Low level laser therapy

For more general use of light in therapy, see Light therapy.

Low level laser therapy
Intervention
MeSH	D028022

Low-level laser therapy (LLLT) is a medical and veterinary treatment that uses low-level lasers or light-emitting diodes to alter cellular function. LLLT is controversial in mainstream medicine with ongoing research to determine the ideal location of treatment (specifically whether LLLT is more appropriately used over nerves versus joints^[1]), dose, wavelength, timing, pulsing and duration.^[2] The effects of LLLT appear to be limited to a specified set of wavelengths of laser,^[3] and administering LLLT below the dose range does not appear to be effective.^[4]

Despite a lack of consensus over its ideal use, specific test and protocols for LLLT suggest it is effective in relieving short-term pain for rheumatoid arthritis,^[1] osteoarthritis,^[5] acute and chronic neck pain,^[6] tendinopathy,^[3][7] and possibly chronic joint disorders.^[4] The evidence for LLLT being useful in the treatment of low back pain,^[8][9] dentistry^[10][11] and wound healing is equivocal.^[12]

History

In 1967 a few years after the first working laser was invented, Endre Mester in Semmelweis University in Budapest, Hungary experimented with the effects of lasers on skin cancer. While applying lasers to the backs of shaven mice, he noticed that the shaved hair grew back more quickly on the treated group than the untreated group.^[13]

Clinical applications

LLLT has primarily been shown useful in the short-term treatment of acute pain caused by rheumatoid arthritis,^[1] osteoarthritis,^[5] tendinopathy,^[3][7] and possibly chronic joint disorders.^[4] LLLT has also been useful in the treatment of both acute and chronic neck pain.^[6] A Cochrane Library review concluded that there is insufficient data to draw a firm conclusion on the clinical effectiveness of low-level laser therapy for low back pain,^[8] a finding echoed in a later review of treatments for chronic low back pain.^[9] Though it has been suggested for decades that LLLT could be useful in speeding wound healing, the appropriate parameters (dose, type of laser, materials, wavelength, etc.) have not been identified.^[12] Similarly, the use of lasers to treat chronic periodontitis^[10] and to speed healing of infections around dental implants^[11] is suggested, but there is insufficient evidence to indicate a use superior to traditional practices.

Stephen Barrett, writing for Quackwatch, concluded there was evidence to support LLLT use for temporary pain relief, but "there's no reason to believe that they will influence the course of any ailment or are more effective than other forms of heat delivery."^[14]

Insurance company Cigna has reviewed the evidence for LLLT and concluded that it is still considered an experimental treatment therefore does not provide coverage for it.^[15]

Mechanism

It is unclear how LLLT works. LLLT may reduce pain related to inflammation by lowering, in a dose-dependent manner, levels of prostaglandin E2, prostaglandin-endoperoxide synthase 2, interleukin 1-beta, tumor necrosis factor-alpha, the cellular influx of neutrophil granulocytes, oxidative stress, edema, and bleeding. The appropriate dose appears to be between 0.3 and 19 joules per square centimetre.^[16] Another mechanism may be related to stimulation of mitochondrion to increase the production of adenosine triphosphate resulting in an increase in reactive oxygen species, which influences redox signalling, affecting intracellular homeostasis or the proliferation of cells.^[17] The final enzyme in the production of ATP by the mitochondria, cytochrome c oxidase, does appear to accept energy from laser-level lights, making it a possible candidate for mediating the properties of laser therapy.^[18]

The effects of LLLT appear to be limited to a specified set of wavelengths of laser,^[3] and though more research is required to determine the ideal wavelengths, durations of treatment, dose and location of treatment (specifically whether LLLT is more appropriately used over nerves versus joints).^[1] Administering LLLT below the dose range does not appear to be effective.^[4] The factors of wavelength, effective dose, dose-rate effects, beam penetration, the role of coherence, and pulses (peak power and repetition rates) are still poorly understood in the clinical setting. The typical laser average power is in the range of 1-500 mW; some high-peak-power, short-pulse-width devices are in the range of 1-100 W with typical pulse-widths of 200 ns. The typical average beam irradiance then is 10 mW/cm² - 5 W/cm². The typical wavelength is in the range 600-1000 nm (red to near infrared), but some research has been done and products outside of this range are available.^[2]

