ULTRASOUND: A DYNAMIC IMAGING MODALITY FOR DIAGNOSING MUSCLE HERNIAS
By Humera Faisal, Physiological Measurements Limited
Aim:
Muscle hernia or myofascial defect is a tear in the epimysium, the outermost connective tissue layer of a muscle, with outward protrusion of the muscular component (Skalski). Muscle hernias are best demonstrated on dynamic imaging.
The fact that the swelling disappears after muscle relaxation and reappears on contraction, dynamic ultrasound examination provides a visual perception, hence achieving a confident diagnosis. The aim of the study is to establish the fact that dynamic ultrasound is the first line, non-invasive imaging tool of choice (Rodríguez-Roiz et al.)
Method:
Dynamic evaluation on ultrasound at rest and during stress, allows to evidence the appearance of a focal mushroom shaped bulge with a visible discontinuity in the echogenic layer of the muscle fascia (Orhan Güvener and Levent Özçakar) Graded compression applied by the ultrasound probe can be used to reduce the muscle protrusion hence providing supporting evidence and increased diagnostic confidence (Dierickx and Filip Vanhoenacker).
Correlation with cross-sectional imaging is used to critically evaluate the diagnostic accuracy of ultrasound and support differential diagnosis.
Results:
Tibialis anterior muscle is involved in majority cases. Most patients present with chronic dull ache or with the appearance of a lump that projects out increasingly after straining or exercise.
Diagnosing a muscle hernia can be challenging in cases where the patients are seen after rest and may not reveal a hernia unless scanned after some exercise or physical activity. (Artul and Habib)
Owing to this fact many cases may remain unrecognized, misdiagnosed or undiagnosed (Quaranta et al).
Conclusion:
Dynamic ultrasound and knowledge of a clinical history of a soft-tissue lump that increases in volume upon muscle contraction or weight-bearing are crucial in the diagnosis of muscle hernia (Dierickx and Filip Vanhoenacker)