Unmodulated 5 Kilohertz Currents Versus TENS: Effect on Pain Thresholds, Tactile Threshold, and Nerve Conduction

Study Overview
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Brief Summary
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The purpose of this study is to determine whether the transcutaneous application of unmodulated 5 Kilohertz (KHz) alternating currents are effective in decreasing the thermal and mechanical experimental pain and cause changes in peripheral nerve conduction. Moreover evidence whether the effect and comfort of this current is greater than Conventional TENS (Transcutaneous Electrical Nerve Stimulation) commonly used for the treatment of clinical pain.

Detailed Description
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In the last years several animal experimental studies have evidenced that high frequency unmodulated currents about 5 KHz can cause a peripheral nerve block. However electric currents with these high frequencies that are usually used for the treatment of pain in humans are interrupted or modulated (i.e. interferential currents) This evidences in animals could have application in pain treatment, characterized by overactive nervous system. For this reason it was decided to compare the effects on experimental pain and peripheral nerve conduction of this new electric current versus sham stimulation and TENS (Transcutaneous Electrical Nerve Stimulation). The scientific literature on transcutaneous electrical stimulation in humans and changes in nerve conduction and / or somatosensory thresholds focuses mainly on TENS (Transcutaneous Electrical Nerve Stimulation). Therefore TENS is a good reference standard to compare the effect of this new currents.

Official Title
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Unmodulated 5 Kilohertz Alternating Currents Versus TENS: Effect on Mechanical and Thermal Pain Thresholds, Tactile Threshold, and Peripheral Nerve Conduction in Humans.

Conditions
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Pain

Intervention / Treatment
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* Device: 5 KHz
* Device: TENS
* Device: Sham stimulation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Participants will be volunteer healthy students of Physiotherapy, University of Castilla - La Mancha, older than 18 years. Exclusion Criteria: Neuromuscular disease. Epilepsy. Trauma, surgery or pain affecting the upper limb, shoulder girdle or cervical area. 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. Sensitivity disturbance in upper limb.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 30 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: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 5 KHz<br>Transcutaneous application of 5 KHz current over the course of the superficial radial nerve in the right forearm 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: 5 KHz<br>* 5 KHz transcutaneous electrical stimulation over superficial radial nerve through the electrotherapy device Myomed 932. (Enraf-Nonius, Delft, Netherlands)<br>|
| Experimental: TENS<br>Transcutaneous application of Conventional TENS current over the course of the superficial radial nerve in the right forearm for a 20 minutes session. The intensity of the current will increase until participants report a strong but comfortable sensation, just below motor threshold. Currents parameters are frequency 110 Hz and pulse width 200 microseconds | Device: TENS<br>* TENS transcutaneous electrical stimulation over superficial radial nerve through the electrotherapy device Myomed 932. (Enraf-Nonius, Delft, Netherlands)<br>|
| Sham Comparator: Sham Stimulation<br>Electrodes are placed over the course of the superficial radial nerve in the right forearm for a 20 minutes in the same manner as experimental groups, but will be applied a sham electrical stimulation increasing the current intensity of an unconnected channel. | Device: Sham stimulation<br>* Sham transcutaneous electrical stimulation over superficial radial nerve through the electrotherapy device Myomed 932. (Enraf-Nonius, Delft, Netherlands)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mechanical Pain Threshold During Treatment | The pressure pain threshold will be measured by a pressure algometer and will be expressed in Newton | during treatment at 15 min | 
| Thermal Pain Threshold During Treatment | The heat pain threshold will be measured by a computer controlled thermo-foil heating device and will be expressed in ºC | during treatment at 15 min. | 
| Nerve Conduction Latency Immediately After Treatment | The compound action potential latencies will be measured and will be expressed in ms. | immediately after treatment at 20 min. | 
| Tactile Threshold During Treatment | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | during treatment at 15 min. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Habituation to Electrical Stimulation | The habituation to electrical stimulation along experimental session will be measured by recording the difference on current intensity (mA) at the start of the treatment session (1 min) and end of the same (20 min) | Start treatment session (1 min), end treatment session (20 min) | 
| Perception Current Comfortability | Participants will choose the current treatment that has found more comfortable | At the end of the third experimental session, 3 days | 
| Change Current Density (mA/cm2) | Change in current density (mA/cm2), it will be recorded at 1 min. start of the treatment session and at 20 min of the same. | at 1 min. treatment session, at 20 min. treatment session | 
| Change From Baseline in Nerve Conduction Amplitude ( µV) | The compound action potential amplitudes ( µV) will be measured. | Baseline,immediately after treatment at 20 min.. | 
| Baseline Mechanical Pain Threshold | The pressure pain threshold will be measured by a pressure algometer and will be expressed in Newton | Baseline at 0 min. | 
| Mechanical Pain Threshold Post-treatment 20 Min. | The pressure pain threshold will be measured by a pressure algometer and will be expressed in Newton | at 20 min. post-treatment | 
| Mechanical Pain Threshold Post-treatment 40 Min. | The pressure pain threshold will be measured by a pressure algometer and will be expressed in Newton. | at 40 min. post-treatment | 
| Baseline Thermal Pain Threshold | The heat pain threshold will be measured by a computer controlled thermo-foil heating device and will be expressed in ºC | Baseline at 0 min. | 
| Thermal Pain Threshold Post-treatment 20 Min. | The heat pain threshold will be measured by a computer controlled thermo-foil heating device and will be expressed in ºC | at 20 min. post-treatment | 
| Thermal Pain Threshold Post-treatment 40 Min. | The heat pain threshold will be measured by a computer controlled thermo-foil heating device and will be expressed in ºC | at 40 min. post-treatment | 
| Baseline Nerve Conduction Latency | The compound action potential latencies will be measured and will be expressed in ms. | Baseline at 0 min. | 
| Nerve Conduction Latency Post-treatment 20 Min. | The compound action potential latencies will be measured and will be expressed in ms. | at 20 min. post-treatment | 
| Nerve Conduction Latency Post-treatment 40 Min. | The compound action potential latencies will be measured and will be expressed in ms. | at 40 min. post-treatment | 
| Baseline Tactile Threshold | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | Baseline at 0 min. | 
| Tactile Threshold Post-treatment 20 Min. | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | at 20 min. post-treatment | 
| Tactile Threshold Post-treatment 40 Min. | The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton | at 40 min. post-treatment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Transcutaneous Electric Nerve Stimulation, Electric Stimulation Therapy, Unmodulated Alternating Currents, Neural Conduction, Pain Threshold