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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
60
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)
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)
Castilla-La Mancha University
Toledo, Spain
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).
Time frame: Baseline at 0 minutes
Tactile Threshold
The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: Baseline at 0 minutes
Pressure Pain Threshold
The PPT will be measured with an algometer and will be expressed in Newtons
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Sham stimulation will be delivered at a frequency of 10 kHz only during the first 30 seconds.
Time frame: Baseline at 0 minutes
Muscle strength
Muscle strength will be measured with a dynamometer and will be expressed in Kgs.
Time frame: Baseline at 0 minutes
Tactile Threshold
The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: During treatment at 15 minutes
Pressure Pain Threshold
The PPT will be measured with an algometer and will be expressed in Newtons
Time frame: 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).
Time frame: Immediately after treatment at 20 minutes
Tactile Threshold
The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: Immediately after treatment at 20 minutes
Pressure Pain Threshold
The PPT will be measured with an algometer and will be expressed in Newtons
Time frame: Immediately after treatment at 20 minutes
Muscle strength
Muscle strength will be measured with a dynamometer and will be expressed in Kgs.
Time frame: 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).
Time frame: Immediately after treatment at 30 minutes
Tactile Threshold
The tactile threshold will be measured with Von Frey filaments and will be expressed in millinewton
Time frame: 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
Time frame: 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
Time frame: 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
Time frame: Immediately after treatment at 30 minutes
Pressure Pain Threshold
The PPT will be measured with an algometer and will be expressed in Newtons
Time frame: Immediately after treatment at 30 minutes
Muscle strength
Muscle strength will be measured with a dynamometer and will be expressed in Kgs.
Time frame: Immediately after treatment at 30 minutes
Baseline nerve temperature
Nerve temperature will be measured using a termodoppler (Celsius degrees)
Time frame: 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
Time frame: 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)
Time frame: 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)
Time frame: 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
Time frame: After the intervention at 35 minutes
Blinding success
Blinding of subjects and researchers will be assessed using the James Index
Time frame: After the intervention at 35 minutes