Low-level Laser Therapy Parameters Research Articles

Photobiomodulation as Medicine: Low-Level Laser Therapy (LLLT) for Acute Tissue Injury or Sport Performance Recovery.

Background/Objectives: Low-level laser therapy (LLLT) has gained traction in sports and exercise medicine as a non-invasive therapeutic for preconditioning the body, exertion recovery, repair and injury rehabilitation. LLLT is hypothesized to modulate cellular metabolism, tissue microenvironment(s) and to decrease inflammation while posing few adverse risks. This review critically examines the evidence-base for LLLT effectiveness focusing on immediate care settings and acute/subacute applications (<6 months post-injury). Methods: A comprehensive literature search was conducted, prioritizing systematic reviews, meta-analyses and their primary research papers. Results: Findings are relevant to trainers and athletes as they manage a wide range of issues from superficial abrasions to deeper tissue concerns. LLLT parameters in the research literature include wide ranges. For body surface structures, studies show that LLLT holds promise in accelerating wound healing. In sport performance studies, LLLT is typically delivered pre-exercise and reveals beneficial effects on exertion recovery, improvements in muscle strength, endurance and reduced fatigue. Evidence is less convincing for acute, deep tissue injury models, where most studies do not report significant benefits for functional outcomes over conventional therapeutic modalities. Conclusions: Variability in LLLT delivery parameters and findings across studies underscores a need for clear treatment guidelines for the profession. Technical properties of laser light delivery to the body also differ materially from LED devices. Sport physiotherapists, team physicians, trainers and athletes should understand limitations in the current evidence-base informing photobiomodulation use in high-performance sport settings and weigh potential benefits versus shortcomings of LLLT use in the mentioned therapeutic contexts.

Low-level laser therapy parameters in the treatment of Orofacial pain in temporomandibular disorder

Temporomandibular disorder (TMD) comprises a group of dysfunctions of the masticatory system involving joint, myofascial, and even sensory alterations. The main symptom of TMD is orofacial pain, which has a negative impact on the quality of life of TMD sufferers, affecting their productivity at work and school, the quality of their sleep, their appetite, and their satisfaction with life. An alternative for the treatment of TMD is the low-level laser therapy (LLLT), which stimulates cellular functions and promotes therapeutic effects. However, there is no consensus in the literature. Objective: This review aimed to elucidate the parameters of low-level laser therapy in the treatment of orofacial pain in patients with temporomandibular disorder. Methods: A search was carried out for scientific articles published between 2013 and 2023 in the MEDLINE, PEDro, LILACS and SciELO databases. Results: A total of 21 studies were previously selected and after the eligibility criteria, 10 studies were included. Can be suggest a protocol for treating patients with temporomandibular disorder by low-level laser therapy with the following parameters: infrared wavelength, energy density less than 10 J/cm2, output power from 100 to 250 mW and at least 8 sessions of treatment. Conclusion: The low-level laser therapy improves orofacial pain in patients with temporomandibular disorder.

Effect of various photobiomodulation regimens on breast cancer-related lymphedema: A systematic review and meta-analysis.

Breast cancer-related lymphedema (BCRL) is common among patients who have completed their cancer treatment. Although low-level laser therapy (LLLT) has been explored as a treatment option for BCRL, we could not find a regimen that is more effective than others. This meta-analysis aimed to organize existing research and determine the optimal combination of LLLT parameters for BCRL treatment. Studies were collected from four online databases: Embase, Ovid Medline, Cochrane, and Cinahl. The collected studies were reviewed by two of the authors. We focused on the aspects of the treatment area, treatment regimen, and total treatment sessions across the included studies. The comparisons between LLLT and non-LLLT were performed through a meta-analysis. Post-treatment QOL was significantly better in the axillary group. The group treated "three times/week with a laser density of 1.5-2J/cm2" had significantly better outcomes in terms of swelling reduction, both immediately post-treatment and at 1-3months follow-ups. The group with > 15 treatment sessions had significantly better post-treatment outcomes regarding reduced swelling and improved grip strength. According to these results, LLLT can relieve the symptoms of BCRL by reducing limb swelling and improving QOL. Further exploration found that a treatment approach targeting the axilla, combined with an increased treatment frequency, appropriate laser density, and extended treatment course, yielded better outcomes. However, further rigorous, large-scale studies, including long-term follow-up, are needed to substantiate this regimen.

