Transcutaneous Electrical Nerve Stimulation (TENS):
TENS is used for pain management by helping to modify the brain’s perception of pain. It is not intended to effect any physiologic problem. It helps to control pain.
Interferential Electrical Stimulation (IF):
IF is primarily used for pain control and to help reduce swelling (edema). IF goes deeper into the tissues than Transcutaneous Electrical Nerve Stimulation (TENS) to reportedly stimulate sensory, motor and pain fibers. Interferential Therapy crosses a carrier frequency (usually 4000 Hz) with a second frequency (usually 4100 Hz). These two frequencies "interfere" with each other and mostly cross each other out, leaving about 100 Hz of therapeutic frequency. Why not just use 100 Hz then? 4000 Hz causes less resistance in the skin than does a lower frequency like 50-100 Hz. Therefore, the patient is more comfortable.
Two channels and four pads are used and placed in a cross pattern with the target area in the middle. The center point between the pads is where most therapeutic effect takes place (like a Bullseye). However, a "Scanning" or “Sweep” method can be used which changes the target area automatically and randomly away from the central point thus increasing the target area.
Tingling or “pins and needles” will be felt by the patient when intensity is increased. Intensity will not be increased beyond patient comfort.
Electrical Muscle Stimulation (EMS):
EMS is used to passively contract muscle fibers to facilitate healing and recovery post trauma, combat muscle atrophy and to increase blood circulation. Electrical impulses are sent to the muscle’s motor neurons causing them to contract without patient involvement (involuntary contraction). EMS is considered a low frequency modality that utilizes a square wave form pattern allowing for direct effect on muscle groupings.
Medium Frequency Muscle Stimulation (Russian):
Medium Frequency Muscle Stimulation is used to reduce muscle spasms and for muscle strengthening. Symmetrical Biphasic Square waveform is produced by dividing a 2500 Hz carrier frequency into 20-80 Hz packets. The patient is actively involved in this method and contracts the muscle along with the stimulation to help strengthen and educate the muscle.
Contraindications to electrical modalities may include: a demand pacemaker (not very common), infection, malignancy, areas of decreased sensation, any diagnosis where muscle contraction is unwanted, and pain of unknown etiology.
Precautions to electrical modalities may include: Cardiac disease, across the chest, anterior neck, trans-cerebrally, pregnancy, and abrasions.
Ultrasound is used to increase local blood flow, heat tissues, reduce edema, reduce joint stiffness, decrease muscle spasms, decrease pain, impact protein function, alter cellular proliferation, increase membrane permeability, increase vascular permeability, increase fibroblastic activity, increase bone healing. Continuous US is used to produce thermal therapeutic effects while Pulsed US will reduce edema and produce non-thermal effects.