Percutaneous High Frequency Alternating Current Stimulation in Healthy Volunteers

Study Overview
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Brief Summary
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High-frequency alternating currents of greater than 1 kHz applied on peripheral nerves has been used in animal studies to produce a motor nerve block. It has been evidenced that frequencies higher than 5 kHz are necessary to produce a complete peripheral nerve block in primates, whose nerve thickness is more similar to humans.

Detailed Description
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Our previous studies with transcutaneous HFAC, suggest high-frequency stimulation (10 and 20 kHz) have an inhibitory effect over muscle strength and somatosensory threshold. However, in these studies the intensity needed to reach block threshold is very high. The purpose of the present work is to reduce the amount of current intensity needed using a percutaneous approach by apply two acupuncture needles near the nerve as electrodes.

Official Title
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Percutaneous High Frequency Alternating Current Stimulation: Effects on Somatosensory and Motor Threshold in Healthy Volunteers

Conditions
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Electrical Stimulation, Neuromodulation

Intervention / Treatment
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* Device: 10 kHz stimulation (Myomed 932, Enraf-Nonius)
* Device: 20 kHz stimulation (Myomed 932, Enraf-Nonius)
* Device: Sham stimulation (Myomed 932, Enraf-Nonius)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers Ability to perform all clinical tests and understand the study process, as well as obtaining informed consent. Tolerance to the application of electrotherapy. That they have not diagnosed any pathology. They do not present a contraindication to puncture and / or the application of electric currents. Exclusion Criteria: Neuromuscular disease. Epilepsy. Trauma, surgery or pain affecting the upper limb Osteosynthesis material in the upper limb. Diabetes. Cancer. Cardiovascular disease. Pacemaker or other implanted electrical device. Take any drug (NSAIDs, corticosteroids, antidepressants, analgesics, antiepileptics, ...) during the study and in the previous 7 days. Presence of tattoos or other external agent introduced into the treatment or assessment area. Pregnancy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 10 kHz stimulation<br>Transcutaneous application of high frequency electrical current at 10 kHz over the median nerve for a 20 minutes session. The intensity of the current will increase until participants report a strong but comfortable sensation, just below motor threshold. | Device: 10 kHz stimulation (Myomed 932, Enraf-Nonius)<br>* A charge-balanced, symmetric, biphasic sinusoidal current without modulation will be delivered at a frequency of 10 kHz. The stimulation intensity will be defined as that sufficient to produce a strong but comfortable sensation, just below motor threshold, over the median nerve through the electrotherapy device Myomed 932. (Enraf-Nonius, Delft,Netherlands)<br>|
| Experimental: 20 kHz stimulation<br>Transcutaneous application of high frequency electrical current at 20 kHz over the median nerve for a 20 minutes session. The intensity of the current will increase until participants report a strong but comfortable sensation, just below motor threshold. | Device: 20 kHz stimulation (Myomed 932, Enraf-Nonius)<br>* A charge-balanced, symmetric, biphasic sinusoidal current without modulation will be delivered at a frequency of 20 kHz. The stimulation intensity will be defined as that sufficient to produce a strong but comfortable sensation, just below motor threshold, over the median nerve through the electrotherapy device Myomed 932. (Enraf-Nonius, Delft,Netherlands)<br>|
| Sham Comparator: Sham stimulation<br>Electrodes are placed over the median nerve for 20 minutes in the same manner as experimental group but will be applied a sham electrical stimulation increasing the current intensity during the first 30 seconds. | Device: Sham stimulation (Myomed 932, Enraf-Nonius)<br>* Sham stimulation will be delivered at a frequency of 10 kHz only during the first 30 seconds.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Antidromic median sensory nerve action potential | The recording electrodes were placed on the second finger and the stimulus will be applied on the median nerve (above the elbow joint). The stimulus will consist of a train of 10 pulses (100 μs width), applied at supramaximal stimulation, presented at 1 Hz (DS7A, Digitimer Ltd). Negative peak latency (NPL), positive peak latency (PPL), and peak-to-peak amplitude (PPA) will be registered with a specific software (Signal software, CED). | Baseline at 0 minutes | 
| Tactile Threshold | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | Baseline at 0 minutes | 
| Oscillation Frequency of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The frequency of the damped oscillations characterizes the muscle tone. The muscle will be assessed is opponens pollicis muscle | Baseline at 0 minutes | 
| Stiffness of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. Stiffness reflects the resistance of the muscle to the force deforming the muscle. The muscle will be assessed is opponens pollicis muscle | Baseline at 0 minutes | 
| Decrement (elasticity) of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The logarithmic decrement of the damping oscillations characterizes muscle elasticity which is the ability of the muscle to restore its initial shape after contraction. The muscle will be assessed is opponens pollicis muscle | Baseline at 0 minutes | 
| Pressure Pain Threshold | The PPT will be measured with an algometer and will be expressed in Newtons | Baseline at 0 minutes | 
| Muscle strength | Muscle strength will be measured with a dynamometer and will be expressed in Kgs. | Baseline at 0 minutes | 
| Tactile Threshold | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | During treatment at 15 minutes | 
