Rehabilitative Ultrasound Imaging of the Posterior Paraspinal Muscles

Abstract

T he role of muscles in joint protection and stabilization has been of increasing interest to researchers and clinicians involved in spinal pain and rehabilitation. Evidence for the importance of deep posterior muscles of the spine in the management of people with low back pain (LBP) has been provided by biomechanical 7,60,80,82 and neurophysiological 46,48 investigations. Imaging studies have further allowed definition of both normal morphology and impairments in paraspinal muscles. 22,27,32,33 Rehabilitative ultrasound imaging (RUSI) is a potentially useful tool in physical therapy for the assessment and treatment of these muscles. The advantages of RUSI over other imaging techniques have been discussed in a recently published related cles can be incorporated into neuromusculoskeletal rehabilitation. The main applications of RUSI for measurement of morphological characteristics (morphometry) and visualization of muscle contraction for biofeedback are discussed. The lumbar multifidus is the most widely studied paraspinal muscle, in both healthy populations 68 and people with spinal pain and injury. 22,26,27 Studies of different cervical muscles are also emerging. 37,39,[61][62][63] In the thoracic region, the lower trapezius is the first muscle to be measured with ultrasound imaging. 53Quantitative evaluation of the posterior paraspinal musculature using static and dynamic imaging has been used to study muscle morphology and behavior during contraction. 34,39,64,74,76 In this context, behavior relates to level of contraction (change in thickness), changes in size over time and with respect to other muscles, as well as observation of contraction as a biofeedback tool for the patient or therapist. In this commentary we review what is known about RUSI as applied to the paraspinal musculature, propose guidelines for standardizing the imaging and measurement techniques in clinical and research applications, and propose future directions for research. SYNOPSIS:Interest in rehabilitative ultrasound imaging (RUSI) of the posterior paraspinal muscles is growing, along with the body of literature to support integration of this technique into routine physical therapy practice. This clinical commentary reviews how RUSI can be used as an evaluative and treatment tool and proposes guidelines for its use for the posterior muscles of the lumbar and cervical regions. Both quantitative and qualitative applications are described, as well as measurement reliability and validity. Measurement of morphological characteristics of the muscles (morphometry) in healthy populations and people with spinal pathology are described. Preliminary normal reference data exist for measurements of cross-sectional area (CSA), linear dimensions (muscle depth/thickness and width), and shape ratios. Compared to individuals without low back pain, changes in muscles' size at rest and during the contracted state have been observed using RUSI in people with spinal pathology. Visual observation of the image during contraction indicates that RUSI may be a va...

Ultrasound transducer shape has no effect on measurements of lumbar multifidus muscle size

“…The habitual activity levels of the present subpopulation could therefore account for both the greater size and different shape of the multifidus muscle to previously studies sedentary populations . In a review of posterior paraspinal ultrasound imaging, it was highlighted that multifidus at L3 was measured to be 4.9cm 2 (Hides et al, 1995;Stokes et al, 2007). However, the CSA of lumbar multifidus in the present study was much larger (6.89cm 2 ), reflecting the young athletic males included in the study.…”

“…The frequency of the transducer can be justified by the depth at which a muscle lies; as a general rule, the highest frequency transducer that can image an area of interest should be used (Whittaker et al, 2007). As highlighted in a recent review by Stokes et al (2007), for lumbar multifidus a 5MHz is often used .…”

Reliability of Thickness Measurements of the Dorsal Muscles of the Upper Cervical Spine: An Ultrasonographic Study

“…25 Furthermore, most functional activities are performed at relatively low levels of muscular efforts. 25 Therefore, measuring the change in muscle thickness below 50% MVIC effort using ultrasonography may best represent muscle activation.…”

“…4,7 Previous work suggests that the muscle architecture changes very little with efforts above 50% maximum voluntary isometric contraction (MVIC), 4 because additional efforts do not further stretch the tendon and surrounding connective tissue and, therefore, contribute to minimal change in muscle length or thickness. 25 Furthermore, most functional activities are performed at relatively low levels of muscular efforts. 25 Therefore, measuring the change in muscle thickness below 50% MVIC effort using ultrasonography may best represent muscle activation.…”

“…25 Furthermore, most functional activities are performed at relatively low levels of muscular efforts. 25 Therefore, measuring the change in muscle thickness below 50% MVIC effort using ultrasonography may best represent muscle activation.RUSI measurement of the thickness R eal-time ultrasonography has been used to investigate changes in muscle morphology during contraction. The ability to quantify changes in muscle morphology to reflect muscle contraction using magnetic resonance imaging (MRI) or ultrasound imaging allows the study of the deep muscles and, in some cases, the visualization of the whole muscle, without the disadvantage t Study deSign: Clinical measurement, reliability.…”