High Voltage Galvanic Current
(HVGC)
High-voltage galvanic stimulation (HVGS) produces a highvoltage current with a high-peak intensity of a maximum of 300 to 400
ma but with a low-frequency current and a very short duration, ranging
between 50 and 100 msec.
Characteristics:
* The high-peak intensity produced is of a twin-pulsed shape.
* It is safer and more comfortable (less painful) to the patient than faradic
current because of its short duration.
* It penetrates deeper than that of low-voltage currents.
* Direct stimulation of deep nerves and muscles can be effective.
* It can stimulate either an isolated muscle or muscle group according to
the appropriate technique.
* High-voltage galvanic current does not produce contraction in the
denervated muscle as the pulse duration is too short to depolarize the
muscle membrane.
* Partially innervated or totally innervated muscle will respond well to
high-voltage galvanic current.
Physiological effects of HVGC:
* Pain reduction:
It is accomplished either through decreasing pain by using two
small electrodes closely-spaced in a narrow area or minimizing pain fiber
stimulation by using two widely-spaced large electrodes. Both of these
methods can stimulate the release of opiate substance; ß-endorphins in
the central nervous system in order to suppress pain.
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* Increase of joint mobility:
This occurs due to reduction of pain through the direct effect of the
current on blood vessels, which leads to improvement of circulation. So,
HVGC is effective after fractures, menisectomy, osteoarthritis and frozen
shoulder. Reduction of post-traumatic edema is evident immediately after
treatment.
* Improvement of peripheral circulation:
This is due to the stimulation of muscle pumping effect on the
venous circulation and stimulation of sympathetic neurons, which
subsequently cause vasodilatation.
* Healing of ulcers:
It is accomplished through electrical stimulation with the positive
electrode, which increases the repair process. Furthermore, electrical
stimulation with the negative pole destroys bacteria.
* Relief of muscle spasm:
It is accomplished due to reduction of pain through strong muscle
contraction, which produces relaxation.
Indications:
As a low-frequency current, with the exception of treating the
denervated muscles, it may be used for:
- Facilitation of muscle contraction inhibited by pain.
- Re-education of weak muscles.
- Reduction of post-traumatic edema.
- Mobilization of joint stiffness.
- Reduction of pain and muscle spasm (arthritis, sprain and strain).
- Improvement of peripheral circulation.
- Healing of ulcers.
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Contraindications:
They are similar to those of the other low frequency currents,
including:
* Skin lesions.
* Acute infections and inflammations.
* Thrombosis.
* Loss of sensation.
* Cardiac pacemakers.
* Superficial metal.
Dosage:
It is adjusted according to the patient’s tolerances. In cases of
edema, muscle spasm and stiff joint, the dose must be high enough to
produce muscle contraction:
- Pulse rate: 80 pulses / sec.
- Treatment duration: 20 - 30 minutes.
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