Faradic Current: Properties, Effects, Indications, and Contraindications, Lecture notes of Basic Electronics

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Faradic current

Dr. Hayam Mahmoud

Professor of P.T. for Neurological & Neurosurgical Disorders

Coordinator of Physical Therapy Dept. Girls- Faculty of Applied Medical Science-UQU.

Faradic Currents  Physiological Effects  Indications  Contra-Indications

Faradic Currents Cont.  The intensity of successive impulses in surged current increases gradually. Each impulse reaching a peak value greater than the preceding one then falls, either suddenly or gradually.  Surges can be adjusted from 2 to 5 second surge continuously.  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.

Physiological Effects of Faradic Current:  Stimulation of sensory nerves is not very marked because of the short duration. It causes reflex vasodilatation of the superficial blood vessels leading to slight erythema. The vasodilatation occurs only in the superficial tissues.  Stimulation of the motor nerves, if the current is of sufficient intensity, causes contraction of the muscle which they supplied by the nerve distal to the point of stimulus.  The contraction is titanic because the stimulus repeated 50 times or more/s if this type is maintained for more than short time, muscle fatigue is occurred. So the current is commonly surged to allow for muscle relaxation.

1 - Facilitation of muscle contraction when inhibited by pain. The stimulation must be stopped when the good voluntary contraction obtained. 2 - Muscle re-education : muscle contraction is needed to restore the sense of movement. In cases of prolonged disuse, flat foot, or incorrect use, and in muscle or tendon transplantation. 3 - Improved venous and lymphatic drainage e.g. edema and gravitational ulcers, by pumping action of alternate muscle contraction & relaxation. Indication of faradic current

Indication of faradic Cont. 4 - Prevention and loosening of adhesions. 5 - Painful knee syndrome : e.g. inhibition of quadriceps contraction by pain after knee surgery (menisectomy). i.e removal of menisci, rheumatoid arthritis ,sublaxation of patella, chondromalicia patella and chronic effusion of knee.

Faradic application

 Modes of faradic stimulation

_1. Continuous mode:

2. Surged mode:
3. Interrupted or pulsed mode:_

 Parameters : must be selected according to

treatment goals (pain control or healing). 1 - Time. 2 - Intensity levels 3 - Frequency. 4 - Polarity

Treatment Procedures  Skin preparation: ***** Prior to application the skin should be washed with soap and water.  ***** To remove skin debris, dead epithelial cell and sebum  ***** To facilitate good contract between electrode and skin.  ***** To reduce resistance of skin to electricity.

Types of electrodes ,and their attachment:  Polymer electrode: carbon-rubber electrode.  It is coupled to skin through conductive gel.  More traditional tin plate or aluminum they are coupled to skin with saline water.  Pen electrode which is used in facial palsy.

Types of electrodes

Pen electrode Carbon-rubber electrode Carbon-rubber electrode

Electrode placement:  Unilateral placement : causes stimulation of one half of a muscle pair.  Bilateral placement : causes stimulation of both halves of a muscle pair.  Unipolar placement : stimulating electrode on target muscle ,and the indifferent electrode at elsewhere (motor point stimulation).  Bipolar placement : two electrodes are placed on origin and insertion of target muscle.

Gel for good conduction

Electrode placement: Bipolar electrode placement for deltoid stimulation Bilateral unipolar electrode placements over the gluteal, sacroiliac and quadratus lumborum regions

Motor points  There are certain points on our body where faradic stimulation of enervated muscle can be elicited with least intensity.  _These points are called motor points_* :  It is located over the belly of the muscle.  Located at junction between upper and middle third Quadriceps stimulation using four electrodes for maximum recruitment.