Polarized Light Therapy in the Treatment of Wounds: A Review

The most prevalent type of photo therapies are low-level laser therapy (LLLT) and ultraviolet (UV) treatments, which are distinguished by the physical properties of the light employed. However, in latest years, it has been suggested that polarization and an extensive light band including all light spectra are essential aspects in light treatment. Light waves are filtered to align and vibrate in a single plane, resulting in polarized light (PL). Light that has been polarized can penetrate tissues more deeply than light that has not been polarized. The visible light spectrum is very broad. PL varies from other types of light therapy in that it uses a considerably wider spectrum of wavelengths than LLLT or UV. As a result, PLT devices are often less expensive and simple to operate. Since the late 1960s, light therapy has been used to treat anything from neonatal jaundice to psoriasis and vitiligo. Fenyö created a PL source and found that it can stimulate wound healing in a similar way to the low-energy laser. In comparison to the laser, this source of light had numerous gains: lesser prices, fewer hazards, a greater area to be treated, and no sophisticated user expertise. Despite several findings from fundamental research (in vitro, in vivo, and animal trials), practitioners continue to have reservations regarding PL's potency and utility in treating musculoskeletal problems. It is even largely believed that the commercial use of these therapies is validated by a sufficient amount of scientific evidence based on reliable clinical papers. The major goal of this study is to gather information on the use of PL for treatment of various wound types in animal and human investigations.

Transcutaneous Electrical Stimulation, Interferential Current and Photobiomodulation May Lead to the Recurrence of Breast Cancer in Rats?

Introduction: Transcutaneous electrical nerve stimulation (TENS), interferential current therapy (IFC) and photobiomodulation therapy (PBMT) have been used in the management of cancer-related pain in adults. However, there are still some controversy regarding the effects of this therapy on tumor cells that may remain after cancer treatment. Objective: To evaluate the risk of recurrence of breast cancer in rats when using TENS, IFC or PBMT. Method: An experimental, randomized, controlled and cross-sectional study. With 90 days of age, 7,12-dimetylbenz(a)anthracene (7,12-DMBA) was administered to rats by gastric gavage to induce mammary cancer. After 120 days the mammary glands of the rats belonging to the group with mammary cancer were removed. Results: 39 female Sprague-Dawley rats were studied: 9 rats without induction of mammary carcinoma; 9 rats with induction of mammary carcinoma and without surgery; 9 rats with induction of mammary carcinoma with surgery and placebo application of TENS, IFC, PBMT; 9 rats with induction of mammary carcinoma, surgery and the application of TENS, IFC and PBMT. Conclusion: This study demonstrated that there was local recurrence of tumors in rats that were stimulated with TENS or IFC, however no evidence of local recurrence with PBMT.

Effects of low level laser therapy on injection pain and anesthesia efficacy during local anesthesia in children: A randomized clinical trial

BACKGROUND

The use of low level laser therapy (LLLT) to reduce injection pain associated with dental local anesthesia is reported in a limited number of studies in adults, but research on the effects of LLLT in children is needed.

AIM

This study aimed to evaluate the effects of topical anesthesia + LLLT on injection pain, anesthesia efficacy, and duration in local anesthesia of children who are undergoing pulpotomy treatment.

DESIGN

The study was conducted as a randomized, controlled-crossover, double-blind clinical trial with 60 children aged 6-9 years. Before local infiltration anesthesia was administered, only topical anesthesia was applied in one side (control group/CG), and topical anesthesia plus LLLT (a diode laser: 810 nm; continuous mode; 0.3W; 20 s; 69 J/cm² ) was applied in the contralateral side (LG) as pre-anesthesia. The injection pain and anesthesia efficacy were evaluated subjectively and objectively using the Wong-Baker Faces Pain Rating Scale (PRS) and the Face, Legs, Activity, Cry, Consolability (FLACC) scale respectively. Data were analyzed for statistical significance (p < .05).

RESULTS

The "no pain" and "severe pain" rates in the PRS were 41.7% and 3.3% for the LG and 21.7% and 11.7% for the CG, respectively, during injection. Similarly, in the FLACC data, the number of "no pain" responses was higher for the LG than the CG (40%, 33.3%) and no "severe pain" rate was observed in both groups. The only statistically significant difference found for the PRS was p < .05. The median pain score was "0" for the LG and the CG in the FLACC data for the evaluation of anesthesia efficacy, and there was no statistically significant difference between the groups in terms of pain and anesthesia duration (p > .05). Also, most of the children preferred injection with topical anesthesia + LLLT (66.7%).

