MUSCULAR ULTRASOUND IN IDIOPATHIC INFLAMMATORY MYOPATHIES OF ADULTS

To evaluate the value of myosonography in inflammatory myopathies ultr asound of skeletal muscles was performed in 70 patients, aged 21-82 ye ars, suffering from histologically proven polymyositis (n = 30), derma tomyositis (n = 18), granulomatous myositis (n = 9), inclusion body my ositis (n = 13), and in 102 control persons. The sensitivity of muscle ultrasound in detecting histopathologically proven disease (82.9%) wa s not significantly different from electromyography (92.4%) or serum c reatine kinase activity (68.7%). The positive predictive value of ultr asound was 95.1%, the negative predictive value 89.2%, and the accurac y 91.3%. The different types of inflammatory myopathies presented with typical, but not specific ultrasound features. Polymyositis showed at rophy and increased echointensity predominantly of lower extremity mus cles, whereas in dermatomyositis clear muscle atrophy was rare and ech ointensities were highest in forearm muscles. Echointensities were low er in dermatomyositis compared to poly- and granulomatous myositis. Gr anulomatous myositis was characterized by the highest echointensities and a tendency towards muscle hypertrophy. Severe muscle atrophy was t he most impressive feature in the majority of patients with inclusion body myositis. Comparison of ultrasound and histopathological findings indicates that muscle lipomatosis has a much greater impact on muscul ar echointensity than does muscle fibrosis. Ultrasound of myositis imp roved clinical assessment of patients by supplying differential diagno stic clues based on precise muscle size measurements and identificatio n of mesenchymal abnormalities, particularly muscle lipomatosis.