| Oscillation Frequency of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The frequency of the damped oscillations characterizes the muscle tone. The muscle will be assessed is opponens pollicis muscle | During treatment at 15 minutes | 
| Stiffness of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. Stiffness reflects the resistance of the muscle to the force deforming the muscle. The muscle will be assessed is opponens pollicis muscle | During treatment at 15 minutes | 
| Decrement (elasticity) of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The logarithmic decrement of the damping oscillations characterizes muscle elasticity which is the ability of the muscle to restore its initial shape after contraction. The muscle will be assessed is opponens pollicis muscle | During treatment at 15 minutes | 
| Pressure Pain Threshold | The PPT will be measured with an algometer and will be expressed in Newtons | During treatment at 15 minutes | 
| Antidromic median sensory nerve action potential | The recording electrodes were placed on the second finger and the stimulus will be applied on the median nerve (above the elbow joint). The stimulus will consist of a train of 10 pulses (100 μs width), applied at supramaximal stimulation, presented at 1 Hz (DS7A, Digitimer Ltd). Negative peak latency (NPL), positive peak latency (PPL), and peak-to-peak amplitude (PPA) will be registered with a specific software (Signal software, CED). | Immediately after treatment at 20 minutes | 
| Tactile Threshold | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | Immediately after treatment at 20 minutes | 
| Oscillation Frequency of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The frequency of the damped oscillations characterizes the muscle tone. The muscle will be assessed is opponens pollicis muscle | Immediately after treatment at 20 minutes | 
| Stiffness of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. Stiffness reflects the resistance of the muscle to the force deforming the muscle. The muscle will be assessed is opponens pollicis muscle | Immediately after treatment at 20 minutes | 
| Decrement (elasticity) of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The logarithmic decrement of the damping oscillations characterizes muscle elasticity which is the ability of the muscle to restore its initial shape after contraction. The muscle will be assessed is opponens pollicis muscle | Immediately after treatment at 20 minutes | 
| Pressure Pain Threshold | The PPT will be measured with an algometer and will be expressed in Newtons | Immediately after treatment at 20 minutes | 
| Muscle strength | Muscle strength will be measured with a dynamometer and will be expressed in Kgs. | Immediately after treatment at 20 minutes | 
| Antidromic median sensory nerve action potential | The recording electrodes were placed on the second finger and the stimulus will be applied on the median nerve (above the elbow joint). The stimulus will consist of a train of 10 pulses (100 μs width), applied at supramaximal stimulation, presented at 1 Hz (DS7A, Digitimer Ltd). Negative peak latency (NPL), positive peak latency (PPL), and peak-to-peak amplitude (PPA) will be registered with a specific software (Signal software, CED). | Immediately after treatment at 30 minutes | 
| Tactile Threshold | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | Immediately after treatment at 30 minutes | 
| Oscillation Frequency of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The frequency of the damped oscillations characterizes the muscle tone. The muscle will be assessed is opponens pollicis muscle | Immediately after treatment at 30 minutes | 
| Stiffness of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. Stiffness reflects the resistance of the muscle to the force deforming the muscle. The muscle will be assessed is opponens pollicis muscle | Immediately after treatment at 30 minutes | 
| Decrement (elasticity) of tissue assessed by MyotonPro | This outcome measure is obtained by a device named MyotonPro. The logarithmic decrement of the damping oscillations characterizes muscle elasticity which is the ability of the muscle to restore its initial shape after contraction. The muscle will be assessed is opponens pollicis muscle | Immediately after treatment at 30 minutes | 
| Pressure Pain Threshold | The PPT will be measured with an algometer and will be expressed in Newtons | Immediately after treatment at 30 minutes | 
| Muscle strength | Muscle strength will be measured with a dynamometer and will be expressed in Kgs. | Immediately after treatment at 30 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Baseline nerve temperature | Nerve temperature will be measured using a termodoppler (Celsius degrees) | Baseline at 0 minutes, at 15 minutes, immediately after treatment at 20 minutes, and immediately after treatment at 30 minutes | 
| Baseline flux temperature | Flux will be measured using a termodoppler | Baseline at 0 minutes, at 15 minutes, immediately after treatment at 20 minutes, and immediately after treatment at 30 minutes | 
| Numerical Discomfort Rate Score | the possible discomfort caused by the interventions will be assess by a numerical rate score. The NRS consists of a scale from 0 (no discomfort) to 10 (worst possible discomfort) | After the intervention at 35 minutes | 
| Numerical Pain Rate Score | The NRS consists of a scale from 0 (no pain) to 10 (worst possible pain) | After the intervention at 35 minutes | 
| Number of participants with intervention-related adverse effects | the possible adverse effects caused by the interventions will be assess by a questionnaire | After the intervention at 35 minutes | 
| Blinding success | Blinding of subjects and researchers will be assessed using the James Index | After the intervention at 35 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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high-frequency alternating current, nerve block, somatosensory threshold, motor threshold, percutaneous electrical stimulation