Advances in the Bioregulation of Mesenchymal Stem Cells by Low-Level Laser Therapy During Bone Formation: A Narrative Review

This article reviews the progress of research on the modulation of the biological effects of low-level laser therapy (LLLT) on Mesenchymal stem cells (MSC) and the influence of the basic LLLT parameters and irradiation scenarios. A thorough search of the literature in the PubMed, Web of Science and Embase databases, including articles published in peer-reviewed journals, was conducted to collect relevant information on LLLT and MSCs. A comprehensive search of PubMed, Web of Science, and Embase databases was performed using the keywords "Low level laser," "mesenchymal stem cells," " cell proliferation," and "osteogenic differentiation." The search was limited to studies published in English between 2009 and 2022, including in vitro and in vivo studies. LLLT has the potential to promote MSC proliferation and osteogenic differentiation, with significant applications in bone tissue engineering. Factors that influence the biological effects of LLLT on MSC include cell type, culture medium, duration of irradiation, the frequency of laser irradiation, irradiation spot size, and type of light flux distribution. The limitations of this review include heterogeneous experimental conditions and the inability to design experiments that consider all influencing factors simultaneously.

Application of low-level laser therapy for carpal tunnel syndrome in Cyprus

Aim: The aim of the study was to create a questionnaire that could be used by physiotherapists in Cyprus to define the parameters of low-level laser therapy (LLLT) in patients suffering from carpal tunnel syndrome (CTS) who had exhibitedsuch symptoms for more than 3 months. Material-Methods:Ninety-four questionnaires were distributed to physiotherapists working in Cyprus. The distribution was random and of the total 94 questionnaires 8 were sent via email and 86 were handed out in person. However, only 30 were answered, 29 in person and 1 via email (31.91% of the total) Results: The following parameters relating to use of the LLLT device in patients with CTS were recorded during the study. The treatment usesan aluminum gallium arsenide laser, set to continuous pulse width and emitting radiation in the form of red visible light.In addition, the non-contact technique is used,the average output power is 1.1W, the spot size is 20cm2 and the duration of treatment is 5 minutes. The energy density is 5J/cm2 and a laser of 30J energy is applied. The LLLT is used 5 times per week and the treatment lasts for 12 sessions. Conclusion: There is a consensus as to the choice of parameters in the LLLT: i.e. the type of laser, the radiation and the frequency of application per week. However, the emission wavelength, the question of contact, the average output power, the energy, the energy density, the duration of treatment, the spot size and the total number of sessions are still controversial issues

Evaluation of lipolysis and toxicological parameters of low-level laser therapy at different wavelengths and doses in the abdominal subcutaneous tissue.

Investigate the effects of low-level lasers therapy (LLLT) aiming abdominal lipolysis. Female Wistar rats received applications of LLLT directly in the abdominal skin twice a week (5weeks). Except the control group (n = 5), animals received treatments with red wavelength 660nm being (I) R3.3 group (n = 5): 3.3J/cm2, and (II) R5 group (n = 5): 5J/cm2, or infrared wavelength 808nm being (III) IR3.3 group (n = 5): 3.3J/cm2, and (IV) IR5 group (n = 5): 5J/cm2. Abdominal subcutaneous and liver tissues were evaluated histologically. Levels of thiobarbituric acid reactive substances (TBARS) and catalase (CAT) activity were analyzed in liver tissue. In the peripheral blood aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), high-density lipoprotein (HDL), low-density lipoprotein (LDL), triglycerides, and total cholesterol were investigated. Micronucleus assay was performed in the bone marrow. Except for the IR3.3 group, all treated groups reduced the body weight (p < 0.001). The R5 group reduced the abdominal subcutaneous tissue weight and thickness (p < 0.05), even though all treated groups reduced the number of adipocytes and its size (p < 0.001). No histological changes in the liver. There were no alterations in the triglycerides and LDL levels. The IR5 group increased the total cholesterol levels and decreased the HDL, ALT (both p < 0.05), and AST levels (p < 0.001). The group IR3.3 showed higher levels of ALP (p < 0.01). The R3.3 group increased the TBARS and CAT activity (p < 0.05). No mutagenic effects were found. The red laser treatment at 5J/cm2 led to lipolysis and did not alter the liver's parameters.

