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.
The previous studies with transcutaneous and percutaneous HFAC, suggest high-frequency stimulation (10 and 20 kHz) have an inhibitory effect over muscle strength and somatosensory threshold. However, the 30 kHz frequency has never been applied, and the hypothesis is that it can produce a greater blockage at the sensitive level and be a more comfortable application for the patient. The purpose of the present work is to determine if a greater blockage of the sensory component of the nerve occurs with this frequency and 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
48
A charge-balanced, symmetric, biphasic sinusoidal current without modulation will be delivered at a frequency of 30 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)
Sham stimulation will be delivered at a frequency of 30 kHz only during the first 30 seconds.
Castilla-La Mancha University
Toledo, Spain
Latency of 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). Latency will be registered with a specific software (Signal software, CED) and will be expressed in millisecond.
Time frame: Baseline at 0 minutes
Amplitude of 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). Peak-to-peak amplitude (PPA) will be registered with a specific software (Signal software, CED) and will be expressed in millivolts.
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
Pressure Pain Threshold
The PPT will be measured with an algometer and will be expressed in Newtons
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
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Pressure Pain Threshold
The PPT will be measured with an algometer and will be expressed in Newtons
Time frame: During treatment at 15 minutes
Latency 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). Latency (NPL) will be registered with a specific software (Signal software, CED) and will be expressed in millisecond.
Time frame: Immediately after treatment at 20 minutes
Amplitude 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). Peak-to-peak amplitude (PPA) will be registered with a specific software (Signal software, CED) and will be expressed in millivolts.
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
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
Latency 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). Latency will be registered with a specific software (Signal software, CED) and will be expressed in millisecond.
Time frame: Immediately after treatment at 30 minutes
Amplitude 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). Peak-to-peak amplitude (PPA) will be registered with a specific software (Signal software, CED) and will be expressed in millivolts.
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
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
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 closed questionnaire, where the presence of any adverse effect would be qualified as 1 point and the negative presence of adverse effect as 0 point.
Time frame: After the intervention at 35 minutes
Blinding success
Blinding of subjects and researchers will be assessed using the Bang questionary. It will be the question after the intervention, "What type of treatment do you think you have received?" Will be asked, with 5 items: (1) "I firmly believe that I have received an experimental treatment"; (2) "I slightly believe that I have received an experimental treatment"; (3) "I strongly believe that I have received a placebo"; (4) "I slightly think I have received a placebo"; (5) "Don't know, don't answer.", Index where -1 is blinded and 1 is unblinded.
Time frame: After the intervention at 35 minutes