scholarly journals Reply: Variability in motor threshold

2021 ◽  
Author(s):  
Gonçalo Cotovio ◽  
Albino J. Oliveira-Maia ◽  
Carter Paul ◽  
Francisco Faro Viana ◽  
Daniel Rodrigues da Silva ◽  
...  
Keyword(s):  
Motor Threshold

scholarly journals Investigating the Intervention Parameters of Endogenous Paired Associative Stimulation (ePAS)

2021 ◽  
Vol 11 (2) ◽  
pp. 224
Author(s):  
Gemma Alder ◽  
Nada Signal ◽  
Alain C. Vandal ◽  
Sharon Olsen ◽  
Mads Jochumsen ◽  
...  
Keyword(s):  
Neural Plasticity ◽  
Repeated Measures ◽  
Single Pulse ◽  
Stroke Recovery ◽  
Motor Threshold ◽  
Additive Interaction ◽  
Post Intervention ◽  
Paired Associative Stimulation ◽  
Intervention Efficacy ◽  
Movement Type

Advances in our understanding of neural plasticity have prompted the emergence of neuromodulatory interventions, which modulate corticomotor excitability (CME) and hold potential for accelerating stroke recovery. Endogenous paired associative stimulation (ePAS) involves the repeated pairing of a single pulse of peripheral electrical stimulation (PES) with endogenous movement-related cortical potentials (MRCPs), which are derived from electroencephalography. However, little is known about the optimal parameters for its delivery. A factorial design with repeated measures delivered four different versions of ePAS, in which PES intensities and movement type were manipulated. Linear mixed models were employed to assess interaction effects between PES intensity (suprathreshold (Hi) and motor threshold (Lo)) and movement type (Voluntary and Imagined) on CME. ePAS interventions significantly increased CME compared to control interventions, except in the case of Lo-Voluntary ePAS. There was an overall main effect for the Hi-Voluntary ePAS intervention immediately post-intervention (p = 0.002), with a sub-additive interaction effect at 30 min’ post-intervention (p = 0.042). Hi-Imagined and Lo-Imagined ePAS significantly increased CME for 30 min post-intervention (p = 0.038 and p = 0.043 respectively). The effects of the two PES intensities were not significantly different. CME was significantly greater after performing imagined movements, compared to voluntary movements, with motor threshold PES (Lo) 15 min post-intervention (p = 0.012). This study supports previous research investigating Lo-Imagined ePAS and extends those findings by illustrating that ePAS interventions that deliver suprathreshold intensities during voluntary or imagined movements (Hi-Voluntary and Hi-Imagined) also increase CME. Importantly, our findings indicate that stimulation intensity and movement type interact in ePAS interventions. Factorial designs are an efficient way to explore the effects of manipulating the parameters of neuromodulatory interventions. Further research is required to ensure that these parameters are appropriately refined to maximise intervention efficacy for people with stroke and to support translation into clinical practice.

scholarly journals Antidepressant effect of repetitive transcranial magnetic stimulation is not impaired by intake of lithium or antiepileptic drugs

2021 ◽  
Author(s):  
T. Hebel ◽  
M. A. Abdelnaim ◽  
M. Deppe ◽  
P. M. Kreuzer ◽  
A. Mohonko ◽  
...  
Keyword(s):  
Valproic Acid ◽  
Transcranial Magnetic Stimulation ◽  
Antiepileptic Drugs ◽  
Magnetic Stimulation ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Factor Group ◽  
Mood Stabilizers ◽  
Motor Threshold ◽  
Chi Square ◽  
Resting Motor Threshold

Abstract Introduction The effect of concomitant medication on repetitive transcranial magnetic stimulation (rTMS) outcomes in depression remains understudied. Recent analyses show attenuation of rTMS effects by antipsychotic medication and benzodiazepines, but data on the effects of antiepileptic drugs and lithium used as mood stabilizers or augmenting agents are sparse despite clinical relevance. Preclinical electrophysiological studies suggest relevant impact of the medication on treatment, but this might not translate into clinical practice. We aimed to investigate the role of lithium (Li), lamotrigine (LTG) and valproic acid (VPA) by analyzing rTMS treatment outcomes in depressed patients. Methods 299 patients with uni- and bipolar depression treated with rTMS were selected for analysis in respect to intake of lithium, lamotrigine and valproic acid. The majority (n = 251) were treated with high-frequency (10–20 Hz) rTMS of the lDLPFC for an average of 17 treatment sessions with a figure-of-8 coil with a MagVenture system aiming for 110% resting motor threshold, and smaller groups of patients were being treated with other protocols including intermittent theta-burst stimulation and bilateral prefrontal and medial prefrontal protocols. For group comparisons, we used analysis of variance with the between-subjects factor group or Chi-Square Test of Independence depending on the scales of measurement. For post-hoc tests, we used least significant difference (LSD). For differences in treatment effects between groups, we used an ANOVA with the between-subjects factor group (groups: no mood stabilizer, Li, LTG, VPA, Li + LTG) the within-subjects factor treatment (pre vs. post treatment with rTMS) and also Chi-Square Tests of independence for response and remission. Results Overall, patients showed an amelioration of symptoms with no significant differences for the main effect of group and for the interaction effect treatment by group. Based on direct comparisons between the single groups taking mood stabilizers against the group taking no mood stabilizers, we see a superior effect of lamotrigine, valproic acid and combination of lithium and lamotrigine for the response and remission rates. Motor threshold was significantly and markedly higher for patients taking valproic acid. Conclusion Being treated with lithium, lamotrigine and valproic acid had no relevant influence on rTMS treatment outcome. The results suggest there is no reason for clinicians to withhold or withdraw these types of medication from patients who are about to undergo a course of rTMS. Prospective controlled work on the subject is encouraged.