Low\u2010level laser therapy using laser diode 940 nm in the mandibular impacted third molar surgery: double-blind randomized clinical trial

BackgroundThe effect of low-level laser therapy (LLLT) on pain mitigation following the third molar surgery is still controversial. The absence of a standard method for using laser among the studies is related to the types of sample selection, sample size, control, and LLLT parameters, which make pain mitigation following surgery more controversial. Therefore, this study aimed to determine the effect of LLLT on reducing pain, swelling, and trismus following the mandibular impacted third molar surgery.MethodsThis study was performed on 25 healthy subjects. After the surgery, amoxicillin 500 mg was prescribed every 8 h for a 7-day period besides oral Ibuprofen (Gelofen) 400 mg every 12 h for a 3-day period. The intraoral Laser diode 940 nm was applied immediately after suture on the tested side, while on the placebo side, a fiber tip was used with no laser radiation following surgery. Eventually, the pain score was evaluated by VAS index from the 1st to the 7th-day post-surgery and then analyzed by SPSS 24.ResultsThe results indicate that the mean swelling and trismus before, during, 2 days after, and 7 days after the intervention did not differ significantly between the two studied groups. However, the results show that on the sixth and seventh days, the pain was significantly lower in the intervention group compared to the control group.ConclusionsThe results suggest that although the pain, swelling, and trismus following surgery were lower on the radiated side, only pain was found to be significant on the radiated side (p < 0.05).The registration number of the clinical trial in a Primary Registry in the WHO Registry Network is IRCT20141209020258N110 and the date of retrospective registration is 04/05/2019. The related URL is https://www.irct.ir/trial/36321.

LOW-INTENSITY LASER RADIATION IN CORRECTION OF BLOOD HEMODYNAMIC AND RHEOLOGICAL PARAMETERS AFTER SURGERY FOR HEAD AND NECK CANCER

Purpose: to study the effect of low-level laser therapy (LLLT) in correction of blood hemodynamic and rheological parameters after surgery for head and neck cancer.Material and Methods. The study included 134 head and neck cancer patients with a median age of 54.24 ± 12.7 years (range: 23–78 years). There were 39 (29.1 %) men and 95 (70.9 %) women. To assess the effectiveness of LLLT, all patients were divided into 3 groups. Group I included 45 patients, who received conventional therapy without the use of LLLT. Group II consisted of 45 patients, who received conventional therapy in combination with LLLT. Group III included 44 patients, who received LLLT alone. Azor 2K-02 was used as a source of LLLT in the red to near infrared spectral range. Characteristics of blood flow in the vessels of the neck and the rheological properties of blood, as well as the parameters of spontaneous platelet aggregation and the content of soluble fibrinmonomer complexes in the blood plasma of patients were studied.Results. The data obtained indicated that the use of LLLT promoted normalization of blood rheological properties in patients, who underwent surgery. Normalization of blood rheological properties occurred faster and lasted for a longer period. In patients, who received conventional therapy in combination with LLLT, the hemodynamic and rheological parameters of blood were improved 2–14 days after therapy, whereas in patients receiving conventional therapy alone, this improvement was seen 30 or more days after therapy.Conclusion. LLLT in combination with conventional therapy was shown to have a positive effect on hemodynamic and rheological parameters after surgery for head and neck cancer.

Low-level laser therapy prevents muscle oxidative stress in rats subjected to high-intensity resistance exercise in a dose-dependent manner.

