Low level laser therapy
Encyclopedia
Low-level laser therapy (LLLT) is a medical
and veterinary
treatment that uses low-level laser
s or light-emitting diode
s 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 nerve
s versus joint
s), dose, wavelength, timing, pulsing and duration. The effects of LLLT appear to be limited to a specified set of wavelengths of laser, and administering LLLT below the dose range does not appear to be effective.
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
, osteoarthritis, acute and chronic neck pain
, tendinopathy
, and possibly chronic joint disorders. The evidence for LLLT being useful in the treatment of low back pain
, dentistry and wound healing
is equivocal.
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.
caused by rheumatoid arthritis
, osteoarthritis, tendinopathy
, and possibly chronic joint disorders. LLLT has also been useful in the treatment of both acute and chronic neck pain
. 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
, a finding echoed in a later review of treatments for chronic low back pain. 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. Similarly, the use of lasers to treat chronic periodontitis
and to speed healing of infections around dental implants
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."
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.
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 granulocyte
s, oxidative stress
, edema
, and bleeding
. The appropriate dose appears to be between 0.3 and 19 joule
s per square centimetre. 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. 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.
The effects of LLLT appear to be limited to a specified set of wavelengths of laser, 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 nerve
s versus joint
s). Administering LLLT below the dose range does not appear to be effective. 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.
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
and veterinary
Veterinary medicine
Veterinary Medicine is the branch of science that deals with the prevention, diagnosis and treatment of disease, disorder and injury in non-human animals...
treatment that uses low-level laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
s or light-emitting diode
Light-emitting diode
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...
s 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 nerve
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
s versus joint
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...
s), dose, wavelength, timing, pulsing and duration. The effects of LLLT appear to be limited to a specified set of wavelengths of laser, and administering LLLT below the dose range does not appear to be effective.
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
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
, osteoarthritis, acute and chronic neck pain
Neck pain
Neck pain is a common problem, with two-thirds of the population having neck pain at some point in their lives.Neck pain, although felt in the neck, can be caused by numerous other spinal problems. Neck pain may arise due to muscular tightness in both the neck and upper back, or pinching of the...
, tendinopathy
Tendinopathy
Tendinopathy refers to a disease of a tendon. More specifically, it can refer to:* Tendinitis* TendinosisTendon injury arise from a combination of intrinsic and extrinsic factors; acute tendon injuries may be predominantly caused by extrinsic factors, whereas in overuse syndromes as in the case of...
, and possibly chronic joint disorders. The evidence for LLLT being useful in the treatment of low back pain
Low back pain
Low back pain or lumbago is a common musculoskeletal disorder affecting 80% of people at some point in their lives. In the United States it is the most common cause of job-related disability, a leading contributor to missed work, and the second most common neurological ailment — only headache is...
, dentistry and wound healing
Wound healing
Wound healing, or cicatrisation, is an intricate process in which the skin repairs itself after injury. In normal skin, the epidermis and dermis exists in a steady-state equilibrium, forming a protective barrier against the external environment...
is equivocal.
History
In 1967 a few years after the first working laser was invented, Endre MesterEndre Mester
Hungarian physician Endre Mester was a pioneer of laser medicine, including the use of low level laser therapy . In 1967, only a few years after the first working laser was invented, he started his experiments with the effects of lasers on skin cancer...
in Semmelweis University
Semmelweis University
Founded in 1769, Semmelweis University is the oldest medical school in Hungary. The faculty became an independent medical school after the Second World War and developed into a university teaching medicine, dentistry, pharmacy, health sciences, health management as well as physical education and...
in Budapest, Hungary experimented with the effects of lasers on skin cancer. While applying lasers to the backs of shaven mice
Mouse
A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...
, he noticed that the shaved hair grew back more quickly on the treated group than the untreated group.
Clinical applications
LLLT has primarily been shown useful in the short-term treatment of acute painPain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
caused by rheumatoid arthritis
Rheumatoid arthritis
Rheumatoid arthritis is a chronic, systemic inflammatory disorder that may affect many tissues and organs, but principally attacks synovial joints. The process produces an inflammatory response of the synovium secondary to hyperplasia of synovial cells, excess synovial fluid, and the development...
, osteoarthritis, tendinopathy
Tendinopathy
Tendinopathy refers to a disease of a tendon. More specifically, it can refer to:* Tendinitis* TendinosisTendon injury arise from a combination of intrinsic and extrinsic factors; acute tendon injuries may be predominantly caused by extrinsic factors, whereas in overuse syndromes as in the case of...
, and possibly chronic joint disorders. LLLT has also been useful in the treatment of both acute and chronic neck pain
Neck pain
Neck pain is a common problem, with two-thirds of the population having neck pain at some point in their lives.Neck pain, although felt in the neck, can be caused by numerous other spinal problems. Neck pain may arise due to muscular tightness in both the neck and upper back, or pinching of the...
. A Cochrane Library
Cochrane Library
The Cochrane Library is a collection of databases in medicine and other healthcare specialties provided by the Cochrane Collaboration and other organisations. At its core is the collection of Cochrane Reviews, a database of systematic reviews and meta-analyses which summarize and interpret the...
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
Low back pain
Low back pain or lumbago is a common musculoskeletal disorder affecting 80% of people at some point in their lives. In the United States it is the most common cause of job-related disability, a leading contributor to missed work, and the second most common neurological ailment — only headache is...
