RECENT ADVANCES IN

LASER APPLICATIONS IN THE FIELD OF PHYSICAL MEDICINE

ESSAY

Submitted in Partial Fulfillment of

Master Degree (M. Sc.) in

Rheumatology and Rehabilitation

By:

Khalid Mahmoud Zayed

(M.B., B. Ch.)

Under Supervision of:

Prof. Dr. Fawkia Morsi

Professor of Rheumatology and Rehabilitation

Faculty of Medicine, Cairo University

Dr. Hala Nassar

Lecturer of Rheumatology and Rehabilitation

Faculty of Medicine, Cairo University

Faculty of Medicine

CAIRO UNIVERSITY

(2001)

Table of contents

ESSAY *

Table of contents *

LIST OF TABLES AND FIGURES *

LIST OF COMMON ABBREVIATIONS *

ACKNOWLEGMENT *

Introduction *

Aim of the work *

Methods *

(I) what is laser? *

LASERS *

HISTORY *

TYPES OF LASERS *

(1) Solid-state lasers: *

(2) Liquid dye laser *

(3) Gas Lasers and Excimers *

(4) Chemical Lasers *

(5) Semi-conductor Lasers *

PROPERTIES OF LASER RADIATION *

(1) Monochromaticity: *

(2) Coherence: *

(3) Non-divergence *

(ii) LASERS IN MEDICINE *

KINDS OF LASERS USED IN MEDICINE *

DELIVERY DEVICES OF LASER *

ARTICULATED ARM *

MICROMANIPULATORS *

SCANNERS *

FIBEROPTICS *

ENDOSCOPIC DEVICES *

CONTACT ND:YAG LASER *

APPLICATIONS OF LASERS IN MEDICINE AND HEALTH CARE *

(iii) LASER IN PHYSICAL MEDICINE *

Absorption of LASER IN TISSUES *

LOW-LEVEL LASERS (LLL) *

Intravenous Laser Blood Irradiation Therapy *

Possible Mechanisms of Action of Low-Level Lasers *

(iv) LASERS IN ARTHRITIDES *

Laser Therapy in Rheumatoid Arthritis *

Treatment of Chronic Rheumatoid Arthritis by Low Level Laser *

Laser Therapy in Osteoarthritis *

(v) LASERS IN MUSCULO-SKELETAL DISORDERS *

Laser Therapy in Tendinitis *

Laser Therapy in Epicondylitis *

Treatment of Tennis Elbow *

Laser Therapy in Painful shoulder syndrome *

Laser Therapy in Carpal Tunnel Syndrome *

Laser Therapy in Myofascial Disorders and Fibromyalgia *

Laser Therapy in Low-back Pain and Intervertebral Disc *

Treatment of Low Back Pain *

(vi) LASERS IN PAIN TREATMENT *

LASERS IN PAIN TREATMENT *

Laser Therapy in Acute Pain *

Laser Therapy in Chronic Facial, Head and neck pains *

Laser in Acupuncture *

(vii) LASERS IN TISSUE REGENERATION *

Effects of Low-Level Laser Irradiation on Wound Healing *

Effects of Low-Level Lasers on Epidermal Wound Healing *

Effects of Low-Level Lasers on Cell Proliferation *

Immune Modulation of Cells by Low-Level Lasers *

Effects of Low-Level Lasers on Other Regenerative Processes *

Neural Regeneration *

Angiogenesis *

(viii) treatment with low level laser *

Wavelength, Output and dosage of Low Level Lasers in physical medicine *

kinds and uses of Low Level Lasers in physical medicine *

IN RHEUMATOLOGY *

IN NEUROLOGY *

IN SPORTS TRAUMAS *

LASER IN ACUPUNCTURE *

The usage of power density for acupuncture: *

The usage of dose for acupuncture: *

SIDE EFFECTS OF LASER THERAPY *

Can therapeutic lasers damage the eye? *

Can LLLT cause cancer? *

What happens if we use a too high dose? *

Does LLLT cause a heating of the tissue? *

CONTRA-INDICATIONS OF LASER THERAPY *

(Ix) SUMMARY and conclusion *

Summary and conclusion *

(x) REFERENCES *

REFERENCES *

THE ARABIC SUMMARY *

Appendix

LIST OF TABLES AND FIGURES

FIG. #		PAGE
(Figure 1)	Maiman with his first ruby laser.
(Figure 2)	The Ruby Laser.
(Table 1)	Examples of Lasers which can be used in Medicine.
(Figure 3)	Laser in ophthalmology.
(Table 2)	Types of lasers used for delivery of Low Level irradiation.
(Figure 4)	Possible mechanisms of action of laser energy in enhancing collagen production in the cells.
(Figure 5)	Possible molecular mechanisms involved in photosignal transduction of low-level laser for activation of cellular proliferation.
(Figure 6)	Treating RA of fingers with LLLT.
(Figure 7)	LLLT in tennis elbow.
(Figure 8)	Points of LLLT acupuncture irradiation to the back (according to the Japanese Laser Society).
(Figure 9)	The process of healing of a three weeks old ulcer treated by LLLT. The treatments took less than 10 min and were conducted twice a week.

LIST OF COMMON ABBREVIATIONS

Å	angstrom (equals 1x10^-12 meter).
ASTM	augmented soft tissue mobilization.
CCDC	charge-coupled device camera.
CI	confidence interval.
CL	confidence limit.
CMC	carpo-metcarpal.
CO2	Carbon Dioxide.
CW (cw)	continuous wave.
DJD	degenerative joint disease.
DYN	dynorphin A1-8-like immuno-activity.
Ga Al As	Gallium aluminum arsenide (arsenate).
Ga As	Gallium arsenide (arsenate).
IV-LBI	Intravenous Laser Blood Irradiation.
IM	intra-mascular.
IP	inter-phalangeal.
IR	infra-red.
LAS	linear analogue scale.
LASER	Light Amplification by Stimulated Emission of Radiation.
LEDs	light-emitting diodes.
LILT	Low Intensity Laser Therapy (Treatment).
LLLI	Low Level Laser Irradiation.
LLLR	Low Level Laser Radiation.
LLLT	Low Level Laser Therapy (Treatment).
LPLT	Low Power Laser Therapy (Treatment).
MCI	monochromatic light irradiation.
MCP	metacarpophalangeal.
Nd-YAG	neodymium-doped yttrium-aluminum-garnet.
OA	osteoarthritis.
PHN	post herpetic neuralgia.
PIP	proximal interphalangeal.
p-n	positive-negative.
QOL	quality of life.
RA	rheumatoid arhritis.
RIA	radio-immuno-assay.
ROM	range of motion (movement).
SF-MPQ	short form of McGill’s Pain Questionnaire.
SMD	standardized mean difference.
TMJ	temporo-mandibular joint.
TPs	tender points.
VAS	visual analogue scale.
VRS	verbal rating scale.
vs	versus (against).
WMD	weighted mean difference.
λ	lambda (the 11^th letter of the Greek alphabet; symbol of expressing the wave length).
μm	micrometer (micron= 1x10^-6 meter).

ACKNOWLEGMENT

Firstly, I wish to extend my deepest praise and thanks God, the most merciful and most beneficent. I wish also to express my profound gratitude to Professor Dr. Fawkia Morsi, professor of Rheumatology & Rehabilitation, Faculty of Medicine, Cairo University. She has always been most patiently helpful, supportive and encouraging throughout the turmoil that entailed the compiling of this essay. Without her meticulous supervision and her unique, simple and clear remarks, I would have never finished this review in its current shape.

I would like also to thank Dr. Hala Nassar, lecturer of Rheumatology & Rehabilitation, Faculty of Medicine, Cairo University, for her kind guidance, advise, help and close support and supervision.

In addition, thanks go to my teachers, fellow colleagues, family and friends for their support and for what they told me. All these, when asked, gave me the truth; the mistakes are all mine.

Khalid M. Zayed.

Cairo, 2001.

Introduction

In 1960, the race to build the first laser was red hot. At Hughes Aircraft,CA, USA, a junior employee named Theodore H. "Ted" Maiman was just one more competitor eager to create the elusive device. Despite a paltry budget and the most important scientists of the day ridiculing his ideas, he would stun the world by creating the world's first laser out of a discredited material –ruby- on 16 May 1960.

Several studies emphasized that laser effects were detected in the case of irradiation of damaged cells and organisms. In the case of irradiation of normal and healthy organisms very slight or no changes at all were registered. The influence of low level laser irradiation on the organism has several clinical effects, including anti-inflammatory, immune stimulating, neurotrophic, analgesic, desensitizing, bactericidal, antiedemic, normalizing the blood rheology and hemodynamics effects. So the areas of application of LLLT are very large and include almost all branches of medicine. 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.

In the review we will see that Low Level Laser Therapy is an entirely new treatment to heal the acute and chronic pain and the inflammation, as in arthritides and musculoskeletal disorders, by the irradiation of very weak (1~10mW) and special wavelength (630~830nm) laser to the surface of body. The main mechanism of the therapy is considered to be the bio-stimulation with the light energy enhancing the level of homeostasis. We cannot afford to fail to mention that the efficacy of LLL therapy is nowadays widely confirmed by the irradiation of laser at the most painful point together with oriental methods to use acupuncture points. Of the typical applications of LLL therapy, which were reported at recent medical conferences are as follows. rheumatoid arthritis, gout, shoulder pain, low back pain, sprains, contusions, tennis and golfer’s elbow, joint pain, tendosynovitis, bedsores, temporomandibular arthrosis, and unusual function of muscles and nerves(pain, swelling, stiffness, numbness). Also, on the basis of the clinical experience, we will see that the Low Level Laser therapy is a future in treatment of slowly healing wounds, ulceration and necrosis. LLL Therapy induces arteriolar vasodilatation, suppress pain and vascular spasm. The values of paraclinical parameters ( Doppler examination, cutaneous temperature, etc.) are changed. The patient can be rehabilitated in 3-4 months!