CONCLUSIONS

It has been determined that the application of topical anesthesia + LLLT with an 810-nm diode laser before local infiltration anesthesia reduced injection pain and did not have an effect on anesthesia efficacy and duration in children.

Evaluating the Preemptive Analgesic Effect of Photo-biomodulation Therapy on Pain Perception During Local Anesthesia Injection in Children: A Split-mouth Triple-blind Randomized Controlled Clinical Trial

To evaluate the impact of photobiomodulation therapy (PBMT) on injection pain perception and compare it with a topical oral anesthetic gel. A total of 30 patients of six to nine years old seeking pulpotomy treatment of maxillary secondary primary molars of both sides were considered for this split-mouth triple-blind randomized clinical trial. On one side of the maxilla, the low-level-laser (diode laser, 808 nm, 250 mW; 16.25 J; 32.5 J/cm² ) was irradiated upon the buccal gingiva of the tooth, while a Benzocaine 20% topical anesthetic gel was applied on the other side. A gel with the same taste (strawberry) was applied for the placebo. The Wong-Baker Faces Pain Rating Scale was used to evaluate the injection pain and post-operation pain at two timestamps, one hour and 24 hours after treatment. Patients' heart rate was also evaluated. Paired-T, Wilcoxon-signed-rank test, McNemar and Friedman tests were used for statistical analyses. Results demonstrated that PBMT could significantly decrease the injection pain perception and heart rate alternations compared to the topical anesthetic gels (P=0.000). However, no significant differences were documented between the two methods concerning the 1hour (P=0.26) and 24-hours (P=1.00) post-operation pain. PBMT can be an effective non-pharmacological technique for controlling injection pain.

An Efficacy of Photobiomodulation of 850 nm on Pain Reduction in a Human Oral Capsaicin Pain Model

Objective: The aim of this clinical trial was to evaluate the efficacy of photobiomodulation (PBM) to reduce oral pain initiated by capsaicin. Background: PBM has been used for pain reduction in oral regions; however, its clinical efficacy to alleviate burning sensations is still unknown. Methods: This clinical study was divided into two phases. There were 10 subjects in each phase. In Phase I, the burning sensation was stimulated using 0.05% in 95% ethanol capsaicin (prepared by the Faculty of Pharmaceutical Sciences, Khon Kaen University, Thailand) on filter paper and recorded with a 10-cm horizontal visual analog scale (VAS) every 1 min until the subject experienced no more pain. The area under the curve (AUC) of the graph between VAS and time was calculated. The washout period was 24 h. In Phase II, a crossover clinical trial was conducted in subjects who received the pain model as stated. Four interventions were included: (1) PBM before & after pain stimulation, (2) PBM before pain stimulation, (3) PBM after pain stimulation, and (4) Placebo. For PBM intervention, a single exposure of 850 nm Laser (AsGaAl; TOP 250 Soft Laser, Berkmed Medikal, distributed by Medical Innovation-MI, Istanbul, Turkey) with 0.10 cm² spot size laser probe continuous wave at 1 W/cm² and 30 J/cm² for 30 sec was used. Results: In Phase I, there was no statistically significant difference (p = 0.09) between the average AUC of day 1 [55.63 (23.38)] and day 2 [48.99 (27.20)]. In phase II, there was no statistical difference (p = 0.20) of the average AUC among the interventions and the placebo; group 1 [56.24 (30.11)], group 2 [45.46 (45.46)], group 3 [64.15 (32.89)], and group 4 [58.59 (30.16)]. Conclusions: The human capsaicin model was suitable for a crossover design clinical trial. The PBM used in this study did not reduce oral burning sensations from capsaicin.

Low intensity laser for reducing pain from anesthetic palatal injection

OBJECTIVE

The aim of this study was to evaluate the effectiveness of pain reduction techniques for palatal injection, namely, low intensity laser therapy (LILT), topical anesthesia, pressure, and light touch.

BACKGROUND DATA

Previous evidence indicates that LILT may prevent pain from palatal injection. However, no clinical trials evaluating this clinical question have been performed.

METHODS

A double-blind clinical trial was conducted using 80 healthy volunteers, 18-25 years of age. The subjects were randomly allocated into four groups with 10 females and 10 males each group. Pain reduction techniques were administered at an injection point that was 10 mm from the margin of the palatal gingiva of the upper left first molar according to the following groups: (1) a 790 nm 30 mW continuous wave with a 0.13 cm2 focal spot at an applied energy of 3.6 J and fluence of 27.69 J/cm2, (2) 20% benzocaine, (3) pressure, and (4) light touch as the control. Then, 2% lidocaine with 1:100,000 epinephrine was injected using a 27-gauge needle with a pressure and volume control intraligamentary syringe. All subjects recorded pain on a 10 cm visual analog scale (VAS).

