intraoperative muscle motor evoked potentials (MMEPs) from lower-limb muscles in patients undergoing surgery for spinal cord tumors was performed to: 1) determine preoperative clinical features that could predict successful recording of lower-limb MMEPs; 2) determine the muscle in the lower limb from which MMEPs could be most consistently obtained; 3) assess the need to monitor more than 1 muscle per limb; and 4) determine the effect of a successful baseline MMEP recording on early postoperative motor outcome. Methods Of 115 consecutive patients undergoing surgery for spinal cord tumors, 110 were included in this study (44 intramedullary and 66 intradural extramedullary tumors). Muscle MEPs were generated using transcranial electrical stimulation under controlled anesthesia and were recorded from the tibialis anterior, quadriceps, soleus, and external anal sphincter muscles bilaterally. The effect of age (≤ 20 or > 20 years old), location of the tumor (intramedullary or extramedullary), segmental location of the tumor (cervical, thoracic, or lumbar), duration of symptoms (≤ 12 or > 12 months), preoperative functional grade (Nurick Grades 0–3 or 4–5), and muscle power (Medical Research Council Grades 0/5–3/5 or 4/5–5/5) on the success rate of obtaining MMEPs was studied using multiple regression analysis. The effect of the ability to monitor MMEPs on motor outcome at discharge from the hospital was also analyzed. Results The overall success rate for obtaining baseline lower-limb MMEPs was 68.2% (75 of 110 patients). Eighty-nine percent of patients with Nurick Grades 0–3 had successful MMEP recordings. Muscle MEPs could not be obtained in any patient in whom muscle power was 2/5 or less, but were obtained from 91.4% of patients with muscle power of 4/5 or more. Analysis showed that only preoperative Nurick grade (p ≤ 0.0001) and muscle power (p < 0.0001) were significant predictors of the likelihood of obtaining MMEPs. Responses were most consistently obtained from the tibialis anterior muscle (68%), but in the other 32% MMEPs could not be recorded from the tibialis anterior but could be recorded from another muscle. The ability to monitor MMEPs was associated with better motor outcome at discharge from the hospital (p = 0.052). Conclusions The likelihood of obtaining lower-limb MMEPs is significantly greater in patients with better functional grades and higher motor power. Muscle MEPs are most consistently obtained from the tibialis anterior muscle but other muscles should also be monitored to optimize the chances of obtaining MMEP responses from the lower limbs.

The Initial Use of Free-running Electromyography to Detect Early Motor Tract Injury during Resection of Intramedullary Spinal Cord Lesions

2005 ◽  
Vol 56 (suppl_4) ◽  
pp. ONS-299-ONS-314 ◽  
Author(s):  
Stanley A. Skinner ◽  
Mahmoud Nagib ◽  
Thomas A. Bergman ◽  
Robert E. Maxwell ◽  
Gaspar Msangi
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
False Negative ◽  
Neurological Deficits ◽  
Motor Deficit ◽  
Spinal Cord Lesions ◽  
Blood Pressure Elevation ◽  
Intramedullary Spinal Cord ◽  
Free Running

Abstract OBJECTIVE: The resection of intramedullary spinal cord lesions (ISCLs) can be complicated by neurological deficits. Neuromonitoring has been used to reduce intraoperative risk. We have used somatosensory evoked potentials (SEPs) and muscle-derived transcranial electrical motor evoked potentials (myogenic TCE-MEPs) to monitor ISCL removal. We report our retrospective experience with the addition of free-running electromyography (EMG). METHODS: Thirteen patients underwent 14 monitored ISCL excisions. Anesthesia was maintained with minimal inhalant to reduce motoneuron suppression and enhance the myogenic TCE-MEPs. Free-running EMG was examined in the four limbs for evidence of abnormal bursts, prolonged tonic discharge, or sudden electrical silence. Warning of an electromyographic abnormality or myogenic TCE-MEP loss prompted interventions, including blood pressure elevation, a pause in surgery, a wake-up test, or termination of surgery. Pre- and postoperative neurological examinations determined the incidence of new deficits. RESULTS: The combined use of free-running EMG and myogenic TCE-MEPs detected all eight patients with a new motor deficit after surgery; there was one false-positive report. In three of the eight true-positive cases, an electromyographic abnormality immediately anticipated loss of the myogenic TCE-MEPs. Two patients with abnormal EMGs but unchanged myogenic TCE-MEPs experienced mild postoperative worsening of motor deficits; myogenic TCE-MEPs alone would have generated false-negative reports in these cases. CONCLUSION: During resection of ISCLs, free-running EMG can supplement motor tract monitoring by TCE-MEPs. Segmental and suprasegmental elicitation of neurotonic discharges can be observed in four-limb EMG. Abnormal electromyographic bursts, tonic discharge, or abrupt electromyographic silence may anticipate myogenic TCE-MEP loss and predict a postoperative motor deficit.

