TENS therapy is useful in

Passive modalities such as ultrasound, laser and transcutaneous electrical nerve stimulation (TENS) are often used to reduce myofascial pain. TENS uses a low-voltage biphasic current of varied frequency and is designed for sensory counter stimulation for the control of pain. It is thought to increase the action of modulation that occurs in pain processing at the dorsal horn of the spinal cord and the trigeminal nucleus of the brain stem. Ultrasound relies on high-frequency oscillations that are produced and converted to heat as they are transmitted through tissue; it is a method of producing deep heat more effectively than the patient could achieve by using surface warming.