RESULTS

The pain score in the LILT group was <50 mm. The median of pain scores of the LILT, 20% benzocaine, pressure, and light touch groups were 11, 23, 27, and 31 mm, respectively. There was no statistically significant difference in VAS among the groups, using Kruskal-Wallis test (p=0.385).

CONCLUSIONS

No statistically significant differences in pain scores were noted among low intensity laser, 20% benzocaine, pressure, and light touch.

Photobiomodulation of the dorsal root ganglion for the treatment of low back pain: A pilot study

BACKGROUND AND OBJECTIVE

Chronic low back pain is a worldwide public health issue with high socioeconomic impact. The aim of this study was to determine the efficacy of laser irradiation of the dorsal root ganglion of the second lumbar spinal nerve for chronic axial low back pain compared to lidocaine injection and radiofrequency treatment.

STUDY DESIGN/MATERIALS AND METHODS

Twenty-eight patients were randomly divided into three treatment groups: lidocaine injection, radiofrequency, or laser. The second intervertebral foramen between the second and third lumbar vertebrae was accessed by percutaneous needle puncture bilaterally, guided by fluoroscopy. In the local anesthetic group, injection of 1 ml lidocaine without epinephrine was applied through a 20-gauge (G20) Quincke tip spinal needle inserted in the second lumbar intervertebral foramen. In the radiofrequency group, the probe (150 mm long with a 5 mm active tip) was directed through a G20 needle placed in the second lumbar intervertebral foramen and neuromodulation was done with a radiofrequency of Cosman G4® in pulses of 20 ms with wash-out period of 480 ms, for 300 seconds at 42°C. A single treatment was used. In the laser treatment group, a continuous wave, 808 nm wavelength diode laser (Photon Lase III® DCM, Brazil), with an output power of 100 mW was used for a single treatment. An 18 gauge needle was placed in the second lumbar intervertebral foramen guided by fluoroscopy. Light was delivered through a 600 µm optical fiber placed in the G18 needle. The tip of the fiber extended 5 mm beyond the tip of the needle in the second lumbar intervertebral foramen. The beam spot size was 0.003 cm(2) , irradiance = 35W/cm(2) , exposure time = 84 seconds, energy density = 2800J/cm(2) , total energy was 8.4 J. The low back pain score was assessed by the visual analog scale (VAS) and Pain Relief Scale (PRS) pre, post procedure and in 1 month follow up. Temperature was measured using a digital thermometer.

RESULTS

All patients in the local anesthetic and laser treatment groups reported a pain reduction of at least 50% immediately post-procedure and 10 out of 11 patients in the radiofrequency group reported a pain reduction of at least 50%. At 1 month post-treatment, the laser treatment group had the greatest number of patients who reported more than 50% pain relief based on PRS (7 out of 10 patients) while only 2 out of 7 patients and 3 out of 11 patients in the lidocaine and radiofrequency treatment groups respectively reported more than a 50% pain relief.

CONCLUSION

Laser irradiation caused an immediate decrease in low back pain post-procedure similar to pain reduction caused by lidocaine injection. Both lidocaine injection and laser irradiation were more effective than radiofrequency treatment for immediate and longer term (1 month post-treatment) chronic back pain. Lasers Surg. Med. 48:653-659, 2016. © 2016 Wiley Periodicals, Inc.

Decreased Bone Volume and Bone Mineral Density in the Tibial Trabecular Bone Is Associated with Per2 Gene by 405 nm Laser Stimulation

Low-level laser therapy/treatment (LLLT) using a minimally invasive laser needle system (MILNS) might enhance bone formation and suppress bone resorption. In this study, the use of 405 nm LLLT led to decreases in bone volume and bone mineral density (BMD) of tibial trabecular bone in wild-type (WT) and Per2 knockout (KO) mice. Bone volume and bone mineral density of tibial trabecular bone was decreased by 405 nm LLLT in Per2 KO compared to WT mice at two and four weeks. To determine the reduction in tibial bone, mRNA expressions of alkaline phosphatase (ALP) and Per2 were investigated at four weeks after 405 nm laser stimulation using MILNS. ALP gene expression was significantly reduced in the LLLT-stimulated right tibial bone of WT and Per2 KO mice compared to the non-irradiated left tibia (p < 0.001). Per2 mRNA expression in WT mice was significantly reduced in the LLLT-stimulated right tibial bone compared to the non-irradiated left tibia (p < 0.001). To identify the decrease in tibial bone mediated by the Per2 gene, levels of runt-related transcription factor 2 (Runx2) and ALP mRNAs were determined in non-irradiated WT and Per2 KO mice. These results demonstrated significant downregulation of Runx2 and ALP mRNA levels in Per2 KO mice (p < 0.001). Therefore, the reduction in tibial trabecular bone resulting from 405 nm LLLT using MILNS might be associated with Per2 gene expression.

