Low level laser therapy

Low-level laser therapy (LLLT) is a form of alternative medicine that uses low-level (low-power) lasers or light-emitting diodes (LEDs). Whereas high-power lasers used in laser medicine destroy or cut tissue, low-power lasers are claimed to stimulate it and to encourage the cells to function.

The effects of LLLT appear to be limited to a specified set of wavelengths of laser,^[1] and administering LLLT below the dose range does not appear to be effective.^[2]

Despite a lack of consensus over its scientific validity, specific test and protocols for LLLT suggest it may be modestly effective, but in most cases no better than placebo, in relieving short-term pain for rheumatoid arthritis,^[3] osteoarthritis,^[4] acute and chronic neck pain,^[5] tendinopathy,^[1][6] and possibly chronic joint disorders.^[2] The evidence for LLLT being useful in the treatment of low back pain,^[7][8] dentistry^[9][10] and wound healing is unclear.^[11]

Medical uses

Various LLLT devices have been promoted for use in treatment of several musculoskeletal conditions including carpal tunnel syndrome (CTS), fibromyalgia, osteoarthritis, and rheumatoid arthritis. They have also been promoted for temporomandibular joint (TMJ) disorders, wound healing, smoking cessation, and tuberculosis. While they may briefly help some people with pain management, evidence does not support claims that they change long term outcomes, or that they work better than other, low tech ways of applying heat.^[12]

The Centers for Medicare and Medicaid Services,^[13] Aetna,^[14] and Cigna^[15] have reviewed the clinical evidence with respect to LLLT and found it insufficient to determine that LLLT is safe or effective for any purpose.

Musculoskeletal

LLLT may be useful in the treatment of both acute and chronic neck pain.^[5] In neck pain the benefit was not of significant importance and the evidence had a high risk of bias.^[16] A 2008 Cochrane Library review concluded that LLLT has insufficient evidence for treatment of nonspecific low back pain,^[7] a finding echoed in a 2010 review of chronic low back pain.^[8] A 2015 review found benefit in nonspecific chronic low-back pain.^[17]

There is tentative data that LLLT is useful in the short-term treatment of pain caused by rheumatoid arthritis,^[3] and possibly chronic joint disorders.^[2] While it does not appear to improve pain in temporomandibular disorders, it may improve function.^[18] Evidence for useful in osteoarthritis is poor.^[4][19]

There is tentative evidence of benefit in tendinopathy.^[1][6] A 2015 review found benefit in shoulder tendinopathy.^[20] A 2014 Cochrane review found tentative evidence that it may help in frozen shoulders.^[21]

Evidence does not support a benefit in delayed-onset muscle soreness.^[22] It may be useful for muscle pain and injuries.^[23]

Teeth

Similarly, the use of lasers to treat chronic periodontitis^[9] and to speed healing of infections around dental implants^[10] is suggested, but there is insufficient evidence to indicate a use superior to traditional practices.^[24]

There is tentative evidence for dentin hypersensitivity.^[25] It does not appear to be useful for orthodontic pain^[26][27]

LLLT might be useful for wisdom tooth extraction (complications)^[28] and oral mucositis.^[29]

Hair loss

2008 and 2012 reviews found little evidence to support the use of lasers to treat hair loss.^[30][31] Additionally none are FDA approved for this use.^[31] They however appear to be safe.^[30]

A 2014 review found tentative evidence of benefit for lasers.^[32] While another 2014 review concluded that the results are mixed, have a high risk of bias, and that its effectiveness is unclear.^[33] A 2015 review also found tentative evidence of benefit.^[34]

Other

LLLT might be effective to reduce pain and swelling in breast-cancer related lymphedema.^[35]

Though it has been suggested that LLLT may be useful in speeding wound healing, the appropriate parameters (dose, type of laser, materials, wavelength, etc.) have not been identified.^[11]

Stephen Barrett, writing for Quackwatch, concluded in 2009 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."^[36] Barrett's position was unchanged as of 2016.^[12]

Mechanism

It is unclear how LLLT might work.^[1]