, a finding echoed in a later review of treatments for chronic low back pain. Though it has been suggested for decades that LLLT could be useful in speeding wound healing
Wound healing
Wound healing, or cicatrisation, is an intricate process in which the skin repairs itself after injury. In normal skin, the epidermis and dermis exists in a steady-state equilibrium, forming a protective barrier against the external environment...
, the appropriate parameters (dose, type of laser, materials, wavelength, etc.) have not been identified. Similarly, the use of lasers to treat chronic periodontitis
Chronic periodontitis
Chronic periodontitis is a common disease of the oral cavity consisting of chronic inflammation of the periodontal tissues that is caused by accumulation of profuse amounts of dental plaque.-Diagnosis:...
and to speed healing of infections around dental implants
Peri-implantitis
Peri-implantitis is a dental term used to describe the destructive inflammatory process affecting the soft and hard tissues surrounding dental implants. The array of periodontal pathogens found around failing implants are very similar to those found in association with various forms of...
is suggested, but there is insufficient evidence to indicate a use superior to traditional practices.
Stephen Barrett
Stephen Barrett
Stephen Joel Barrett is a retired American psychiatrist, author, co-founder of the National Council Against Health Fraud , and the webmaster of Quackwatch. He runs a number of websites dealing with quackery and health fraud. He focuses on consumer protection, medical ethics, and scientific...
, writing for Quackwatch
Quackwatch
Quackwatch is an American non-profit organization founded by Stephen Barrett with the stated aim being to "combat health-related frauds, myths, fads, fallacies, and misconduct" and with a primary focus on providing "quackery-related information that is difficult or impossible to get elsewhere."...
, 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."
Insurance company Cigna
CIGNA
Cigna , headquartered in Bloomfield, Connecticut, is a global health services company, owing to its expanding international footprint and the fact that it provides administrative services only to approximately 80 percent of its clients...
has reviewed the evidence for LLLT and concluded that it is still considered an experimental treatment therefore does not provide coverage for it.
Mechanism
It is unclear how LLLT works. LLLT may reduce painPain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
related to inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
by lowering, in a dose-dependent
Dose (biochemistry)
A dose is a quantity of something that may impact an organism biologically; the greater the quantity, the larger the dose. In nutrition, the term is usually applied to how much of a specific nutrient is in a person's diet or in a particular food, meal, or dietary supplement...
manner, levels of prostaglandin E2, prostaglandin-endoperoxide synthase 2
PTGS2
Prostaglandin-endoperoxide synthase 2, also known as cyclooxygenase-2 or simply COX-2, is an enzyme that in humans is encoded by the PTGS2 gene.- History :...
, interleukin 1-beta
IL1B
Interleukin-1 beta also known as catabolin, is a cytokine protein that in humans is encoded by the IL1B gene. IL-1β precursor is cleaved by caspase 1 . Cytosolic thiol protease cleaves the product to form mature IL-1β.- Function :Interleukin 1 was discovered by Gery in 1972...
, tumor necrosis factor-alpha, the cellular influx of neutrophil granulocyte
Neutrophil granulocyte
Neutrophil granulocytes are the most abundant type of white blood cells in mammals and form an essential part of the innate immune system. They are generally referred to as either neutrophils or polymorphonuclear neutrophils , and are subdivided into segmented neutrophils and banded neutrophils...
s, oxidative stress
Oxidative stress
Oxidative stress represents an imbalance between the production and manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage...
, edema
Edema
Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
, and bleeding
Bleeding
Bleeding, technically known as hemorrhaging or haemorrhaging is the loss of blood or blood escape from the circulatory system...
. The appropriate dose appears to be between 0.3 and 19 joule
Joule
The joule ; symbol J) is a derived unit of energy or work in the International System of Units. It is equal to the energy expended in applying a force of one newton through a distance of one metre , or in passing an electric current of one ampere through a resistance of one ohm for one second...
s per square centimetre. Another mechanism may be related to stimulation of mitochondrion
Mitochondrion
In cell biology, a mitochondrion is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 1.0 micrometers in diameter...
to increase the production of adenosine triphosphate
Adenosine triphosphate
Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...
resulting in an increase in reactive oxygen species
Reactive oxygen species
Reactive oxygen species are chemically reactive molecules containing oxygen. Examples include oxygen ions and peroxides. Reactive oxygen species are highly reactive due to the presence of unpaired valence shell electrons....
, which influences redox
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
signalling, affecting intracellular homeostasis
Homeostasis
Homeostasis is the property of a system that regulates its internal environment and tends to maintain a stable, constant condition of properties like temperature or pH...
or the proliferation of cells. The final enzyme in the production of ATP by the mitochondria, cytochrome c oxidase
Cytochrome c oxidase
The enzyme cytochrome c oxidase or Complex IV is a large transmembrane protein complex found in bacteria and the mitochondrion.It is the last enzyme in the respiratory electron transport chain of mitochondria located in the mitochondrial membrane...
, does appear to accept energy from laser-level lights, making it a possible candidate for mediating the properties of laser therapy.
The effects of LLLT appear to be limited to a specified set of wavelengths of laser, 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 nerve
Nerve
A peripheral nerve, or simply nerve, is an enclosed, cable-like bundle of peripheral axons . A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves are found only in the peripheral nervous system...
s versus joint
Joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...
s). Administering LLLT below the dose range does not appear to be effective. The factors of wavelength, effective dose, dose-rate effects, beam penetration, the role of coherence
Coherence (physics)
In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....
, and pulses (peak power and repetition rates) are still poorly understood in the clinical setting. The typical laser average power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...
is in the range of 1-500 mW
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
; 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
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
), but some research has been done and products outside of this range are available.