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Scandinavian Journal of Pain

Official Journal of the Scandinavian Association for the Study of Pain

Editor-in-Chief: Werner, Mads


CiteScore 2018: 0.85

SCImago Journal Rank (SJR) 2018: 0.494
Source Normalized Impact per Paper (SNIP) 2018: 0.427

Online
ISSN
1877-8879
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Volume 16, Issue 1

Issues

Acute muscle pain alters corticomotor output of the affected muscle stronger than a synergistic, ipsilateral muscle

Dennis Boye Larsen
  • Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Thomas Graven-Nielsen
  • Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ Rogerio Pessoto Hirata / Shellie A. Boudreau
  • Center for Neuroplasticity and Pain (CNAP), SMI, Department of Health Science and Technology, Aalborg University, Aalborg, Denmark
  • Email
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
Published Online: 2017-07-01 | DOI: https://doi.org/10.1016/j.sjpain.2017.04.038

Abstract

Aims

Muscle pain affects corticomotor areas representing the affected muscle, by changing the size of representation and reduces the corticospinal output as assessed by transcranial magnetic stimulation (TMS). Less work has been done to understand how pain in one muscle group may affect synergistic ipsilateral muscles distal to the pain. This study aimed to explore the effects of acute extensor carpi radialis (ECR) muscle pain on TMS motor-evoked potentials (MEPs) of the ECR and the first dorsal interosseus (FDI) muscle, which are known to strongly overlap within the corticomotor area.

Methods

Eight healthy volunteers (1 woman) were injected with hypertonic saline (5.8%, 0.5 mL) into the ECR muscle. Pain intensity was assessed by the visual analogue scale (VAS) every minute for 10 min. TMS was applied at 120% of ECR resting motor threshold, and MEPs were acquired from the ECR and the FDI muscles. At baseline, 10 TMS pulses were delivered. Temporal mapping of ECR and FDI MEPs over 10 min duration was performed by delivering 100 single-pulses of TMS, at 6 s interstimulus-interval. The MEPs for each muscle were averaged at baseline, peak-pain (1 –2 min epoch), and 10 min post-injection

Results

Pain intensity reduced significantly at 10 min postinjection as compared to peak-pain (P = 0.011). Further, one-way repeated measures analysis of variance revealed that ECR MEPs were altered at peak-pain compared to baseline (P > 0.05), but not 10 min post-injection (P > 0.05). Baseline and 10 min post-injection of ECR MEPs did not differ significantly (P = 0.67). The MEPs of the FDI muscle did not show a similar alteration over time (P = 0.1).

Conclusions

Despite the overlap between ECR and FDI representations, acute muscle pain of the ECR only significantly altered cortical excitability of the ECR muscle representation.

About the article

Published Online: 2017-07-01

Published in Print: 2017-07-01


Citation Information: Scandinavian Journal of Pain, Volume 16, Issue 1, Pages 177–177, ISSN (Online) 1877-8879, ISSN (Print) 1877-8860, DOI: https://doi.org/10.1016/j.sjpain.2017.04.038.

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© 2017 Scandinavian Association for the Study of Pain.Get Permission

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