In fact, most people are aware of high-powered lasers either in the context of a "Star Wars"-type weapon or as a surgical tool, which burns and cuts tissue. Less well known is that low-level lasers have been used internationally for decades to promote pain relief and wound healing. The "death ray" Maiman invented has turned out to be a "life ray" -- and that is what makes him happiest. Ted Maiman has written a book about his experiences in the race to build a laser called Brighter Than the Sun. It was published a few months ago in the summer of 2000. The year 2000, incidentally, is an auspicious point in time to mark: forty is the ruby anniversary!

Aim of the work

The aim of this essay is to study and report the most recent advances and uses of lasers in the field of physical medicine with the treatment of cetain maladies in its scope Thus, attempts are made –in the review- to study the therapeutic effects of Low Level Laser (LLL) in arthritides, musculoskeletal disorders, pain and tissue regeneration with an overview of its uses, dosage, indications, side-effects and contraindications. In addition, an appendix is added for lasers’ users in the field of physical medicine to benefit from using this modern method.

Methods

We reviewed the most recent published studies and data on the subject since 1973 until now.

review of literature

(I) What is laser?

LASERS

Technically, a laser is a device for producing electromagnetic radiation, the same as light, but of considerably higher radiant energy. The word “LASER” is an acronym derived from “Light Amplification by Stimulated Emission of Radiation,”⁽¹⁾ and is generally used in referring either to the radiation or to the device that produces it. Laser radiation can be produced in the spectral ranges from ultraviolet, through visible, to infrared radiation. The laser generator is an optically active medium confined in an optical cavity located between two reflecting surfaces. The generated light oscillates in this cavity and becomes amplified by the cumulative increase of the light by the reflection between the reflectors. The amplified light possesses the characteristics of a monochromatic radiation, high radiant intensity, and directionality; it is projected through air or space in a pencil beam. The lasing (active) medium may be gas, a solid, or a liquid.

The wavelengths of lasers differ from those of light waves in that for each type of laser radiation there is, practically speaking, only one wavelength and one frequency range, neglecting harmonic wavelengths, and frequency-multiplied radiations produced artificially. This characteristic makes the radiation coherent and monochromatic, with all emission wave amplitudes in phase with each other. Thus, such a radiation is easily adaptable to convergence to a sharp focus without a fuzzy peripheral area about the focus, as usually produced by ordinary light. Since it is the focus of the laser radiation that is generally used in industry and medical work, this characteristic of sharpness of focus of the beam makes it ideal for cutting, drilling and welding materials (Hrand, 1983).

HISTORY

According to Jayasurya (1984), the history of laser development should be traced as far back as 1917, when Albert Einstein⁽²⁾ showed the process of stimulation must exist! (Einstein, 1967). The prediction of the existence of coherent stimulated emission implied that an amplifier could be built and, by extension, an oscillator, which is an amplifier in which some of the output energy is fed back into the input to keep the process going. Amplification entails the establishment of a population inversion, in which there are more excited-state atoms waiting to be stimulated to emit photons than there are lower-state atoms waiting to absorb photons. Then one photon begets two and two beget four and the electromagnetic beam grows until the supply of excited atoms saturates (Itzkan, 1997).

In 1958, Schwalow and Townes proposed the idea of building an “optical maser,” which today is known as the laser [replacing the word microwave in the acronym with the word light]. Similar work was being conducted in the Soviet Union at about the same time, led by Basov and Prokhov (1954). All four eventually became Nobel laureates.

The race was now on to make the first laser, with hundreds of labs working on various systems. Schwalow and Townes (1958) worked with an electrically excited gas discharge laser. However, an optically pumped solid-state ruby system proved to be the easier laser to build, and in 1960, Maiman⁽¹⁾, a 32-year-old researcscientist at Hughes Aircraft Company in Malibu, California, demonstrated the first production of laser energy using a ruby crystal. Most of the lasers now used in medicine were first operated in the decade between 1960 and 1970. The first gas-discharge laser, using an infrared line at 1.15 μm in a mixture of helium and neon gases (He-Ne), was operated by Javan and colleagues in 1961. White and Rigden demonstrated the familiar visible red line of He-Ne laser, at 633 nm, now used extensively as an aiming and alignment beam, in 1962.

The impurity neodymium in the host crystal yttrium-aluminum-garnet (Nd:YAG) was first used to produce laser energy by Geusic and colleagues in 1964. Q-switching⁽²⁾ was suggested by Hellwarth in 1961. Adding a Q-switch to a ruby or Nd:YAG laser enables these lasers to generate extremely intense pulses of short duration. Although Bridges first operated the argon-ion laser in pulsed mode in 1964, it was not until the continuous-wave version, developed by Gordon et al (1964), came available that it was possible to achieve the necessary power to affect tissue.

Patel (1964) first operated the CO2 laser at the milliWatt level, but he soon discovered that this laser could produce 10 to 100 W of continuous-wave power, a power sufficient to ablate most materials, including biological tissue. The first organic dye laser was a flashlamp pumped by Sorokin and Lankard in 1966 with a microsecond pulsewidth.

TYPES OF LASERS

Lasers are usually classified by their active media and means employed for excitation. Solids, liquids as well as gases are used herein. The heart of the laser is a certain medium: solid, liquid or gas deployed as an active medium. This medium contains atoms, ions or molecules capable of emitting their high-energy states radioactively in the form of photons or quanta (Hrand, 1983).

(1) Solid-state lasers:

This type is also called “doped insulator laser” to avoid connotation of semi-conductors. It is built around active media prepared as insulating material (dielectric crystal or glass), doped with ions of impurity in its host structure. These lasers are ruby, Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet), Nd-Glass, holmium-doped YLF, erbium-doped YLF, alexandrite, and the like. They are rugged, simple to maintain and capable of generating high peak powers as they employ optical pumping only (Hrand, 1983).

The ruby laser was the first to be made on a wide scale owing to high mechanical strength and thermal conductivity of ruby crystals which can be rendered to high optical quality (McKenzie, 1984). The first successfully optical laser constructed by Maiman (1960), consisted of a ruby crystal surrounded by a helicoidal flash tube enclosed within a polished aluminum cylindrical cavity cooled by forced air. The ruby cylinder forms a Fabry-Perot cavity by optically polishing the ends to be parallel to within a third of a wavelength of light. Each end was coated with evaporated silver, one end was made less reflective to allow some radiation to escape as a beam. Photo-pumped by a fast discharge flash-lamp, the first ruby lasers operated in pulsed mode for reasons of heat dissipation and the need for high pumping powers.

A short while after the initial announcement of the first successful optical laser, other labs around the world jumped on the bandwagon trying out many different substrates and ions such as rare earths like Nd, Pr, Tm, Ho, Er, Yb, Gd and even Uranium was successfully lased! Many different substrates were tried such as Yttrium Aluminum Garnet (YAG), glass (which was easier to manufacture), and CaF2. As manufacturing techniques improved, these lasers rapidly made the transition from the lab bench to commercial applications. The principal output line of ruby is 6,940 Å and for Nd: YAG is 10,640 Å. All solid-state lasers are pumped optically by the use of either a xenon flashlamp or tungsten-arc lamp. The optical pump usually consists of a quartz tube containing xenon gas with nonreactive metal electrodes, such as stainless steel, aluminum, or the like. Some manufacturers, to excite the Nd: YAG to emission, also use a tungsten-halogen-arc lamp. The output from a ruby laser is from 1 to 50 joules per pulse per second, or variation thereof. Nd: YAG lasers operate continuous-wave and pulsed repetition rates of 50 or more hertz (Hrand, 1983).

Nd: YAG laser is the most popular type of solid-state laser. It has rather low excitation threshold and a high conductivity, thus leading to generation of light pulses of a high repetition rate or continuously. The efficiency of this laser is comparatively high, running to a small percentage failure (McKenzie, 1984). There is one other recent laser that is the F-center laser; it is tunable and its active medium is a crystal defect containing electrons. The emission occurs at the quantum energy levels in the defect sites. They operate at 24,000 to 32,000Å in the far infrared spectrum (Hrand, 1983).

(2) Liquid dye laser

Liquid lasers are called so because their active media are either liquid solutions of organic dyes or specifically prepared liquids doped with rare earth ions. These special liquids may be of two types; namely organometallic (chelate) or inorganic (aprotonic) liquids (McKenzie, 1984). Accordingly, in these lasers, the active medium is an organic dye dissolved in an organic solvent, such as ethanol, and the solution thus prepared is optically clear. The advantages of dye solution lasers is that they can be tuned to various wavelengths in the range of 1,900 through 11,000Å by using different types of dye in solution. Flashlamps, nitrogen laser, argon laser, Nd:YAG laser, ruby laser, krypton laser, and ionic copper laser optically pump the solutions. Various dye solutions have different affinities for coupling with the optical pump illumination; therefore, no one pump can be generally used for all types of dye lasers. Pulsed lasers are found to emit laser radiations in broader range and have much higher power than continuous-wave lasers. While the continuous-wave dye lasers are limited in their tuning range, they can produce narrow linewidths at greater stability than pulsed lasers (Hrand, 1983).

(3) Gas Lasers and Excimers

Laser systems that produce radiations in a gaseous medium enclosed in an electric discharge tube are generally known as gas lasers. These lasers employ neon, helium, argon, krypton, xenon, and interim, unstable compounds of these elements. These compounds are ArF, XeF, KrF, XeBr, HF-DF, etc., and are known as excimers. These compounds are formed in an electric discharge tube in an electric field, and after radiation they dissociate into their elemental forms. However, in the form of excimer lasers, they produce very intense and important radiations that are used even in experiments of atomic fusion.

