Sensitivity and specificity of qualitative muscle ultrasound in assessment of suspected neuromuscular disease in childhood

Abstract

Muscle ultrasound is considered a useful noninvasive technique for visualizing normal and pathological skeletal muscle. We determined the accuracy of qualitative muscle ultrasound in the discrimination of normal muscle from myopathic, neurogenic, and unspecifically abnormal tissue changes in the evaluation of suspected NMD in childhood. Sensitivity and specificity of muscle ultrasound were assessed by comparing sonographic classification of muscle tissue changes in 134 children with definitive diagnosis as provided by muscle histology or mutation analysis performed subsequently to the sonography. We found a sensitivity of 81% and a specificity of 96% for detection of any abnormal muscle tissue alteration by ultrasound. For detection of neurogenic changes, sensitivity was 77% with even higher specificity (98%). Accuracy was slightly lower for myopathic changes (79%) and clearly lower for unspecific abnormal tissue alterations (70%). Accuracy of ultrasound was lower in younger children. High reliability of muscle sonography justifies a more widespread use of this method in evaluation of suspected NMD in childhood.