High-intensity resistance exercise (RE) increases oxidative stress leading to deleterious effects on muscle performance and recovery. The aim of this study was to assess the effect of applying low-level laser therapy (LLLT) prior to a RE session on muscle oxidative stress and to determine the possible influence of the dosimetric parameters. Female Wistar rats were assigned to non-LLLT (Ctr: non-exercised control; RNI: RE) or LLLT groups subjected to RE (radiant energy: 4J, 8J, and 12J, respectively). RE consisted of four maximum load climbs. An 830-nm DMC Lase Photon III was used to irradiate three points in gastrocnemius muscles (two limbs) before exercise. Animals were euthanized after 60min after the end of the exercise, and muscle tissue was removed for analysis of oxidative stress markers. All doses resulted in the prevention of increased lipoperoxidation; however, LLLT prevented protein oxidation only in rats that were pretreated with 8J and 12J of energy by LLLT. RE and LLLT did not change catalase activity. However, RE resulted in lower superoxide dismutase activity, and the opposite was observed in the LLLT group. These data indicate that LLLT prior to RE can prevent muscle oxidative stress. This study is the first to evaluate the impact of dosimetric LLLT parameters on the oxidative stress induced by RE, wherein both 8J and 12J of energy afforded significant protection.

Should open excisions and sutured incisions be treated differently? A review and meta-analysis of animal wound models following low-level laser therapy.

Although low-level laser therapy (LLLT) was discovered already in the 1960s of the twentieth century, it took almost 40years to be widely used in clinical dermatology/surgery. It has been demonstrated that LLLT is able to increase collagen production/wound stiffness and/or improve wound contraction. In this review, we investigated whether open and sutured wounds should be treated with different LLLT parameters. A PubMed search was performed to identify controlled studies with LLLT applied to wounded animals (sutured incisions-tensile strength measurement and open excisions-area measurement). Final score random effects meta-analyses were conducted. Nineteen studies were included. The overall result of the tensile strength analysis (eight studies) was significantly in favor of LLLT (SMD = 1.06, 95% CI 0.66-1.46), and better results were seen with 30-79mW/cm2 infrared laser (SMD = 1.44, 95% CI 0.67-2.21) and 139-281mW/cm2 red laser (SMD = 1.52, 95% CI 0.54-2.49). The overall result of the wound contraction analysis (11 studies) was significantly in favor of LLLT (SMD = 0.99, 95% CI 0.38-1.59), and the best results were seen with 53-300mW/cm2 infrared laser (SMD = 1.18, 95% CI 0.41-1.94) and 25-90mW/cm2 red laser (SMD = 1.6, 95% CI 0.27-2.93). Whereas 1-15mW/cm2 red laser had a moderately positive effect on sutured wounds, 2-4mW/cm2 red laser did not accelerate healing of open wounds. LLLT appears effective in the treatment of sutured and open wounds. Statistical heterogeneity indicates that the tensile strength development of sutured wounds is more dependent on laser power density compared to the contraction rate of open wounds.

Influence of low-level laser therapy on the healing of human bone maxillofacial defects: A systematic review

PurposeThis systematic review evaluates the effectiveness of low-level laser therapy (LLLT) to enhance maxillofacial area bone repair. MethodsA comprehensive search of studies published up to February 2017 and listed in PubMed/MEDLINE, Scopus, and Cochrane Library databases was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. ResultsThe 15 selected studies evaluated a total of 374 patients (mean age, 28.5years) who were treated with LLLT. Gallium-arsenide (GaAs) and gallium aluminium arsenide (GaAlAs) were the most commonly used devices, and LLLT parameters varied greatly. Wavelengths varied from 500 to 1000nm. Tooth extraction, distraction osteogenesis, maxillary expansion, periodontal defects, orthodontic movement and maxillary cystic defects were evaluated. From the 15 selected studies, six evaluated bone repair (primary outcomes). Of these, four studies showed improvement in bone formation after using LLLT, two demonstrated improved results for only one follow up period, and one showed no additional benefits. The other 9 studies evaluated secondary parameters related to healing (secondary outcomes) in the maxillofacial area after applying LLLT, including anti-inflammatory, analgesic, and healing accelerator effects, and quality of life related to oral health. There were no adverse or negative effects of LLLT reported. ConclusionWithin the limitation of this review, a possible improvement in bone density can be found when LLLT is applied postoperatively in maxillofacial bony defects. LLLT also seems to promote anti-inflammatory and analgesic effects and accelerate healing, as well as enhance quality of life related to oral health. However, LLLT use protocols need to be standardized before more specific conclusions can be drawn about this subject.