The gas lasers produce radiation by ionization and emission of photons, as in ordinary neon tube we see on storefronts. However, in addition to emission of photons, the laser tube is designed so that the photons are reflected from one end of the tube to the other. In their oscillation between the ends of the tube, the photons encounter excited atoms in the gaseous medium and produce additional photons from the accelerated electrons of the excited atoms, thus amplifying the intensity of the photon radiation (Hrand, 1983). Henceforth, gas lasers were further classified into the following:

a. Photo-dissociation lasers: Optical pumping in gaseous media.

b. Ionic and atomic lasers (He-Ne lasers): These are gas-discharge lasers and operate with rarified gases as their active media, at pressures of 1 to 10 Torr; they are excited by an electric discharge.

c. Molecular lasers (surgical lasers): The CO2 lasers, from the standpoint of potential industrial applications, unquestionably rank first. They are capable of continuously generating laser in high powers as 10 kilowatts, with a relatively high efficiency (up to 40%). The active medium of such lasers is a gas mixture of CO2, molecular N2, and diver’s additives as He and water vapor.

d. Electronization laser: It produces radiation by ionization of an electric field. The ionizing radiation knoout free electrons while the electric field accelerates them.

e. Gas-dynamic lasers: The gas-dynamic CO2 lasers which employ a mixture of CO2, N2 and water vapor as an active medium; the active centers are the CO2 molecules. Available gas-dynamic CO2 lasers yield record continuous output power of up to 100 kilowatts (McKenzie & Canuth, 1984).

(4) Chemical Lasers

They can laze at wavelengths as short as 2 μm (near I.R.). The chemical lasers are exactly the systems where such a conversion has been realized. The current chemical lasers oscillate on the vibration transition of molecules (McKenzie & Canuth, 1984).

(5) Semi-conductor Lasers

Also known as diode or injection laser, is a semi-conductor diode having a p-n junction (between a p’positive’-layer and an n’negative’-layer) and emitting laser radiation when the diode is forward biased with a current above the threshold of the p-n junction material. There are several types of laser diodes, the most commonly used being the gallium arsenide (GaAs) diode, which emits in the infrared spectrum in the range of 8,200 to 9,050Å. These diodes can operate at room temperature and can be modulated; for this reason, they find much use in the communication field. The diodes can be constructed to emit peak powers in tens of watts in the pulsing mode; they can operate in continuous-wave mode at lower power within milliWatt levels (Hrand, 1983). The semi conductor lasers used in Physical medicine are GaAs (904 nm), GaAlAs (780-820-870 nm) and InGaAlP (630-685 nm).

PROPERTIES OF LASER RADIATION

Laser radiation has a number of unique properties; namely, high intensity (power) of electromagnetic energy fluxes, high monochromaticity and high spatial and temporal coherence Therefore, laser radiation differs from other types of electromagnetic radiation in that it travels via a very narrow beam. Also, lasers of various types emit radiation in a very wide wavelengths range, from ultraviolet to the far infrared region (approximately 1,000-70,000 Å) and this range is still expanding (Robert, 1983).

(1) Monochromaticity:

This refers to the specificity of light in a single-defined wavelength, which gives it more purity not found in most sources of light. The ordinary light is comprised of a conglomeration of many wavelengths, commonly known as ROYGBIV, or the visible spectrum of red, orange, yellow, green, blue, indigo, and violet, all merging to produce “white light”. Laser light, however, consists of one wavelength only. In the case of therapeutic unit, the band is 6,328Å. Because this wavelength falls within the red section of the visible spectrum (3,900-7,700Å), the laser light of 6,328 Å is brilliant red in color. Monochromaticity describes radiation, which spectrographically forms a very narrow spectral line. In the production of laser beam, this entails that only one definite wavelength is amplified to cause the radiation (Jayasurya, 1984).

(2) Coherence:

As the wavelengths of ordinary light are so variable and not matching in waveforms, frequencies or shape, there is much scrambling of waveforms, cancellations and reinforcements of individual waves and interference, i.e. the production of energy in general. These factors minimize the power of ordinary light as an energy source. The identical wavelengths and forms that comprise laser light render it greatly amplified since the “waves and troughs” of the radiation are reinforced. Thus, as they are parallel and in line with each other, they are termed “coherent”.

Jayasurya (1984) proposed that a simple way to explain this difference is that ordinary light radiation is emitted in a random fashion. That is to say, like a group of people hitting the water at one end of a swimming pool with oars without harmony with one another and creating lots of little ripples. Comparatively, in a laser, the light from each molecule comes out in an orderly and regulated fashion. Again, that is as if a group of oarsmen were hitting the water at the same time so that each wave is added up with all the others to form a much larger and continuous series of waves. Such orderly property is designated “coherence” and all the light waves sent out by a laser have the same wavelength and frequency. This means that the light is emitted in an almost parallel beam that can travel great distances without diffusing appreciably. The color of the laser radiation, therefore, has a particular purity that does not normally occur in nature.

(3) Non-divergence

The laser beam is unique in the absolute “straightness” of the directed radiation. Ordinary light shines in all directions, as an electric bulb or even the sun. Laser, on the other hand, shines only in one direction, not unlike a flashlight, although its beam is far more concentrated and narrowed. The divergence of laser beam to the surface of the moon from earth showed a deflection of just a few meters after a journey of more than 260,000 miles.

When an electron drops from a configuration of higher energy level to one of lower energy, the surplus energy appears as radiation, partly electromagnetic and partly acoustic or vibrational. The electromagnetic radiation from one type of electronic configuration always has the same frequency. However, in a heated solid, many different types of electronic configurations are possible and light is emitted as many different frequencies. The specific difference between a conventional light source and a laser lies in the extent to which the emission of surplus energy can be controlled⁽¹⁾ (Jayasurya, 1984).

(II) LASERS IN MEDICINE

KINDS OF LASERS USED IN MEDICINE

In medicine, three kinds of lasers are mainly used; the argon laser, the CO2 laser, and the Neodymium-doped Yttrium Aluminum garnet (Nd:YAG). The laser the physician chooses for a particular procedure depends primarily on where the wavelength of that laser is best absorbed. For instance, tissues containing high concentrations of hemoglobin or melanin effectively absorb the argon laser. Consequently, the argon laser may be the laser of choice for working with tissue where many blood vessels are involved, such as the retina of the eye or a portwine birthmark. The carbon dioxide (CO2) laser has a longer wavelength, one that does not really differentiate pigmentation. It is used to cut out certain types of cancers, including cervical cancer. The Nd: YAG laser is used with fiber-optic technology. Optical fibers are extremely thin threads of glass that can transmit light over distance with very little loss of intensity. Rays of laser light travelling down such fibers are reflected off the sides. In endoscopies, the flexible fiber-optic device is used to let doctors look directly into portions of the body that otherwise they could not see, such as bile ducts or the lungs. The Nd: YAG laser beam can pass through such a flexible scope and down to the area needing treatment. The surgeon can direct the laser beam to the target and use the beam to cut out tumors. The YAG laser penetrates tissue very deeply but its energy is dissipated because it scatters over a large volume of tissue; consequently, it is good for cauterizing (Hrand, 1983)

(Table 1) Examples of Lasers which can be used in Medicine⁽¹⁾

Laser name	Wavelength	Pulsed or Cont.	Use in medicine
Crystalline laser medium:
Ruby.	694 nm	p	holograms, tattoo.
Nd:YAG	1.640 nm	p	coagulation
Ho:YAG 2	130 nm	p	surgery, root canal
Er:YAG 2	940 nm	p	surgery, dental drills.
KTP/532	532 nm	p/c	dermatology.
Alexandrite	720-800 nm	p	bone cutting.
Semiconductor lasers:
GaAs	904 nm	p	biostimulation
GaAlAs780	820-870 nm	c	biostimulation, surgery
InGaAlP	630-685 nm	c	biostimulation
Liquid laser:
Dye laser	(tunable)	p	kidney stones.
Rhodamine:	560-650 nm	p/c	PDT, dermatology.
Gas lasers:
HeNe	633, 3 390 nm	c	biostimulation
Argon	350-514 nm	c	dermatology, eye.
CO2 10	600 nm	p/c	dermatology, surgery
Excimer	193, 248, 308 nm	p	eye, vascular surgery
Copper vapor	578 nm	p/c	dermatology.
There are many other types, but those mentioned above are the most common.

DELIVERY DEVICES OF LASER

ARTICULATED ARM

An articulated arm is a precision assembly of hollow tube, mirrors and joints. It permits the delivery of a light beam, through simple reflection, from the laser head to the operating site. The beam emerging from the distal end of the arm retains the same spatial and temporal characteristics of the original laser beam and can be focused or defocused by lenses to produce the spot size and resulting power density appropriate for a particular application.

MICROMANIPULATORS

Many applications of laser energy require or benefit from manipulation of the laser beam through an optomechanical mechanism. Such a device, referred to as a micromanipulator or joystick, is generally used with a surgical microscope.

SCANNERS

With the advent of the scanner, an accurate and repeatable micro-processor-controlled delivery of pulsed or continuous wave (cw) laser output was possible, circumventing the problems posed by inconsistent freehand methods. The scanner’s nonaligned treatment pattern allows the thermal energy in adjacent tissue to cool adequately between pulses of laser energy. The scanner has proved of value to both dermatologists and plastic surgeons.

FIBEROPTICS

The most common and convenient way of delivering laser energy to tissue is through flexible optical fibers. They can be used with micromanipulators or handpieces or can be passed through most standard operating endoscopes. Fiberoptics are composed of two or more concentrically arranged optical materials, and light is carried along the length of the fiber by total internal reflection. Lenses and contact probes can be used to focus the emergent beam.

ENDOSCOPIC DEVICES

In the beginning, endoscopy was an exclusively diagnostic technique, but over the last decade, small incision endoscopic surgery has revolutionized the treatment of numerous diseases. This is attributable to the simultaneous development of practical laser systems (capable of vaporizing and coagulating via flexible fiberoptics) and the achievement of technological advances in high-resolution charge-coupled device (CCD) cameras, endoscopic devices, safer surgical instrumentation and an expanding array of manipulating instruments.

CONTACT ND:YAG LASER

When affixed to the distal end of a fiberoptic, contact laser probes can alter the optical, mechanical, and thermodynamic properties of the delivery device. Whereas light merges from a fiberoptic as a slightly divergent beam, it refracts within a contact tip. Depending on such factors as the angle of convergence and the size and shape of the distal face, the beam can be emitted as a divergent or convergent beam or it can be laterally radiated from the sides of the contact tip. Contact probes are made of durable, rigid materials with high melting points (Hecht, 1992).

