scholarly journals Torque gains and neural adaptations following low-intensity motor nerve electrical stimulation training

2019 ◽  
Vol 127 (5) ◽  
pp. 1469-1477
Author(s):  
Florian Vitry ◽  
Alain Martin ◽  
Maria Papaiordanidou
Keyword(s):  
Electrical Stimulation ◽  
Isometric Contraction ◽  
Evoked Potential ◽  
Motor Nerve ◽  
Motor Evoked Potential ◽  
H Reflex ◽  
Stimulation Frequency ◽  
Maximal Voluntary Isometric Contraction ◽  
Neural Adaptations ◽  
Low Intensity

The purpose of the study was to assess neural adaptations of the plantar-flexors induced by an electrical stimulation training applied over the motor nerve at low intensity using two different stimulation frequencies. Thirty subjects were randomly assigned into 3 groups: 20 Hz, 100 Hz, and control group. The training consisted of 15 sessions of 25 stimulation trains applied over the tibial nerve and delivered at an intensity evoking 10% maximal voluntary isometric contraction (MVIC). Before and after training, MVIC was assessed and neural adaptations were evaluated by the voluntary activation level (VAL) and the V-wave (normalized by the superimposed muscle compound action potential, V/MSUP). H-reflex and motor-evoked potential (MEP) recorded during MVIC were studied to assess spinal and corticospinal excitabilities [i.e., maximal H-reflex during maximal voluntary isometric contraction (HSUP)/MSUP and maximal motor-evoked potential during maximal voluntary isometric contraction (MEPSUP)/MSUP]. MVIC significantly increased after training only for the two training groups ( P = 0.017). This increase was accompanied by a significant increase of VAL only for these groups ( P = 0.014), whereas statistical analysis revealed a time effect for V/MSUP ( P = 0.022). HSUP/MSUP and MEPSUP/MSUP were significantly increased at post conditions only for the 100 Hz group ( P = 0.021 and P = 0.029). Results show that low-intensity electrical stimulation training applied over the motor nerve can induce torque gains, accompanied by neural adaptations. Stimulation frequency differentially affected spinal and corticospinal excitabilities, indicating that neural adaptations could have a supraspinal origin for the 20-Hz protocol, whereas spinal and supraspinal mechanisms were implicated in the torque increases after the 100-Hz training. NEW & NOTEWORTHY This study brings new insights into the neurophysiological mechanisms responsible for torque gains after electrical stimulation training using wide pulse duration and low stimulation intensity applied over the motor nerve. Stimulation frequency had a distinct impact on spinal and/or supraspinal origins of the observed neural adaptations. The use of the aforementioned stimulation parameters in rehabilitation settings can be proved beneficial in terms of strength gains while avoiding any serious discomfort because of stimulation.

Motor evoked potential monitoring of the vagus nerve with transcranial electrical stimulation during skull base surgeries

2013 ◽  
Vol 118 (1) ◽  
pp. 195-201 ◽  
Author(s):  
Eiji Ito ◽  
Masahiro Ichikawa ◽  
Takeshi Itakura ◽  
Hitoshi Ando ◽  
Yuka Matsumoto ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Endotracheal Tube ◽  
Skull Base ◽  
Evoked Potential ◽  
Control Level ◽  
Motor Evoked Potential ◽  
Transcranial Electrical Stimulation ◽  
Postoperative Dysphagia ◽  
Swallowing Function ◽  
Surface Electrodes

