Ultrasound therapy: 

Ultrasound is a method of stimulating the tissue beneath the skin’s surface using very high frequency sound waves, between 0.8 MHz and 3MHz. These cannot be heard by the human ear. This process can aid the healing process by relaxing tissues and increasing the local blood flow below the surface of the skin.


Ultrasound is a therapy that has been used by the medical profession since the 1940s and is now a widely accepted medical practice.  Indeed a medical practice that is accepted without question.

Ultrasound therapy is applied using a round-headed wand or probe that is put into direct contact with the patient’s skin. Sound waves are generated by a piezoelectric effect caused by the vibration of crystals within the head of the wand/probe. These are transmitted to the patient’s skin via the probe.  It is usual to use a lubricating gel to avoid friction and improve conductivity. The sound waves pass through the skin and cause a vibration of the local tissues.

This vibration (or cavitation) can cause a deep heating locally athough usually no sensation of heat will be felt by the patient. In situations where a heating effect is not desirable, such as a fresh injury with acute inflammation, the ultrasound can be pulsed rather than continuously transmitted.

Ultrasound can produce many effects:  increases in tissue relaxation and local blood flow, and breakdown of scar tissue.

All of these can be beneficial in the right circumstances.  For example, the increase in blood flow can help reduce local swelling and chronic inflammation – and according to some studies, even promote the healing of bone fractures. The intensity or power density of the ultrasound can be adjusted depending on the desired effect. A greater power density is often used in cases where scar tissue breakdown is the goal.

Ultrasound – the technology:

Ultrasound energy is widely used at all levels within the healthcare profession – for imaging and fro pain relief.

Ultrasound devices used for pain relief deliver longer and higher energy pulses than the type used for imaging – the kind of ultrasound that many of us are most familiar with.

Therapeutic ultrasound penetrates tissue, resulting in a slight heating effect. The treatment  can improve circulation and aid the intake of nutrients, which can help tissue recover more quickly and alleviate pain.

Ultrasound therapy uses high and low energy sound waves in the frequency range 0.8 to 3.0 MHz which penetrate the body tissue. Most machines are set either at 1 or 3 MHz.

An increase in the blood flow helps to reduce swelling and inflammation.  Ultrasound, at a frequency of 1MHz, is absorbed primarily by tissues at a depth of 3-5 cm; it is therefore recommended for deeper injuries.  A frequency of 3 MHz gives a more focused treatment at a depth of 1-2 cm.

Treatment sessions:

A typical ultrasound treatment will take from 3-5 minutes depending on the size of the area being treated. In cases where scar tissue breakdown is the goal, this treatment time can be much longer – up to 15 minutes.

Most ultrasound units use probes or wands sliding across the skin to deliver the energy – aided by a lubricating gel. During the treatment the head of the ultrasound probe is kept in constant motion. In such cases the patient should feel no discomfort at all. If the probe is held in one place for more than just a few seconds, a build up of the sound energy can occur and this can become uncomfortable.

The intensity (power density) of the ultrasound equpiment can be adjusted depending on the desired effect. A greater power density (measured in watt/cm2) is often used in cases where scar tissue breakdown is the goal. Because the machines are hand-held, treatment is generally limited to 15 minutes usually much less as noted above.

Some scientists believe that longer treatments will be more effective.

Ultrasound can also be used to achieve phonophoresis. This is a non-invasive way of administering medication to tissues below the skin – perfect for patients who are uncomfortable with injections. With this technique, the ultrasonic energy forces the medication through the skin. Cortisone, used to reduce inflammation, is one of the more commonly used substances delivered in this way.

Published research?

Ultrasound treatment is a widely accepted therapeutic treatment for a range of muscular and other disorders. Despite this, there is little independent published research on the effectiveness of this technique and few (if any) clinical trials … or so it is argued.

This raises a number of questions; the fundamental one being: why the lack of published research?  This has lead some people to question the validity of the treatment.

Yet, there are many laboratory-based research studies that have demonstrated the physiological effects of ultrasound on living tissue.  Not to mention the fact that a considerable amount of research was carried out just before and during World War 2. 

There are also recent research papers published showing the effectiveness of using ultrasound on patients with a frange of conditions.  One source of these is Midline, which publishes papers from ChiroAccess amongst others.  This organization has a number of entries showing the results of trials using ultrasound, low level laser and other treatments.

Considerable evidence available:

Yet, many of the quoted systemic studies of the subject ignore these and claim that the only evidence available on the effectiveness of ultrasound is, at best, inconclusive. 

This is misleading.

Many of the so called systematic reviews of the research into the effectiveness of ultrasound are now well over 10-15 years old …. sometimes much older
They therefore cannot include any of the more recent research into ultrasound
In compiling data for these systematic reviews, the authors use a variety of arbitrary criteria to determine which research to include and which to exclude.
There seems to be a belief in the medical profession that the only valid form of research is large scale, quantified research using double blind trials and the like.  Unfortunately, not all treatments can be tested in this way.

There are several treatments that adopt a holistic approach and treat individual patients as a whole, with their own unique health characteristics.  On this basis, no two patients are alike.  This means that the combination of treatments used is specific to that patient and not the ailment in isolation. Trying to put together two matched samples is therefore well nigh impossible.

Ultrasound and the carpal tunnel:

There is certainly a body of empirical evidence now available on the benefit of using ultrasound for Carpal Tunnel Syndrome, either on its own or in combination with another form of treatment.

What is more, there is also a large number of doctors, therapist and other healthcare professionals who have used ultrasound for many years.

Clearly not every treatment works for every individual.  People react differently to different treatments.  It is natural therefore for anyone recommending a treatment for Carpal tunnel Syndrome to consider all the options …. and to suggest that several treatments be tried to see which one/ones work the best.  A holistic approach is highly recommended by many therapists.

There are now wearable devices. available for home use. The new machines use small round applicators, or patches, that attach to the skin and are connected by wires to a controller.



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