See also

• Photomedicine
• Light therapy
• Blood irradiation therapy

References

1. ^ ^{a b c d} Brosseau, L.; Welch, V.; Wells, G. A.; De Bie, R.; Gam, A.; Harman, K.; Morin, M.; Shea, B. et al. (2005). Brosseau, Lucie. ed. "Low level laser therapy (Classes I, II and III) for treating rheumatoid arthritis". Cochrane Database of Systematic Reviews (4): CD002049. doi:10.1002/14651858.CD002049.pub2. PMID 16235295.  edit
2. ^ ^{a b} Huang, Y.; Chen, A.; Carroll, J.; Hamblin, M. (2009). "Biphasic Dose Response in Low Level Lightherapy". Dose-Response 7 (4): 358. doi:10.2203/dose-response.09-027.Hamblin. PMC 2790317. PMID 20011653. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2790317.  edit
3. ^ ^{a b c d} Bjordal, J. M.; Lopes-Martins, R. A.; Joensen, J. .; Couppe, C. .; Ljunggren, A. E.; Stergioulas, A. .; Johnson, M. I. (2008). "A systematic review with procedural assessments and meta-analysis of Low Level Laser Therapy in lateral elbow tendinopathy (tennis elbow)". BMC Musculoskeletal Disorders 9: 75. doi:10.1186/1471-2474-9-75. PMC 2442599. PMID 18510742. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2442599.  edit
4. ^ ^{a b c d} Bjordal, JM; Couppé, C; Chow, RT; Tunér, J; Ljunggren, EA (2003). "A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders". The Australian journal of physiotherapy 49 (2): 107–16. PMID 12775206.  edit
5. ^ ^{a b} Jamtvedt, G.; Dahm, K. T.; Christie, A.; Moe, R. H.; Haavardsholm, E.; Holm, I.; Hagen, K. B. (2007). "Physical Therapy Interventions for Patients with Osteoarthritis of the Knee: an Overview of Systematic Reviews". Physical Therapy 88 (1): 123–136. doi:10.2522/ptj.20070043. PMID 17986496.  edit
6. ^ ^{a b} Chow, R.; Johnson, M.; Lopes-Martins, R.; Bjordal, J. (Nov 2009). "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.". Lancet 374 (9705): 1897–1908. doi:10.1016/S0140-6736(09)61522-1. PMID 19913903.  edit
7. ^ ^{a b} Tumilty, S. .; Munn, J. .; McDonough, S. .; Hurley, D. A.; Basford, J. R.; Baxter, G. D. (2010). "Low Level Laser Treatment of Tendinopathy: A Systematic Review with Meta-analysis". Photomedicine and Laser Surgery 28 (1): 3. doi:10.1089/pho.2008.2470. PMID 19708800.  edit
8. ^ ^{a b} Yousefi-Nooraie, R.; Schonstein, E.; Heidari, K.; Rashidian, A.; Pennick, V.; Akbari-Kamrani, M.; Irani, S.; Shakiba, B. et al. (2008). Yousefi-Nooraie, Reza. ed. "Low level laser therapy for nonspecific low-back pain". Cochrane database of systematic reviews (Online) (2): CD005107. doi:10.1002/14651858.CD005107.pub4. PMID 18425909.  edit
9. ^ ^{a b} Middelkoop, M.; Rubinstein, S. M.; Kuijpers, T.; Verhagen, A. P.; Ostelo, R.; Koes, B. W.; Tulder, M. W. (2010). "A systematic review on the effectiveness of physical and rehabilitation interventions for chronic non-specific low back pain". European Spine Journal 20 (1): 19–39. doi:10.1007/s00586-010-1518-3. PMC 3036018. PMID 20640863. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3036018.  edit
10. ^ ^{a b} Cobb, C. M. (2006). "Lasers in Periodontics: A Review of the Literature". Journal of Periodontology 77 (4): 545–564. doi:10.1902/jop.2006.050417. PMID 16584335.  edit
11. ^ ^{a b} Sculean, A.; Schwarz, F.; Becker, J. (2005). "Anti-infective therapy with an Er:YAG laser: influence on peri-implant healing". Expert Review of Medical Devices 2 (3): 267. doi:10.1586/17434440.2.3.267. PMID 16288590.  edit
12. ^ ^{a b} Da Silva, J. P.; Da Silva, M. A.; Almeida, A. P. F.; Junior, I. L.; Matos, A. P. (2010). "Laser Therapy in the Tissue Repair Process: A Literature Review". Photomedicine and Laser Surgery 28 (1): 17. doi:10.1089/pho.2008.2372. PMID 19764898.  edit
13. ^ Mester, E.; Szende, B., and Tota, J.G. (1967). "Effect of laser on hair growth of mice". Kiserl Orvostud 19: 628–631. 
14. ^ Barrett, S (2009-07-17). "A Skeptical Look at Low Level Laser Therapy". Quackwatch. http://www.devicewatch.org/reports/lllt.shtml. Retrieved 2010-07-23. 
15. ^ "Cigna Medical Coverage Policy - Subject: Low Level Laser Therapy" (pdf). Cigna. 2010-07-15. http://www.cigna.com/customer_care/healthcare_professional/coverage_positions/medical/mm_0115_coveragepositioncriteria_lowlevel_laser_therapy.pdf. Retrieved 2010-08-06. 
16. ^ Bjordal, J. M.; Johnson, M. I.; Iversen, V.; Aimbire, F.; Lopes-Martins, R. A. B. (2006). "Low-Level Laser Therapy in Acute Pain: A Systematic Review of Possible Mechanisms of Action and Clinical Effects in Randomized Placebo-Controlled Trials". Photomedicine and Laser Surgery 24 (2): 158. doi:10.1089/pho.2006.24.158. PMID 16706694.  edit
17. ^ Tafur, J. .; Mills, P. J. (2008). "Low-Intensity Light Therapy: Exploring the Role of Redox Mechanisms". Photomedicine and Laser Surgery 26 (4): 323. doi:10.1089/pho.2007.2184. PMC 2996814. PMID 18665762. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2996814.  edit
18. ^ Karu, T. I. (2008). "Mitochondrial Signaling in Mammalian Cells Activated by Red and Near-IR Radiation". Photochemistry and Photobiology 84 (5): 1091–1099. doi:10.1111/j.1751-1097.2008.00394.x. PMID 18651871.  edit