Low level laser therapy: An effective tool to enhance quality of life in head and neck cancer survivors

Patients treated for head and neck cancer commonly suffer from oral mucositis, ulceration, bacterial infection causing pain, discomfort, impairment of speech and deglutition, leading to dehydration, poor nutrition and mortality. Low level laser therapy (LLLT) is a promising state of the art method which can be used effectively to reduce these side effects. It works on the principle of photo-bio stimulation. LLLT induces a biological response through energy transfer within the cells. It has anti-inflammatory effects, stimulates the immune system, increases of blood flow, upsurges cellular metabolism thus boosts rapid wound healing. Cells play a crucial role in oral healing. However, little is known about the molecular basis of LLLT to modulate cell mechanism. Hence for better understanding, this review article aims to discuss the mechanism of action, recommended parameters of LLLT, biological effects on various oral cells and potential application to revive the adverse effects of onco-therapy on head and neck cancer patients.

Heavy load eccentric exercise for Achilles tendinopathy; too much of a good thing?

Background: A recent study estimated the incidence of Achilles tendinopathy in the 21–60 year age group as 235/100,000. The combination of eccentric exercise and low-level laser therapy (LLLT) may be beneficial in treating Achilles tendinopathy. In recent years the most common regime of eccentric exercise for Achilles tendinopathy advocates twice daily sessions, every day for 12 weeks; something patients find laborious and issues of compliance arise. Controversy exists over LLLT parameters and dose, especially irradiance and the 100 mW/cm2 limit set for Achilles tendons. The optimum dose for either modality, singularly or in combination has yet to be defined.

Low-level laser therapy as an alternative for pulpotomy in human primary teeth

This study aimed to evaluate the effects of low-level laser therapy (LLLT) on pulpal response of primary teeth. Twenty mandibular primary molars were randomly divided into the following groups: group I Buckley's formocresol (diluted at 1:5), group II calcium hydroxide, group III LLLT + zinc oxide/eugenol, and group IV LLLT + calcium hydroxide. LLLT parameters were set at 660-nm wavelength, 10-mW power output, and 2.5 J/cm(2) energy density for 10 s in continuous mode (InGaAlP laser, Twin Laser®, MMOptics, Sao Carlos, Sao Paulo, Brazil). The teeth were extracted at the regular exfoliation period. The dentin-pulp complex was graded by an established histopathological score system. Statistical analysis was performed by Kruskal-Wallis and chi-square test. The histopathological assessment revealed statistically significant differences among groups (P < 0.05). The lowest degree of pulpal inflammation was present in LLLT + calcium hydroxide (P = 0.0296). Calcium hydroxide showed the highest rate of hard tissue barrier (P = 0.0033), odontoblastic layer (P = 0.0033), and dense collagen fibers (P = 0.0095). On the other hand, formocresol showed the highest incidence of internal resorption (P = 0.0142). Based on this study, low-level laser therapy preceding the use of calcium hydroxide exhibited satisfactory results on pulp tissue healing. However, further clinical studies on human teeth with long-term follow-up are needed to test the low-level laser therapy efficacy.

Low-Level Laser Therapy with 810 nm Wavelength Improves Skin Wound Healing in Rats with Streptozotocin-Induced Diabetes

