Clinical use of low level laser therapy

DISCUSSION AND CONCLUSIONS

Clinical uses of LLLT: Trelles et al 1987 reviewed the use of local irradiation with cold laser in therapy. The stimulus was applied mainly to local lesions to elicit the following types of effect:

biostimulatory (reparative effects in ulcers, granulomas, burns, septic wounds and trauma to superficial tissues (tendon, bursa, sheath, joint and muscle); it stimulates local cell metabolism in damaged tissues in vivo and in vitro (mitosis, local DNA and protein synthesis, local phagocytosis, antibody formation and activity of local tissue enzymes (succinyl- and lactate- dehydrogenase, acid phosphatase, non-specific esterase). It enhances scar formation and tissue regeneration (wounds, ulcers of skin and portio uteri), enhances mitogenic activity (cell proliferation), enhances osteogenic activity (in bone fractures, arthritis, osteomyelitis),

 

analgesic, antiexudative, antihaemorrhagic,

 

antiinflammatory (in herpes lesions, urethritis, haemorrhoids, sinusitis etc),

 

antineuralgic, antioedematous, antiseptic,

 

antispasmodic (in muscle injury),

 

vasodilatory (in local disorders, organic disorders and alopecia areata).

 

Trelles et al 1987 and Muxeneder 1987 also reviewed the effects of LLLT in vertebral pain, headaches and local immune responses. The main clinical uses include wound healing, pain control, soft tissue injury, arthropathy and osteopathy and treatment of existing scars.

(a) Wound healing: Most He-Ne and IR lasers, even those <5 mW/cm sq, are said to be effective in treating wounds (surgical, accidental or septic) and superficial disorders (cuts, bruises, granulomas, ulcers, fistulas). Local irradiation stimulates extremely rapid healing, even of extensive indolent superficial wounds. It is effective and safe. Wound area decreases after 2 sessions and strength of the peripheral area increases due to growth of collagen tissue. Scarring is minimal. The effects in wound healing (including wounds refractory to other treatment) are dramatic (Mester et al 1985; Dyson and Yang 1986; Muxeneder 1987). It increases peripheral vascularisation and local tissue nutrition; a "halo phenomenon" is evident around treated wounds after 1-2 sessions (Muxeneder 1987). Speed of granulation, tensile strength of the scar and speed of resolution are enhanced. Many irradiated septic wounds heal as if by first intention.

Clean wounds can be irradiated (edges, underneath the flaps, exposed tissue). Septic wounds, fistulas, ulcers and granulomas should be debrided before irradiation. LLLT is superb in the management of post-operative wounds.

Apart from the review of Trelles et al (1987), little has been published on LLLT of burns but it is probable that it would be effective. Sumano & Casaulon (1987) reported dramatic effects of electro-AP and TENS in treating infected wounds and burns in experimental animals.

b. Pain control: Acute and chronic pain, especially traumatic pain in superficial tissues (including joints) can be alleviated if the primary sites are irradiated. Results are even better if the associated superficial TPs and APs are also treated (Airaksinen et al 1988; Pontinen 1987).

c. Soft tissue injury: Pain, swelling and inflammation in superficial muscles, tendons, ligaments, bursae and sheaths can be alleviated by irradiation of the affected areas, TPs and associated APs. In a double blind crossover study in humans, IR LLLT (1.5 J/point) caused a highly significant elevation of pressure thresholds of TPs as compared with placebo LLLT(Airaksinen et al 1988).

d. Arthropathy and osteopathy: Pain, swelling and inflammation of accessible joints can be alleviated by mid lasers. Initially, the effect was thought to be anti-inflammatory but recent work has shown that LLLT enhances the inflammatory response, to reach the proliferative and healing stage much earlier. It is effective also in pain control and resolution of osteitis and periostitis in superficial areas (splints, ringbone, curb, sore shins etc). It is preferable to ultrasound in these conditions, as ultrasound can heat bone.

e. Treatment of existing scars: Old scars (surgical or traumatic) can act as TPs if there are tender areas, keloid formation and adhesions along the scar. Such scars can be associated with chronic, refractory functional (reflex) pain, lameness and autonomic effects.LLLT of such scars, especially if concentrated on the tender and keloid- areas and on those with obvious adhesions, can produce dramatic clinical improvement in these cases.

