Low-Threshold Monopolar Motor Mapping for Resection of Primary Motor Cortex Tumors

2012 ◽  
Vol 71 (suppl_1) ◽  
pp. ons104-ons115 ◽  
Author(s):  
Kathleen Seidel ◽  
Jürgen Beck ◽  
Lennart Stieglitz ◽  
Philippe Schucht ◽  
Andreas Raabe
Keyword(s):  
Motor Neurons ◽  
Evoked Potential ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
National Institutes Of Health ◽  
Motor Deficit ◽  
Motor Threshold ◽  
Motor Mapping ◽  
Low Threshold ◽  
A Minor

Abstract BACKGROUND: Microsurgery within eloquent cortex is a controversial approach because of the high risk of permanent neurological deficit. Few data exist showing the relationship between the mapping stimulation intensity required for eliciting a muscle motor evoked potential and the distance to the motor neurons; furthermore, the motor threshold at which no deficit occurs remains to be defined. OBJECTIVE: To evaluate the safety of low threshold motor evoked potential mapping for tumor resection close to the primary motor cortex. METHODS: Fourteen patients undergoing tumor surgery were included. Motor threshold was defined as the stimulation intensity that elicited motor evoked potentials from target muscles (amplitude > 30 μV). Monopolar high-frequency motor mapping with train-of-5 stimuli (HF-TOF; pulse duration = 500 microseconds; interstimulus interval = 4.0 milliseconds; frequency = 250 Hz) was used to determine motor response--negative sites where incision and dissection could be performed. At sites negative to 3-mA HF-TOF stimulation, the tumor was resected. RESULTS: HF-TOF mapping localized the motor neurons within the precentral gyrus by using variable, low-stimulation intensities. The lowest motor thresholds after final resection ranged from 3 to 6 mA, indicating close proximity of motor neurons. Postoperatively, 12 patients had no new motor deficit, 1 patient had a minor new temporary deficit (M4+, National Institutes of Health Stroke Scale 1), and another patient had a minor new permanent deficit (M4+, National Institutes of Health Stroke Scale 2). Thirteen patients had complete or gross total resection. CONCLUSION: These preliminary data demonstrate that a monopolar HF-TOF threshold > 3 mA was not associated with a significant new motor deficit.

Gross Total Resection of a Grade IV Astrocytoma Adjacent to the Precentral Gyrus With Nonawake Motor Mapping and Motor-Evoked Potential Monitoring: 3-Dimensional Operative Video

2019 ◽  
Author(s):  
Burak Ozaydin ◽  
Ihsan Dogan ◽  
Bryan J Wheeler ◽  
Mustafa K Baskaya
Keyword(s):  
Motor Cortex ◽  
Evoked Potential ◽  
Primary Motor Cortex ◽  
Motor Evoked Potential ◽  
Gross Total Resection ◽  
Precentral Gyrus ◽  
Total Resection ◽  
Motor Mapping ◽  
3 Dimensional ◽  
Intraoperative Adjuncts

Abstract Surgical treatment of the gliomas located in or adjacent to the eloquent areas poses significant challenge to neurosurgeons. The main goal of the surgery is to achieve maximal safe resection while preserving the neurological function. This might be possible with utilizing pre- and intraoperative adjuncts such as functional magnetic resonance imaging (MRI), image guidance, mapping of the function of interest, intraoperative MRI, and neurophysiological monitoring. In this video, we demonstrate the utilization of nonawake mapping and motor-evoked potential (MEP) monitoring for the resection of a right-sided posterior superior frontal gyrus grade IV astrocytoma adjacent to the primary motor cortex. The patient is a 69-yr-old woman presented with multiple episodes of simple partial seizures involving her left leg and spreading to the left arm. MRI and functional MRI examinations showed a heterogeneously enhancing mass with peritumoral edema adjacent to the primary motor cortex. Because the patient did not want to undergo an awake craniotomy, a decision was made to perform the resection of the tumor with nonawake motor mapping and continuous MEP monitoring. Nonawake motor mapping and MEP monitoring enabled us to perform gross total resection. Because it has been shown that supratotal resection may provide improved survival outcome,1,2 we extended the white matter resection beyond the contrast enhancing area in noneloquent parts of the tumor. Surgical steps in dealing with vascular anatomy as well as utilizing intraoperative adjuncts such as motor mapping and MEP monitoring to enhance the extent of resection while preserving the function are demonstrated in this 3-dimensional surgical video.  The patient consented to publication of her operative video.

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.

