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Low-level laser therapy

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

Low level laser therapy (LLLT, also known as photobiomodulation, cold laser therapy and laser biostimulation) is a medical and veterinary technique which uses low-level lasers or light-emitting diodes to stimulate or inhibit cellular function.[1] The technique is also known by some other ambiguous terms such as laser therapy and phototherapy (though the latter more accurately refers to light therapy), which may also be used to describe other medical techniques. Basic research and work on specific treatments are being pursued with various modulations of wavelength, intensity, duration and treatment interval being tested.[2] The method is not yet accepted as routine medical therapy despite a significant body of published evidence that is at least equal pharmaceutical, surgical and alternative therapies for a range of pathologies including neck pain [3], tendinopathies [4] [5] and osteoarthritis. [6]

History

In 1967 a few years after the first working laser was invented, Endre Mester in Semmelweis University 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.[7]

US Food and Drug Administration has cleared the use of Low level lasers for the treatment of lymphedema (November 2006),[8] osteoarthritis (March 2009), and chronic pain.[9]

Clinical applications

Clinical applications that show some potential of effectiveness include treating soft tissue injury, chronic pain, and wound healing. More uses include tinnitus and nerve regeneration. Resolution of viral and bacterial infections has been claimed, but no plausible mechanism for this has been proposed. A Cochrane Library review has concluded that there is insufficient data to draw a firm conclusion on the clinical effectiveness of low-level laser therapy for low back pain.[10]

Mechanism

Certain wavelengths of light at certain intensities (or irradiance to use the technically correct term) delivered by laser, LED or another monochromatic source may affect tissue regeneration, inflammation, or pain.[11] The exact mechanism is still being explored and debated but it is likely that the mechanism is photochemical rather than heat-related.[12][13][14]Observed biological and physiological effects include changes in cell membrane permeability, up-regulation and down-regulation of adenosine triphosphate and nitric oxide.

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. Laser average power is typically in the range of 1-500 mW; some high peak power, short pulse width devices are in the range of 1-100 W with typically 200 ns pulse widths. The average beam irradiance then is typically 10 mW/cm2 - 5 W/cm2. The wavelength is typically in the range 600-1000 nm (red to near infrared) but some research has been done and products are available outside this range.[15]

See also

References

  1. ^ Huang, Y.Y. (2009). {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)|"Biphasic Dose Response in Low Level Light Therapy" (PDF). Dose Response. pp. Pre Press.
  2. ^ "Abstracts from 7th international congress of the world association for laser therapy october 19-22, 2008". Photomed Laser Surg. 27 (1): 155–209. 2009. doi:10.1089/pho.2009-9959. PMID 19250054. {{cite journal}}: Unknown parameter |month= ignored (help)
  3. ^ Chow, RT.; Johnson, MI.; Lopes-Martins, RA.; Bjordal, JM. (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. doi:10.1016/S0140-6736(09)61522-1. PMID 19913903. {{cite journal}}: Unknown parameter |month= ignored (help)
  4. ^ Tumilty, S.; Munn, J.; McDonough, S.; Hurley, DA.; Basford, JR.; Baxter, GD. (2009). "Low Level Laser Treatment of Tendinopathy: A Systematic Review with Meta-analysis". Photomed Laser Surg. doi:10.1089/pho.2008.2470. PMID 19708800. {{cite journal}}: Unknown parameter |month= ignored (help)
  5. ^ Bjordal, JM.; Lopes-Martins, RA.; Joensen, J.; Couppe, C.; Ljunggren, AE.; Stergioulas, A.; Johnson, MI. (2008). "A systematic review with procedural assessments and meta-analysis of low level laser therapy in lateral elbow tendinopathy (tennis elbow)". BMC Musculoskelet Disord. 9: 75. doi:10.1186/1471-2474-9-75. PMID 18510742. {{cite journal}}: Cite has empty unknown parameter: |month= (help)CS1 maint: unflagged free DOI (link)
  6. ^ Bjordal JM, Couppe C, Chow RT, Tuner J, Ljunggren EA. "A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders". Aust J Physiother 2003 49(2) 107-16. PMID 12775206.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  7. ^ Mester, E. (1967). "Effect of laser on hair growth of mice". Kiserl Orvostud. 19: 628–631. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  8. ^ dotmed.com, Dec 27, 2006 Low Level Laser FDA Cleared for the Treatment of Lymphedema (accessed 9 Nov 09)
  9. ^ FDA website: pain relief
  10. ^ Yousefi-Nooraie, R (2008). "Low level laser therapy for nonspecific low-back pain". Cochrane Database Syst Rev. 16 (2): CD005107. doi:10.1002/14651858.CD005107.pub4. PMID 18425909. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  11. ^ Abramovitch-Gottlib L, Gross T, Naveh D, Geresh S, Rosenwaks S, Bar I, Vago R (2007). "Low level laser irradiation stimulates osteogenic phenotype of mesenchymal stem cells seeded on a three-dimensional biomatrix". Lasers in medical science. 20 (3): 143–57. doi:10.1007/s10103-005-0355-9. PMID 16292614.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  12. ^ Karu, T. "Primary and secondary mechanisms of action of visible to near-IR radiation on cells". J Photochem Photobiol B 1999 Mar 49(1) 1-17. PMID 10365442.
  13. ^ Lane N. "Power Games". Nature. 2006 Oct 26;443(7114):901-3. PMID 17066004.
  14. ^ Tafur J, Mills PJ. "Low-intensity light therapy: exploring the role of redox mechanisms". Photomed Laser Surg 2008 Aug 26(4) 323-8. PMID 18665762.
  15. ^ Huang, Y.Y. (2009). {{cite journal}}: Cite journal requires |journal= (help); Missing or empty |title= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)|"Biphasic Dose Response in Low Level Light Therapy" (PDF). Dose Response. pp. Pre Press.
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