Long-term effect of pulsed high-intensity laser therapy in the treatment of post-mastectomy pain syndrome: a double blind, placebo-control, randomized study

We assess the long-term effect of pulsed high-intensity laser therapy (HILT) in the treatment of the post-mastectomy pain syndrome (PMPS). A total of 61 women participated in this study (30 in the laser group and 31 in the placebo laser group), with a mean age of 53.56 ± 1.11 years. Patients who were randomly assigned to the laser group received HILT three times per week for 4 weeks, plus a routine physical therapy program (RPTP). The placebo laser group received placebo HILT plus RPTP. The outcomes measured were pain level by visual analog scale (VAS), shoulder range of motion (ROM), and quality of life (QOL). Statistical analysis was performed by ANOVA with repeated measures to compare the differences between baseline and post-treatment measurements and after 12 weeks of follow-up for both groups. The level of statistical significance was set at P < 0.05. Shoulder ROM significantly increased in the laser group after 4 weeks of treatment and after 12 weeks of follow-up compared with the placebo group. VAS results showed a significant decrease post-treatment in the laser group relative to the placebo group, and QOL results showed a significant improvement in the laser group compared with the placebo group and still improved after 12 weeks of follow-up. HILT combined with an RPTP appears to be more effective in patients with PMPS than a placebo laser procedure with RPTP.

Low-dose laser acupuncture for non-specific chronic low back pain: a double-blind randomised controlled trial

Objective

To determine if infrared laser acupuncture (LA) may have a specific effect in reducing pain and disability in treatment of chronic low back pain (LBP).

Methods

This was a double-blind sham laser controlled trial performed in general practices in Perth, Western Australia. The participants were 144 adults with chronic non-specific LBP. They were randomised to receive eight once-weekly treatments. Laser machines (20 mW, 840 nm diode, power density 0.1 W/cm²) stimulated points in three treatment groups: sham (0 joules/point), low dose (0.2 J/point) and high dose (0.8 joules/point). Participants were followed-up at 1 and 6 weeks, and 6 and 12 months post treatment. Primary outcomes were pain (Numerical Pain Rating Scale (NPRS)) and disability (Oswestry Disability Inventory (ODI)) at 6 weeks post treatment. Secondary outcomes included numerical rating scale for limitation of activity, global assessment of improvement, analgesic usage and adverse effects after treatment.

Results

The analysis showed no difference between sham and the laser groups at 6 weeks for pain or disability. There was a significant reduction in mean pain and disability in all groups at 6 weeks (p<0.005); NPRS: sham (−1.5 (95% CI −2.1 to −0.8)), low dose (−1.3 (−2.0 to −0.8)), high dose (−1.1 (−1.7 to −0.5)). ODI: sham (−4.0 (−7.1 to −1.0)), low dose (−4.1, (−6.7 to −1.5)), high dose (−2.6 (−5.7 to 0.5)). All secondary outcomes also showed clinical improvement over time but with no differences between groups.

Conclusions

LA using energy density range (0–4 J/cm²) for the treatment of chronic non-specific LBP resulted in clinical improvement unrelated to laser stimulation.

Trial registration

http://www.anzctr.org.au ACTRN12610000043033.

Is low-level laser therapy in relieving neck pain effective? Systematic review and meta-analysis

The aim of this study is to determine the efficacy of low-level laser therapy (LLLT) in reducing acute and chronic neck pain as measured by the visual analog scale (VAS). A systematic search of nine electronic databases was conducted to identify original articles. For study selection, two reviewers independently assessed titles, abstracts, and full text for eligibility. Methodological quality was assessed using the Detsky scale. Data were analyzed using random-effects model in the presence of heterogeneity and fixed-effect model in its absence. Heterogeneity was assessed using Cochran's Q statistic and quantifying I (2). Risk ratios (RR) with 95 % confidence intervals (CI) were reported. Eight randomized controlled trials involving 443 patients met the strict inclusion criteria. Inter-rater reliability for study selection was 92.8 % (95 % CIs 80.9-100 %) and for methodological quality assessment was 83.9 % (95 % CIs 19.4-96.8 %). Five trials included patients with cervical myofascial pain syndrome (CMPS), and three trials included different patient populations. A meta-analysis of five CMPS trials revealed a mean improvement of VAS score of 10.54 with LLLT (95 % CI 0.37-20.71; Heterogeneity I (2 )= 65 %, P = 0.02). This systematic review provides inconclusive evidence because of significant between-study heterogeneity and potential risk of bias. The benefit seen in the use of LLLT, although statistically significant, does not constitute the threshold of minimally important clinical difference.

