[Myosonographic findings in inflammatory muscular diseases]

Inflammatory myopathies are rare diseases with an annual incidence of about 1-8 per 1 million persons. However, they are of special importance in myology as they can be treated successfully. There are auto-immune mediated and infectious forms of myositis. From the clinical and myopathological view, one can distinguish acute and chronic forms: the former presenting with distinct inflammatory reactions in the muscle tissue and often causing myalgia. Muscle atrophy, the latter presenting with marked muscle weakness, often with clear muscle atrophy and mesenchymal abnormalities in the biopsy. Ultrasound well documents muscle atrophy, sometimes compensatory hypertrophy, as well as mesenchymal abnormalities such as lipomatosis and fibrosis. In very acute myositis, as in pyomyositis muscle edema and abscesses can be depicted. Typical findings in autoimmune mediated myositis are reported based on our own experiences in 75 patients and according to the literature. The degree and distribution of muscle atrophy and mesenchymal abnormalities visualized by ultrasound can give clues to the type and prognosis regarding muscle function. Additionally, ultrasound can be used for searching the optimal biopsy site.