From Practical Pain Management, Nov/Dec 2003

Laser-Accelerated Inflammation/Pain Reduction and Healing


Please note: These pages represent only a tiny sample of the resarch available on Low Level Laser, and are purely for general information purposes, to give you an idea of the scope of Low Level laser, how it works, what Low Level Laser research studies show about its general effects, and the wide range of health issues that have been helped by it. The thousands of published studies on Low Level Laser have used various systems from various manufacturers, or more basic or specialised systems built in research centres, so strictly speaking, similar results can not be extrapolated to systems other than those used in the studies. Health and wellness are also very individual issues, so these studies should not be interpreted as proof that anyone other than the study participants would receive the same reported benefits. This section is provided purely as a source of inspiration in how Low Level laser might help you improve your own health. We do not treat or diagnose conditions -- our approach is that if your body has the optimal conditions for good health, it will be better equipped to deal with any health challenges it may face, now or in the future.


Low Level Laser Therapy (LLLT) precipitates a complex set of physiologial interations at the cellular level that redues acute inflammation, reduces pain, and accelerates tissue healing

Richard Martin, BS, CLT

Compromised cells and tissues respond more readily than healthy cells or tissues to energy transfers that occur between LLLT-emitted photons and the receptive chromophores found in the various cells and sub-cellular organelles. Cells and tissues that are ischemic and poorly perfused as a result of inflammation, edema and injury have been shown to have a significantly higher response to irradiation than normal healthy strutures. Cell membranes, mitochondria and damaged neurological structures exhibit less than optimal metaolism and stasis conditions. Multiple studies have demonstrated that under these compromised conditions, the introdution of energy transfers and the resultant enhancement of metabolic activity is most pronouned in biologically challenged components. While it may appear that is thus selectively targeting compromised cells, in reality, these cells exhibit a lowered reaction threshold to the effets of laser light and are more easily triggered to energy transfer responses. The result is that has a significant effect on damaged cells and tissues while normative biological constituents are appreciably less affected

The cellular casade effect precipitated the actions of enzymes and having a significant in the presence of has a significant impact on cellular and tissue function. Since a considerable number of the reactive proteins that respond to laser stimulation are enzymes, laser light effects are amplified in the stimulation of beneficial enezymes and depression of deleterious enzymes.

At the cellular level, cytochromes can be defined as electron or proton-transfer proteins that act as energy producers for human biological functions. Both of the cytochrome enzymes, Cytochrome Oxydase and Nitrix Oxide Synthase (NOS) have been found to be particularly reactive to laser photon stimulation. The particular affinity of these and other photoreactive enzymes to accelerate their funtions in the presence of provides critical increases in the molecule and Nitrix Oxide (NO) which enhances cellular metabolism, circulatory improvement and nerve funtion.

Although the various actions of in regards to inflammation, pain and healing have been separated categorically here for the purpose of process identification, their interactions are not so easily distinguished. In response to LLLT, the reduction in inflammation, pain and healing time all compliment each other and many of the processes are either simultaneous or overlapping.


Acute Inflammation Reduction

Immediately after an acute injury event, the body, in response to the disruption of the integrity of vasular, soft tissue, connective tissue and neurological processes, initiates a series of biologial responses. The inflammatory reaction consists of both vasuclar and cellular events. Injury responsive components such as Mast cells, Bradykinins and Prostaglandins are activated along with the vascular responses and cellular membrane reactions. All of these combined processes and events are represented the symptoms of edema, inflammation, pain and functional debility LLLT can be effective in mediating both the symptoms and the underlying inflammatory process the following actions.

1. Stabilization of cellular membrane . Ca++, Na+ and concentrations as well as the proton gradient over the mitochondria membrane are positively influenced. This is accomplished in part the prodution of beneficial Reactive Oxygen Species (ROS) wherein triplet oxygen molecules absorb laser light producing singlet oxygen molecules. These ROS modulate intracellular Ca++ concentrations and laser therapy improves Ca++ uptake in the mitochondria. 2,3,4

2. ATP production and synthesis are significantly enhanced, contributing to cellular repair, reproduction and functional ability. Laser stimulation of Cytochrome c Oxidase, a chromophore found on the mitochondria of cells, plays a major role in this rapid
increase in production and synthesis of ATP. 3

3. Vasodilation is stimulated via Histamine, Nitric Oxide (NO) and Serotonin increases, resulting in reduction of ischemia and improved perfusion. Laser mediated vasodilation enhances the transport of nutrients and oxygen to the damaged cells and facilitates repair and removal of cellular debris. 5, 6

4. Beneficial acceleration of leukocytic activity results in enhanced removal of non-viable cellular and tissue components, allowing for a more rapid repair and regeneration process.