The most important property of contact laser probes is the manner in which they titrate the light and thermal energy that emerges from the delivery device. Rather than delivering a beam of pure light energy that is converted to heat entirely within the tissue, special absorbent coatings and surfaces on the contact laser probes can transform a predetermined portion of the light energy into heat at the probe’s surface. With longer-wavelength lasers, such as the diode or Nd:YAG, it is possible to use the full penetration or, when deep thermal effects are not wanted, to reduce penetration by transforming more light energy into heat at the probe surface (Arndt et al., 1997).

APPLICATIONS OF LASERS IN MEDICINE AND HEALTH CARE

Lasers have become extremely important in medicine and health care. Although no one knows precisely how many laser procedures are being performed, the American Society for Laser Medicine and Surgery estimated there were nearly a million such procedures a year in the US alone in 1988; later estimates were difficult to procure. The society estimated, also, that 60% of all laser procedures being done at that time in the US involved the eye. Other physicians using lasers extensively include gynecologists, dermatologists and plastic surgeons, pulmonologists, and otolaryngologists. Gastroenterologists and neurosurgeons use lasers; so do podiatrists and physiatrists. In the past few years, laser emerged as a promising tool in the field of physical medicine (Bone, 1988). In medicine there are three main areas in which laser has successfully established itself. These are in surgery as a cutting tool, in ophthalmology and in dermatology.

(1) As far as surgery is concerned, the CO2 laser has been proved the most successful all-rounder, although Nd:YAG lasers can also be used. The 10.6-ýμmýoutput of the CO2 laser is strongly absorbed by the water molecules present in tissue and the subsequent evaporation of the water leads to the physical removal of the tissue. There are several advantages over mechanical cutting: the laser beam can be positioned and controlled with a high accuracy, relatively inaccessible regions can be reached, limited damage is caused to adjacent tissue and the laser beam has a cauterizing effect on nearby blood vessels which reduces bleeding. Obviously, an essential requirement is an easily maneuverable beam delivery system. The ideal solution to this is to use some type of optical fiber.

(2) In ophthalmology, lasers have successfully treated detached retinas for many years now. Although ruby lasers were used initially in such operations, the green output from argon ion lasers is now more popular. The radiation is strongly absorbed by red blood cells and the resulting thermal effects lead to a re-attachment of the retina.

(3) Some disfiguring skin conditions can be successfully treated with lasers. Portwine marks, for example are often difficult to treat using conventional surgery because of the extensive areas that can be involved. Uniform exposure of such areas to an argon ion laser beam can cause bleaching of the affected areas, which appears to be permanent. Similar treatment can be used in the removal of tattoos, hair, skin vascular diseases and resurfacing of the skin (Bone, 1988).

(III) LASER IN PHYSICAL MEDICINE

Absorption of LASER IN TISSUES

According to Jayasurya (1984), the laser radiation has different absorption coefficients in the various types of tissues. This effect depends, naturally and to a great extent, on the wavelength. During absorption, the larger portion of the laser radiation is transformed after an intermediate process into heat vibrations. Lasers in the range below 0.4 μm or above 1.8 μm are readily completely absorbed in a thin layer of tissue. Accordingly, the total energy irradiation is converted inside a small volume of tissue. Depending on the power of the laser device used and the duration of irradiation as well as the tissue properties, the sequence of the following effects occurs (please note that the drastic thermal effects happen only with surgical lasers and not low level therapeutic lasers whose effect is not thermal):

1. Local warming up of tissue.

2. Acceleration of physiological processes.

3. Mitosis speeding and dehydration.

4. Shrinking of tissues.

5. Irreversible protein denaturation (coagulation).

6. Thermolysis (carbonization).

7. Evaporation of tissue.

8. Dispersion: The dispersion greatly depends on the wavelength and type of tissues. It affects adjacent zones even in the case of extreme local irritation. The length of coherence does not disappear when entering the tissues. It is split into very small coherent "islands" called speckles. These speckles remain coherent and will penetrate deeply into the tissue.

The depth of penetration of laser light depends not only on the light's wavelength, on whether the laser is super-pulsed, and on the power output, but also on the technical design of the apparatus and the treatment technique used. When we press lightly with a laser probe against skin, the blood flows to the sides, so that the tissue right in front of the probe (and some distance into the tissue) is fairly empty of blood. As the hemoglobin in the blood is responsible for most of the absorption, this mechanical removal of blood greatly increases the depth of penetration of the laser light. It is worth noting that laser light can even penetrate bone (as well as it can penetrate muscle tissue). Fat tissue ismore transparent than muscle tissue. For example: a HeNe laser with a power output of 3.5 mW has a greatest active depth of 6-8 mm depending on the type of tissue involved. A HeNe laser with an output of 7 mW has a greatest active depth of 8-10 mm. A Ga-Al-As probe of some strength has a penetration of 3.5 cm with a 5.5 cm lateral spread. A GaAs laser has a greatest active depth of between 20 and 30 mm (sometimes down to 40-50 mm), depending on its peak pulse output (around a thousand times greater than its average power output). If we work in direct contact with the skin, and pressed the probe against the skin, then the greatest active depth would be achieved ⁽¹⁾.

LOW-LEVEL LASERS (LLL)

The discovery in the 60s of the possibility of intensify light by stimulated radiation resulted in the creation of lasers, which found immediate application in medicine. In 1974 the Ministry of Medical Care of the USSR gave permission for clinical use of the first device for laser therapy. So the Low Level Laser Therapy (LLLT) is one of the latest developments of the phototherapy. During the last 20 years laser therapy has received wide recognition in medical practice and has occupied a stable important position among the medical physical factors used before.

The range of laser applications is so wide that sometimes the question of separation of this method into an independent branch of medical science arises. If up to mid 80-s red HeNe laser (632.8 nm) was actively studied and used in clinical practice, during the last ten years, red (630 - 670 nm) and infrared (830 - 1300 nm) laser diodes have been widely applied, which is explained by their small size, simple maintenance, long service life, economy and rather high clinical efficiency (Khachatryan et al., 1997)⁽¹⁾.

The term “Low Level Laser Therapy (LLLT)” shall be used throughout this review denoting treatment with lasers in the physiotherapeutic sense. This is the dominant term in use today, but there is still a lack of consensus. In the literature LPLT (Low Power Laser Therapy) is also frequently used The term "soft laser" was originally used to differentiate therapeutic lasers from "hard lasers", i.e. surgical lasers. Several different designations then emerged, such as "MID laser" and "medical laser". "Bio-stimulating laser" is another term, with the disadvantage that one can also give inhibiting doses. The term "bio-regulating laser" has thus been proposed. An unsuitable name is "low-energy laser". The energy transferred to tissue is the product of laser output power and treatment time, which is why a "low-energy laser", over a long period of time, can actually emit a large amount of energy. Other suggested names are "low-reactive-level laser", "low-intensity-level laser", "photo-bio-stimulation laser" and "photo-bio-modulation laser". Low-level lasers emit energy densities that are too low to cause temperature increases beyond 0.5ºC in the target tissue. Thus, the effects of LLL irradiation are presumably not attributable to thermal events.

The early literature on the effects of LLL, published mostly in eastern Europe some three decades ago, generally consisted of reports on largely anecdotal observations, and the scientific value of these lasers was not appreciated because the data could not hold up to the scrutiny of the research community. However, in the 1970s reports of more controlled clinical studies performed in both human and animal models and evaluating wound healing in response to LLLT began to appear in the literature. Subsequently, considerable interest grew in the biomodulation of tissue and tissue and cell metabolism produced by LLL, and during the past decade or so, findings from numerous studies assessing various aspects of the effects of LLL on biologic systems have been published. Many of the recent studies deal with the effects of low-level lasers on cellular metabolism, extracellular matrix production, tissue repair, and immune functions of the cells. Although these studies are in general carefully controlled and the laser parameters well defined, the results on the whole remain controversial and the efficacy of LLL irradiation in the context of certain biologic functions remains in question (Halcin & Uitto, 1997).

Intravenous Laser Blood Irradiation Therapy

Currently the methods of laser and non-laser (incoherent monochromic, narrow-band or broadband) light blood irradiation therapy - the methods of photohemotherapy - are widely applied in the treatment of different pathologies. Direct intravenous and extracorporeal (with red, UV and blue light) as well as transcutaneous (with red and infrared light) irradiation of blood are used. Unlike the treatment mechanisms of procedures of local laser therapy, the medical effects of photohemotherapy methods are determined by predominance of systemic healing mechanisms above the local ones, increasing the efficacy of functioning of vascular, respiratory, immune, other systems and organism as a whole. The method of HeNe intravenous laser blood irradiation (IV-LBI) was developed in experiment and introduced in clinic in 1981 by soviet scientists E.N. Meshalkin and V.S. Sergievskiy. Originally the method was applied in the treatment of cardiovascular pathologies. Some authors reported that the treatment possibilities of the method are very large and include the improvement of rheological characteristics of the blood and microcirculation, normalization of parameters of hormonal, immune, reproductive and many other systems.

HeNe laser (632.8 nm) is generally used for carrying out the intravenous laser blood irradiation (IV-LBI). Usual parameters of blood irradiation procedure are: output power at the end of the light-guide inserted into a vein from 1 up to 3mW, exposition 20 - 60 minutes. Procedures are conducted on a daily base, from 3 up to 10 sessions on a course of therapy. It was shown, that IV HeNe LBI stimulates the immune response of the organism, activates erythrogenesis and improves deformability of erythrocyte membranes, has anti-hypoxic activity on tissues and general antitoxic influence on the organism at different pathological processes. IV-LBI is used for its biostimulative, analgesic, antiallergic, immunocorrective, antitoxic, vasodilative, antiarrhythmic, antibacterial, antihypoxic, spasmolytic, anti-inflammatory and some other properties. IV-LBI activates nonspecific mechanisms of anti-infectious immunity. Intensifying of bactericidal activity of serum of the blood and system of the complement, reduction of the degree of C - reactive protein, level of average molecules and toxicity of plasma, increasing the content of IgA, IgM and IgG in the serum of the blood, as well as decreasing of the level of circulating immune complexes are proved. There are studies on boosting effect of IV-LBI on the cellular part of immunity. Under influence of IV-LBI the phagocytic activity of macrophages markedly increases, concentration of microbes in exudate in the abdominal cavity of patients with peritonitis decreases, reduction of inflammatory exhibiting of disease, activation of microcirculation are detected. The medical effect of IV-LBI is stipulated by its immuno-corrective activity by normalization of intercellular relationships within the subpopulation of T-lymphocytes and increasing the amount of immune cells in a blood. It elevates the function activity of B-lymphocytes, strengthens the immune response, reduces the degree of intoxication and as a result improves the general condition of patients (Gasparyan, 1998).