Object Dysphasia is one of the most serious complications of skull base surgeries and results from damage to the brainstem and/or cranial nerves involved in swallowing. Here, the authors propose a method to monitor the function of the vagus nerve using endotracheal tube surface electrodes and transcranial electrical stimulation during skull base surgeries. Methods Fifteen patients with skull base or brainstem tumors were enrolled. The authors used surface electrodes of an endotracheal tube to record compound electromyographic responses from the vocalis muscle. Motor neurons were stimulated using corkscrew electrodes placed subdermally on the scalp at C3 and C4. During surgery, the operator received a warning when the amplitude of the vagal motor evoked potential (MEP) decreased to less than 50% of the control level. After surgery, swallowing function was assessed clinically using grading criteria. Results In 5 patients, vagal MEP amplitude permanently deteriorated to less than 50% of the control level on the right side when meningiomas were dissected from the pons or basilar artery, or when a schwannoma was dissected from the vagal rootlets. These 5 patients had postoperative dysphagia. At 4 weeks after surgery, 2 patients still had dysphagia. In 2 patients, vagal MEPs of one side transiently disappeared when the tumors were dissected from the brainstem or the vagal rootlets. After surgery, both patients had dysphagia, which recovered in 4 weeks. In 7 patients, MEP amplitude was consistent, maintaining more than 50% of the control level throughout the operative procedures. After surgery all 7 patients were neurologically intact with normal swallowing function. Conclusions Vagal MEP monitoring with transcranial electrical stimulation and endotracheal tube electrode recording was a safe and effective method to provide continuous real-time information on the integrity of both the supranuclear and infranuclear vagal pathway. This method is useful to prevent intraoperative injury of the brainstem corticobulbar tract or the vagal rootlets and to avoid the postoperative dysphagia that is often associated with brainstem or skull base surgeries.

The effects of long-term bed rest on H-reflex and motor evoked potential in the human soleus muscle during standing

1999 ◽  
Vol 266 (2) ◽  
pp. 101-104 ◽  
Author(s):  
Kentaro Yamanaka ◽  
Shin-ichiroh Yamamoto ◽  
Kimitaka Nakazawa ◽  
Hideo Yano ◽  
Yoji Suzuki ◽  
...  
Keyword(s):  
Soleus Muscle ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Bed Rest ◽  
H Reflex

scholarly journals Acute Neuromuscular Electrical Stimulation (NMES) With Blood Flow Restriction: The Effect of Restriction Pressures

2020 ◽  
pp. 1-9
Author(s):  
Paul Head ◽  
Mark Waldron ◽  
Nicola Theis ◽  
Stephen David Patterson
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Isometric Contraction ◽  
Perceived Exertion ◽  
Neuromuscular Electrical Stimulation ◽  
Muscle Thickness ◽  
Ratings Of Perceived Exertion ◽  
Experimental Conditions ◽  
Maximal Voluntary Isometric Contraction ◽  
Flow Restriction

Context: Neuromuscular electrical stimulation (NMES) combined with blood flow restriction (BFR) has been shown to improve muscular strength and size better than NMES alone. However, previous studies used varied methodologies not recommended by previous NMES or BFR research. Objective: The present study investigated the acute effects of NMES combined with varying degrees of BFR using research-recommended procedures to enhance understanding and the clinical applicability of this combination. Design: Randomized crossover. Setting: Physiology laboratory. Participants: A total of 20 healthy adults (age 27 [4] y; height 177 [8] cm; body mass 77 [13] kg). Interventions: Six sessions separated by at least 7 days. The first 2 visits served as familiarization, with the experimental conditions performed in the final 4 sessions: NMES alone, NMES 40% BFR, NMES 60% BFR, and NMES 80% BFR. Main Outcome Measures: Maximal voluntary isometric contraction, muscle thickness, blood pressure, heart rate, rating of perceived exertion, and pain were all recorded before and after each condition. Results: The NMES 80% BFR caused greater maximal voluntary isometric contraction decline than any other condition (−38.9 [22.3] N·m, P < .01). Vastus medialis and vastus lateralis muscle thickness acutely increased after all experimental conditions (P < .05). Pain and ratings of perceived exertion were higher after NMES 80% BFR compared with all other experimental conditions (P < .05). No cardiovascular effects were observed between conditions. Conclusion: The NMES combined with 80% BFR caused greater acute force decrement than the other conditions. However, greater perceptual ratings of pain and ratings of perceived exertion were observed with NMES 80% BFR. These acute observations must be investigated during chronic interventions to corroborate any relationship to changes in muscle strength and size in clinical populations.

