Apport du scanner, de l’échographie et de l’IRM dans la pathologie musculaire de l’adulte

Experimental muscle injury: Correlation between ultrasound and histological findings

“…The degenerative process induced by mepivacaine involves an initial phase of intrinsic degeneneration characterized by edema and hypercontracted fibers, followed by extrinsic degeneration, marked by inflammatory cell invasion; here, this latter phase correlated with a characteristic increase in echogenicity. This finding is in good agreement with the sonographic pattern reported in a number of neuromuscular disorders involving muscle fiber degeneration and inflammatory cell invasion, including muscular dystrophy and inflammatory myopathies5, 25 and in infectious processes such as pyomyositis 2. This pattern differs from both that observed following the tearing of muscle fibers in sports injuries—either directly due to extrinsic compression (crushing) or indirectly due to overstretching of muscle fibers (strain)6, 26—and that reported in an experimental injury caused by stabbing,15 in which the resulting hematoma‐filled cavity was visible sonographically as an anechoic or hypoechoic image 1.…”

“…Ultrasonography revealed an injured zone, which was generally oval or rectangular in shape. It had clearly defined borders and a mean area of 32.30 ± 3.13 mm,2 which remained stable throughout the process except at 20 dpi, when it was not identifiable. From 3 dpi, injury borders became progressively obscured, and by 10 dpi they had disappeared.…”

“…The regenerative phase was characterized sonographically by a progressive decrease in the hyperechogenicity observed during the degenerative phase, until the lower reflectivity characteristic of normal muscle was recovered 2, 5. During this phase, marked by the formation, maturation, and increased size of regenerating muscle fibers, perimysial connective tissue—normally visible in the form of echogenic lines due to greater reflectivity—was not detected initially,2, 5 probably due to remodeling of the extracellular matrix during regeneration 27. Moreover, the successful and efficient regeneration of the injured muscle depends on other factors, including revascularization, reinnervation of regenerating muscle fibers, and restored integrity of tendon connections, allowing normal recovery of regenerating muscle tissue architecture 28…”

“…Because of its many advantages, musculoskeletal sonography is widely recommended as an adjunct to magnetic resonance imaging (MRI) for diagnosis of neuromuscular disorders and evaluation of muscle injuries sustained during sporting or work activities 1–5. In sports‐related injuries, follow‐up monitoring is as important as diagnosis 6, 7.…”

“…Normal skeletal muscle appears on ultrasound as alternating bundles of hypoechogenic muscle fibers and hyperechogenic connective tissue. The latter forms the perimysium, which demarcates parallel muscle‐fiber bundles, and the epimysium, which ensheaths the entire muscle 2, 5, 7. Normal values for quantitative muscle sonography have been established for comparison with values recorded in a range of neuromuscular diseases 13, 14.…”