Dangers, contraindications and problems of LLLT: Mid lasers (Class 3A, 3B) may damage the retina and should not be shone directly into the eye. They are used to treat keratitis and corneal ulcers but should be aimed tangentially at the target for 30 seconds/session. Operators who use mid lasers every day are advised to wear appropriate goggles. This is especially important when IR lasers are used, as the beam is invisible.

Over-stimulation does not seem to cause problems but, because of the mitotic effects, it is wise not to irradiate cancerous tissue. Some authors advise against using laser over acutely infected closed swellings, as this may spread the local infection.

Faulty lasers may not emit at the stated MOP or may have a too wide divergence (angle of irradiation). For maximum effect the light beam should be parallel and the light-spot should be small (concentrated). The glass at the probe-tip should be cleaned regularly, as dirt may limit MOP. The better IR lasers have an in-built optical sensor to monitor MOP before use.

Some devices, sold as lasers, do not emit laser light. Some "lasers" are based on light emitting diodes and not on laser diodes. They emit non-parallel light of different wavelengths simultaneously or by selective control. Sunlight or a cheap flashlight would probably be just as effective.

Clinical results: From September 1989 and April 1990, my experimental use of IR LLLTgave very encouraging results in equine, human and canine muscle pain/ lameness; equine flexor tendon strain; equine and human periostitis; human and canine "disc disease" and miscellaneous human conditions. In particular it gave dramatic results in skin lesions, wounds and (minor) burn cases.

Cases which failed to respond to LLLT (and also failed to respond to AP) included human cervical vertebral spondylosis and idiopathic lameness, posterior paresis in old dogs, carpal swelling in horses and misdiagnosed cases.

From April 1990 and September 1991, I reduced my use of LLLT in horses. I have reverted to injection of the AP points as the routine method of treating horses. Most cases respond to APpoint injection in 2-4 sessions, as compared with 2-6 sessions of LLLT.

In spite of initially encouraging results in equine tendon strain, most (70%) of the cases treated by LLLT relapsed, broke down on the other leg, failed to heal or were shot or retired. Therefore, unless the trainer undertakes not to work the horse for 10 months, I am reluctant to use LLLT in equine tendon strain (as distinct from trauma due to brushing or superficial traumatic swelling).

The present: Now, I use IR LLLT regularly with very good success in human and canine conditions but I often combine it with standard AP techniques to get a faster and more long-lasting response.

LLLT sessions in horses (because of their large size and the number of APs which may need to be treated) take too much time (20-30 minutes, including examination time), or too many sessions are needed. In the more common equine muscular problems, AP point injection is 10-20 minutes faster and the clinical results are 10% points better than LLLT. I confine LLLTuse in horses mainly to superficial injuries and periostitis.

There are also reports from veterinary colleagues that low MOP lasers (especially those <10 mW/cm sq) are not as effective as AP (Rogers, Jagger & Janssens 1987). These agree with my experience that an IR mid-power laser (30 mW/cm sq) was not as effective as AP in horses.

The future ?: Further work is needed to document the uses and limitations of LLLT, the effects of power, wavelength, different pulse frequencies, different exposure dosage etc. With the rapid pace of research in physical therapies, I believe that we will see increased use of electromagnetic therapy, including LLLT, ultrasound and microwave stimulation in medical and vet therapy in the next few years.

ACKNOWLEDGEMENT

I thank Normedica, PO Box 392, 8201 Schaffhausen, Switzerland for presenting me with the laser for experimental purposes.