A Photomechanic Effect of High-Intensity Laser of Class 4 1064nm on the Pain Transfer Via Free Nerve Endings: a Multi-Centric, Randomized, Placebo-Controlled Study

Authors: M. Procházka 1;  P. Davídek 2;  K. Kazalakova 3;  O. Prouza 4
Authors‘ workplace: Rehabilitačníoddělení Jarov, Praha 1;  Katedra základů kinantropologie a humanitních věd, Fakulta tělesné kultury a sportu Univerzita Karlova v Praze 2;  Katedra fyzikální medicíny a rehabilitace, Pirogov univerzitní nemocnice, Sofie, Bulharsko 3;  Katedra anatomie a biomechaniky, Fakulta tělesné kultury a sportu, Univerzita Karlova v Praze 4
Published in: Rehabil. fyz. Lék., 24, 2017, No. 1, pp. 11-18.
Category: Original Papers


Chronic pain is a globally widespread problem, which could become an epidemic. Chronic pain is the cause of working incapacity for people in productive age and the therapy cot millions of crowns annually. It is therefore necessary to understand mechanism of effects of chronic pain and the search for noninvasive, effective and safe solution of the problem. Laser therapy is one way for the solution, which fulfils these criteria. The study is aimed at demonstration of an analgesic effect of high-intensity laser (HIL) energy as a consequence of photo-mechanic effect in human tissue.

A multi-centric, randomized placebo-controlled study is performed for the purpose of evaluating the relief from pain, caused by the photomechanic effect of high intensity laser energy on free nerve endings. Fifty six patients were enrolled in the study (27 man and 29 women) at the age of 42 to 64 years, who suffered from chronic back pain causing difficulties in common daily activities. The patients were randomly distributed into an experimental and control group. The experimental group treated with high-intensity laser (BTL-6000 High Intensity Laser 12W, BTL Company Ltd.). Each patient underwent nine treatments in the course of three weeks ‘three treatments per week). The pain intensity was evaluated in a 10point Visual analog scale (VAS) (Supplement 1). A questionnaire celled PFAG (Patient Functional Assessment Questionnaire) was used for the evaluation of functional dysfunction in common daily activities (ADL). It contains 2 items evaluated on the 0 to 6 scale (Supplement 2). The data were obtained for the period before, after three weeks of treatment and after subsequent 30 days.

In the experimental group there was a 69% decrease in pain perception (from strong to medium) and in 69% there was an improvement of functional dysfunction in ADL (from moderate to low or no problems). In contrast, ni the control group we observed 38% decrease in pain perception (from strong to medium strong pain intensity) and 34% improvement in the ADL area (from mild to low problems). The results obtained after the 30 days time lapse show a 52% decrease in pain perception (from strong to low) and 53% decrease in functional dysfunction ADL (form moderate to low or no problems) in the experimental group or a 6% pain decrease (from strong to mild) and 6% improvement in ADL (from mild problems to low or mild) in the control group.

Results of the study demonstrated a pain relief and the effect of high–intensity laser of 12 W-power in the pulse regimen. The difference in the decrease of pain intensity between the control and experimental group reached the level of probability p <0.05 (p = 3.01E-10. The results support the theory of mechanic inhibition of free nerve endings. The results in the area of functional dysfunction in ADL measured by the questionnaire (PFAG) demonstrated a decreased of limiting factors in ADL in the experimental group. The evaluation of data obtained in the experimental group after the 30-day time-lapse from the treatment indicated a lasting effect in both parameters: in the pain relief and in improved ability to perform ADL. These results also demonstrate the effect of HIL on a decrease of pain and decrease of limiting factors in ADL. The HIL treatment is therefore an easy solution of these problems.

high intensity laser, pain, chronic backpain, analgesic effect, pain relief, well-being


1. BJORDAL, J. M. et al.: A systematic review of low level laser therapy with location-specific doses for pain from chronic joint disorders.Australian Journal of Physiotherapy, roč. 49, 2003, s. 107-116.

2. BJORDAL, J. M. et al.: Low-kevel 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, roč. 24, 2006, č. 2, s. 158-168.

3. CAMERON, M. H.: Physical agents in rehabilitation: from research to practice. St. Louis, Elsevier, 4. vydání, 2013, ISBN 978-1-4557-2848-0.

4. CHOW, R. T., BARNSLEY, L.: Systematic review of the literature of low-level laser therapy (LLLT) in the management of neck pain. Lasers Surg. Med., roč.37, 2005, č. 1, s. 46-52.

5. CHOW, R. T. et al.: 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. The Lancet., roč. 374, 2009, č. 9705, s. 1897-1908.

6. CHOW, R. T. et al.: Inhibitory effects of laser irradiation on peripheral mammalian nerves and relevance to analgesic effects: A systematic review. Photomedicine and Laser Surgery, roč. 29, 2011, č. 6, s. 365-381.

