Effects of photobiomodulation on different application points and different phases of complex regional pain syndrome type I in the experimental model

Abstract

Background: Complex regional pain syndrome type I (CRPS-I) consists of disorders caused by spontaneous pain or induced by some stimulus. The objective was to verify the effects of photobiomodulation (PBM) using 830 nm wavelength light at the affected paw and involved spinal cord segments during the warm or acute phase. Methods: Fifty-six mice were randomized into seven groups. Group (G) 1 was the placebo group; G2 and G3 were treated with PBM on the paw in the warm and acute phase, respectively; G4 and G5 treated with PBM on involved spinal cord segments in the warm and acute phase, respectively; G6 and G7 treated with PBM on paw and involved spinal cord segments in the warm and acute phase, respectively. Edema degree, thermal and mechanical hyperalgesia, skin temperature, and functional quality of gait (Sciatic Static Index [SSI] and Sciatic Functional Index [SFI]) were evaluated. Results: Edema was lower in G3 and G7, and these were the only groups to return to baseline values at the end of treatment. For thermal hyperalgesia only G3 and G5 returned to baseline values. Regarding mechanical hyperalgesia, the groups did not show significant differences. Thermography showed increased temperature in all groups on the seventh day. In SSI and SFI assessment, G3 and G7 showed lower values when compared to G1, respectively. Conclusions: PBM irradiation in the acute phase and in the affected paw showed better results in reducing edema, thermal and mechanical hyperalgesia, and in improving gait quality, demonstrating efficacy in treatment of CRPS-I symptoms.

Effect of photobiomodulation therapy (660 nm and 830 nm) on carrageenan-induced edema and pain behavior in mice

“…The study 24 demonstrated that laser (650 nm) inhibited inflammatory response through release of adrenal hormones. According to the study 27 , 780 nm laser with dose of 0.4 J decreased the inflammatory process, down regulated TNF level, however no alteration in IL-6 expression was observed.…”

“…This experimental model provides variation of different therapeutic and pharmacological resources, with the objective of minimizing the inflammatory process 6,7,[13][14][15][16][17][18] . Electrophysical resources, as the photobiomodulation therapy (PBMT), are being largely used in research on different experimental models, such as tendons, peripheral nerve, cutaneous tissue, bones, and muscles [19][20][21][22][23][24] . Moreover, they are being applied for the treatment of acute inflammatory processes, and ensuing resolution of the acute edema 5,6,[25][26][27][28][29][30] .…”

“…The authors observed a modulating effect of PBM in the inflammatory process of the evaluated animals. In another study 24 , the authors described the action of PBM on edema and pain in a model of complex reaction type 1 pain syndrome. The authors demonstrated improvement in the variables evaluated in the study.…”