The effects of LLLT appear to be limited to a specified set of wavelengths of laser,^[1] and administering LLLT below the dose range does not appear to be effective.^[2]

Photochemical reactions are well known in biological research; it may be that the light applied in low level laser therapy might react with the respiratory enzyme cytochrome c oxidase which is involved in the electron transport chain in mitochondria.^[37][38]

History

Hungarian physician and surgeon Endre Mester (1903-1984) is credited with the discovery of the biological effects of low power lasers,^[39] which occurred a few years after the 1960 invention of the ruby laser and the 1961 invention of the helium–neon (HeNe) laser.^[40] Mester accidentally discovered that low-level ruby laser light could regrow hair during an attempt to replicate an experiment that showed that such lasers could reduce tumors in mice. The laser he was using was faulty and wasn't as powerful as he thought; it failed to affect the tumors but he noticed that in the places where he had shaved the mice in order to do the experiments, the hair grew back faster on mice he treated compared with the placebos.^[41] He published those results in 1967.^[40] He went on to show that low level HeNe light could accelerate wound healing in mice.^[40] By the 1970s he was applying low level laser light to treat people with skin ulcers.^[40] In 1974 he founded the Laser Research Center at the Semmelweis Medical University in Budapest, and continued working there for the remainder of his life.^[42] His sons carried on his work and brought it to the United States.^[39]

By 1987 companies selling lasers were claiming that they could treat pain, accelerate healing of sports injuries, and treat arthritis, but there was little evidence for this at that time.^[39] By 2016 they had been marketed for wound healing, smoking cessation, tuberculosis, and musculoskeletal conditions such as temporomandibular joint disorders carpal tunnel syndrome, fibromyalgia, osteoarthritis, and rheumatoid arthritis, and there was still little evidence for these uses, other than a possible use in temporarily treating muscle or joint pain.^[12]

Mester originally called this approach "laser biostimulation'", but it soon became known as “low level laser therapy" and with the adaptation of light emitting diodes by those studying this approach, it became known as "low level light therapy", and to resolve confusion around the exact meaning of "low level", the term "photobiomodulation" arose.^[41]

Society and culture

Reimbursement

As of 2006, the Centers for Medicare and Medicaid Services did not provide coverage for LLLT,^[13] as of 2014 Aetna did not provide coverage,^[14] and as of 2016 Cigna did not provide coverage.^[15]

Names

Variations of LLLT have gone by a variety of alternate names including low-power laser therapy (LPLT), soft laser therapy, low-intensity laser therapy, low-energy laser therapy, cold laser therapy, bio-stimulation laser therapy, photo-biotherapy, therapeutic laser, and monochromatic infrared light energy (MIRE) therapy.^[43] When LLLT is administered to so-called "acupuncture points", the procedure may be called laser acupuncture.

Veterinary use

Veterinary clinics use cold laser devices to treat a wide variety of ailments, from arthritis to wounds, on dogs and cats.^[44][45] Very little research has been done on the effects of this treatment on animals. Currently, laser therapy equipment is aggressively marketed to veterinarians as a supposedly powerful therapeutic tool and revenue generator. Brennen McKenzie, president of the Evidence-Based Veterinary Medical Association, has stated that “research into cold laser in dogs and cats is sparse and generally low quality. Most studies are small and have minimal or uncertain controls for bias and error”. ^[46][47] While allowing that some studies show promising results, he reports that others do not. While believing that there is enough evidence to warrant further study, he concludes that there is not enough evidence to support routine clinical use of cold laser in animals.

If vets want to try this therapy, they have an obligation to be clear with client that the risks and benefits have not been established and that the treatment is essentially experimental. There is nothing wrong with using such a treatment given appropriate informed consent, but the aggressive marketing of laser equipment to vets as a profitable treatment is ethically questionable given the lack of good evidence that it is a truly safe and effective treatment for any condition. ^[48]

Research

An area of research is the application of LLLT for increasing cell proliferation, including stem cells.^[49]

See also

• Photomedicine
• Light therapy
• Blood irradiation therapy

References