scholarly journals Transcranial Electrical Motor Evoked Potential in Predicting Positive Functional Outcome of Patients after Decompressive Spine Surgery: Review on Challenges and Recommendations towards Objective Interpretation

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Mohd Redzuan Jamaludin ◽  
Khin Wee Lai ◽  
Joon Huang Chuah ◽  
Muhammad Afiq Zaki ◽  
Yan Chai Hum ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Functional Outcome ◽  
Evoked Potential ◽  
Motor Nerve ◽  
Motor Evoked Potential ◽  
Nerve Roots ◽  
Motor Pathway ◽  
Positive Functional ◽  
Prognostic Tool ◽  
Objective Interpretation

Spine surgeries impose risk to the spine’s surrounding anatomical and physiological structures especially the spinal cord and the nerve roots. Intraoperative neuromonitoring (IONM) is a technology developed to monitor the integrity of the spinal cord and the nerve roots via the surgery. Transcranial motor evoked potential (TcMEP) (one of the IONM modalities) is adopted to monitor the integrity of the motor pathway of the spinal cord and the motor nerve roots. Recent research suggested that the IONM is conducive as a prognostic tool towards the patient’s functional outcome. This paper summarizes the researches of IONM being adopted as a prognostic tool. In addition, this paper highlights the problems associated with the signal parameters as the improvement criteria in the previous researches. Lastly, we review the challenges of TcMEP to achieve a prognostic tool focusing on the factors that could interfere with the generation of a stable TcMEP response. The final section will discuss recommendations for IONM technology to achieve an objective prognostic tool.

scholarly journals Effect of blood flow occlusion on corticospinal excitability during sustained low-intensity isometric elbow flexion

2020 ◽  
Vol 123 (3) ◽  
pp. 1113-1119 ◽  
Author(s):  
D. B. Copithorne ◽  
C. L. Rice ◽  
C. J. McNeil
Keyword(s):  
Blood Flow ◽  
Evoked Potential ◽  
Motor Evoked Potential ◽  
Elbow Flexion ◽  
Group Iii ◽  
Low Intensity ◽  
Blood Flow Occlusion ◽  
Motor Cortical ◽  
Flow Occlusion ◽  
Contractile Failure

Blood flow occlusion (BFO) has been used to study the influence of group III/IV muscle afferents after fatiguing exercise, but it is unknown how BFO-induced activity of these afferents affects motor cortical and motoneuronal excitability during low-intensity exercise. Therefore, the purpose of this study was to assess the acute effect of BFO on peripheral [maximal M wave (Mmax)], spinal [cervicomedullary motor evoked potential (CMEP) normalized to Mmax], and motor cortical [motor evoked potential (MEP) normalized to CMEP] excitability. Nine healthy men completed a sustained isometric contraction of the elbow flexors at 20% of maximal force under three conditions: 1) contractile failure with BFO, 2) a time-matched trial without restriction [free flow (FFiso)], and 3) contractile failure with free flow (FFfail). Time to failure for BFO (and FFiso) were ~80% shorter than that for FFfail ( P < 0.05). For FFfail and FFiso, Mmax area decreased ~17% and ~7%, respectively ( P < 0.05), with no change during BFO. CMEP/Mmax area increased ~226% and ~80% during BFO and FFfail, respectively ( P < 0.05), with no change during FFiso ( P > 0.05). The increase in normalized CMEP area was greater for BFO and FFfail compared with FFiso and for BFO compared with FFfail. MEP/CMEP area was not different among the protocols ( P > 0.05) and increased ~64% with time ( P < 0.05). It is likely that group III/IV muscle afferent feedback to the spinal cord modulates the large increase in motoneuronal excitability for the BFO compared with FFfail and FFiso protocols. NEW & NOTEWORTHY We have observed how blood flow occlusion modulates motor cortical, spinal, and peripheral excitability during and immediately after a sustained low-intensity isometric elbow flexion contraction to failure. We conclude that blood flow occlusion causes a greater and more rapid increase in motoneuronal excitability.

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