 Summary and conclusion
A laser is a device that produces coherent light by stimulated emission. Some people give more detailed definitions, but the more detail, the more likely a
definition will exclude some devices that are generally, and rightly, accepted as being lasers.
Most of the modalities used in physical therapy, including moist heat, ultrasound and short wave diathermy, derive their benefit from a thermal (heating)
effect upon tissues. Low-level laser therapy (LLLT), on the other hand, causes virtually no thermal effect and therefore works via entirely different
mechanisms. The laser appears to have diverse and significant effects on cells and cell functions, including reparative processes and neurotransmitter
release. Clinically, this may be expressed as an enhancement of wound healing and nerve repair, as an anti-inflammatory and as an analgesic. The LLL
models can be used in conjunction with ultrasonic therapy, physiotherapy, chiropractic therapy and concurrent with most other therapy. Full details of the
treatment methods for various injuries are provided in the comprehensive owners manual which is included with the units. Low Level Laser therapy (LLLT)
is the treatment of various conditions using laser to bring about a photochemical reaction at a cellular level. The laser light penetrates into tissue where it is
absorbed by cells and converted into energy that influences the course of metabolic processes.
What happens is that Laser Therapy produces a photochemical effect at a cellular level. It effects various processes within the cell and cell membrane that
activates cell processes. At therapeutic levels, following absorption, light reacts with the target cells in two clearly different photobiological mechanisms,
depending on the wavelength of the light. Visible light, such as HeNe or visible diode laser energy, passes through the membrane of the cells, and initiates a
photochemical cascade reaction in the target organelles, usually the mitochondria or the lysosomes. This cascade eventually involves the cytoplasm and then
the cellular membrane resulting in intra- and extracellular transport of photoproducts from alterations of the membrane potential. In addition, Infrared
energy is absorbed in the cell membrane, where it induces a photophysical reaction which directly mediates the membrane potential, resulting in the
intra-and extracellulation phase and leading to the same photoresponse although the reaction is photophysical in the membrane rather than photochemical in
the intracellular organelles. The ultimate photoresponse is cellular proliferation. This also explains how two different mechanisms of absorption can lead to
the same end result, such as reports which show pain attenuation for both visible light HeNe lasers (photochemical reaction) and infrared diode lasers
(photophysical reaction). The cellular mechanisms discussed are immediate, and are followed by secondary or delayed local reactions as the photoproducts
interact with surrounding cells and tissue, producing such well documented effects as enhanced blood and lymphatic flow and photomediated neural
response. The local delayed reactions are followed in turn by systemic effects as the photoproducts are carried by the blood and lymphatic systems around
the body, and the photomediated neuroresponses take effect.
The pulsed lasers are quite different to the continuous wave lasers. Many so-called pulsed systems have peak powers in the milliwatt range and the pulsing is
simply turning the laser on and off.The difference in the average power may effect the treatment times (higher average power units may have a shorter
treatment time) , but they tend to not be portable, are a higher safety class (and therefore require extra precautions) are quite often more expensive, and have
a greater risk of over treatment.In general, most of the clinical research has been conducted with lower powers and positive effects have been reported.
On studying the mechanisms and effects of using LLLT, some essential general conclusions may be drawn:
1. Light impact on tissue may be recorded.
2. All other physical parameters being equal, the effect of coherent beam is more distinct than that of the non-coherent light.
3. The biological effect consists of a higher level of biochemical reactions due to their activation under the influence of laser.
The subtle mechanisms of light energy uptake by the cell still remain obscure. As it was found that laser penetrates the skin and mucous membranes, it was
clinically applied in quite different pathologies:
Articles have been written and published in peer reviewed journals since the 1960s. Some double blind cross over studies have been completed and the
therapy is accepted in Europe and Japan. Not every study has demonstrated positive results, and work will continue to determine the most efficient use of
laser therapy. The low level laser was found to be capable of positively dispersing the symptomatology leading to patients complete cure (Maturo, 1981);
(Bigelio, 1984) and (Palmieri, 1984). Laser treatment is recommended in numerous diseases, such as articular distortion, tendinitis, pararthritis, lumbar
and cervical pains, sciatic pain, carpal tunnel syndrome and arthralgia.