Evaluation of the effectiveness of diode laser on pain and edema in individuals with cleft lip and palate submitted to secondary bone graft

OBJECTIVE : To clinically evaluate the effects of diode laser, Gallium-Aluminum-Arsenide laser (GaAlAs), on the pain and edema after secondary alveolar bone graft. DESIGN : Case-control, double-blind study. Setting : Institutional tertiary referral hospital. Participants : The sample was composed of 60 individuals with complete unilateral cleft lip and palate, of both genders, aged 9 to 15 years, submitted to secondary alveolar bone graft. MAIN OUTCOME MEASURES : The individuals were divided into an experimental group (patients irradiated with diode laser GaAlAs, energy density of 4 J/cm(2), power of 100 mW, and wavelength in the infrared spectrum, for 10 seconds per point on 10 points, adding up to a dose of 40 J/cm(2)) and a placebo group (simulated laser application for 60 seconds per point, also on 10 points). Applications were made on the receptor site immediately postoperatively and after 24 and 48 hours. The pain and edema were assessed preoperatively and at each application. RESULTS : The two groups presented increase in pain and edema in 24 and 48 hours. No statistically significant difference was found between groups. CONCLUSIONS : According to the present methodology, the use of low-level laser to control the pain and edema in the postoperative period of secondary alveolar bone graft was not effective.

Efficacy of low-level laser therapy in the management of neck pain: a systematic review and meta-analysis of randomised placebo or active-treatment controlled trials

BACKGROUND

Neck pain is a common and costly condition for which pharmacological management has limited evidence of efficacy and side-effects. Low-level laser therapy (LLLT) is a relatively uncommon, non-invasive treatment for neck pain, in which non-thermal laser irradiation is applied to sites of pain. We did a systematic review and meta-analysis of randomised controlled trials to assess the efficacy of LLLT in neck pain.

METHODS

We searched computerised databases comparing efficacy of LLLT using any wavelength with placebo or with active control in acute or chronic neck pain. Effect size for the primary outcome, pain intensity, was defined as a pooled estimate of mean difference in change in mm on 100 mm visual analogue scale.

FINDINGS

We identified 16 randomised controlled trials including a total of 820 patients. In acute neck pain, results of two trials showed a relative risk (RR) of 1.69 (95% CI 1.22-2.33) for pain improvement of LLLT versus placebo. Five trials of chronic neck pain reporting categorical data showed an RR for pain improvement of 4.05 (2.74-5.98) of LLLT. Patients in 11 trials reporting changes in visual analogue scale had pain intensity reduced by 19.86 mm (10.04-29.68). Seven trials provided follow-up data for 1-22 weeks after completion of treatment, with short-term pain relief persisting in the medium term with a reduction of 22.07 mm (17.42-26.72). Side-effects from LLLT were mild and not different from those of placebo.

INTERPRETATION

We show that LLLT reduces pain immediately after treatment in acute neck pain and up to 22 weeks after completion of treatment in patients with chronic neck pain.

FUNDING

None.

Low level laser therapy for nonspecific low-back pain

BACKGROUND

Low-back pain (LBP) is a major health problem and a major cause of medical expenses and disablement. Low level laser therapy (LLLT) can be used to treat musculoskeletal disorders such as back pain.

OBJECTIVES

To assess the effects of LLLT in patients with non-specific LBP.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2005, Issue 2), MEDLINE, CINAHL, EMBASE, AMED and PEDro from their start to November 2007 with no language restrictions. We screened references in the included studies and in reviews and conducted citation tracking of identified RCTs and reviews using Science Citation Index. We also contacted content experts.

SELECTION CRITERIA

Randomised controlled clinical trials (RCTs) investigating LLLT to treat non-specific low-back pain were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed methodological quality using the criteria recommended by the Cochrane Back Review Group and extracted data. Studies were qualitatively and quantitatively analysed according to Cochrane Back Review Group guideline.

