Ultrasound-guided-electromyography in plegic muscle: Usefulness of nerve stimulation.

Abstract

In traumatic nerve lesions (TNLs), motor unit potentials (MUPs) may be difficult to detect in early injury. Ultrasound-guided electromyography (US-EMG) can aid in identifying areas of muscle activation, but its sensitivity can be improved. In this study we compare the sensitivity of US-EMG alone with US-EMG after peripheral nerve stimulation (NC-US-EMG) to better identify active muscle regions. In this prospective study, 32 patients with severe TNLs were evaluated with standard EMG (ST-EMG), US-EMG, and NC-US-EMG at baseline (T0), after 2 to 3months (T1), and after 5 to 6months (T2). NC-US-EMG was more sensitive in detecting MUPs compared with US-EMG and ST-EMG at T0 (19 patients vs 14 and 5 patients, respectively). In addition, both US-guided techniques were more sensitive than ST-EMG in detecting MUPs (ST-EMG vs US-EMG: P=.014; ST-EMG vs NC-US-EMG: P=.003). At T1, ST-EMG remained less sensitive NC-US-EMG (P=.019). No significant differences were observed among the three techniques at T2. In the evaluation of severe TNLs, the combination of peripheral nerve stimulation and US increases the sensitivity of EMG for MUP detection at baseline and 2 to 3months postinjury.