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Visually induced analgesia in a deep tissue experimental pain model: A randomised crossover experiment
Author(s) -
Selm M.J.,
Gibson W.I.,
Travers M.J.,
Moseley G.L.,
Hince D.,
Wand B.M.
Publication year - 2018
Publication title -
european journal of pain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.305
H-Index - 109
eISSN - 1532-2149
pISSN - 1090-3801
DOI - 10.1002/ejp.1234
Subject(s) - delayed onset muscle soreness , medicine , thigh , magnification , crossover study , physical therapy , physical medicine and rehabilitation , intensity (physics) , anesthesia , surgery , computer science , physics , alternative medicine , pathology , quantum mechanics , muscle damage , computer vision , placebo
Background Visualizing one's own painful body part appears to have an effect on reported pain intensity. Furthermore, it seems that manipulating the size of the viewed image can determine the direction and extent of this phenomenon. When visual distortion has been applied to clinical populations, the analgesic effects have been in opposition to those observed in some experimental pain models. To help resolve this problem, we explored the effect of visualisation and magnification of the visual image on reported pain using a delayed onset muscle soreness ( DOMS ) pain model. Methods We induced DOMS in the quadriceps of 20 healthy volunteers. Forty‐eight hours later, participants performed a series of painful contractions of the DOMS ‐affected muscle under four randomised conditions: (1) Viewing the injured thigh; (2) Viewing the contralateral thigh; (3) Viewing a neutral object; and (4) Viewing the injured thigh through magnifying glasses. For each condition, participants rated their pain intensity during a series of painful contractions. Results We observed that direct visualisation of the injured thigh had no effect on pain intensity when compared to viewing the contralateral thigh or neutral object. However, magnification of the DOMS ‐affected leg during the performance of painful contractions caused participants to report more pain than when viewing the injured thigh normally. Conclusions These results further demonstrate that the effect of visualisation varies between different pain conditions. These results may have implications for the integration of visual feedback into clinical practice. Significance We present delayed onset muscle soreness as a model for exploring visually induced analgesia. Our findings suggest that this phenomenon is expressed differently in exogenous and endogenous experimental pain models. Further exploration may offer a potential pathway for the integration of visual analgesia into the management of clinical pain.