MAIN RESULTS

Seven heterogeneous English language RCTs with reasonable quality were included. Three small studies (168 people) separately showed statistically significant but clinically unimportant pain relief for LLLT versus sham therapy for sub-acute and chronic low-back pain at short-term and intermediate-term follow-up (up to six months). One study (56 people) showed that LLLT was more effective than sham at reducing disability in the short term. Three studies (102 people) reported that LLLT plus exercise were not better than exercise, with or without sham in the short-term in reducing pain or disability. Two studies (90 people) reported that LLLT was not more effective than exercise, with or without sham in reducing pain or disability in the short term. Two small trials (151 people) independently found that the relapse rate in the LLLT group was significantly lower than in the control group at the six-month follow-up. No side effects were reported.

AUTHORS' CONCLUSIONS

Based on the heterogeneity of the populations, interventions and comparison groups, we conclude that there are insufficient data to draw firm conclusions on the clinical effect of LLLT for low-back pain. There is a need for further methodologically rigorous RCTs to evaluate the effects of LLLT compared to other treatments, different lengths of treatment, wavelengths and dosages.

WITHDRAWN: Low level laser therapy for nonspecific low-back pain

BACKGROUND

Low-back pain (LBP) and related disabilities are major public health problems and a major cause of medical expenses, absenteeism and disablement. Low level laser therapy (LLLT) can be used as a therapeutic intervention for musculoskeletal disorders such as back pain.

OBJECTIVES

To assess the effects of LLLT in patients with non-specific low-back pain and to explore the most effective method of administering LLLT for this disorder.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2005, Issue 2), MEDLINE and CINAHL from their start to January 2007 and EMBASE, AMED and PEDro from their start to 2005 with no language restrictions. We screened references in the included studies and in reviews of the literature and conducted citation tracking of identified RCTs and reviews using Science Citation Index. We also contacted content experts.

SELECTION CRITERIA

Only randomised controlled clinical trials (RCTs) investigating low level laser therapy as a light source treatment for non-specific low-back pain were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed methodological quality using the criteria recommended by the Cochrane Back Review Group and extracted data. Consensus was used to resolve disagreements. Clinically and statistically homogeneous studies were pooled using the fixed-effect model; clinically homogeneous and statistically heterogeneous studies were pooled using the random-effects model.

MAIN RESULTS

Six RCTs with reasonable quality were included in the review. All of them were published in English. Because of clinical heterogeneity in study populations, interventions used and reported outcomes, meta-analysis was not possible to determine an overall effect for pain, disability and range of motion. Three studies (n=168) separately showed a significant pain relief effect of LLLT compared to sham therapy for sub-acute and chronic low-back pain. These effects were only observed at short-term and intermediate-term follow-ups. Long-term follow-ups were not reported. There was insufficient evidence to investigate the difference between LLLT and comparison groups for pain-related disability. There is insufficient evidence to determine the effectiveness of LLLT on anterior-posterior lumbar range of motion compared to control group in short-term follow-up. The relapse rate in the LLLT group was significantly lower than in the control group at six months follow-up period according to the findings of two trials. One study (n=50) reported a significant improvement in pain in LLLT group versus exercise therapy.

AUTHORS' CONCLUSIONS

No side effects were reported. However, we conclude that there are insufficient data to draw firm conclusions. There is a need for further methodologically rigorous RCTs to evaluate the effects of LLLT compared to other treatments, different lengths of treatment, different wavelengths and different dosages. Comparison of different LLLT treatments will be more reasonable if dose calculation methods are harmonized.

The effect of 300 mW, 830 nm laser on chronic neck pain: A double-blind, randomized, placebo-controlled study

A randomized, double-blind, placebo-controlled study of low-level laser therapy (LLLT) in 90 subjects with chronic neck pain was conducted with the aim of determining the efficacy of 300 mW, 830 nm laser in the management of chronic neck pain. Subjects were randomized to receive a course of 14 treatments over 7 weeks with either active or sham laser to tender areas in the neck. The primary outcome measure was change in a 10 cm Visual Analogue Scale (VAS) for pain. Secondary outcome measures included Short-Form 36 Quality-of-Life questionnaire (SF-36), Northwick Park Neck Pain Questionnaire (NPNQ), Neck Pain and Disability Scale (NPAD), the McGill Pain Questionnaire (MPQ) and Self-Assessed Improvement (SAI) in pain measured by VAS. Measurements were taken at baseline, at the end of 7 weeks' treatment and 12 weeks from baseline. The mean VAS pain scores improved by 2.7 in the treated group and worsened by 0.3 in the control group (difference 3.0, 95% CI 3.8-2.1). Significant improvements were seen in the active group compared to placebo for SF-36-Physical Score (SF36 PCS), NPNQ, NPAD, MPQVAS and SAI. The results of the SF-36 - Mental Score (SF36 MCS) and other MPQ component scores (afferent and sensory) did not differ significantly between the two groups. Low-level laser therapy (LLLT), at the parameters used in this study, was efficacious in providing pain relief for patients with chronic neck pain over a period of 3 months.

