Abstract
BackgroundHigh density surface electromyography (EMG) can be used to estimate muscle innervation zones (IZ). The objective of this study was to compare the differences in the distribution of the biceps brachii (BB) IZ derived from voluntary contractions (VC) and electrical stimulation (ES) of the musculocutaneous nerve.MethodsSurface EMG signals were recorded from the medial and lateral BB with two 64-channel high density electrode matrices in eight healthy men. The surface EMG was recorded at different percentages of the maximal voluntary contraction (MVC) force (20–100% MVC) and at different percentages of the current needed to elicit a maximal M-wave (20–100% Imax). The IZs of the medial and lateral BB were identified from the EMG signals and expressed as a row number within a given medial-lateral column.ResultsES current intensity had no significant effect on the group mean IZ location (p > 0.05). However, The IZ during VC was located more proximally with increasing force (p < 0.05), likely due to muscle shortening. The position of the IZ varied slightly (by up to ~ 8 mm) in a medial-lateral direction under both contraction types, but this spatial effect was not significant. The IZ during ES and weak VC (20, 40% MVC) was similar (p > 0.05), but was more proximal in the latter than the former during 60–100% MVC (p < 0.05).ConclusionES can be used to detect spatial differences in IZ location free of the confounding effects of muscle shortening and recruitment order of different sized motor units. The method may prove beneficial for locating the IZ in patients who lack voluntary control of their musculature.
Highlights
Muscle spasticity often occurs in patients with neurological damage such as stroke and can have a negative impact on motor function [1]
The innervation zones (IZ) locations obtained through all voluntary contractions (VC) and electrical stimulation (ES) intensities showed normal distributions (p > 0.05)
Typical surface EMG recordings of maximal M-waves and VC at 60% maximal voluntary contraction (MVC) are shown for one subject in Fig. 2a-b, respectively
Summary
Muscle spasticity often occurs in patients with neurological damage such as stroke and can have a negative impact on motor function [1]. It has been demonstrated that intramuscular injection of botulinum neurotoxins (BTX) is an effective and relatively safe treatment for spasticity [2, 3]. The effectiveness of BTX treatment depends on the distance between the injection site and the location of the neuromuscular junctions [5, 6], which tend to cluster in a relatively narrow band termed the innervation zone (IZ) [7]. Surface electromyography (EMG) signals recorded by linear arrays or a matrix of electrodes have been widely used to identify the IZ location in many lower and upper limb muscles [7,8,9,10]. High density surface electromyography (EMG) can be used to estimate muscle innervation zones (IZ). The objective of this study was to compare the differences in the distribution of the biceps brachii (BB) IZ derived from voluntary contractions (VC) and electrical stimulation (ES) of the musculocutaneous nerve
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
