Faradism is a type of short duration interrupted direct current with a pulse duration of 0.1-1MS and with a frequency of 50-100Hz. It is used for any partially or completely innervated muscle. Galvanism is an interrupted direct current with a long duration modular pulsed current and the pulse duration is more than 1MS. It is used for the case of denervated muscle.
Faradic current is a type of current with short duration interrupted direct current with a pulse duration of 0.1-1MS with a frequency 50-100Hz. This type of current is mainly used for partially or completely innervated muscle which the nerve still intact with muscle. As the innervated muscle need only a short duration to stimulate the intact nerve. When the current is applied, it stimulates the intact nerve by changing the permeability of cell membrane and varying the resting potential of the membrane. When the resting potential is exceeds the threshold level it will become excited, and the muscle supplied by the nerve will contract. The sensory stimulation of nerve will also be produced accompanied by the motor stimulation. The sensory stimulation resulting in the feeling of prickling sensation. There are few waveform types of faradic current which is also referred as pulse duration, for example, trapezoidal surging, triangular surging and saw tooth. Trapezoidal surging and triangular surging happen when the impulse increase and decrease gradually, so these two type of current is suitable for mild and moderate injury. While for saw tooth type to happen when the impulses increase gradually but suddenly fall and it is usually used for severe injury.
Type of faradic current
The indication is that it can facilitation the muscle contraction which is inhibited by pain. Training a new muscle action, for the post tendon transplantation, as the muscle may need to perform the action that is different with its previous action and the muscle will not know how to perform that action. It also helps the patient who has neurapraxic nerve lesion to produced muscle contraction. Other than that, it also helps patient who is having lymphadenopathy, edema, muscle weakness, stiffness and reduced in range of motion. The contraindication is that patient who has skin lesion or open wound are not allowed to use this current as they may feel more irritating sensation at the injured site. Patient that having infection also not allow to used faradic current as it may spread the infection. Patient have thrombosis not suitable using faradic current as the electrical stimulation will break the clot and may block the small blood vessels. Last but not least, patient who is loss of sensation also not suitable to used faradic current as they will not able to feel the intensity of current and it may hurt the skin if the intensity is too high.
Galvanic current is an interrupted direct current with a long duration of more than 1 MS with a frequency of 30 pulses per minutes and is commonly used for denervated muscle either it is partially or completely denervated. The denervated muscle will not respond to a duration which is less than 1MS as the injured nerve needs time to respond and send impulses to the brain. When the current is applied, the nerve of the muscle close to the denervated muscle is contracted. The sensory stimulation of nerve will also be produced accompanied by the motor stimulation. The sensory stimulation resulting in the feeling of burning sensation. There are few type of pulse shape, rectangular, triangle, trapezoidal and saw tooth. The rectangular type is the current turn on and off intensity abruptly; triangular type is it slow rise and slow fall of intensity; trapezoidal type is it raise slowly, plateau’s and then falls slowly. Saw tooth is the gradual rise of current and abruptly falls.
The indication of galvanic current is it can maintaining or increasing the range of motion, re-educate muscle, reduction of edema, swelling, inflammation, reduce motor spasticity, prevent muscle atrophy. While the contraindication is it cannot be used on the front of the neck, head or over the eyes or lungs. It is also cannot be used for the patient who is having epilepsy or seizures and cancer. Lastly, pregnant lady and who is having pacemaker also not allow to treat by galvanic current.
The physiological effects of faradic current and galvanic current is almost the same, such as stimulation of sensory nerves and motor nerves. Firstly, for faradic current, a mild prickling sensation is feel when current is applied to skin due to the stimulation of sensory nerves by short duration current. While for the galvanic current, a stabbing or burning sensation is feel when current is applied to skin due to stimulation of sensory nerves by long duration current. Both of the current will causes a reflex vasodilation of the cutaneous blood vessels, so there will be a slightly redness of the skin or erythema. Next, stimulation of motor nerves. Faradic current stimulates the motor nerves and causes the muscle supplied by the nerve to contract. The contraction is called as tetanic contraction. If this contraction is maintained for a long period, it may cause the muscle to become fatigued. So, to prevent this to happen, the current is surge to allow relaxation of muscle. So that, the muscle will contract gradually increase and decrease in the strength of muscle, which is similar to the voluntary muscle contraction. For galvanic current, it will stimulate the muscle to produce muscle twitch followed by immediate relaxation due to the repeated stimuli.