scholarly journals Focal Cooling Suppresses Spontaneous Epileptiform Activity without Changing the Cortical Motor Threshold

Epilepsia ◽  
2002 ◽  
Vol 43 (8) ◽  
pp. 932-935 ◽  
Author(s):  
Kameel M. Karkar ◽  
Paul A. Garcia ◽  
Lisa M. Bateman ◽  
Matthew D. Smyth ◽  
Nicholas M. Barbaro ◽  
...  
Keyword(s):  
Epileptiform Activity ◽  
Motor Threshold ◽  
Cortical Motor ◽  
Focal Cooling

scholarly journals Day-to-day variability in motor threshold during rTMS treatment for depression: Clinical implications

2021 ◽  
Author(s):  
Gonçalo Cotovio ◽  
Albino J. Oliveira-Maia ◽  
Carter Paul ◽  
Francisco Faro Viana ◽  
Daniel Rodrigues da Silva ◽  
...  
Keyword(s):  
Clinical Implications ◽  
Motor Threshold

Assessing head acceleration to identify a motor threshold to galvanic vestibular stimulation

2021 ◽  
Author(s):  
Youstina Mikhail ◽  
Jonathan Charron ◽  
Jean-Marc Mac Thiong ◽  
Dorothy Barthélemy
Keyword(s):  
Center Of Pressure ◽  
Vestibular Function ◽  
Vestibular Stimulation ◽  
Galvanic Vestibular Stimulation ◽  
Head Acceleration ◽  
Motor Threshold ◽  
Recruitment Curve ◽  
Eyes Closed ◽  
Postural Responses ◽  
Significant Difference

Galvanic vestibular stimulation (GVS) is used to assess vestibular function, but vestibular responses can exhibit variability depending on protocols or intensities used. We measured head acceleration in healthy subjects to identify an objective motor threshold on which to base GVS intensity when assessing postural responses. Thirteen healthy right-handed subjects stood on a force platform, eyes closed, head facing forward. An accelerometer was placed on the vertex to detect head acceleration, and electromyography activity of the right soleus was recorded. GVS (200 ms; current steps 0.5;1-4mA) was applied in a binaural and bipolar configuration. 1) GVS induced a biphasic accelerometer response at a latency of 15 ms. Based on response amplitude, we constructed a recruitment curve for all participants and determined the motor threshold. In parallel, the method of limits was used to devise a more rapid approach to determine motor threshold. 2) We observed significant differences between motor threshold based on therecruitment curve and perceptual thresholds (sensation/perception of movement). No significant difference was observed between the motor threshold based on the method of limits and perceptual thresholds . 3) Using orthogonal polynomial contrasts, we observed a linear progression between multiples of the objective motor threshold (0.5, 0.75, 1, 1.5x motor threshold) and the 95% confidence ellipse area, the first peak of center of pressure velocity, and the short and medium latency responses in the soleus. Hence, an objective motor threshold and a recruitment curve for GVS were determined based on head acceleration, which could increase understanding of the vestibular system.

Reversal of Cortical Reorganization in Human Primary Motor Cortex Following Thumb Reconstruction

2010 ◽  
Vol 103 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Zhen Ni ◽  
Dimitri J. Anastakis ◽  
Carolyn Gunraj ◽  
Robert Chen
Keyword(s):  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Short Interval ◽  
Body Part ◽  
Cortical Reorganization ◽  
Traumatic Amputation ◽  
Motor Threshold ◽  
Thumb Reconstruction ◽  
Intact Side ◽  
Injured Side

Deafferentation such as the amputation of a body part causes cortical reorganization in the primary motor cortex (M1). We investigated whether this reorganization is reversible after reconstruction of the lost body part. We tested two patients who had long-standing thumb amputations followed by thumb reconstruction with toe-to-thumb transfer 9 to 10 mo later and one patient who underwent thumb replantation immediately following traumatic amputation. Using transcranial magnetic stimulation, we measured the motor evoked potential (MEP) threshold, latency, short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF) at different time points in the course of recovery in abductor pollicis brevis muscle. For the two patients who underwent late toe-to-thumb transfer, the rest motor threshold was lower on the injured side than that on the intact side before surgery and it increased with time after reconstruction, whereas the active motor threshold remained unchanged. The rest and active MEP latencies were similar on the injured side before and ≤15 wk after surgery and followed by restoration of expected latency differences. SICI was reduced before surgery and progressively normalized with the time after surgery. ICF did not change with time. These physiological measures correlated with the recovery of motor and sensory functions. All the measurements on the intact side of the toe-to-thumb transfer patients and in the patient with thumb replantation immediately following traumatic amputation remained stable over time. We conclude that chronic reorganization occurring in the M1 after amputation can be reversed by reconstruction of the lost body part.

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.

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