Diagnostic Ultrasound

What is diagnostic ultrasound?

Ultrasound uses sound-echo technology to generate images of structures inside the body. The transducer head contains a crystal that uses the piezoelectric effect to convert electrical energy into high frequency sound waves, which are sent into the body and subsequently reflect to produce an image. Whether a tissue reflects or transmits the sound wave is determined by its acoustic impedance, or resistance to sound waves. Fluid transmits well whereas bone reflects sound waves. Muscle is full of blood, so generates an image. The quality of the muscle can be assessed on higher resolution machines. The advantage of ultrasound is that it is relatively inexpensive (compared to a multi-million dollar MRI), emits no radiation or electrical current, and produces images in real-time. Hence it not only demonstrates form (what a structure looks like), but function (how a structure appears as it performs).

Why do physiotherapists use diagnostic ultrasound?

Diagnostic ultrasound enables physiotherapists to visualise function and performance of the deep or core muscles of the body, which are otherwise inaccessible to the naked eye. This can be used to demonstrate and diagnose dysfunction of the core muscles that can produce or predispose to pain syndromes. Secondary to the diagnostic role, because physiotherapist and patient can visualise the image in real-time, diagnostic ultrasound can be used as visual feedback to help retrain and correct core muscle dysfunction. Physiotherapists currently use diagnostic ultrasound to visualise pelvic floor problems for incontinence issues, abdominal and back muscles for spinal problems and deep hip muscles for pelvic stability and hip pathologies. The range of uses will only increase with time.

What is the rationale behind use of diagnostic ultrasound to treat the core stabilising muscles?

A landmark series of research projects cast a new light over spine rehabilitation about 10 years ago, and research development has been prolific since. It was found that the multifidus (deep back muscle) ceased to function and wasted in size and quality after the onset of LBP. Significantly, even when the LBP settled after time and rest, the back muscles did not regain their function, which lead to a recurrence of pain in 80% of cases within a year! However, the use of diagnostic ultrasound to diagnose deep muscle wastage and restore full function reduced the recurrence rate to 30% – a major improvement. Ultrasound has also enabled visualisation of the performance of the abdominal muscles, which in the presence of injury or pain, dysfunction. Notably, the deeper, core muscles that protect the spine ‘turn off’, while the more exterior muscles (that are designed to produce movement and torque), become overactive. This mismatch of muscle-for-task produces and perpetuates strain, pain and poor performance of motor tasks. This has major implications for traditional exercise and strengthening programmes. Rehabilitation is not about increasing the strength of the power muscles, but carefully and selectively restoring the stabilising role of the deeper core muscles. Unfortunately this requires time, skill, passion and investment in latest technology on behalf of the physiotherapist, to provide a service to the patient which is cutting edge in rehabilitation.

What happens if my physiotherapist doesn’t use diagnostic ultrasound to image my deep stabilising muscles?

It is becoming increasingly evident that you can be guaranteed that in absence of diagnostic ultrasound to image these deep muscles, you will activate the wrong muscles in rehabilitation. While only a few physiotherapy clinics currently own and utilise diagnostic ultrasound in day-to-day practice, they will become essential and commonplace examination and treatment tools in future. To not use diagnostic ultrasound to examine for spinal stability and prescribe therapeutic exercise is to treat with your fingers crossed behind your back – hopeful at best.