In physiotherapy, faradic and Galvanic current is used to stimulate the nerve and thereby eliciting the muscle contraction. But both faradic and Galvanic current are two different types and they are used in two very different situations.
In this article, we will try to understand what is the difference between faradic and Galvanic current and what are there uses and indications.
Table of Contents
Faradic and galvanic current
Faradic and galvanic current is a part of electrotherapy, which uses low voltage, low-frequency impulse current for therapeutic uses.
Electrical Muscle Stimulator, a physiotherapy device is used to produce and apply this therapeutic current for treatment of pain, muscle strengthening, muscle re-education in a paralytic patient.
Usually, two electrodes are connected from the machine to the patient’s skin. The electrodes are often placed on the affected area of pain or at a pressure point, creating a closed circuit of electrical impulse that travels along nerve fibers.
Do you know that each and every movement of our body happens due to the flow of electric impulse in our body? Normally, this electric impulse is produced by brain cell and travels through the nerve to the concerned muscle.
If there is a problem in the flow of electric impulse, a balance is lost and the symptoms such as neuralgia, paresis may appear. This is where the
Types of low-frequency current
The most commonly used pulse waveforms in muscle rehabilitation are
- Galvanic Current.
- Interrupted Galvanic Current.
- Faradic Current.
- Surged Faradic Current
Galvanic current
In this treatment method, the duration of current flow is long and continuous. The Galvanic current creates an electric field over the treated area that theoretically, changes blood flow.
When a steady flow of direct current is passed through tissue, its effect is primarily chemical. It causes the movement of ions and their collection at the skin areas lying immediately beneath the electrodes[1].
Direct Galvanic current is mainly used for iontophoresis/ Ionization i.e. transference of ions of drugs into the tissues through the skin by electrolytic means for pain relief, for stimulation of weak muscles, for preliminary treatment of atonic paralysis and disturbance in the blood flow.
In general, the intensity of current passed through any part of the body does not exceed 0.3 to 0.5 mA/cm2 of electrode surface. The duration of treatment is 10-20 minutes [1].
Indication of galvanic type current.
- Contraction of denervated muscle. For example, use of galvanic current in foot drop
- Stimulation of small muscles which easily gets tired. Like muscles of
face . - This is mainly used to influence the pain threshold.
- Produce hyperemia
- Iontophoresis and analgesia with the stimulation simultaneous application of certain medicines will facilitate better penetration of medicine.
Interrupted Galvanic Current
As the term suggests, in an Interrupted Galvanic current, the duration of current is interrupted. The duration of impulse is long and together with frequency, it can be adjusted.
Duration of 100 ms is being commonly used. It is often an advantage to increase this to 300 or 600ms. Current pulses of about 100 ms duration, requires a frequency of about 30 per minute. The interval between the impulses should never be of shorter duration than the impulses themselves and is usually appreciably longer [zotpressInText item=”{5956979:A23VC9KM}” format=”%num%” brackets=”yes”].
The rise and fall of intensity may be sudden (square impulses) or gradual (trapezoidal, triangular and saw-tooth impulses). Fig. shows the unidirectional, interrupted galvanic pulses.
Faradic current
Faradic current is a sequence of pulses with defined shape and current intensity, as shown in fig. The pulse duration is of 0.1-1 ms and frequency of 50-100 Hz.
During such a waveform, the rise rate is rapid but not instantaneous, falling back rapidly to zero immediately after reaching the maximum i.e. spike.
Faradic current acts upon muscle tissue and upon the motor nerves to produce muscle contraction. There is no ion transfer and consequently, no chemical effect. This may be used for the treatment of muscle weakness after lengthy immobilization and of disuse atrophy [1].
The following figures differentiates between a alternating current (AC), direct current (DC), interrupted direct current.
Indications of faradic type current.
- Muscle re-education.
- Training new muscle action.
- Muscle strengthening.
Surged faradic current
If the peak current intensity applied to the patient increases and decreases rhythmically, and the rate of increase and decrease of the peak amplitude is slow, the resulting shape of the current waveform is called a surging current.
It is possible to produce surges of various durations, frequencies and waveforms. The main field of application of the Faradic surge current is in the treatment of functional paralysis.
Surges can be adjusted from 2 to 5-second surge, continuously or by regularly selecting frequencies from 6 to 30 surges/minute. Rest period (pause duration) should be at least 2 to 3 times as long as that of the pulse to give the muscle sufficient time to recover (regain its normal state).
The ratio of interval to the duration of the surging is also adjustable so that graded exercise may be administered. This type of current is usually required for the treatment of spasm and pain [1].
Galvanic vs Faradic current
Here is a brief difference between a galvanic type current and faradic type current.
Galvanic | Faradic | |
Type of current | Direct Current | Direct Current |
Duration of interruption | Galvanic: Direct currect; Interrupted Gavanic: Long duration interrupted D.C of 100 ms | Short duration Interrupted D.C of 0.1 to 1 ms |
Frequency of current | 30 per minute | 50 to 100 Hz |
Denervated muscle contraction | Can produce contraction of denervated muscle | Can NOT produce contraction of denervated muscle |
Indications | Commonly used to stimulate small muscles (like facial muscles) | Commonly used to stimulate large muscles (ex: quadriceps) |
References:
Mangala B. Satardekar*(ME Student), and Deepak V. Bhoir (H.O.D. \& Guide). “ANALYSIS AND ENHANCEMENT IN THE PERFORMANCE OF ELECTRICAL MUSCLE STIMULATOR.” INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY 6 (n.d.): 235–41. https://doi.org/10.5281/zenodo.246592.
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From – Kolkata. Wb
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Quite confused with the video and the information written below it.The video states Faradic current CAN stimulate denervated muscles and Galvanic current can not,yet one of the indication for Galvanic current on the text above states for denervated muscles. Which is which really? Thanks
Very nice and helpful subject
Very good and helpful subject
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A very good clarification from the medical end
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