IV-LBI promotes improving the rheological properties of blood, rising fluidity and activating transport functions. That is accompanied by increasing the oxygen level, as well as decreasing the carbon dioxide partial pressure. The arterio-venous difference by oxygen is enlarged, that testifies the liquidation of a tissue hypoxia and enrichment the oxygenation. It is a sign of normalization of tissue metabolism. Probably, the basis of activation of oxygen transport function of IV-LBI is the influence on hemoglobin with transforming it in more favorable conformation state. The augmentation of oxygen level improves meof the organism tissues. In addition, the laser irradiation activates the ATP synthesis and energy formation in cells. Application of IV-LBI in a cardiology has shown that procedures have analgesic effect, show reliable rising tolerance of patients towards physical tolerance test, elongation of the period of remission. It was proved that IV-LBI reduces aggregation ability of thrombocytes, activates fibrinolysis, which results in peripheral blood flow velocity increasing and tissues oxygenation enriching. The improvement of microcirculation and utilization of oxygen in tissues as a result of IV-LBI is intimately linked with positive influence on metabolism: higher level of oxidation of energy-carrying molecules of glucose, pyruvate, and other substances. The improvement in microcirculation system is also stipulated by vasodilation and change in rheological properties of blood as a result of drop of its viscosity, decrease of aggregation activity of erythrocytes due to changes of their physicochemical properties, in particular rising of negative electric charge. Finally the activation of microcirculation, unblocking of capillaries and collaterals, improvement of tissue trophical activity, normalization of a nervous excitability are take place. IV-LBI is recommended to apply before surgical operations as preparation for intervention, as well as in the postoperative stage, because the laser irradiation of blood has not only analgesic effect, but also spasmolytic and sedative activity. In order to explain the generalized and multifactor effects of IV-LBI, its positive influence practically on all tissues and functional systems of the body, clinical effectiveness for the treatment of different diseases, some authors mentioned that the improvement of microcirculation after IV-LBI is detected in all structures of central nervous system, but this improvement the most active in the hypothalamus, which has highly developed vascular system. The capillaries of a hypothalamus are remarkable for high permeability for macro-molecular proteins, which should even more amplify influence of the irradiated blood to subthalamic nuclei. So it is supposed, that IV-LBI increases the functional activity of hypothalamus and all limbic system, and as a result the activation of energetic, metabolism, immune and vegetative responses, mobilization of adaptive reserves of an organism is reached (Gasparyan, 2001).

A randomized placebo-controlled study was made by the Russians Zvereva et al. in 1994 of the clinical efficacy of four different methods of intravenous laser blood irradiation (IV-LBI) with helium-neon (He-Ne) laser in 150 patients suffering from rheumatoid arthritis (RA). As to IV-LBI methods used, the most remarkable clinical effect was produced by daily procedures. The positive effect of IV-LBI was of liminal character bearing in mind the power range examined whereas the negative effect of irradiation was dose-dependent. However, it is to be noted that IV-LBI may cause an exacerbation of the inflammatory process in RA in case of a single dose or frequency of procedures. The best clinical effect with daily IV-LBI was attained in women, individuals with the presence of rheumatoid factor but with low titers thereof, and in-patients with initial stages of RA and minimum inflammation activity. The authors claimed that the efficacy of IV-LBI may be predicted on the basis of the patient's clinical findings (Zvereva et al. 1994).

In general, a variety of different types of laser light sources have been used to deliver the laser energy at low levels (Table 2). These lasers deliver energy at different wavelengths, which targets different structures, molecules, or both with different absorption spectra within the cells and tissues. The He-Ne, Ga-Al-As and Ga-As lasers have been used in most of the recent studies, but the incident energy density used, the total dose delivered, and the treatment schedules followed have varied considerably from one study to another. This variability, combined with the fact that different cells and tissues have been used as targets for irradiation, may explain some of the variable and even controversial results yielded (Halcin & Uitto, 1997).

Active medium	Wavelength (nm)
Argon Helium-neon Krypton Gallium-aluminum-arsenide (arsenate) Ruby crystal Gallium-arsenide (arsenate) Neodymium: yttrium-aluminum-garnet CO2	488,514.5 632.8 647.1 660,820,870,880 694.3 904 1064 10,600

Possible Mechanisms of Action of Low-Level Lasers

Literary data concerning favorable effects of low level laser radiation on series of diseases covering different medical specialties are cited in many volumes and researches, pointing to possibility of significant enrichment of already available arsenal of physical methods, therapies and rehabilitation procedures. The great American researcher in laser therapy, Basford reviewed the scientific basis and clinical role of laser therapy in the last three decades in a study published in 1993. Here, he pointed out to the ability of laser irradiation to destroy tissue. But, less well known is the fact that the same radiation, at much lower intensities, can non-destructively alter cellular function. This later phenomenon, which occurs in the absence of significant heating, is now the basis for the conservative treatment of a variety of musculoskeletal, neurological, and soft tissue conditions in many parts of the world.

In 1998, Takac and Stojanovic explained that the world famous Hungarian scientist Mester, who is one of the pioneers with the greatest experimental and clinical experience in the use of biostimulating effects of lasers, concluded that the biostimulating effect of low-level laser treatment (LLLT) is in its anti-inflammatory, analgesic and anti-edematous effect on tissues (Mester et al., 1985). There is absolute increase in the microcirculation, higher rates of ATP, RNA and DNA synthesis and, thus, better tissue oxygenation and nutrition. There is also increase in the absorption of the interstitial fluid, better tissue regeneration and stimulation of the analgesic effect. Moreover, Mester’s former student, Ribari⁽¹⁾ first used biostimulating effects of He-Ne laser (390-mJ power) for epithelization of perforated tympanic membrane and treatment of post-operative fistulas of the neck and of the mastoid. He also explained that the past three decades of laser medicine and surgery have shown great progress and promise for the future (Takac and Stojanovic, 1998).

There is a recent hypothesis, which may unravel the obscure role of low-level laser as a therapeutic tool biophysically. This is the formulated hypothesis of free radical mechanisms of stimulating action of Low-Level Laser Radiation (LLLR) used for therapy of a variety of inflammatory diseases. The main points of the above hypothesis are as follows. Endogenous porphins are an LLLR-chromofor in the red band (lambda l = 632.8 nm). Light absorption induces the production of initiating radicals that are involved in subsequent free radical reactions, in lipid peroxidation in particular. Modified lipid peroxidation in the cell membranes causes an increase in ion permeability, including that for Ca2+. The higher levels of Ca2+ in the leukocytic cytosol result in Ca2+-dependent cellular priming, which appeared as the increased cell functional potential and which is seen in subsequent leukocytic stimulation of the greater production of pro-oxidants and other biologically active products. These products include nitric oxide and a number of cytokines involved in the regulation of microcirculation. A paper, produced by the Russians Chichuk et al. in 1999, presents experimental findings that can be regarded as evidence for some points of the above hypothesis which are used to provide a chain of events underlying the free radical mechanisms of stimulating action of low-level laser radiation (Chichuk et al. 1999).

Moreover, to explain the mechanisms of low level laser therapy, Karu (1998 & 2000) discussed cytochrome c oxidase is as a possible photo-acceptor when cells are irradiated with monochromatic red to near-IR radiation. Five primary action mecare reviewed:

· changes in the redox properties of the respiratory chain components following photoexcitation of their electronic states;

· generation of singlet oxygen;

· localized transient heating of absorbing chromophores;

· release of NO; and

· increased superoxide anion production with subsequent increase in concentration of the product of its dismutation, H202. A cascade of reactions connected with alternation in cellular homeostasis parameters is considered as a photosignal transduction and amplification chain in a cell (secondary mechanisms) (Karu, 1998 & 2000).

Another study was made whose aim was to verify the effects of LLLT performed with Ga-Al-As (780 nm, 2500 mW) on human cartilage cells in vitro. The cartilage sample used for the biostimulation treatment was taken from the right knee of a 19-year-old patient. After the chondrocytes had been isolated and suspended for cultivation, the cultures were incubated for 10 days. The cultures were divided into four groups. Groups I, II, III were subject to biostimulation with laser. Group IV did not receive any treatment. The laser biostimulation was conducted for five consecutive days. The data showed good results in terms of cell viability and levels of Ca and Alkaline Phosphatase in the groups treated with laser compared to the untreated group. The results obtained confirm previous positive in vitro results by the same researchers that the Ga-Al-As laser provides biostimulation without cell damage (Morrone et al., 2000).

And, to explore the effect of a low-level diode laser (lambda l = 780 nm) on normal skin tissue blood microcirculation, time-dependent contrast enhancement was determined by magnetic resonance imaging (MRI). This is the most recent study made to clarify the role of LLLT in biostimulation and was conducted by Schaffer et al. in 2000. In the examinations, six healthy volunteers were irradiated on their right planta pedis (sole of foot) with 5 J/cm² at a fluence rate of 100 mW/cm². T1-weighted magnetic resonance imaging was used to quantify the time-dependent local accumulation of Gadolinium-DPTA, its actual content in the local current blood volume as well as its distribution to the extracellular space. Images were obtained before and after the application of laser light. When laser light was applied, the signal to noise ratio increased by more than 0.35 plus-or-minus sign 0.15 (range 0.23-0.63) after irradiation according to contrast-enhanced MRI. It can be observed that, after biomodulation with light of low energy and low level, wound healing improves and pain is reduced. This effect might be explained by an increased blood flow in this area. Therefore, the use of this kind of laser treatment might improve the outcome of other therapeutic modalities such as tumor ionizing radiation therapy and local chemotherapy (Schaffer et al., 2000).