Low-level laser therapy in acute pain: a systematic review of possible mechanisms of action and clinical effects in randomized placebo-controlled trials

OBJECTIVE

The aim of this study was to review the biological and clinical short-term effects of photoradiation in acute pain from soft-tissue injury.

BACKGROUND DATA

It is unclear if and how photoradiation can reduce acute pain.

METHODS

Literature search of (i) controlled laboratory trials investigating potential biological mechanisms for pain relief and (ii) randomized placebo-controlled clinical trials which measure outcomes within the first 7 days after acute soft-tissue injury.

RESULTS

There is strong evidence from 19 out of 22 controlled laboratory studies that photoradiation can modulate inflammatory pain by reducing levels of biochemical markers (PGE(2), mRNA Cox 2, IL-1beta, TNFalpha), neutrophil cell influx, oxidative stress, and formation of edema and hemorrhage in a dose-dependent manner (median dose 7.5 J/cm(2), range 0.3-19 J/cm(2)). Four comparisons with non-steroidal anti-inflammatory drugs (NSAIDs) in animal studies found optimal doses of photoradiation and NSAIDs to be equally effective. Seven randomized placebo-controlled trials found no significant results after irradiating only a single point on the skin overlying the site of injury, or after using a total energy dose below 5 Joules. Nine randomized placebo-controlled trials (n = 609) were of acceptable methodological quality, and irradiated three or more points and/or more than 2.5 cm(2) at site of injury or surgical incision, with a total energy of 5.0-19.5 Joules. Results in these nine trials were significantly in favor of photoradiation groups over placebo groups in 15 out of 18 outcome comparisons. Poor and heterogeneous data presentation hampered statistical pooling of continuous data. Categorical data of subjective improvement were homogeneous (Q-value = 7.1) and could be calculated from four trials (n = 379) giving a significant relative risk for improvement of 2.7 (95% confidence interval [CI], 1.8-3.9) in a fixed effects model.

CONCLUSION

photoradiation can modulate inflammatory processes in a dose-dependent manner and can be titrated to significantly reduce acute inflammatory pain in clinical settings. Further clinical trials with adequate photoradiation doses are needed to precisely estimate the effect size for photoradiation in acute pain.

Analgesic Effect of He-Ne (632.8 nm) Low-Level Laser Therapy on Acute Inflammatory Pain

OBJECTIVE

The aim of this study was to evaluate the analgesic effect of the low level laser therapy (LLLT) with a He-Ne laser on acute inflammatory pain, verifying the contribution of the peripheral opioid receptors and the action of LLLT on the hyperalgesia produced by the release of hyperalgesic mediators of inflammation.

BACKGROUND DATA

All analgesic drugs have undesired effects. Because of that, other therapies are being investigated for treatment of the inflammatory pain. Among those, LLLT seems to be very promising.

MATERIAL AND METHODS

Male Wistar rats were used. Three complementary experiments were done. (1) The inflammatory reaction was induced by the injection of carrageenin into one of the hind paws. Pain threshold and volume increase of the edema were measured by a pressure gauge and plethysmography, respectively. (2) The involvement of peripheral opioid receptors on the analgesic effect of the laser was evaluated by simultaneous injection of carrageenin and naloxone into one hind paw. (3) Hyperalgesia was induced by injecting PGE2 for the study of the effect of the laser on the sensitization increase of nociceptors. A He-Ne laser (632.8 nm) of 2.5 J/cm2 was used for irradiation.

RESULTS

We found that He-Ne stimulation increased the pain threshold by a factor between 68% and 95% depending on the injected drug. We also observed a 54% reduction on the volume increase of the edema when it was irradiated.

CONCLUSION

He-Ne LLLT inhibits the sensitization increase of nociceptors on the inflammatory process. The analgesic effect seems to involve hyperalgesic mediators instead of peripheral opioid receptors.

An inexpensive, automated instrument for laser irradiation of cultured cells

OBJECTIVE

Laser irradiation of cultured cells is a valuable technique for elucidating the mechanisms of low-level laser therapy, but is often tedious because of the need to manually change the position of the laser beam. Consequently, we developed a computer-based system that automatically moves a cell culture plate over a laser beam and times the exposure.

BACKGROUND DATA

There are presently no commercial devices available for automated laser irradiation of cultured cells. Many investigators thus manually aim and time laser exposure, a time-consuming task that is prone to errors.