5. Increased Prostaglandin synthesis, particularly in conversion of the prostaglandins PGG2 and PGH2 periossides into prostaglandin PGI2. PG|2 (Prostacyclin), has a vasodilating and anti-inflammatory action with some attributes similar to Cox-I and Cox-II inhibitors. 7

6. Reduction in Interleukin 1(IL-1). Laser irradiation has a reducing effect on this pro-inflammatory cytokine that has been implicated in the pathogenesis of rheumatoid arthritis and other inflammatory conditions. 8

7. Enhanced lymphocyte response. In addition to increasing the number of lymphocytes, laser irradiation mediates the action of both lymphatic helper T-cells and suppressor T-cells in the inflammatory response. Along with laser modification of beta cell activity, the entire lymphatic response is beneficially affected by LLLT. 9

8. Increased angiogenesis. Both blood capillaries and lymphatic capillaries have been clinically documented to undergo significant increase and regeneration in the presence of laser irradiation. The resulting improvement in circulation and perfusion enhances all repair and healing processes. Laser induced increases in NO and the growth factors, in particular cytokine INF-g are contributory to this process. 10, 11

9. Temperature modulation. Areas of inflammation typically demonstrate temperature variations with the inflamed portion having an elevated temperature. Laser therapy has been shown to accelerate temperature normalization, demonstrating its beneficial influence on the inflammatory process.

10. Enhanced superoxide dismutase (SOD) levels. Laser stimulated increases in cytokine SOD levels interact with other anti-inflammatory processes to accelerate the termination of the inflammatory process. Interactions between SODand Reactive Oxygen Species (ROS) production subsequent to LLLT balance free radical activity and allows for the beneficial effects of ROSwhiIe inhibiting detrimental interactions. 12

11. Decreased C-reactive protein and neopterin levels. Laser therapy has been shown to lower the serum levels of these inflammation markers, particularly in rheumatoid arthritis patients. Decreased marker levels are indicative that the combined effects of all LLLT-induced anti-inflammatory actions are effectively reducing the inflammatory process.

A summary flowchart of the cellular cascade in reducing tissue inflammation is presented in Figure 1. The cumulative effect of these multiple inter-active processes and events is an accelerated inflammatory cycle with diminished symptoms and earlier normalization.

Since LLLT does not exacerbate the inflammatory process but rather condenses the time frame from onset to resolution through acceleration of processes, it can be used immediately post injury. This rapid initiation of therapy in acute inflammation will assist in limiting the scope and duration of the inflammatory event and minimize the pain and severity associated with it.

Most of the beneficial effects seen from LLLT in the treatment of acute inflammatory events will also have medical efficacy as LLLT is initiated in more chronic Inflammatory conditions While the treatment regimen and course of therapy may be modified in chronic situations, the physiological responses and interactions remain consistent. Chronic conditions may require longer treatment times and results will vary with the patient, condition and length of the chronic condition.


Pain Reduction

The unique pain reduction abilities of LLLT have been extensively researched and documented in numerous clinical studies and medical papers. While there remains much to learn in respect to the various processes through which LLLT achieves its pain reduction characteristics, there is a wealth of knowledge currently available to demonstrate the effectiveness of laser therapy in this regard. Because the pain amelioration capabilities of LLLT are accomplished via the combination of local and systemic actions, utilizing enzymatic, chemical and physical interventions . the process is very complex. However, there is a preponderance of medical evidence thatjustifies a conclusion that effective pain reductions can be achieved via LLLT. Following are processes and events that are promoted by LLLT therapy:

1. Increase in b-Endorphins. the localized and systemic increase of this endogenous peptide after LLLT irradiation has been clinically reported in multiple studies with subsequent pain reductions.

