How does ultrasound work to relieve pain?

Most people are acquainted with ultrasound imaging, but how does ultrasound work to relieve pain? Ultrasound therapy uses sound waves for the treatment of musculoskeletal problems such as tendinitis and bursitis, which are characterized by inflammation. Even though sound is the crux of this form of pain management, the waves that ultrasound produces are beyond the range of human hearing, meaning that it is actually inaudible. Although imperceptible to the ear, the patient may feel moderate pulsing and light warming of the skin during therapy. Some patients may fell a slight discomfort while others feel nothing at all, but in general ultrasound therapy is fairly tolerable.
There are two main types of ultrasound therapy; thermal ultrasound therapy, and mechanical ultrasound therapy. The former employs continual sound wave transmission to produce microscopic vibrations in deep tissue molecules, in turn creating heat and friction. The resulting warmth promotes healing by boosting the metabolism at tissue cell level. The latter, on the other hand, employs pulses of sound waves to permeate tissues in order to expand and contract the soft tissues’ small gas bubbles and reducing inflammatory response, tissue swelling, and ultimately pain. The type of therapy depends on the condition causing the pain. For instance, thermal therapy is used for conditions like myofascial pain or muscle strains and sprains, while mechanical therapy is for conditions like carpal tunnel syndrome. 
Ultrasound therapy is administered through a piezoelectric crystal in the transducer in a sound head.

Gel may be applied to the transducer head as well as to the skin of the surface area that the therapist will work on for approximately 5 to 10 minutes. The gel is meant to help distribute the sound waves evenly through the skin. The FDA considers ultrasound units therapy to be safe as long as it is performed by a licensed therapist, who must keep moving the transducer head moving over the treatment area constantly. If the therapist leaves the transducer head in a single place for too long, he might burn the tissues underneath, not unlike an iron left on ironing board, except that you may not notice the damage as it is occurring. 
Moreover, there are certain body parts that ultrasound therapy should not be applied to under any circumstances. Those areas of the body are the abdomen, pelvic regions, or the lower back in women who are pregnant or menstruating, around the eyes, breasts, or genitals. Additionally, ultrasound should never be used on lesions, broken skin, or healing factures, or on areas with plastic implants or malignant tumors, or on people who have a pacemaker.
Some people don’t wonder so much about ‘how does ultrasound work,’ but about whether it does actually work. The fact is that when ultrasound works, it works very well. However, that doesn’t mean that ultrasound therapy is for everybody. Every individual is different and experiences `pain differently, so it’s safe to surmise that they any given individual will react differently, if ever so slightly, to treatment.
Of course there is no way of knowing how well ultrasound therapy will work for a particular person before actually trying it, but it is definitely worth a try. And if it doesn’t work at first, it might mean that the patient should attempt a different modality, instead of giving up altogether. This is part of the importance of being under the supervision of a certified physician. While it’s true that there are portable and lightweight ultrasound units available, and which can be operated by the patient themselves, they most certainly require a prescription. Ultrasound devices should only be used when and how directed by a doctor.

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