Simultaneous ultrasound and needle electromyography recording of fasciculations in amyotrophic lateral sclerosis

Objective Fasciculations can be detected using both muscle ultrasonography and needle electromyography, yet the correspondence between ultrasonographically observed fasciculations (U-fas) and needle electromyography–detected fasciculation potentials (N-fas) has not been clarified. This study investigated their correspondence using fully synchronized recordings. Methods Adult patients showing fasciculation-like contractions on muscle ultrasonography were enrolled; all were subsequently diagnosed with amyotrophic lateral sclerosis. Ultrasound and needle electromyography were recorded simultaneously in up to three muscles per patient, with a recording duration of 3 min per muscle. For each ultrasonographically observed fasciculation, the presence of a corresponding electromyographic event and contraction duration assessed by M-mode imaging were evaluated. Results Ten patients with amyotrophic lateral sclerosis were included. A total of 472 focused U-fas events were analyzed. Corresponding N-fas were detected in 437 events, yielding an overall concordance rate of 92.6% (95% confidence interval, 90.2–95.0%). U-fas contraction duration ranged from 343 to 971 ms, whereas N-fas duration ranged from 10.9 to 76.4 ms. The number of phases of N-fas observed during U-fas events ranged from 1 to 10. Conclusions Most ultrasonographically observed fasciculations corresponded to electromyography-detected events on simultaneous recording. Significance Ultrasonographically detected fasciculations may serve as a supplementary indicator of lower motor neuron involvement in amyotrophic lateral sclerosis.