2. Blocked depolarization of C-fiber afferent nerves. The pain blocking effect of LLLT can be pronounced, particularly in low velocity neural pathways, such as non-mylenated afferent axons from nociceptors. Laser irradiation suppresses the excitation of these fibers in the afferent sensory pathway. 13, 14

3. Increased nitric oxide production. NO has both a direct and indirect impact on pain sensation. As a neurotransmitter it is essential for normal nerve cell action potential in impulse transmission activity and, indirectly, the vasodilation effect of NO can enhance nerve cell perfusion and oxygenation.

4. Increased nerve cell action potential. Healthy nerve cells tend to operate at about -70 mV and fire at about -20 mV. Compromised cells membrane potential approximates -20 mV thereby resulting in pain stimulus. LLLT can help restore the action potential closer to the normal -70 mV range. Both compound muscle action potential (CMAP) values and nerve latency values have shown improvement with laser therapy. 15

5. Axonal sprouting and nenxe cell regeneration. Several studies have documented the ability of LLLT to induce axonal sprouting and some nerve regeneration in damaged nerve tissues. Where pain sensation is being magnified due to nerve structure damage, cell regeneration and sprouting may assist in pain decrease. 16, 17

6. Decreased Bradykinin levels. Since Bradykinins elicit pain by stimulating nociceptive afferents in the skin and viscera, mitigation of elevated levels through LLLT can result in pain reduction. Laser-induced decrease in plasma kallikrein, increase in Kininase II, and increase in NO are considered the contributors to this Bradykinin decrease.

7. Increased release of acetylcholine. By increasing the available acetylcholine, LLLT helps in normalizing nerve signal transmission in the autonomic, somatic and sensory neural pathways.

8. Ion channel normalization. LLLT promotes normalization in Ca++, NA+ and K+ concentrations resulting in beneficial pain reduction results from these ion concentration shifts. Figure 2 presents a simplified representation of the effects of LLLT on pain improvement at the cellular level.


Tissue Healing

One of the truly unique characteristics of LLLT is that it has the ability to actually promote and enhance healing, not just treat symptoms. The irradiation by low-level laser light accelerates and enhances healing activities carried out by the body. Several of the unique characteristics of LLLT that work to alleviate pain and inflammation also play an important role in accelerating the healing process; the LLLT-mediated reduction in inflammation and pain frees the body’s natural ability to repair and heal itself. As wound healing progresses through the stages of inflammation, proliferation, remodeling and maturation, laser therapy presents the opportunity to impact each of these phases in positive and beneficial ways. LLLT can provide the following beneficial impacts in both open surface wounds and closed connective or soft tissue injuries as follows:

1. Enhanced leukocyte infiltration. LLLT stimulates activity involving neutrophils, monocytes and lymphocytes.

2. Increased macrophage activity. LLLT accelerates macrophage activity in phagocytosis, growth factor secretion and stimulation of collagen synthesis.

3. Increased neovascularization. The significant angiogenesis that occurs with laser therapy promotes revascularization with subsequent improvement in perfusion and oxygenation. Endothelial cell regeneration is accelerated. 18

4. Increased fibroblast proliferation. LLLT stimulation increases fibroblast numbers and fibroblast-mediated collagen production. 19

5. Keratinocyte proliferation. The beneficial synthesis activities and growth factor ability of keratinocytes are enhanced by proliferation secondary to LLLT. 20

6. Early epithelialization. Laser-stimulated acceleration of epithelial cell regeneration speeds up wound healing, minimizes scarring, and reduces infection opportunities.

7. Growth factor increases. Two to five fold increases in growth-phase-specific DNAsynthesis in normal fibroblasts, muscle cells, osteoblasts and mucosal epithelial cells irradiated with IR light are reported. Increases in vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) secondary to IR light irradiation have also been reported.

