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

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.

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.

scholarly journals Measurement of Motor Evoked Potential in Acute Ischemic Stroke: Based on Latency, Amplitude, Central Motoric Conduction Time and Resting Motor Threshold

2016 ◽  
Vol 8 (3) ◽  
pp. 157 ◽  
Author(s):  
Tugas Ratmono ◽  
Andi Wijaya ◽  
Cahyono Kaelan ◽  
Andi Asadul Islam ◽  
Ferry Sandra
Keyword(s):  
Ischemic Stroke ◽  
Acute Ischemic Stroke ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Conduction Time ◽  
Size Measurement ◽  
Motor Threshold ◽  
Dynamic Changes ◽  
Resting Motor Threshold ◽  
Function Impairment

BACKGROUND: After stroke, there are dynamic changes of motor evoked potential (MEP), including latency, amplitude, central motoric conduction time (CMCT) and resting motor threshold (RMT) in cerebral. However, latency, CMCT, amplitude and RMT have not been clearly shown in acute ischemic stroke patients with motoric function impairment based on Modified Motoric Research Council Scale (MRCs).METHODS: Patients with motoric function impairment after acute ischemic stroke were recruited, scored based on MRCs and grouped. Latency, amplitude, CMCT and RMT (% intensity) was measured using transcranial magnetic stimulation (TMS). Latency, amplitude, CMCT and RMT of subjects based on affected hemisphere (AH) and unaffected hemisphere (UH); stroke onset; and motoric severity; were analyzed and compared statistically.RESULTS: Thirty-seven subjects with complete assessments were selected. Results of MEP size measurement between AH and UH showed that latency, amplitude, CMCT and RMT of AH and UH were significantly different (p<0.05). In accordance to AH and UH results, latency, amplitude, CMCT and RMT of mild, moderate and severe groups based on motoric severity, showed that latency and CMCT were prolonged, RMT was increased, while amplitude was decreased along with severity increment. The amplitude and RMT among the groups were significantly different with p=0.034 and p=0.029, respectively.CONCLUSION: MEP size measurement including latency, amplitude, CMCT and RMT have significant different in AH and UH. In addition, amplitude and RMT were significantly different in MRCs groups, therefore the MEP size measurement could be suggested as prognostic tool.KEYWORDS: MEP, latency, amplitude, CMCT, RMT

scholarly journals Effect of Therapy on Motor Cortical Excitability in Parkinson’s Disease

2008 ◽  
Vol 35 (2) ◽  
pp. 166-172 ◽  
Author(s):  
Aysun Soysal ◽  
Ismail Sobe ◽  
Turan Atay ◽  
Aysu Sen ◽  
Baki Arpaci
Keyword(s):  
Parkinson’S Disease ◽  
Late Stage ◽  
Evoked Potential ◽  
Cortical Excitability ◽  
Early Stage ◽  
Motor Evoked Potential ◽  
Motor Threshold ◽  
Potential Amplitude ◽  
Motor Cortical Excitability ◽  
Motor Cortical

Objective:To assess the impact of the disease stage and therapy on motor cortical excitability in Parkinson’s disease (PD).Methods:Twenty newly diagnosed and medication-free, early stage patients, 20 late stage patients under antiparkinsonian therapy and 20 normal healthy controls were included. Motor threshold (MT), amplitudes of motor evoked potential (MEP), motor evoked potential amplitude/compound muscle action potential amplitude (MEP/CMAP) ratio, central motor conduction time (CMCT) and cortical silent period (CSP) were measured by stimulation of the motor cortex using a 13.5 cm circular coil and recordings from abductor digiti minimi muscle. Following the first study protocol, early stage patients were given therapy and the same protocol was repeated three months later.Results:Motor threshold was lower; and the MEP/CMAP ratio was higher in early and late stage patients than normals. In early stage patients after proper therapy, the MTs became higher than before therapy, but still remained lower than normals. In late stage patients, the CMCTs were shorter than the early stage patients before therapy and normals, but there was no difference between the early stage patients and normals. In early stage patients after therapy, the CMCT became longer than before therapy and this difference was significant in both late stage patients and normals. Although more prominent in late stage patients, the CSP duration in both PD groups was found shorter than normals. In early stage patients, after therapy, the CSP durations became significantly longer compared with before therapy.Conclusion:These findings suggest that the motor cortical excitability increases in PD because of the impairment of the corticomotoneuronal inhibitory system.

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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