For the faradic current, there are some more physiological effect such as effects of muscle contraction and chemical effect. First, effect of muscle contraction. The electrical stimulation caused the muscle contraction which can help in increasing the metabolism and the removal of waste of products. The contraction and relaxation of the muscle exerts a pumping action on the blood vessels and increased the metabolism by pumping more blood supply and nutrients to muscle thus increase demand of oxygen and nutrients to muscle. Other than that, the pumping action will also occur on veins and lymphatic vessels within the muscle and around it, thus increase the removal of waste products. Then, the chemical effect of faradic current. Chemicals effects produced at the electrodes due to passing the direct current through electrolyte, which is introduce medicine into body through electricity, such as iontophoresis. But it do not allow considerable amount of collection of chemicals under the electrode. We have to examined the skin after every stimulation to rule out any chemical burn or erythema.
Then is the therapeutic effect of faradic current. First of all, is facilitation of muscle contraction. Electrical stimulation will help muscle to contract voluntary when the muscle contraction is inhibit by pain or recent injury. For example, rheumatoid arthritis, post fracture immobilization, etc. Next, is re-educate of muscle action. Muscle unable to contract may because of the prolonged disuse of the particular muscle. Faradic current can help to produce muscle contraction and enhance the sense of movement. When we observe a movement our brain will appreciate the movement and not muscle action. So, to enhance the rehabilitation of the patient, the patient should practice the movement actively along with observation which would improve the movement pattern effectively. Also, after the tendon transplantation or any other reconstructive procedures a muscle may need to perform the action that is different from it’s previous action. But the muscle will not able to know what is the action of the previous muscle. So, patient need to observe the new action and try do it actively along with the electrical stimulation. Then, it can help to improved venous and lymphatic drainage as electrical stimulation can produce pumping action which can increase the venous and lymphatic return. It can be more effective when applying under the pressure. It is good in reduced edema. Lastly, it can help in prevention and loosening of adhesion. The formation of adhesion can be stretched and loosen by muscle contraction, for example, the scar tissue binding to muscle and tendons.
Next is the therapeutic effect of galvanic current. The electrical stimulation can help in minimize the extent of muscle atrophy thru the period while the nerve is degenerating. Actually, electrical stimulation has no effect on the rate of nerve regeneration or muscle reinnervation. It is just provided a platform for the degenerative nerve. But if the reinnervation does not occur within 2 years, it means that the contractile element of muscle may have already replaced by the fibrous connective tissue and recovery of the muscle is not possible. In addition, Galvanic current can also limit the edema and venous stasis and result in delaying the muscle fiber fibrosis and degeneration by pumping action.
There are 2 method of application of faradic current, one is group muscle stimulation another is motor point stimulation. For multiple motor point or a group of muscle, the electrical stimulation is applied 30 muscle contraction and it is repeated successively. While for individual muscle or motor point stimulation, 90 muscle contraction is chosen. The intensity given should be based on the patient’s tolerance, check on the patient’s condition, observe the muscle contract and can attempt to duplicate this muscular response. The pulse per second should be 35-55 per second, as higher pulse may cause muscle fatigue. The current intensity has to be adequate for muscle contraction but comfortable for the patient. The pulse duration is between 300-600microsec.
For galvanic current, there are also have 2 methods of applications. One pad can be used to fix over the origin of muscle group and use an electrode pen to stimulate individual muscle. Or using two pad, one is placed over the origin of muscle group the other one is placed over the distal end of the bulk.
Equipment for faradic and galvanic current
In conclusion, faradic current is a type of current which have longer pulse duration. So, it just need a short duration for treatment and is more suitable for innervated muscle. While galvanic has high intensity current with short pulse duration. So, it need a longer duration for the treatment and more suitable for denervated muscle. But both of the current are having almost the same physiological effect and therapeutic effect. As both current are help in improve blood circulation and increase metabolism.