8. Enhanced cell proliferation and differentiation. Laser-induced increases in NO, ATPand other compounds that stimulate higher activity in cell proliferation and differentiation into mature cells. Increased numbers of myofibroblasts, myofibrils, myotubes etc., as well as bone cell proliferation, have been clinically documented after LLLT. Satellite cells, the precursor cells in the process of muscle regeneration, show significant increase in proliferation when irradiated with LLLT. 21,22,23

9. Greater healed wound tensile strength. In both soft tissue and connective tissue injuries, LLLT can increase the final tensile strength ofthe healed tissue. By increasing the amount of collagen production/synthesis and by increasing the intra and inter-molecular hydrogen bonding in the collagen molecules, laser therapy contributes to improved tensile strength. 24,25,26,27 The preceding effects combine to achieve an accelerated healing rate (see Figure 3). The time from onset of injury to mature healed wound is reduced. 28



The FDA has recently cleared multiple laser and LED devices for treatment of a variety of medical conditions including carpal tunnel syndrome, cervical neck pain, low back pain, joint pain, generalized muscle pain and acceleration of wound healing. Governmental agencies such as NASA are currently using technical light therapy for medical conditions in space applications. The U.S. Olympic training facilities have just released statements of endorsement for laser therapy for athletes. All of these events validate the growing acceptance in mainstream medicine for the medical efficacy of laser therapy as a viable, often superior therapeutic treatment modality.

With over 200 clinical studies. many of which are double-blind, placebo-controlled, and in excess of 2000 published articles on LLLT, this innovative new technology has a well-documented research and application history. Having grown far beyond its distant Institutional Review Board (IRB) and experimental treatment status, LLLT is now being considered a therapy of choice for many difficult pain management challenges such as fibromyalgia and myofascial pain. New and ongoing clinical investigations offer growing potential for even more widespread applications of this truly unique light therapy.

Richard Martin, BS, CLT is a photobiologist specializing in laser therapy and holds the position of Director of Science at Micro Light Laser, a subsidiary of Innovative Medical Group Corporation in Santa Monica, CA. He has taught laser physics and photodynamics for eight years. He has sewed as manager for several biomedical design and service facilities and participated as lead researcher for biomedical devices involved in emergency cardiac care, warmed intravenous fluid therapy and laser therapy. Richard has participated in medical clinical trials for 15 years as a clinical trial analyst and contributing clinician.



1. Almeida-Lopes L. Human gingival fibroblast proliferation enhanced by LLLT. Analysis in vitro of the cellular proliferation of human gingival fibroblasts with low level laser. Dissertation at Universidade do Vale do Pararba, Sao Paulo, Brazil. 1999.

2. Lubart R, Friedman H, and Lavie R. Photobiostimulation as a function of different wavelengths. bone regeneration. The Journal of Laser Therapy. Vol 12. World Association of Laser Therapy. 2000.

3. Karu T. et al. Changes in absorbance on monolayer of living cells induced by laser irradiation. IEEE Journal of Selected Topics in Quantum Electronics. IEEE Lasers and Electro-Optical Society. December 2001. 7(G):982.

4. De Castro E Silva Jr. O, et al. Laser enhancement in hepatic regeneration for partially hepatectomized rats. Lasers in Surgery and Medicine. 2001. 29(1):73-77

5. Silveira LB, et al. In vivo study on mast cells behaviour following low-intensity visible and near infrared laser radiation. Laser Surg Med. Abstract issue. Abstract 304. 2002.

6. Trelles MA, et al. LLLT in vivo effects on mast cells. Department of Tissue Pathology, University Hospital, Tarragona, Spain. Abstract from the 7th International Congress of European Medical Laser Association, Dubrovnik, Croatia, June 2000.

7. Tam G. Action of 904 nm diode laser in orthopedics and traumatology. Laser Center, Tolmezzo, Italy. Meridian Co, Ltd. Website:httpJ/ product1_8.htm. Last visited 10/27/03.

8. Bjordal JM, and Couppe C. What is optimal dose, power density and timing for low level laser therapy in tendon injuries?A review of in vitro and in vivo trials. Department of Physiotherapy Science, University of Bergen, Norway. Abstract from the 7th International Congress of European Medical Laser Association, Dubrovnik, Croatia, June 2000.

9. Stadler I, etal. In vitro effects of low level laser irradiation at 660 nm on peripheral blood lymphocytes. Lasers Surg Med. 2000. 27(3):255-61

10. Kubota J. Laser and sports medicine in plastic and reconstructive surgery. Department of Plastic and Reconstructive Surgery, Kyorin University School of Medicine, Tokyo, Japan. Abstract from II Congress ofthe Internat. Assn for Laser and Sports Medicine, Rosario, Argentina, March 10-12, 2000.