The aim of present study was to evaluate whether low-level laser therapy (LLLT) can reverse the impaired wound healing process in diabetic rats. Impaired wound healing in diabetic patients represents a major health problem. Recent studies have indicated that LLLT may improve wound healing in diabetic rats, but the optimal treatment parameters are still unknown. Male Sprague-Dawley rats (n=21) were randomly divided into three groups: a healthy control group, a diabetic sham-treated group, and a diabetic LLLT-treated group. Diabetes mellitus was then induced by streptozotocin administration to the two diabetic groups. One 4 cm long full thickness skin incision and one full thickness circular excision (diameter=4 mm) were performed on the back of each rat. An infrared 810 nm laser with an output of 30 mW, a power density of 30 mW/cm(2), and a spot size of 1 cm(2) was used to irradiate each wound for 30 sec (daily dose of 0.9 J/cm(2)/wound/day). In diabetic rats, the histology of LLLT-treated excisions revealed a similar healing response to that in nondiabetic controls, with significantly more mature granulation tissue than in the sham-treated diabetic control group. LLLT reduced the loss of tensile strength, and increased the incision wound stiffness significantly compared with sham-irradiated rats, but this did not achieve the same level as in the nondiabetic controls. Our study demonstrates that infrared LLLT can improve wound healing in diabetic rats. Nevertheless, further research needs to be performed to evaluate the exact underlying mechanism and to further optimize LLLT parameters for clinical use.

A Meta-analysis of Clinical Effects of Low-level Laser Therapy on Temporomandibular Joint Pain.

[Purpose] Temporomandibular joint (TMJ) pain is a symptom of TMJ disease. Low-level laser therapy (LLLT) is often used in the clinical treatment of TMJ pain. The aim of this study was to review the effective parameters of LLLT for TMJ pain. [Methods] This study was a systematic review in which electronic databases were searched for the period of January 2005 to January 2010. We selected reports of randomized controlled trials and calculated the effect size (ES) of the pain relief to evaluate the effect of LLLT. [Results] Seven reports are found to meet the inclusion criteria and discussed. Based on the calculation results, the pooled ES was –0.6, indicating a moderate effect of pain relief. In addition, the dosages and treatments with wavelengths of 780 and 830 nm can cause moderate and large pain relief effects. [Conclusion] Use of LLLT on the masticatory muscle or joint capsule for TMJ pain had a moderate analgesic effect. The optimal parameters for LLLT to treat TMJ pain have not been confirmed. However, our results can be a vital clinical reference for clinical physicians in treatment of patients with TMJ pain.

Biostimulatory effects of low-level laser therapy on epithelial cells and gingival fibroblasts treated with zoledronic acid

Low-level laser therapy (LLLT) has been considered as an adjuvant treatment for bisphosphonate-related osteonecrosis, presenting positive clinical outcomes. However, there are no data regarding the effect of LLLT on oral tissue cells exposed to bisphosphonates. This study aimed to evaluate the effects of LLLT on epithelial cells and gingival fibroblasts exposed to a nitrogen-containing bisphosphonate—zoledronic acid (ZA). Cells were seeded in wells of 24-well plates, incubated for 48 h and then exposed to ZA at 5 μM for an additional 48 h. LLLT was performed with a diode laser prototype—LaserTABLE (InGaAsP—780 nm ± 3 nm, 25 mW), at selected energy doses of 0.5, 1.5, 3, 5, and 7 J cm−2 in three irradiation sessions, every 24 h. Cell metabolism, total protein production, gene expression of vascular endothelial growth factor (VEGF) and collagen type I (Col-I), and cell morphology were evaluated 24 h after the last irradiation. Data were statistically analyzed by Kruskal–Wallis and Mann–Whitney tests at 5% significance. Selected LLLT parameters increased the functions of epithelial cells and gingival fibroblasts treated with ZA. Gene expression of VEGF and Col-I was also increased. Specific parameters of LLLT biostimulated fibroblasts and epithelial cells treated with ZA. Analysis of these in vitro data may explain the positive in vivo effects of LLLT applied to osteonecrosis lesions.

