Photobiomodulation Decreases Hyperalgesia in Complex Regional Pain Syndrome: An Experimental Mouse Model Subjected to Nicotine

Abstract

Background and Objectives: Complex regional pain syndrome (CRPS) is defined as an extreme and chronic pain condition, and photobiomodulation has relevance as a complementary treatment for CRPS. The objective of this study was to verify the effects of photobiomodulation (PBMT) therapy protocols at two wavelengths 660 and 830 nm, associated or not to nicotine in complex regional pain syndrome type I (CRPS-I). Study Design/Materials and Methods: Sixty-four Swiss mice were divided into the following groups: (i) Naive, (ii) Sham, (iii) Control, (iv) 660 nm, (v) 830 nm, (vii) Nicotine, (vii) Nicotine/660 nm, and (viii) Nicotine/830 nm. CRPS-I was induced in an experimental ischemia/reperfusion model by affixing an elastic ring, proximal to the ankle joint of the right hind mouse paw, for 3 hours. Nicotine, in the respective groups was administered for 28 days prior to the induction of CRPS-I. PBMT was applied immediately after the procedure and for 20 consecutive days. The animals were evaluated for mechanical hyperalgesia, thermal hyperalgesia, paw edema at baseline and for 7, 14, and 21 days. Statistical analyses comprised a mixed-effects model, using the Tukey post hoc test (P < 0.05). Results: The PBMT wavelengths in 660 and 830 nm groups had beneficial effects (P < 0.05) in reducing mechanical and thermal hyperalgesia, but the effects at 660 nm were significantly better than 830 nm. At reducing edema, both wavelengths had significant effects statistically, absolutely no difference between them. Conclusions: The use of PBMT (660 and 830 nm) was effective in reducing mechanical hyperalgesia and thermal hyperalgesia; however, PBMT at 660 nm generated significant results. In reducing edema, both wavelengths had similar effects, which were significant statistically. The deleterious effects of nicotine were evident statistically and were softened when treated with PBMT (P < 0.05). Lasers Surg. Med.

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

“…As previously described, CRPS-I has three stages [5]. The study by Rodrigues et al [13] evaluated the effects of PBM 660 and 830 nm on CRPS-I and reported that mechanical hyperalgesia decreased significantly from the fourth day of application in the groups treated with PBM 660 and 830 nm, corroborating with the data of the present study, where the group treated with PBM in the acute phase (G3) obtained reduced values of mechanical hyperalgesia. These findings can be explained by the rapid action of PBM, promoting peripheral and sympathetic nerve blockage and reducing pain [17].…”

“…Some studies [13,14,24,26,32,33,39,40] have evaluated the effects of different wavelengths including 660 and 830 nm on CRPS-I, and found a reported decrease in mechanical hyperalgesia [13], decreased temperature, and early functional recovery [33] in the groups treated with PBM Group 1: control (placebo), Group 2: photobiomodulation (PBM) applied to the paw with complex regional pain syndrome type I (CRPS-I) from the warm phase, Group 3: PBM applied to the paw with CRPS-I from the acute phase, Group 4: PBM applied close to the area of the region between L4 and L5 from the warm phase, Group 5: PBM applied close to the area of the region between L4 and L5 from the acute phase, Group 6: PBM applied at two points: right paw and region between L4 and L5 from the warm phase, Group 7: PBM applied at two points: right paw and region between L4 and L5 from the acute phase, 3rd: third evaluation day, 7th: seventh evaluation day, 14th: fourteenth evaluation day, 21st: twenty-first evaluation day. .…”

“…The CRPS-I treatment guidelines recommend a multidisciplinary approach, however, the search for an ideal treatment remains a challenge [ 13 , 34 ]. This is the first study to describe the effects of PBM with 830 nm on CRPS-I applied at different sites, the affected leg and final segment of the region between L4 and L5, and to compare the effects of PBM 830 nm introduced in the warm and acute phases of CRPS-I.…”

“…It is also described that, because CRPS-I presents with mild and subtle injury to the sciatic nerve, it goes unnoticed in most cases [38]. Furthermore, in previous studies [13], a change in the support of the affected paw of the mice was verified, which allowed us to evaluate using the SFI and the SSI.…”

“…Along the spectrum of physiotherapy, some studies have suggested the use of electrophysical agents for the complementary treatment of CRPS-I, such as photobiomodulation (PBM) [ 12 - 14 ]. PBM seems to enhance the effects of sodium-potassium pumps.…”