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Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans

We have previously shown that during muscle pain induced by infusion of hypertonic saline (HS), concurrent application of vibration and gentle brushing to overlying and adjacent skin regions increases the overall pain. In the current study, we focused on muscle-muscle interactions and tested whether...

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Autores principales: Dunn, James S., Mahns, David A., Nagi, Saad S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8915694/
https://www.ncbi.nlm.nih.gov/pubmed/35295695
http://dx.doi.org/10.3389/fpain.2020.601544
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author Dunn, James S.
Mahns, David A.
Nagi, Saad S.
author_facet Dunn, James S.
Mahns, David A.
Nagi, Saad S.
author_sort Dunn, James S.
collection PubMed
description We have previously shown that during muscle pain induced by infusion of hypertonic saline (HS), concurrent application of vibration and gentle brushing to overlying and adjacent skin regions increases the overall pain. In the current study, we focused on muscle-muscle interactions and tested whether HS-induced muscle pain can be modulated by innocuous/sub-perceptual stimulation of adjacent, contralateral, and remote muscles. Psychophysical observations were made in 23 healthy participants. HS (5%) was infused into a forearm muscle (flexor carpi ulnaris) to produce a stable baseline pain. In separate experiments, in each of the three test locations (n = 10 per site)—ipsilateral hand (abductor digiti minimi), contralateral forearm (flexor carpi ulnaris), and contralateral leg (tibialis anterior)—50 μl of 0.9% normal saline (NS) was infused (in triplicate) before, during, and upon cessation of HS-induced muscle pain in the forearm. In the absence of background pain, the infusion of NS was imperceptible to all participants. In the presence of HS-induced pain in the forearm, the concurrent infusion of NS into the ipsilateral hand, contralateral forearm, and contralateral leg increased the overall pain by 16, 12, and 15%, respectively. These effects were significant, reproducible, and time-locked to NS infusions. Further, the NS-evoked increase in pain was almost always ascribed to the forearm where HS was infused with no discernible percept attributed to the sites of NS infusion. Based on these observations, we conclude that intramuscular infusion of HS results in muscle hyperalgesia to sub-perceptual stimulation of muscle afferents in a somatotopically unrestricted manner, indicating the involvement of a central (likely supra-spinal) mechanism.
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spelling pubmed-89156942022-03-15 Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans Dunn, James S. Mahns, David A. Nagi, Saad S. Front Pain Res (Lausanne) Pain Research We have previously shown that during muscle pain induced by infusion of hypertonic saline (HS), concurrent application of vibration and gentle brushing to overlying and adjacent skin regions increases the overall pain. In the current study, we focused on muscle-muscle interactions and tested whether HS-induced muscle pain can be modulated by innocuous/sub-perceptual stimulation of adjacent, contralateral, and remote muscles. Psychophysical observations were made in 23 healthy participants. HS (5%) was infused into a forearm muscle (flexor carpi ulnaris) to produce a stable baseline pain. In separate experiments, in each of the three test locations (n = 10 per site)—ipsilateral hand (abductor digiti minimi), contralateral forearm (flexor carpi ulnaris), and contralateral leg (tibialis anterior)—50 μl of 0.9% normal saline (NS) was infused (in triplicate) before, during, and upon cessation of HS-induced muscle pain in the forearm. In the absence of background pain, the infusion of NS was imperceptible to all participants. In the presence of HS-induced pain in the forearm, the concurrent infusion of NS into the ipsilateral hand, contralateral forearm, and contralateral leg increased the overall pain by 16, 12, and 15%, respectively. These effects were significant, reproducible, and time-locked to NS infusions. Further, the NS-evoked increase in pain was almost always ascribed to the forearm where HS was infused with no discernible percept attributed to the sites of NS infusion. Based on these observations, we conclude that intramuscular infusion of HS results in muscle hyperalgesia to sub-perceptual stimulation of muscle afferents in a somatotopically unrestricted manner, indicating the involvement of a central (likely supra-spinal) mechanism. Frontiers Media S.A. 2020-12-15 /pmc/articles/PMC8915694/ /pubmed/35295695 http://dx.doi.org/10.3389/fpain.2020.601544 Text en Copyright © 2020 Dunn, Mahns and Nagi. https://creativecommons.org/licenses/by/4.0/This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Pain Research
Dunn, James S.
Mahns, David A.
Nagi, Saad S.
Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans
title Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans
title_full Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans
title_fullStr Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans
title_full_unstemmed Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans
title_short Modulation of Muscle Pain Is Not Somatotopically Restricted: An Experimental Model Using Concurrent Hypertonic-Normal Saline Infusions in Humans
title_sort modulation of muscle pain is not somatotopically restricted: an experimental model using concurrent hypertonic-normal saline infusions in humans
topic Pain Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8915694/
https://www.ncbi.nlm.nih.gov/pubmed/35295695
http://dx.doi.org/10.3389/fpain.2020.601544
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