Therapeutic Modalities

Electrical Stimulation - TENS and IFC

Electrical stimulating currents such as transcutaneous electrical nerve stimulation and interferential current  utilize electrical energy, the flow of electrons or other charged particles from one area to another, causing depolarization of muscle or nervous tissue. Electrical stimulation has most commonly been used for the modulation of pain through stimulation of cutaneous sensory nerves and the following analgesic mechanisms:

1. activation of large diameter A-beta fibers inhibits the pain transmission, carried by A-delta and C afferent fibers, from the spinal cord to the brain - also known as the gate control theory of pain
2. stimulation of A-delta and C fibers causes the release of endogenous opioids (endorphin and enkephalin) resulting in prolonged activation of descending analgesic pathways

Additional Considerations

• test sensory integrity prior to application by asking patients to differentiate between light touch and painful stimuli
  

• tissues with high resistance to electrical current include skin, bone, and necrotic tissue - electrodes should not be placed directly over bony prominences

• factors increasing skin impedance include the presence of hair and oil, and cooler skin temperatres

• applying IFC or TENS in combination with a thermal modality is not recommended as it increases the likelihood of an adverse effect

• large electrodes are more comfortable and allow current to travel deeper but the target is less specific - only large electordes should be used with medium frequencies (IFC) to disperse the current

• placing electrodes farther apart will allow the current to travel deeper - at lease 1 inch apart for pain control

• with any electrical device, increasing the intensity will first cause an electrical sensation followed by a motor repose and finally noxious stimuli

• remember that the modulation of pain is not treating the cause of pain