Therapeutic Effects of Low-Level Laser Therapy After Premolar Extraction in Adolescents: A Randomized Double-Blind Clinical Trial

The purpose of this study was to evaluate the effect of low-level laser therapy (LLLT) on wound healing process and pain levels after premolar extraction in adolescents. The advantage of using LLLT in oral surgeries is the reduction of inflammation and postoperative discomfort; however, the optimal dosing parameters and treatment effects in surgical procedures are inconclusive. A double-blind, randomized, controlled clinical trial was conducted with 14 patients who were to undergo surgical removal of premolars. Patients were randomly allocated to the LLLT (test) group and placebo (control) group. Patients in the test group received 5.1 J (60 J/cm(2)) of energy density of a gallium-aluminum-arsenide (GaAlAs) diode laser (wavelength, 830 nm; output power, 0.1 W) at three different points intraorally, 1 cm from the target tissue immediately and at 48 and 72 h after the surgical procedure. For patients in the placebo group, the laser device was applied to the same points without activating the hand piece. The wound healing process was evaluated by an independent examiner by visual inspection with the support of digital photographs at baseline and 2, 7, and 15 days postoperatively. Patients recorded the degree of pain using the visual analogue scale (VAS). Compared with the placebo group, the test group showed a lower intensity of pain, but this difference was not statistically significant at any time point. The wound healing process was similar in both groups. Within the limitations of this study, the LLLT parameters used neither increased the wound healing process nor significantly decreased pain intensity after premolar extraction in adolescents.

Effects of low-level laser therapy after nerve reconstruction in rat denervated soleus muscle adaptation

Peripheral nerve injury (PNI) rehabilitation remains a challenge for physical therapists because PNI effects are very disabling. Low-level laser therapy (LLLT) has been described as a physical resource that is able to influence enzymes called metallopeptidases (MMPs) associated with extracellular matrix (ECM) turnover, thus accelerating neuromuscular recovery after nerve crush injuries. However, the effects of LLLT in the treatment of severe nerve injuries and denervated slow-twitch muscles are still inconclusive. The aim of this study was to evaluate the effects of different wavelengths and energy densities of LLLT irradiation, applied to a severe nerve injury after reconstruction, on denervated slow-twitch skeletal muscle adaptation. Rats were submitted to a neurotmesis of the sciatic nerve followed by end-to-end neurorrhaphy. They received transcutaneous LLLT irradiation at the lesion site. The LLLT parameters were: wavelengths--660 or 780 nm; energy densities--10, 60 or 120 J/cm²; power--40 mW; spot--4 mm². Sciatic functional index (SFI), histological, morphometric, and zymographic analyses were performed. One-way ANOVA followed by Tukey's test was used (p≤0.05). An atrophic pattern of muscle fibers was observed in all injured groups. The MMP activity in the soleus muscle reached normal levels. On the other hand, SFI remained below normality after PNI, indicating incapacity. No difference was found among PNI groups submitted or not to LLLT in any variable. LLLT applied to the nerve post-reconstruction was ineffective in delaying degenerative changes to the slow-twitch denervated muscles and in functional recovery in rats. New studies on recovery of denervated slow-twitch muscle are necessary to support clinical practice.

Low-level laser therapy in different stages of rheumatoid arthritis: a histological study

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease of unknown etiology. Treatment of RA is very complex, and in the past years, some studies have investigated the use of low-level laser therapy (LLLT) in treatment of RA. However, it remains unknown if LLLT can modulate early and late stages of RA. With this perspective in mind, we evaluated histological aspects of LLLT effects in different RA progression stages in the knee. It was performed a collagen-induced RA model, and 20 male Wistar rats were divided into 4 experimental groups: a non-injured and non-treated control group, a RA non-treated group, a group treated with LLLT (780nm, 22mW, 0.10W/cm(2), spot area of 0.214cm(2), 7.7J/cm(2), 75s, 1.65J per point, continuous mode) from 12th hour after collagen-induced RA, and a group treated with LLLT from 7th day after RA induction with same LLLT parameters. LLLT treatments were performed once per day. All animals were sacrificed at the 14th day from RA induction and articular tissue was collected in order to perform histological analyses related to inflammatory process. We observed that LLLT both at early and late RA progression stages significantly improved mononuclear inflammatory cells, exudate protein, medullary hemorrhage, hyperemia, necrosis, distribution of fibrocartilage, and chondroblasts and osteoblasts compared to RA group (p < 0.05). We can conclude that LLLT is able to modulate inflammatory response both in early as well as in late progression stages of RA.