Transform a Clinical Impression into a Verifiable Diagnosis

Real-time ultrasound imaging is used to help verify a physical therapy diagnosis of a muscle impairment via visual confirmation of muscle movement and pattern of activation.  The deep stabilizing muscles of the trunk (including transversus abdominis, deep fibers of multifidus, pelvic floor, diaphragm, and psoas) are targeted during rehabilitation because they become impaired after back injury or degenerative changes. 

The deep stabilizing muscles that have received the most attention in rehabilitation studies are transversus abdominis and multifidus.  To test the independent motor control of transversus abdominis in a clinic situation, the patient is asked to attempt a corset-like action of drawing in the lower abdominal wall.  An isolated contraction of transversus abdominis with minimal effort is an indication of adequate motor control and is the desired "ideal response."  This is an easy task to learn for people with no history of lower back pain, but an "ideal response" is practically impossible after back injury without specific training. 

Intra-muscular EMG is the "gold standard" device for accurate measurement of muscle activity.  This invasive procedure requires fine wire electrodes to be injected into the muscle which is not reasonable for clinical practice.  Surface EMG is useful for monitoring unwanted activity (or to teach relaxation) of the superficial muscles (rectus abdominis, external obliques, and thoracic portion of erector spinae) of the outer unit if they are overactive.  Unfortunately, surface EMG is not very useful for providing feedback from transversus abdominis or multifidus because of their depth and cross-talk from adjacent muscles (Stokes IA, Henry SM, Single RM). 

Another recommended method of testing transversus abdominis is the STABILIZER Pressure Biofeedback.  This indirect method does not seem to be highly reliable and may not be a valid test for transversus abdominis motor control in many patients.  I have not found it to be very consistent with ultrasound imaging findings.  The patient is instructed to attempt to perform the corset-like action while prone (face down) with the air-filled bag of the STABILIZER under his or her lower abdominal wall.  This has been purported to indirectly measure the motor control of transversus abdominis by measuring pressure changes resulting from the drawing in action.  If a patient fails this test (and you can bet that they will), then the physical therapist can use his or her clinical skills to assess this deep stabilizing muscle. 

When the patient makes the attempt again (this time in supine hook-lying), the physical therapist will analyze the patient's motor control through observation of the corset-like action of the abdominal wall and palpation of the lower abdominal wall for a deep tensioning of muscle fibers.  Unwanted activity of the superficial muscles (rectus abdominis, internal obliques, and external obliques) of the outer unit can be monitored by surface EMG, observation of the contours of the abdominal wall, observation of aberrant breathing patterns, and palpation of suspected muscles. 

To assess the segmental multifidus, the physical therapist palpates the muscle size at rest and during activation as the patient attempts "a slow, gentle and subtle isometric contraction."  A comparison is made from side to side and between vertebral levels.  Surface EMG is useful for monitoring unwanted activity (or to teach relaxation) of the thoracic portion of the erector spine muscles if they are overactive. 

Once the physical therapist has completed the physical examination, he or she should have a clinical impression of the problem.  Ultrasound imaging may then be used to visualize the motor control quality and precision of the deep stabilizing muscles in real-time on the monitor.  So, a clinical impression is thereby transformed into a verifiable diagnosis with real time ultrasound imaging.