scholarly journals Surgery for intramedullary spinal cord tumors: the role of intraoperative (neurophysiological) monitoring

2007 ◽  
Vol 16 (S2) ◽  
pp. 130-139 ◽  
Author(s):  
Francesco Sala ◽  
Albino Bricolo ◽  
Franco Faccioli ◽  
Paola Lanteri ◽  
Massimo Gerosa
Keyword(s):  
Spinal Cord ◽  
Intraoperative Neurophysiological Monitoring ◽  
Neurophysiological Monitoring ◽  
Spinal Cord Tumors ◽  
Intramedullary Spinal Cord

Spinal Cord Mapping as an Adjunct for Resection of Intramedullary Tumors: Surgical Technique with Case Illustrations

Neurosurgery ◽  
2002 ◽  
Vol 51 (5) ◽  
pp. 1199-1207 ◽  
Author(s):  
Alfredo Quinones-Hinojosa ◽  
Mittul Gulati ◽  
Russell Lyon ◽  
Nalin Gupta ◽  
Charles Yingling
Keyword(s):  
Spinal Cord ◽  
Evoked Potentials ◽  
Motor Evoked Potentials ◽  
Cervical Spinal Cord ◽  
Tumor Resection ◽  
Neurological Deficits ◽  
Electromyographic Activity ◽  
Intramedullary Spinal Cord ◽  
Motor Tracts ◽  
Stimulation Of

Abstract OBJECTIVE Resection of intramedullary spinal cord tumors may result in transient or permanent neurological deficits. Intraoperative somatosensory evoked potentials (SSEPs) and motor evoked potentials are commonly used to limit complications. We used both antidromically elicited SSEPs for planning the myelotomy site and direct mapping of spinal cord tracts during tumor resection to reduce the risk of neurological deficits and increase the extent of tumor resection. METHODS In two patients, 3 and 12 years of age, with tumors of the thoracic and cervical spinal cord, respectively, antidromically elicited SSEPs were evoked by stimulation of the dorsal columns and were recorded with subdermal electrodes placed at the medial malleoli bilaterally. Intramedullary spinal cord mapping was performed by stimulating the resection cavity with a handheld Ojemann stimulator (Radionics, Burlington, MA). In addition to visual observation, subdermal needle electrodes inserted into the abductor pollicis brevis-flexor digiti minimi manus, tibialis anterior-gastrocnemius, and abductor halluces-abductor digiti minimi pedis muscles bilaterally recorded responses that identified motor pathways. RESULTS The midline of the spinal cord was anatomically identified by visualizing branches of the dorsal medullary vein penetrating the median sulcus. Antidromic responses were obtained by stimulation at 1-mm intervals on either side of the midline, and the region where no response was elicited was selected for the myelotomy. The anatomic and electrical midlines did not precisely overlap. Stimulation of abnormal tissue within the tumor did not elicit electromyographic activity. Approaching the periphery of the tumor, stimulation at 1 mA elicited an electromyographic response before normal spinal cord was visualized. Restimulation at lower currents by use of 0.25-mA increments identified the descending motor tracts adjacent to the tumor. After tumor resection, the tracts were restimulated to confirm functional integrity. Both patients were discharged within 2 weeks of surgery with minimal neurological deficits. CONCLUSION Antidromically elicited SSEPs were important in determining the midline of a distorted cord for placement of the myelotomy incision. Mapping spinal cord motor tracts with direct spinal cord stimulation and electromyographic recording facilitated the extent of surgical resection.

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