Investigating the Association Between Muscular Ultrasonographic Alterations and Clinical Symptoms in Patients With Inflammatory Myopathy

Muscle biopsy is commonly used to diagnose inflammatory myopathies. We evaluated the ability of muscle ultrasound, a non-invasive and simple tool, to distinguish between healthy subjects and patients with inflammatory myopathy.

This study was conducted on 17 patients recently diagnosed with biopsy inflammatory myopathies (12 dermatomyositis, 5 polymyositis) compared with 17 age- and gender-matched healthy control adults. All patients underwent clinical assessments, including manual muscle testing, hand-held dynamometry, and muscle ultrasound evaluations, including thickness and echo intensity in predefined muscle groups. 

The disease duration was seven months (interquartile range: 3 to 11 months). Except for the biceps and gastrocnemius, patients’ muscles had significantly higher echo intensity and lower thickness than the control group. The echo intensity sum-score manifested the highest area under the curve compared to the sum-scores of other variables (echo intensity vs manual muscle testing: Area under curves-difference=0.18, P<0.01; echo intensity vs dynamometry: Area under curves-difference=0.14, P=0.02; echo intensity vs thickness: Area under curves-differences-difference=0.25, P<0.01). 

The echo intensity of muscles differed significantly between healthy individuals and patients with inflammatory myopathies and may serve as a useful diagnostic biomarker.