MATERIALS AND METHODS

We used outdated, surplus computer components to construct a system for automated laser exposure of cultured cells. This design strategy makes the system quite inexpensive.

RESULTS

Construction and operation of the system is described and an example of its use is presented. Alternate means of accomplishing automated laser irradiation are also presented.

CONCLUSION

Inexpensive and relatively simple devices can be constructed for automated laser irradiation of cultured cells. These devices can eliminate the tedium and errors of manual laser exposure.

Enhancement of bone formation in rat calvarial bone defects using low-level laser therapy

OBJECTIVE

To evaluate the effect of low-level laser therapy (LLLT), using a GaAlAs diode laser device, on bone healing and growth in rat calvarial bone defects.

STUDY DESIGN

An animal trial of 4 weeks' duration was conducted using a randomized blind, placebo-controlled design. Standardized round osseous defects of 2.7 mm diameter were made in each parietal bone of 20 rats (n=40 defects). The animals were randomly divided into an experimental and a control group of 10 animals each. In the experimental group, a GaAlAs diode laser was applied immediately after surgery and then daily for 6 consecutive days. The control group received the same handling and treatment, but with the laser turned off. Five rats from each group were killed on day 14 and the remainder on day 28 postoperatively. From each animal, tissue samples from one defect were prepared for histochemistry and samples from the contralateral defect for histology. Levels of calcium, phosphorus, and protein were determined by using atomic absorption spectrometry, colorimetry, and photometry, respectively. Student t-test and Mann-Whitney were used for statistical analyses.

RESULTS

At both time points the tissue samples from the experimental animals contained significantly more calcium, phosphorus, and protein than the controls. Similarly, histological analyses disclosed more pronounced angiogenesis and connective tissue formation, and more advanced bone formation in the experimental group than in the controls.

CONCLUSION

LLLT may enhance bone formation in rat calvarial bone defects.

Efficacy of 904 nm gallium arsenide low level laser therapy in the management of chronic myofascial pain in the neck: A double-blind and randomize-controlled trial

BACKGROUND AND OBJECTIVES

A prospective, double-blind, randomized, and controlled trial was conducted in patients with chronic myofascial pain syndrome (MPS) in the neck to evaluate the effects of infrared low level 904 nm Gallium-Arsenide (Ga-As) laser therapy (LLLT) on clinical and quality of life (QoL).

STUDY DESIGN/PATIENTS AND METHODS

The study group consisted of 60 MPS patients. Patients were randomly assigned to two treatment groups: Group I (actual laser; 30 patients) and Group II (placebo laser; 30 patients). LLLT continued daily for 2 weeks except weekends. Follow-up measures were evaluated at baseline, 2, 3, and 12 weeks. All patients were evaluated with respect to pain at rest, pain at movement, number of trigger points (TP), the Neck Pain and Disability Visual Analog Scale (NPAD), Beck depression Inventory (BDI), and the Nottingham Health Profile (NHP).

RESULTS

In active laser group, statistically significant improvements were detected in all outcome measures compared with baseline (P < 0.01) while in the placebo laser group, significant improvements were detected in only pain score at rest at the 1 week later of the end of treatment. The score for self-assessed improvement of pain was significantly different between the active and placebo laser groups (63 vs. 19%) (P < 0.01).

CONCLUSION

This study revealed that short-period application of LLLT is effective in pain relief and in the improvement of functional ability and QoL in patients with MPS.

A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders

We investigated if low level laser therapy (LLLT) of the joint capsule can reduce pain in chronic joint disorders. A literature search identified 88 randomised controlled trials, of which 20 trials included patients with chronic joint disorders. Six trials were excluded for not irradiating the joint capsule. Three trials used doses lower than a dose range nominated a priori for reducing inflammation in the joint capsule. These trials found no significant difference between active and placebo treatments. The remaining 11 trials including 565 patients were of acceptable methodological quality with an average PEDro score of 6.9 (range 5-9). In these trials, LLLT within the suggested dose range was administered to the knee, temporomandibular or zygapophyseal joints. The results showed a mean weighted difference in change of pain on VAS of 29.8 mm (95% CI, 18.9 to 40.7) in favour of the active LLLT groups. Global health status improved for more patients in the active LLLT groups ( relative risk of 0.52; 95% CI 0.36 to 0.76). Low level laser therapy with the suggested dose range significantly reduces pain and improves health status in chronic joint disorders, but the heterogeneity in patient samples, treatment procedures and trial design calls for cautious interpretation of the results.