7. COZEAN, C. et al.: Dentistry for the 21st Century? Erbium:YAG Laser for Teeth. Journal of the American Dental Association, roč. 128, 1997, č. 8, s. 1080-1087.

8. EMELIANOV, S. Y. et al.: Photoacoustics for molecular imaging and therapy. Phys. Today, roč. 62, 2009, č. 8, s. 34-39.

9. EUROPEAN AGENCY FOR SAFETY AND HEALTH AT WORK.: European Agency for Safety and Health at Work.European Agency for Safety and Health at Work,[Online] 30. June 2014. doi: 10.2802/20493 . https://osha.europa.eu/en/tools-and-publications/publications/literature_reviews/calculating-the-cost-of-work-related-stress-and-psychosocial-risks. ISBN: 978-92-9240-420-8/ISSN: 1831-9351 .

10. HERASCU, N. et al.: Low-level laser therapy (LLLT) efficacy in Post-Operative Wounds. Photomedicine and Laser Surgery, roč. 23, 2005, č. 1, s. 70-73.

11. INTERNATIONAL STANDARD: International Standard IEC 60825-1. Group Safety Publication, 2001, vydání 1.2. IEC 60825-1:1993+A1:1997+A2:2001.

12. JULIAN, F. J., GOLDMAN, D. E.: The effects of mechanical stimulation on some electrical properties of axons. The Journal of General Physiology, roč. 46, 1962, s. 297-313.

13. KELLER, U. et al.: Erbium:YAG Laser application in caries therapy. Evaluation of patient perception and acceptance. Journal of Dentistry, roč. 28, 1998, č. 8, s. 649-656.

14. KOLKMAN, R. G. M. et al.: In vivo photoacoustic imaging of blood vessels using an extreme-narrow aperture sensor. IEEE Journal of Selected Topics in Quantum Electronics, roč. 9, 2003, č. 2, s. 343-346.

15. MELZACK, R., Wall, P. D.: Pain mechanisms: A new theory. Science, roč. 150, 1965, č. 3699, s. 971-979.

16. NATIONAL CENTER FOR HEALTH STATISTICS.: Disease Control and Prevention.Centers for Disease Control and Prevention.Hyattsville, MD, USA , November 2006.

17. NAVRÁTIL, L., DYLEVSKÝ, I.: Mechanism of the analgesic effect of therapeutic lasers in vivo. Laser Therapy, 1997, č. 9, s. 33-40.

18. POZZA, D. H. et al: Analgesic action of laser therapy (LLLT) in an animal model. Med. Oral Patol. Oral Cir. Bucal, roč. 13, 2008, č. 10, s. 648-652.

19. RIZZI, C. F. et al.: Effect of low-level laser therapy (LLLT) on the nuclear factor (NF)-kB signaling pathway in traumatized muscle. Lasers in Surg., roč. 38, 2006, č. 7, s. 704-713.

20. ROCKWELL LASER INDUSTRIES.: Rockwell Laser Industries.Rockwell Laser Industries,[Online] https://www.rli.com/resources/articles/classification.aspx.

21. RUARO, J. A. et al.: Low-level laser therapy to treat firbromyalgia. Lasers Med. Sci., roč. 29, 2014, č. 6, s. 1815-1819.

22. SCHULTZ, M. et al.: Nanosecond laser pulse stimulation of the inner ear - A wavelength study. Biomedical Optics, roč. 3, 2012, č. 12. s. 3332- 3345.

23. SERWAY, R. A., JEWETT, J. W.: Physics for scientists and engineers. Vydání 9.,Brooks Cole, 2013, ISBN-13: 978-1133947271.

24. VÉLE, F.: Kineziologie. Praha,Triton, 2006, ISBN 80-7254-837-9.

25. WALSH, L. J. et al.: Laser analgesia with pulsed infrared lasers: Theory and practice. J. Oral Laser Applications, roč. 8, 2008, č. 1, s. 7-16.

26. WANG, L. V. et al.: Prospects of photoacoustic tomography. Med. Phys., roč. 35, 2008, č. 12, s. 5758.

27. WANG, X. et al.: Noninvasive laser-induced photoacoustic tomofraphy for structural and functional in vivo imaging of the brain. Nature Biotechnology, roč. 21, 2003, s. 803-806.

28. ZHANG, Q. et al.: Gold nanoparticles as a contrast agent for in vivo tumor imaging with photoacoustic tomography. Nanotechnology, roč. 20, 2009, č. 29.

29. ZLATKO et al.: Lasers in medicine and dentistry. European Medical Laser Association, 2000, ISBN 953-6059-30-4.

Physiotherapist, university degree Rehabilitation Sports medicine
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