Intraoperative Motor Evoked Potential Alteration in Intracranial Tumor Surgery and Its Relation to Signal Alteration in Postoperative Magnetic Resonance Imaging

Neurosurgery ◽  
2010 ◽  
Vol 67 (2) ◽  
pp. 302-313 ◽  
Author(s):  
Andrea Szelényi ◽  
Elke Hattingen ◽  
Stefan Weidauer ◽  
Volker Seifert ◽  
Ulf Ziemann
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Motor Cortex ◽  
Evoked Potential ◽  
Corticospinal Tract ◽  
Motor Evoked Potential ◽  
Motor Deficit ◽  
Warning Sign ◽  
Precentral Gyrus ◽  
Resonance Imaging

Abstract OBJECTIVE To determine the degree to which the pattern of intraoperative isolated, unilateral alteration of motor evoked potential (MEP) in intracranial surgery was related to motor outcome and location of new postoperative signal alterations on magnetic resonance imaging (MRI). METHODS In 29 patients (age, 42.8 ± 18.2 years; 15 female patients; 25 supratentorial, 4 infratentorial procedures), intraoperative MEP alterations in isolation (without significant alteration in other evoked potential modalities) were classified as deterioration (> 50% amplitude decrease and/or motor threshold increase) or loss, respectively, or reversible and irreversible. Postoperative MRI was described for the location and type of new signal alteration. RESULTS New motor deficit was present in all 5 patients with irreversible MEP loss, in 7 of 10 patients with irreversible MEP deterioration, in 1 of 6 patients with reversible MEP loss, and in 0 of 8 patients with reversible MEP deterioration. Irreversible compared with reversible MEP alteration was significantly more often correlated with postoperative motor deficit (P < .0001). In 20 patients, 22 new signal alterations affected 29 various locations (precentral gyrus, n = 5; corticospinal tract, n = 19). Irreversible MEP alteration was more often associated with postoperative new signal alteration in MRI compared with reversible MEP alteration (P = .02). MEP loss was significantly more often associated with subcortically located new signal alteration (P = .006). MEP deterioration was significantly more often followed by new signal alterations located in the precentral gyrus (P = .04). CONCLUSION MEP loss bears a higher risk than MEP deterioration for postoperative motor deficit resulting from subcortical postoperative MR changes in the corticospinal tract. In contrast, MEP deterioration points to motor cortex lesion. Thus, even MEP deterioration should be considered a warning sign if surgery close to the motor cortex is performed.

Comparison of navigated and non-navigated TMS: motor threshold and motor evoked potential

2008 ◽  
Vol 1 (3) ◽  
pp. 245-246
Author(s):  
P. Julkunen ◽  
L. Säisänen ◽  
N. Danner ◽  
E. Niskanen ◽  
T. Hukkanen ◽  
...  
Keyword(s):  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Motor Threshold

scholarly journals Predicting response to motor therapy in chronic stroke patients using Machine Learning

2018 ◽  
Author(s):  
Ceren Tozlu ◽  
Dylan Edwards ◽  
Aaron Boes ◽  
Douglas Labar ◽  
K. Zoe Tsagaris ◽  
...  
Keyword(s):  
Machine Learning ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Chronic Stroke ◽  
Motor Threshold ◽  
Stroke Patients ◽  
Post Intervention ◽  
Machine Learning Methods ◽  
Neurophysiological Data ◽  
The Difference

AbstractAccurate predictions of motor improvement resulting from intensive therapy in chronic stroke patients is a difficult task for clinicians, but is key in prescribing appropriate therapeutic strategies. Statistical methods, including machine learning, are a highly promising avenue with which to improve prediction accuracy in clinical practice. The first main objective of this study was to use machine learning methods to predict a chronic stroke individual’s motor function improvement after 6 weeks of intervention using pre-intervention demographic, clinical, neurophysiological and imaging data. The second main objective was to identify which data elements were most important in predicting chronic stroke patients’ impairment after 6 weeks of intervention. Data from one hundred and two patients (Female: 31%, age 61±11 years) who suffered first ischemic stroke 3-12 months prior were included in this study. After enrollment, patients underwent 6 weeks of intensive motor and transcranial magnetic stimulation therapy. Age, gender, handedness, time since stroke, pre-intervention Fugl-Meyer Assessment, stroke lateralization, the difference in motor threshold between the unaffected and affected hemispheres, absence or presence of motor evoked potential in the affected hemisphere and various imaging metrics were used as predictors of post-intervention Fugl-Meyer Assessment. Five machine learning methods, including Elastic-Net, Support Vector Machines, Artificial Neural Networks, Classification and Regression Trees, and Random Forest, were used to predict post-intervention Fugl-Meyer Assessment based on either demographic, clinical and neurophysiological data alone or in combination with the imaging metrics. Cross-validated R-squared and root of mean squared error were used to assess the prediction accuracy and compare the performance of methods. Elastic-Net performed significantly better than the other methods for the model containing pre-intervention Fugl-Meyer Assessment, demographic, clinical and neurophysiological data as predictors of post-intervention Fugl-Meyer Assessment (). Pre-intervention Fugl-Meyer Assessment and difference in motor threshold between affected and unaffected hemispheres were commonly found as the strongest two predictors in the clinical model. The difference in motor threshold had greater importance than the absence or presence of motor evoked potential in the affected hemisphere. The various imaging metrics, including lesion overlap with the spinal cord, largely did not improve the model performance. The approach implemented here may enable clinicians to more accurately predict a chronic stroke patient’s individual response to intervention. The predictive models used in this study could assist clinicians in making treatment decisions and improve the accuracy of prognosis in chronic stroke patients.

