Physical agent modalities such as (electrotherapy, ultrasound, TENS etc) are used by physiotherapists as an adjunct to or preparation for rehabilitation. When used before, during or after a therapy session these modalities can enhance the effects of the treatment. They help to reduce pain, muscle spasm, stiffness and decreased movement.
Heat is one of the most common modalities in use and may take the form of ultrasound. This is the application of high frequency sound waves and the conversion of this energy into heat. At 1 MHz it can heat tissues to a depth of 5 cm. Sound waves are applied to the skin with a transducer, which glides across the skin in slow continuous motions. Gel is used to improve the transmission of the sound to the tissues. Because of its ability to heat deeper tissues, ultrasound is excellent in treating joint contractures, scar tissue and muscle spasms.
Electrotherapy is the use of electrical currents to treat diseases. These currents are delivered by electrodes placed either on or under the surface of the body and are connected to external circuits. Electrodes can also be placed directly into the tissue with surgery or catheterization. Electrode stimulation can be done through pacemakers to control heart rhythms, or in muscles such as the diaphragm or the urinary bladder. Electrodes can relieve pain when they are implanted in the spinal canal. Used on the surface of the body they can provide temporary relief from pain and prevent muscle atrophy after surgery or immobilization.
Transcutaneous electrical nerve stimulation or TENS as it is popularly called is another electrical modality that controls pain. TENS provides a constant electrical stimulation and is guided to the peripheral nerves via electrodes. Used at a low-frequency setting, TENS causes the release of opiates which reduce the sensation of pain. TENS can be applied for acute or chronic pain. It is especially helpful in postsurgical cases where early movement is needed and after fractures. TENS is useful in treating individuals who have a low threshold for pain.
Neuromuscular electrical stimulation provides a continuous current to increase range of motion, facilitate muscle contraction and strengthen muscles. The current is applied through an electrode to the muscles to produce a muscle contraction. The current is interrupted to allow the muscle to relax between contractions and the length of these pauses can be controlled by the physiotherapist. This and the other modalities mentioned must be administered by a trained professional and all precautions observed.