11. Lievens P and Van der Veen PH. Wound healing process: influence of LLLT on the proliferation of fibroblasts and on the lymphatic regeneration. Department of Rehabilitation research, Vrije University, Brussels, Belgium. Abstract from the 7th International Congress of European Medical Laser Association, Dubrovnik, Croatia, June 2000.

12. Karu TI. Mechanisms of low-power laser light action on cellular level. In Lasers in Medicine and Dentistry. Ed. by Z.Simunovic. Rijeka. Vitgraph. 2000. pp. 97-125.

13. Ohno T. Pain suppressive effect of low power laser irradiation. A quantitative analysis of substance P in the rat spinal dorsal root ganglion. J Nippon Med Sch. 1997. 64 (5):395-400.

14. Tsuchiya K etal. Diode laser irradiation selectively diminishes slow component of axonal volleys to dorsal roots from the saphenous nerve. Neuroscience Letters. 1993. 161 :65-68.

15. Rochkind S, etal. Laser therapy as a new modality in the treatment of incomplete peripheral nerve injuries: Prospective Clinical Double-Blind PIaceboControIled Randomized Study. Department of Neurosurgery, Rehabilitation and Physiotherapy, Tel Aviv Sourasky Medical Center, Israel. Abstract from the 7th International Congress of European Medical Laser Association, Dubrovnik, Croatia, June 2000.

16. Byrnes KR, et al. Cellular invasion following spinal cord lesion and low power laser irradiation. Lasers Surg Med. 2002. S14:11.

17. Rochkind S, Shahar A, and Nevo Z. An innovative approach to induce regeneration and the repair of spinal cord injury. Laser Therapy. 1997; 9 (4):151.

18. Schindler A, etal. Increased dermal neovascularization after low dose laser therapy. 2nd Congress, World Association for Laser Therapy. Kansas City. 1998.

19. Almeida-Lopes L, etal. Comparison of the low level laser therapy effects on cultured human gingival fibroblasts proliferation using different irradiance and same fluence. Lasers in Surgery and Medicine. 2001. 29(2):179-184.

20. Samoilova KA, et al. Enhancement of the blood growth promoting activity after exposure of volunteers to visible and infrared polarized light. Part I: stimulation of human keratinocyte proliferation in vitro. Advance Article of 2004 Photochemical & Photobiological Sciences. Published on the web at Sept 1, 2003.

21. Barber A, etal. Advances in laser therapy for bone repair. The Journal of Laser Therapy. VoI.13. World Association of Laser Therapy. 2000.

22. Antonio L, et al. Biomodulatory effects of LLLT on bone regeneration. The Journal of Laser Therapy. Vol. 13. World Association of Laser Therapy. 2000.

23. Shefer G, et al. Low energy laser irradiation promotes the survival and cell cycle entry of skeletal muscle satellite cells. Journal of Cell Science. 2002. 115:1461-1469.

24. Enwemeka CS and Reddy GK. The biological effects of laser therapy and other modalities on connective tissue repair processes. The Journal of Laser Therapy. Vol. 12. World Association of Laser Therapy. 2000.

25. Reddy GK, Stehno-Bittel L, and Enwemeka CS. Laser photo stimulation accelerates wound healing in diabetic rats. Wound Repair and Regeneration. 2001. 9:248-255.

26. Stadler I, et al. 830 nm irradiation increases the wound tensile strength in diabetic murine model. Lasers in Surgery and Medicine. 2001. 28 (3):220226.

27. Parizotto N, etal. Structural analysis of collagen fibrils after He-Ne laser photostimulation. 2nd Congress, World Association for Laser Therapy. Kansas City. 1998.

28. Simunovic Z, etal. Low level laser therapy of soft tissue injuries upon sport activities and traffic accidents: a multicenter, double-blind, placebo-controlled clinical study on 132 patients. Pain Center-Laser Center, Locarno, Switzerland. Abstract from II Congress of the Internat. Assn for Laser and Sports Medicine, Rosario, Argentina. March 10-12, 2000.