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.