Pre-clinically, the inter-relationship between laser and biological tissues was in the highlight. Extensive experiments were conducted and numerous papers appeared in the 60s and 70s. The publications correlated physical characteristics as time (exposure), density of light (energy per unit of area), wave length, continuity and impulse feeding with metabolic responses in cells. More frequently use was made of He-Ne laser. Today, laser therapy, laser surgery and photodynamic therapy constitute a whole new world of dazzling potentialities yet to be explored for the benefit of the mankind. The low-level laser may be successfully used as a sole therapeutic factor according to the indications and in combination with other physiotherapeutic methods and means of medication (Plouznikov, 2000).

Considering the complexity of the biologic systems that have been subjected to laser irradiation and the variability in the different experimental modes studied, it has been somewhat different to formulate a unifying hypothesis concerning the mechanisms of action of laser energy that had been proposed (Abergel et al., 1984; Ohta et al., 1987; Enwemeka, 1988; Karu, 1989; Young et al., 1989 and Labbe et al., 1990).

The stimulation of collagen gene expression and an alteration in the protein synthesis at the transcriptional or posttranscriptional level are two mechanisms that have been postulated (Figure 4) (Uitto et al., 1981 and Alberts et al., 1989). These effects can be attributed to the direct modulation of regulatory elements within the cells, such as the promoter regions of type I and III collagen genes that have been shown to be overexpressed after laser irradiation (Abergel et al, 1984 and Lam et al., 1986). Similarly, laser radiation may have a direct effect on cell proliferation by affecting the nuclear chromatin structure and other elements that regulate cell proliferation. The effects could also be more indirect, as suggested by the finding of an enhanced uptake of ascorbic acid after laser irradiation, this vitamin being a critical cofactor in the formation of collagen (Labbe et al., 1990). Furthermore, the effects can be indirectly elicited by paracrine factors, as indicated by the release of fibroblast stimulatory factors from macrophage-like U-937 cells after laser irradiation.

Laser irradiation could affect immune function at several different levels, including alterations in the circulating factors that exert systemic effects at the tissue level. On the other hand, alterations in the function of resident lymphocytes at the site of laser irradiation could also modulate the repair process in such a way as to enhance wound healing (Ohta et al., 1987).

Karu (1989) has proposed a unifying hypothesis embracing the various molecular events triggered by laser irradiation. The central theme of her proposal is that components of the respiratory chain are the primary photo-acceptors of laser energy (Figure 5). The photo-signal transduction and amplification that occur are then determined by the physiologic state of the cell at the time of laser irradiation. For example, if the redox potential in the cells is low, the magnitude of the laser effect will be stronger than that in the cells with a higher redox potential (Karu, 1989). This suggestion is compatible with the observation that cells which constitutively show a low level of collagen production in culture are considerably more susceptible to up-regulation by laser energy than are cells that produce considerable collagen (Lam et al., 1986).

The mechanistics of photosignal transduction have been proposed to involve the absorption of laser energy by enzymes that activate the mitochondrial respiratory chain (Figure 5). The resulting changes in the respiratory chain alter the redox potential by accelerating electron transfer, which in turn activates the electrical potential of mitochondria and increases the intracellular pool of ATP. These events may lead to an increase in the intracellular hydrogen ion concentration, a necessary component for mitogenic signal transmission in the cells. These events may also alter certain phenomena that activate the membrane ion transport systems, including the sodium-potassium pump of ATPase. The changes in the cellular redox potential can then alter proliferation, macromolecular synthesis, and the response of cells to immunologic modulator molecules (Karu, 1989).

(IV) LASERS IN ARTHRITIDES

Laser Therapy in Rheumatoid Arthritis

Many studies have been made to evaluate the effect of LLLT in treatment of RA. The earliest was a Japanese one conducted by Asada et al. in 1991. The authors had been involved in the treatment of rheumatoid arthritis (RA), in particular chronic poly-arthritis and the associated pain complaints. The biggest problem facing such patients is joint contracture, leading to bony ankylosis. This in turn severely restricts the range of motion (ROM) of the RA-affected joints, thereby seriously restricting the patient's quality of life (QOL). The authors determined that in these cases, daily rehabilitation practice is necessary to maintain the patient's QOL at a reasonable level. The greatest problem in the rehabilitation practice is the severe pain associated with RA-affected joints, which inhibits restoration of mobility andimproved ROM. LLLT or low level laser therapy had been recognized in the literature as being effective in pain removal and attenuation. The authors accordingly designed a clinical trial to assess the effectiveness of LLLT in RA related pain (subjective self-assessment) and ROM improvement (objective documented data). From July 1988 to June 1990, 170 patients with a total of 411 affected joints were treated using a Ga-Al-As diode laser system (830 nm, 60 mW CW). Patients mean age was 61 years, with a ratio of males: females of 1: 5.25 (16%: 84%). Effectiveness was graded under three categories: excellent (remarkable improvement), good (clearly apparent improvement), and unchanged (little or no improvement). They found that for pain attenuation, scores were: excellent 59.6%; good 30.4%; unchanged 10%. Also, for ROM improvement, the scores were: excellent 12.6%; good 43.7%; unchanged 43.7%. This gave a total effective rating for pain attenuation of 90%, and for ROM improvement of 56.3% (Asada et al., 1991).

And to define the value of low level laser treatment in small joint rheumatoid arthritis, a double blind randomized trial was conducted by Heussler et al., in 1993. They carried out the experiment on twenty-five women with active disease. The metacarpophalangeal and proximal interphalangeal joints of one hand were treated with 12 J/cm² for 30 seconds with a gallium-aluminum-arsenate (Ga-Al-As) laser. The other hand received a sham laser treatment designed so that neither therapist nor patient could distinguish the active laser from the sham laser. Each patient received 12 treatments over four weeks. The following parameters were measured: pain as assessed by visual analogue scale (VAS); range of joint movements; grip strength; duration of early morning stiffness, joint circumference, Jebsen's hand assessment; drug usage; total swollen joint counts; Arthritis Impact Measurement Scales; three phase bone scans and hematological and serological tests. The results showed that a total of 72% of patients reported pain relief but this reduction was reported equally in both hands. No significant changes were seen in other clinical, functional, scintigraphic, or laboratory features. Neither patients nor staff was able to detect which hand was treated with the active laser. This, naturally, means that when this specific laser and dose regimen was used, low level laser treatment had no objective effect on patients with rheumatoid arthritis. It did appear to produce analgesia through a powerful placebo effect (Heussler et al., in 1993).

The beneficial effects of low level laser irradiation on rheumatoid arthritis (RA) joints have been reported, yet the mechanisms of action of therapeutic lasers in RA are not satisfactorily clear. But, even if LLLT has only an analgesic effect on RA patients without actual effect on the disease itself, one should understand how this really occurs. To explain the mechanism of the action of laser therapy, a study was conducted by the Russians Kozlova et al in 1994. In this study, 48 patients with rheumatoid arthritis (RA) were exposed to He-Ne laser radiation. Due to the course of the above laser therapy, the patients displayed reduced levels of E and F2-a prostaglandins, a trend to a decrease of lipid peroxidation products, glycosaminoglycans and collagen-peptidase activity. This evidences for suppression of the inflammation and destruction in the connective tissue. Catalase activity in red cells enhanced. Thus, the authors pointed to high efficacy of low-level He-Ne laser in moderate rheumatoid inflammation (Kozlova et al., 1994).

In addition, some histological studies were carried on by Amano et al. in 1994 to find out the histological changes that occur in the synovial membrane irradiated by low level laser. Thus, fourteen knee joints of RA cases, which had been scheduled for arthroplasty, were irradiated with a gallium-aluminum-arsenate (Ga-Al-As) laser (790 nm in wavelength and 10 mW of output power) prior to the surgical operation, at six points of the external aspect of the knee joint for 80 seconds at each point once a day for 6 days. On the day following the last irradiation, pieces of synovial membrane from the lateral irradiated area and from the median non-irradiated area as a control were resected during the arthroplasty. The histological findings of the irradiated synovial membrane showed flattening of epithelial cells, decreased villous proliferation, narrowed vascular lumen, and less infiltration of inflammatory cells compared with those of nonirradiated synovia. The evaluation of slides was done in a blinded manner, and significant differences were seen by Wilcoxon's t-test. Histological findings suggested that the low level laser irradiation induced suppression of inflammation in the synovial membrane of RA (Amano et al., 1994).

Low-level laser therapy (LLLT) is a relatively new and increasingly popular form of electrotherapy. It is used by physiotherapists in the treatment of a wide variety of conditions including RA despite the lack of scientific evidence to support its efficacy. According to this background, Hall et al. conducted a randomized double-blind and placebo-controlled study, in 1994 to evaluate the efficacy of LLLT. The patient sample consisted of chronic RA patients with active finger joint synovitis. Forty RA patients with involvement of some or all of MCP or PIP joints were recruited. Following random allocation, they received either active or placebo laser three times a week for 4 weeks. Measurements were taken prior to entry, after the treatment, 1 month and 3 months at follow-up. The groups were well matched in terms of age, sex, disease duration and severity. However, in this study, few significant differences were noted in grip strength, duration of morning stiffness, joint tenderness, temperature of inflamed joints, range of movement or pain either within or between groups. Thus, using these irradiation parameters in the study, the efficacy of LLLT was ineffective (Hall et al., 1994).

Again, in another double-blind placebo-controlled study conducted by Johannsen et al. in 1994, they examined the LLL effect on Rheumatoid Arthritis (RA). Twenty-two patients completed the study (10 receiving LLL treatment) according to protocol. A significant effect on pain score was found due to LLL treatment, but when data were corrected for disease variation the effect disappeared. So, no effect of LLL could be demonstrated on the other assessed variables: grip strength, morning stiffness, flexibility, erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP). In conclusion, they did not find that LLL had any clinically relevant effects on RA (Johannsen et al., 1994).

