Photobiological basis and clinical role of low-intensity lasers in biology and medicine.
ABSTRACT The purpose of this article is to provide a comprehensive review on the clinical role of low intensity laser therapy (laser photostimulation) in biology and medicine. Studies on wound healing and pain relief are highlighted to show the clinical efficacy of laser therapy. Controversies about the use of low intensity laser as a therapeutic modality for wound healing and pain relief are presented and a brief explanation is provided to overcome these controversies. The importance of standard parameters is emphasized for the applications of low intensity lasers in biology and medicine. A justification has been made to warrant further research on the use of low intensity laser as a therapeutic modality. Although the therapeutic applications of low intensity laser are imminent, the heterogeneity in treatment protocols and study design calls for a vigilant interpretation of the findings.
Article: Effects of a single near-infrared laser treatment on cutaneous wound healing: biometrical and histological study in rats.[show abstract] [hide abstract]
ABSTRACT: Low intensity laser therapy has been recommended to support the cutaneous repair; however, so far studies do not have evaluated the tissue response following a single laser treatment. This study investigated the effect of a single laser irradiation on the healing of full-thickness skin lesions in rats. Forty-eight male rats were randomly divided into three groups. One surgical lesion was created on the back of rats using a punch of 8mm in diameter. One group was not submitted to any treatment after surgery and it was used as control. Two energy doses from an 830-nm near-infrared diode laser were used immediately post-wounding: 1.3 J cm(-2) and 3 J cm(-2). The laser intensity 53 m W cm(-2) was kept for both groups. Biometrical and histological analyses were accomplished at days 3, 7 and 14 post-wounding. Irradiated lesions presented a more advanced healing process than control group. The dose of 1.3 J cm(-2) leaded to better results. Lesions of the group irradiated with 1.3 J cm(-2) presented faster lesion contraction showing quicker re-epithelization and reformed connective tissue with more organized collagen fibers. Low-intensity laser therapy may accelerate cutaneous wound healing in a rat model even if a single laser treatment is performed. This finding might broaden current treatment regimens.Journal of Photochemistry and Photobiology B Biology 07/2007; 87(3):145-53. · 2.81 Impact Factor
Article: Psychological benefits 2 and 4 weeks after a single treatment with near infrared light to the forehead: a pilot study of 10 patients with major depression and anxiety.[show abstract] [hide abstract]
ABSTRACT: Many studies have reported beneficial effects from the application of near-infrared (NIR) light photobiomodulation (PBM) to the body, and one group has reported beneficial effects applying it to the brain in stroke patients. We have reported that the measurement of a patient's left and right hemispheric emotional valence (HEV) may clarify data and guide lateralized treatments. We sought to test whether a NIR treatment could 1. improve the psychological status of patients, 2. show a relationship between immediate psychological improvements when HEV was taken into account, and 3. show an increase in frontal pole regional cerebral blood flow (rCBF), and 4. be applied without side effects. We gave 10 patients, (5 M/5 F) with major depression, including 9 with anxiety, 7 with a past history of substance abuse (6 with an opiate abuse and 1 with an alcohol abuse history), and 3 with post traumatic stress disorder, a baseline standard diagnostic interview, a Hamilton Depression Rating Scale (HAM-D), a Hamilton Anxiety Rating Scale (HAM-A), and a Positive and Negative Affect Scale (PANAS). We then gave four 4-minute treatments in a random order: NIR to left forehead at F3, to right forehead at F4, and placebo treatments (light off) at the same sites. Immediately following each treatment we repeated the PANAS, and at 2-weeks and at 4-weeks post treatment we repeated all 3 rating scales. During all treatments we recorded total hemoglobin (cHb), as a measure of rCBF with a commercial NIR spectroscopy device over the left and the right frontal poles of the brain. At 2-weeks post treatment 6 of 10 patients had a remission (a score </= 10) on the HAM-D and 7 of 10 achieved this on the HAM-A. Patients experienced highly significant reductions in both HAM-D and HAM-A scores following treatment, with the greatest reductions occurring at 2 weeks. Mean rCBF across hemispheres increased from 0.011 units in the off condition to 0.043 units in the on condition, for a difference of 0.032 (95% CI: -0.016, 0.080) units, though this result did not reach statistical significance. Immediately after treatment the PANAS improved to a significantly greater extent with NIR "on" relative to NIR "off" when a hemisphere with more positive HEV was treated than when one with more negative HEV was treated. We observed no side effects. This small feasibility study suggests that NIR-PBM may have utility for the treatment of depression and other psychiatric disorders and that double blind randomized placebo-controlled trials are indicated. ClinicalTrials.gov Identifier: NCT00961454.Behavioral and Brain Functions 12/2009; 5:46. · 2.13 Impact Factor
Article: Low-level laser therapy in acute pain: a systematic review of possible mechanisms of action and clinical effects in randomized placebo-controlled trials.[show abstract] [hide abstract]
ABSTRACT: The aim of this study was to review the biological and clinical short-term effects of photoradiation in acute pain from soft-tissue injury. It is unclear if and how photoradiation can reduce acute pain. 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. 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. 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.Photomedicine and Laser Surgery 05/2006; 24(2):158-68. · 1.25 Impact Factor