How Laser Therapy Works

Overview

• Photo-Chemical Action
• Role of Chromophores
• Summary of the Photochemical Process
• Acute Inflammation Reduction – How does Laser Therapy reduce inflammation?
• Analgesia – How does Laser Therapy reduce pain?

All light is composed of photons. Photons are small packets of light energy—in the form of waves— with a defined wavelength and frequency. Photon energy is able to more effectively penetrate the skin and underlying structures, therefore accelerating the healing process. Light travels at a constant speed and oscillate up and down as it moves forward.

However, all light is not the same. It is measured in wavelengths, with each wavelength of light representing a different color of the spectrum. The number of oscillations per second represents the frequency of each wavelength; shorter waves have a greater frequency than longer waves. Laser energy is coherent (well-ordered photons), monochromatic (single-color) light energy. When produced as a narrow, bright beam. Laser light holds its intensity until it is absorbed by a medium (the body). When applied to an organism, Laser light, tuned to specific wavelengths and frequencies, stimulates metabolic processes at the cellular level.

Photo-Chemical Action

Studies have shown that when tissue cultures are irradiated by Lasers, enzymes within cells absorb energy from laser light. Visible (red) light and Near Infrared (NIR) are absorbed within the mitochondria and the cell membrane. This produces higher ATP levels and boosts DNA production, leading to an increase in cellular health and energy. When applied as treatment, therefore, Lasers have been shown to reduce pain and inflammation as well as stimulate nerve regeneration, muscle relaxation and immune system response.

Lasers have no effect on normal tissues, as photons of light are only absorbed and utilized by the cells that need them.

Role of Chromophores

Chromophores are components of various cells and sub-cellular organelles which absorb light. The stimulation of Chromophores on mitochondrial membranes incites the production of ATP rusulting in:

• Increases cellular energy levels
• Allows pain relief
• Accelerates cellular healing

Summary of the Photochemical Process:

Photons

Absorbed in Mitochondria and Cell Membrane within cytochromes and Porphyry’s

Singlet Oxygen is Produced

Changes in Membrane Permeability

ATP Synthesized and DNA Produced

Increase in Cell Metabolism from a Depressed Rate to a Normal Level

Selective Bio-Stimulatory Effect on Impaired Cells
note cells and tissues functioning normally are not affected

Acute Inflammation Reduction – How do Lasers reduce inflammation?

Summary of Light Induced, Anti Inflammatory Responses

1. Stabilization of the cellular membrane
2. Enhancement of ATP production and synthesis
3. Stimulation of vasodilation
4. Acceleration of leukocytic activity
5. Increased prostaglandin synthesis
6. Reduction in interleukin 1
7. Enhanced lymphocyte response
8. Increased angiogenesis
9. Temperature modulation
10. Enhanced superoxide dismutase (SOD) levels
11. Decreased C-reactive protein and neopterin levels

1. Stabilization of the cellular membrane

1. Ca++, Na+ and K+ concentrations, as well as the proton gradient over the mitochondria membrane are positively influenced.
2. This is accomplished in part, by the production of beneficial Reactive Oxygen Species aka (ROS).
3. These ROS’s modulate intracellular Ca++ concentrations and laser therapy improves Ca++ uptake in the mitochondria.

2. Enhancement of ATP production and synthesis

1. ATP production and synthesis are significantly enhanced, contributing to cellular repair, reproduction and functional ability
2. Photonic 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. Stimulation of vasodilation

1. Vasodilation is stimulated via an increase in Histamine, Nitric Oxide (NO) and Serotonin levels, resulting in reduction of ischemia and improved perfusion
2. Laser-mediated vasodilation enhances the transport of nutrients and oxygen to the damaged cells and facilitates repair and removal of cellular debris.

4. Acceleration of leukocytic activity

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

5. Increased prostaglandin synthesis

1. Prostaglandins have a vasodilating and anti-inflammatory action

6. Reduction in interleukin 1

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.

7. Enhanced lymphocyte response

1. 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.
2. Along with laser modification of beta cell activity, the entire lymphatic response is beneficially affected by laser therapy.

8. Increased angiogenesis

1. Both blood capillaries and lymphatic capillaries have been clinically documented to undergo significant increase and regeneration in the presence of laser irradiation.

9. Temperature modulation

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

10. Enhanced superoxide dismutase (SOD) levels

1. Laser stimulated increases in cytokine SOD levels interact with other anti-inflammatory processes to accelerate the termination of the inflammatory process.

11. Decreased C-reactive protein and neopterin levels

1. Laser therapy has been shown to lower the serum levels of these inflammation markers, particularly in rheumatoid arthritis patients

Analgesia – How does Laser Therapy reduce pain?

Summary of Light Induced, Analgesic Responses

1. Increase in beta endorphins
2. Increased nitric oxide production
3. Decreased bradykinin levels
4. Ion channel normalization
5. Blocked depolarization of C-fiber afferent nerves
6. Increased nerve cell action potentials
7. Increased release of acetylcholine
8. Axonal sprouting and nerve cell regeneration

1. Increase in beta endorphins

1. The localized and systemic increase of this endogenous peptide, after laser therapy irradiation has been clinically reported in multiple studies, to promote pain reduction.

2. Increased nitric oxide production

1. Nitric oxide 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.
2. And indirectly, the vasodilation effect of nitric oxide can enhance nerve cell perfusion and oxygenation.

3. Decreased bradykinin levels

1. Since Bradykinins elicit pain by stimulating nociceptive afferents in the skin and viscera, mitigation of elevated levels through laser therapy can result in pain reduction.

4. Ion channel normalization

1. Photobiomodulation promotes normalization in Ca++, NA+ and K+ concentrations, resulting in pain reduction as a result of these ion concentration shifts.

5. Blocked depolarization of C-fiber afferent nerves

1. The pain blocking effect of therapeutic lasers can be pronounced, particularly in low velocity neural pathways, such as non-myelinated afferent axons from nociceptors.
2. Laser irradiation suppresses the excitation of these fibers in the afferent sensory pathway.

6. Increased nerve cell action potentials

1. Healthy nerve cells tend to operate at about -70 mV, and fire at about -20 mV. Compromised cell membranes have a lowered threshold as their resting potentials average around this -20 mV range.
2. That means that normal non-noxious activities produce pain.
3. Laser therapy can help restore the action potential closer to the normal -70 mV range.

7. Increased release of acetylcholine

1. By increasing the available acetylcholine, Laser Therapy helps in normalizing nerve signal transmission in the autonomic, somatic and sensory neural pathways.

8. Axonal sprouting and nerve cell regeneration

1. Several studies have documented the ability of laser therapy to induce axonal sprouting and some nerve regeneration in damaged nerve tissues.
2. Where pain sensation is being magnified due to nerve structure damage, cell regeneration and sprouting may assist in reducing pain.