Yet, laser therapy has been found effective in the management of pain associated with rheumatoid and degenerative joint arthritis and disease in many other studies. In one study by Bertolucci et al., in 1995, the efficacy of low-level laser therapy was tested specifically on patients with degenerative joint disease (DJD) involving the temporomandibular joint (TMJ). The controlled clinical study, hitherto, was designed to test the efficacy of low-level laser therapy vs placebo therapy in the reduction of pain associated with TMJ disorders specific to arthralgic DJD. The results concluded great improvements on the part of low-level laser against placebo (Bertolucci et al., 1995).

A Canadian accumulative study was made as recent as few months ago in year 2000. The study was made by Brousseau et al. of the School of Rehabilitation Sciences, Faculty of Health Sciences, University of Ottawa. The purpose of the study was to assess the effectiveness of LLLT in the treatment of RA. They searched MEDLINE, EMBASE, the registries of the Cochrane⁽¹⁾ Musculoskeletal group and the field of Rehabilitation and Related Therapies as well as the Cochrane Controlled Trials Register up to January 30, 2000. Following an a priori protocol, they selected only randomized controlled trials of LLLT for the treatment of patients with a clinical diagnosis of RA that were eligible. Abstracts were excluded unless further data could be obtainedfrom the authors. Two reviewers independently selected trials for inclusion, then extracted data and assessed quality using predetermined forms. Heterogeneity was tested with Cochran's Q test. A fixed effects-model was used throughout for continuous variables, except where heterogeneity existed, in which case, a random effects-model was used. Results were analyzed as weighted mean differences (WMD) with 95% confidence intervals (CI), where the difference between the treated and control groups was weighted by the inverse of the variance. Standardized mean differences (SMD) were calculated by dividing the difference between treated and control by the baseline variance. SMD were used when different scales were used to measure the same concept (e.g. pain). Dichotomous outcomes were analyzed with odds ratios. Subsequently, the main results showed that a total of 204 patients were included in the five placebo-controlled trials, with 112 randomized to laser therapy. Relative to a separate control group, LLLT reduced pain by 70% relative to placebo and reduced morning stiffness duration by 27.5 minutes (95%CI: 2.9 to 52 minutes) and increased tip to palm flexibility by 1.3 cm (95%CI: 0.8 to 1.7 cm). Other outcomes such as functional assessment, range of motion and local swelling did not differ between groups. There were no significant differences between subgroups based on LLLT dosage, wavelength, site of application or treatment length. For RA, relative to a control group using the opposite hand, there was no difference between the control and treatment hand, but all hands improved in terms of pain relief and disease activity. Accordingly, the reviewers concluded that LLLT for RA is beneficial as a minimum of a four-week treatment with reductions in pain and morning stiffness. On the one hand, this meta-analysis found that pooled data gave some evidence of a clinical effect, but the outcomes were in conflict and it must, therefore, be concluded that firm documentation of the application of LLLT in RA is not possible. Presumably, clinicians and researchers should consistently report the characteristics of the LLLT devices and the application techniques used. New trials on LLLT should make use of standardized validated outcomes. Despite some positive findings, this meta-analysis lacked data on how LLLT effectiveness is affected by four important factors: wavelength, treatment duration of LLLT, dosage and site of application over nerves instead of joints (Brousseau et al., 2000).

And, another group of 115 patients with rheumatoid arthritis (RA) of II & III degrees was treated with basic RA medications and infrared laser. In a control group of 20 patients, only basic medication was given. 10 areas of the body were irradiated daily, increasing the dose every day over a period of 8-10 days. The effectiveness of the therapy was controlled through laboratory tests on inflammatory agents and the activity of lipid peroxidation. The results were statistically significant. The best effect was found in patients with degree-II RA. Steroid medication could be reduced 8-10 days earlier in this group of patients and in some cases the medication could even be excluded. Degree-III patients had a more moderate benefit of the laser treatment (Korolkova et al., 2001).

Finally, we can see that even with all the contradiction thereof, low-level laser (LLL) is a widely used treatment for RA although convincing documentation of the effect is still missing. I surmise the reason may be that the effect of LLLT, a most alternative non-invasive treatment for RA is not thermal, but rather related to photochemical reactions in the cells. It has been claiming its place as a runner-up amongst the physical modalities for the last ten years even though its effectiveness for rheumatoid arthritis is still controversial.

Treatment of Chronic Rheumatoid Arthritis by Low Level Laser⁽¹⁾

According to Kazuyoshi Zenba (2001), the president of Isehara Clinical Research Institute, Japan, the low level laser irradiation is very effective to the treatment of Chronic Rheumatoid Arthritis. It can restrain the progress of the illness and also mitigates inflammation, pains or stiffness. The mechanism of treatment is considered to be the anti-inflammatory effect of low level laser and the improvement of immunity by low level laser. The improvement of blood circulation before and after the irradiation of low level laser is clearly confirmed by thermography. The earlier treatment seems to bring about the better result. The method of laser irradiation is as follows.

*Low level laser: Semiconductor laser, 780nm, 10mW.

*Irradiation time: 10-30 seconds/point.

*Total irradiation time: 2-3 minutes/diseased part.

*Interval of treatment: 2-3 times/week.

*Judgment of treatment: 2-3 months.

According to his experience, mild laser of 10mW compared with strong lasers such as 60 or 100mW is said to be much more suitable for the treatment of Rheumatism patients. As Rheumatism patients are very sensitive to any stimulations, a stronger laser is feared to cause negative results such as the increase of pains etc. Another important factor to overcome this illness is the mental strength of patients. Patience is required in order to continue the laser therapy (Zenba, 2001).

Laser Therapy in Osteoarthritis

OA is an abnormality of diarthroidal (synovial) joints characterized by focal splitting and fragmentation (fibrillation) of articular cartilage, which is not directly attributable to an inflammatory process. Fibrillation is not discernible in a radiograph. It may or may not be accompanied by subchondral bone sclerosis, subchondral bone cysts, narrowing of the joint space and bony outgrowths at the joint margins (osteophytes) –all of which can be regarded as manifestations of abnormal articular remodeling. When these radiological changes are prominent, cartilage fibrillation will usually have progressed to full-thickness loss in some part of the articular surface. At present, OA is best defined in these anatomic terms; and radiology is the main diagnostic tool. Radiological evidence of OA is common and almost all elderly people are found to have it to some extent, though it is often symptomless (Lawrence et al., 1956 & 1966 and Gordon, 1968).

Of the various physical interventions used to relieve the symptoms of osteoarthritis (OA), low level laser therapy has been reported to be extremely successful in Russia and Eastern Europe. However, chronologically, Basford et al. were the first to publish a study in 1987 in which they tested the LLL effect in OA. It was a blinded controlled study to assess the effectiveness of 0.9 mW continuous wave HeNe laser treatment. Eighty-one patients with symptomatic osteoarthritis of the thumb took part in the study. The subjects were randomly placed in either a control group or a treatment group. In each group the carpometacarpal (CMC), metacarpophalangeal (MCP), and interphalangeal (IP) joints of the most symptomatic thumb were "treated" with 15 sec irradiations at four equally spaced intervals around each joint three times a week for three weeks. The same protocol was used for both groups except that a hidden switch on the laser was placed in the "on" position for the treated group and in the "off" position for the control group. Although the laser-treated group noted slightly lessened tenderness of the treated MCP and IP joints (p < 0.01 and 0.05, respectively, Wilcoxon signed-rank test), and a small increase in three-finger chuck pinch strength (p < 0.04, paired t-test), changes in ROM, pain, joint tenderness, grip and pinch strength, activity level, and medication use did not significantly differ between the groups. But, at any rate, adverse effects were rare (one in each group), minimal, and subjective. The authors concluded that HeNe laser irradiation at 0.9 mW is safe but not an effective treatment of osteoarthritis of the thumb (Basford et al., 1987).

Also, Reed et al. in 1994 carried on an in vivo study of the effect of excimer laser irradiation on degenerate rabbit articular cartilage. In this study, eighteen adult rabbits with mechanically induced degenerative arthriof one knee were divided into two groups. The first group underwent arthrotomy and lavage of the arthritic joint. The second group underwent arthrotomy and irradiation of the degenerate articular surface with the Excimer (Xenon chloride ultraviolet, 308-nm) laser (Arthrex Arthrolase MAX-10, Germany) in a saline environment. Rabbits from each group were killed at intervals up to 12 weeks for histological and metabolic studies of their articular cartilage. In the control group there was no improvement in the macroscopic or microscopic appearance of the articular surface. In the laser-irradiated group initially there was macroscopic and microscopic smoothing of the fibrillated surface. By 6 weeks the surface had begun to show the reappearance of fibrillation. There was no evidence that there was any increase or decrease in mitotic or metabolic activity in the laser-irradiated group as compared with the controls (Reed et al., 1994).

But, there is a new experimental technique that was developed to study short-pulsed laser ablation of biologic tissues (human meniscus and bovine tibial bone), water, and acrylic. The experimental technique was based on interferometric monitoring of the motion of the tissue surface to measure its laser-induced expansion after irradiation. The thermoelastic expansion of these materials after laser irradiation under subablation threshold was examined to determine its role in the initiation of ablation. The experimentally observed surface expansion of cortical bone and acrylic was in agreement with theoretical predictions. The movement of meniscal tissue was similar to that shown by water. The latter 2 materials showed additional features consistent with the growth and collapse of cavitation bubbles. The exact role of cavitation in the irradiation of meniscal tissue by laser light remains unknown, but may represent a clinically important mode of tissue ablation and postirradiation trauma (Schaffer. et al., 1995).

Over and above, the influence of low-level (810 nm) laser on bone and cartilage during joint immobilization was examined with rats' knee model. The hind limbs of 42 young Wistar rats were operated on in order to immobilize the knee joint. They were assigned to three groups 1 wk after operation; irradiance 3.9 W/cm², 5.8 W/cm², and sham treatment. After 6 times of treatment for another 2 wks, both hind legs were prepared for: Indentation of the articular surface of the knee (stiffness and loss tangent) and dual energy X-ray absorptiometry (bone mineral density) of the focused regions. The indentation test revealed preservation of articular cartilage stiffness with 3.9 and 5.8 W/cm² therapy. Low level laser treatment may possibly prevent biomechanical changes by immobilization (Akai et al., 1997).