Generally speaking, there are more than 100 positive double blind studies in the field of Low Level Laser Therapy (LLLT). This is more than the critics
seem to be aware of. However, in a thorough Medline se, only 26 of these studies were found. 34 of the 100 studies have only been found as abstracts and
another ten only as references. Also, there are more than 2000 research reports published. Looking at the limited LLLT dental literature alone (265 studies),
more than 90% of these studies do verify the clinical value of laser therapy. In conclusion, the positive double blind studies are more than usually expected
but they are difficult to find. In our essay here, studies and articles dealing with effects of LLLT on certain maladies mounted to over 100. Of these, 16
explained the scientific basis and mechanisms of LLLT. For rheumatoid arthritis, 10 were mentioned; 3 found no effect, 1 found the effect more due
to placebo effect and 6 found a good effect for LLLT in treatment of RA. And, in Osteoarthritis there were 8; 2 were against its use and 4 found positive
effects but there was two more studies: one that analyzed the results of 6 other studies and found distinct improvements in all, the other study reviewed 5
studies of which 2 showed conflicting results and 3 showed good effects of LLLT use in OA.
For musculoskeletal disorders, 4 were mentioned in treatment of tendinitis. Of these, one was against its use in rotator cuff tendinitis, one against its
use in Achilles tendinitis, one found good effect in its use in acute tendinitis and one that searched the literature of 77 randomized trials. The overall results
showed very good effect of LLLT in treatment of tendinitis. Also, 3 were mentioned in treatment of epicondylitis. Of these, one found no effect in lateral
epicondylitis, one found that it is better than placebo in treatment of lateral epicondylitis and the third found that LLLT has good effect in treatment of both
medial and lateral epicondylitis. In addition, a study found the LLLT good in treatment of painful shoulder syndrome and two found positive effects in
treatment of carpal tunnel syndrome. In myofascial disorders and fibromyalgia, 6 were mentioned. Of these, two of the same author found no effect
but the other four found positive results. Moreover, for skeletal low back pain, 3 were mentioned. Of these, one negative, the other two positive.
For pain in general, 16 studies and articles were quoted. Of these, 4 were found against use of LLLT and the other 12 found great effects of laser therapy
especially in musculoskeletal pain and neuralgic pain; it was found that laser acupuncture is one of the best methods for treating pain. For the treatment of
contusions and hematomas, it has proven to be quite effective. The pain disappears very early. Therefore, permitting rapid function and recovery. In fact,
laser is already being used with great success in sport trauma to accelerate, to maximum, the course of healing in sports injuries. In inflammation, laser is
being used for treatment of all of its forms (Cabrero et al., 1985 and Bian et al., 1989). Also, it is used for all inflammations in the oral region, nose and
the paranasal sinuses (Cabrero et al., 1985). In edema, by its biostimulating effect, leads to an increase in the metabolic rate with production of more
quantities of metabolites and heat. The metabolites, in turn, cause an arteriolar dilatation with significant increase in capillary blood flow and hydrostatic
pressure. This, ultimately, leads to decrease in the resultant edema and extravasated effusion and swelling. Pain of various origins can be relieved or
alleviated by laser. Generally, it is used in cases of headache, nerve pain, spastic pain, pain after trauma, etc. (Foster & Palastagna, 1988 and Hu, 1989).
However, more than 30 studies and trails were mentioned in the part of the effect of LLLT in biostimulation and wound healing. All of these found
LLLT one of the best methods in treating slowly healing wounds and ulcerations. As a biostimulant of blood cells, laser encourages formation of blood in
the spongia to enhance bone regeneration (Christov, 1989). Laser is also capable of stimulating re-epithelization in case of burns, ulcers and wounds,
leading in a short time to healing without surgery of incapacitating injuries (Savaasand, 1985 and Hansson, 1988) and (Baibekov & Nurallaev, 1990).
Treated skin wounds show the following reactions:-
1. Reduced scar formation
2. Reduced pain and inflammation
3. Increased collagen and reduced cellular substances
4. Increased epithelial activity
5. Increased capillary blood vessel formation
In any case, it was also found that the most important precaution that should be taken during laser therapy is its direction to the eyes and the only eminent
contraindication is lack of experience.
Finally, we must add that it goes without saying that all medicines have a level of placebo effect, even visiting a doctor has a placebo effect. If Laser
Therapy makes patients feel better, has no side effects and does not incur much cost (apart from the capital cost), is not it better to use laser therapy than
prescribe drugs or inject cortisone?. It is evident Laser Therapy is not the complete solution but just another tool in a clinicians armory. At any rate, many of
the medical professions are requesting more conclusive data and this is slowly being conducted. There certainly appears to be variation in treatment
outcomes between patients (as with most drug treatments) and this means that the clinical trial numbers need to be quite larger. The future will show and
most probably before the end of the 21st century, we shall see to where the laser beam can reach.
|