Motor threshold, motor evoked potential, central motor conduction time

2021 ◽  
Author(s):  
Sein H. Schmidt ◽  
Stephan A. Brandt
Keyword(s):  
Magnetic Stimulation ◽  
Evoked Potential ◽  
Motor Evoked Potentials ◽  
Motor Evoked Potential ◽  
Conduction Time ◽  
Optical Navigation ◽  
Motor Threshold ◽  
Pathological Conditions ◽  
Latency Variability ◽  
First Time

In this chapter, we survey parameters influencing the assessment of the size and latency of motor evoked potentials (MEP), in normal and pathological conditions, and methods to allow for a meaningful quantification of MEP characteristics. In line with the first edition of this textbook, we extensively discuss three established mechanisms of intrinsic physiological variance and collision techniques that aim to minimize their influence. For the first time, in line with the ever wider use of optical navigation and targeting systems in brain stimulation, we discuss novel methods to capture and minimize the influence of extrinsic biophysical variance. Together, following the rules laid out in this chapter, transcranial magnetic stimulation (TMS) can account for spinal and extrinsic biophysical variance to advance investigations of the central origins of MEP size and latency variability.

The value of intraoperative motor evoked potential monitoring during surgical intervention for thoracic idiopathic spinal cord herniation

2012 ◽  
Vol 16 (2) ◽  
pp. 114-126 ◽  
Author(s):  
Klaus Novak ◽  
Georg Widhalm ◽  
Adauri Bueno de Camargo ◽  
Noel Perin ◽  
George Jallo ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Evoked Potential ◽  
Surgical Repair ◽  
Motor Evoked Potential ◽  
Motor Deficit ◽  
Dural Defect ◽  
Spinal Cord Herniation ◽  
Dural Graft ◽  
Evoked Potential Monitoring ◽  
Idiopathic Spinal Cord Herniation

Object Thoracic idiopathic spinal cord herniation (TISCH) is a rare neurological disorder characterized by an incarceration of the spinal cord at the site of a ventral dural defect. The disorder is associated with clinical signs of progressive thoracic myelopathy. Surgery can withhold the natural clinical course, but surgical repair of the dural defect bears a significant risk of additional postoperative motor deficits, including permanent paraplegia. Intraoperative online information about the functional integrity of the spinal cord and warning signs about acute functional impairment of motor pathways could contribute to a lower risk of permanent postoperative motor deficit. Motor evoked potential (MEP) monitoring can instantly and reliably detect dysfunction of motor pathways in the spinal cord. The authors have applied MEPs during intraoperative neurophysiological monitoring (IOM) for surgical repair of TISCH and have correlated the results of IOM with its influence on the surgical procedure and with the functional postoperative outcome. Methods The authors retrospectively reviewed the intraoperative neurophysiological data and clinical records of 4 patients who underwent surgical treatment for TISCH in 3 institutions where IOM, including somatosensory evoked potentials and MEPs, is routinely used for spinal cord surgery. In all 4 patients the spinal cord was reduced from a posterior approach and the dural defect was repaired using a dural graft. Results Motor evoked potential monitoring was feasible in all patients. Significant intraoperative changes of MEPs were observed in 2 patients. The changes were detected within seconds after manipulation of the spinal cord. Monitoring of MEPs led to immediate revision of the placement of the dural graft in one case and to temporary cessation of the release of the incarcerated spinal cord in the other. Changes occurred selectively in MEPs and were reversible. In both patients, transient changes in intraoperative MEPs correlated with a reversible postoperative motor deficit. Patients without significant changes in somatosensory evoked potentials and MEPs demonstrated no additional neurological deficit postoperatively and showed improvement of motor function during follow-up. Conclusions Surgical repair of the dural defect is effected by release and reduction of the spinal cord and insertion of dural substitute over the dural defect. Careful monitoring of the functional integrity of spinal cord long tracts during surgical manipulation of the cord can detect surgically induced impairment. The authors' documentation of acute loss of MEPs that correlated with reversible postoperative motor deficit substantiates the necessity of IOM including continuous monitoring of MEPs for the surgical treatment of TISCH.

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