Quantitative ultrasound of denervated hand muscles

Introduction Presentations to the neuromuscular clinic commonly involve hand muscle denervation, but few studies have evaluated hand muscle ultrasound. Methods Ultrasound studies of abductor pollicis brevis, first dorsal interosseous, and abductor digit minimi were prospectively performed in a cohort of 34 patients (77 muscles) with electromyography (EMG)-confirmed denervation, compared with 58 healthy control subjects. Results In control subjects, muscle thickness was highly reproducible [intraclass correlation coefficient (ICC) = 0.88–0.98], and echogenicity was moderately reproducible (ICC = 0.542–0.686). Age, gender, and body mass index influenced muscle thickness and echogenicity. Ultrasound changes in denervated muscles correlated with the severity of EMG abnormalities. A z-score cutoff of 0 identified denervated muscles with a sensitivity of 100% and 89% for echogenicity and muscle thickness, respectively. Conclusions Hand muscle ultrasound provides a noninvasive method to quantify muscle denervation and may be useful as a screening tool before EMG studies. Muscle Nerve 52: 221–230, 2015