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Ultrasound-guided motor unit scanning electromyography

Lookup NU author(s): Dr Ian Schofield, Professor Roger Whittaker



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2022 The Authors. Muscle & Nerve published by Wiley Periodicals LLC.Introduction/Aims: Measuring the spatial dimensions of a single motor unit remains a challenging problem, and current techniques, such as scanning electromyography (EMG), tend to underestimate the true dimensions. In this study we aimed to estimate more accurately the dimensions of a single motor unit by developing a clinically applicable scanning EMG protocol that utilizes ultrasound imaging to visualize and target a transect through the center of a single motor unit. Methods: Single motor unit twitches in the tibialis anterior muscles of healthy volunteers were elicited via stimulation of the fibular nerve, visualized with ultrasound, and targeted with an intramuscular EMG electrode. The electrode was moved by hand in small steps through the motor unit territory. Ultrasound video output was synchronized to EMG capture, and the needle position was tracked at each step. Results: Eight recordings from six participants were collected. The technique was quick and easy to perform (mean time, 6.1 minutes) with reasonable spatial resolution (mean step size, 1.85 mm), yielding motor unit territory sizes between 1.53 and 14.65 mm (mean, 7.15 mm). Discussion: Ultrasound-guided motor unit scanning EMG is a quick and accurate method for obtaining a targeted motor unit transect. This combination of two readily available clinical tools provides insights into the dimensions and internal structure of the motor unit as a marker for neuromuscular conditions.

Publication metadata

Author(s): Maitland S, Hall J, McNeill A, Stenberg B, Schofield I, Whittaker R

Publication type: Article

Publication status: Published

Journal: Muscle and Nerve

Year: 2022

Volume: 66

Issue: 6

Pages: 730-735

Print publication date: 01/12/2022

Online publication date: 15/09/2022

Acceptance date: 11/09/2022

Date deposited: 24/10/2022

ISSN (print): 0148-639X

ISSN (electronic): 1097-4598

Publisher: John Wiley and Sons Inc


DOI: 10.1002/mus.27720

PubMed id: 36106775


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