In addition, there is a Spanish study by Calatrava et al. in 1997, which was carried out to evaluate the effects of low-level laser irradiation on experimental lesions of articular cartilage. A standard lesion was practiced on the femoral trochlea of both hind limbs of 20 clinically normal Californian rabbits. These animals were divided into two groups of 10 individuals each, depending on the laser equipment used for treatment. One group was treated with HeNe laser (8 J/cm², 632.8 nm wavelength) and the other with infra-red (IR) laser (8 J/cm², 904 nm wavelength). In both groups, five points of irradiation to the right limb alone were irradiated per session for a total of 13 sessions, applied with an interval of 24 hrs between sessions. These points were: left and right femoral epicondyles, left and right tibial condyles, and the center of articulation. The distance between these points was approximately 1 cm. The untreated left limb was left as a control. During treatment, extension angle and periarticular thickness were considered. At the end of the treatment, samples were collected for histopathological study and stained with: Haematoxylin-Eosin, PAS and Done. The results showed a statistically higher anti-inflammatory capacity of the IR laser. The functional recovery was statistically similar for both treatments. Histological study showed, at the end of the treatment, hyaline cartilage in the IR group, fibrocartilage in the HeNe group and granulation tissue in the control limbs. Clinical and histological results indicated that this laser treatment had a clear anti-inflammatory effect that provided a fast recuperation and regeneration of the articular cartilage (Calatrava et al., 1997).

And another Italian study conducted by Giavelli et al. in 1998 proved a great value in treatment of osteoarthritic old patients. In this study, the researchers commented that laser light absorption through the skin causes tissue changes, targeting the nervous, the lymphatic, the circulatory and the immune systems with an antalgic, anti-inflammatory, anti-œdemic effect and stimulating tissue repair. Therefore, low level laser therapy is now commonly used in numerous rehabilitation centers. However, to activate the treatment program, the basic medical research results must always be considered to choose the best optical wavelength spectrum, technique and dose, for rehabilitative laser therapy. They analyzed the therapeutic effects of different wavelengths and powers in various treatment schedules. In particular, a protocol was designed to test such physical parameters as laser type, doses and individual schedule in different pathologic conditions. They reported the results obtained with low level laser therapy in the rehabilitation of geriatric patients, considering the various physical and technical parameters used in their protocol. In the experiment, they used the following laser equipment: an HeNe laser with 632.8 nm wavelength (Mectronic), a GaAs laser with 904 nm wavelength (Mectronic) and a CO2 laser with 10,600 nm wavelength (Etoile). To evaluate the patient clinical status, they used a different form for each involved joint; the laser beam was targeted on the region of interest and irradiation was carried out with the sweeping method or the points technique. Irradiation technique, doses and physical parameters (laser type, wavelength, session dose and number) were indicated on the form. The complete treatment cycle consisted of 5 sessions per week, that is 20 sessions in all. At the end of the treatment cycle, the results were scored on a 5-grade semiquantitative scale, i.e. excellent, good, fair, poor and no results. They examined 3 groups of patients affected with gonarthrosis (149 patients), lumbar arthrosis (117 patients), and algodystrophy (140 patients) respectively. The results showed the following: In gonarthrosis patients, the statistical analysis of the results showed no significant differences between CO2 laser and GaAs laser treatments (p= .975), but significant differences appeared between CO2 laser and HeNe laser treatments (p= .02) and between GaAs laser and HeNe laser treatments (p= .003). In lumbar arthrosis patients treated with GaAs or HeNe laser, significant differences were found between the two laser treatments and the combined sweeping-points techniques appeared to have a positive trend relative to the sweeping method alone, especially in sciatic suffering. In the algodystrophy syndrome, in hemiplegic patients, significant differences were found between CO2 and HeNe laser treatments (p= .026), between high and low CO2 laser doses (p= .024), and between low CO2 laser dose and high HeNe laser dose (p= .006). Accordingly, the authors concluded that low level laser therapy can be used to treat osteoarticular pain in geriatric patients. They also advised that in order to optimize the results, the diagnostic picture must be correct and a treatment program defining the physical parameters used (wavelength, dose and irradiation technique) must also be designed (Giavelli et al., 1998).

Although the overall number of studies was small, there is a recent review of literature, with six analyzed cases, made in the OA Research Center, Toronto, Canada in 1999 by Marks and de Palma. In brief, this review indicates that, despite their shortcomings, the six studies analyzed did report post-treatment improvin a variety of osteoarthritic problems, including pain, mobility, tenderness and function, with few adverse effects. Possible mechanisms documented for the observed results included peripheral nerve stimulation, resolution of inflammation, enhanced chondrocyte proliferation and increased matrix synthesis. However, not all studies were affirmative and few detailed how reliable their measurements were. Clearly, much more work is still needed in this area (Marks and de Palma, 1999).

And to wrap up this subject, comes again the most recent accumulative study by Brousseau et al. in year 2000. As in the same study by the same authors in RA treatment with LLLT, they studied the effect of LLLT (classes I, II and III) for the treatment of OA. Here, the authors commented that osteoarthritis (OA) affects a large proportion of the population and that LLLT was introduced as an alternative non-invasive treatment for OA about 10 years ago, but its effectiveness is still controversial. They searched MEDLINE, EMBASE, the Cochrane Musculoskeletal registry, the registry of the Rehabilitation and Related Therapies field and the Cochrane Controlled Trials Register up to January 30, 2000. Again, following an a priori protocol, they traced the same steps they used in their study, mentioned above, to assess the effectiveness of LLLT in treatment of rheumatoid arthritis (RA). This time their results showed that five trials were included, with 112 patients randomized to laser, 85 patients to placebo laser. Treatment duration ranged from 4 to 10 weeks. Pain was assessed by four trials. The pooled estimate (random effects) of three trials showed no effect on pain measured using a scale weighted mean differences (WMD) with 95% confidence intervals (CI), where the difference between the treated and control groups was weighted by the inverse of the variance. Standardized mean differences (SMD: -0.2, 95% CI: -1.0, +0.6), but there was statistically significant heterogeneity. Two of the trials showed no effect and one demonstrated very beneficial effects with laser. In another trial, with no scale-based pain outcome, significantly more patients reported pain relief (yes/no) with laser with an odds-ratio of 0.05, (95% CI: 0.0 to 1.56). Other outcomes of joint tenderness joint mobility and strength were not significant. Finally, the researchers concluded that for OA, the results are conflicting in different studies and may depend on the method of application and other features of the LLLT application. Needless to say that there is clearly a need to investigate the effects of these factors on LLLT effectiveness for OA in randomized controlled clinical trials (Brousseau et al., 2000).

(V) LASERS IN MUSCULO-SKELETAL DISORDERS

Laser Therapy in Tendinitis

Tendinitis occurs when at least one of the following occurs: synovial tendon sheaths become inflamed or trauma induces ischemia and subsequent inflammation with crystal deposition into the tendon (especially basic calcium phosphate crystals) causing calcific tendinitis. Most of these conditions can be classified as “overuse” syndromes. Aging can decrease the integrity of the tendon, making it more prone to injury (Hunter & Poole, 1987).

Rotator cuff tendinitis is one of the lesions of the shoulder joint where the supraspinatus and infraspinatus tendons are mostly involved. Both give rise to a painful arc on passive elevation. When the muscles are tested in static contraction a supraspinatus lesion causes sharp discomfort on resisted abduction and an infraspinatus lesion on resisted external rotation. A double-blind study was carried out by Vecchio et al., in 1993 to determine the effectiveness of LLLT in treatment of rotator cuff tendinitis. For such purpose, thirty-five patients with rotator cuff tendinitis were randomly allocated to active (CB Medico Master III 830 nm Ga-Al-As diode) laser or dummy laser treatment twice weekly for 8 weeks. Movement range, painful arc score, resisted movement score and responses to visual analogue scales for night pain, rest pain, movement pain and functional limitation were measured second weekly. All responses improved from baseline but there was no difference between the two groups. Needless to say that these results, ultimately, failed to demonstrate a significant effectiveness of laser therapy in the treatment of rotator cuff tendinitis (Vecchio et al., 1993).

The Achilles tendon is invested by a thin paratenon, not a full tendon sheath. Inflammatory changes are induced by overuse, either by running or pressure from footwear and may become chronic. Rupture can occur in a tendon affected by degeneration, particularly in rheumatic disease. The patient experiences severe pain in the lower calf and can no longer actively flex the ankle (Copeman, 1978). The effects of low level laser treatment in soldiers with Achilles tendinitis were studied in a Danish prospective, randomized and double blind trial by Darre et al. in 1994. Eighty-nine soldiers were enrolled in the study. Forty-six were randomized to treatment with active laser and 43 to treatment with placebo laser. No statistically significant differences in the number of consultations, morning stiffness, tenderness, crepitation, swelling, redness, VAS-score of pain and degree of unfitness for duty were found between the two treatment groups (Darre et al., 1994).

On the other hand, there is this Swedish study by Logdberg-Andersson et al. in 1997. The purpose of this randomized, double-blind study was to examine the effect of GaAs laser therapy for tendinitis and myofascial pain in a sample from the general population of Akersberga in the northern part of Greater Stockholm. 176 patients (of an original group of 200) completed the scheduled course of treatment. The patients were assigned randomly to either a laser group (92 patients, of whom 74 had tendinitis, completed the study) or a placebo group (84 patients, of whom 68 had tendinitis, completed the study). All 176 patients received six treatments of 904 nm, 8 mW, at 0.5-1.0 J/cm², at 1 Joule per point during a period of 3-4 weeks. Their pain was estimated objectively using a pain threshold meter, and subjectively with a visual analogue scale before, at the end of, and four weeks after the end of treatment. Laser therapy had a significant, positive effect compared with placebo measured from the first assessment to the third assessment, four weeks after the end of treatment. Laser treatment was most effective on acute tendinitis (Logdberg-Andersson et al., 1997).

Finally, a literature search identified 77 randomized clinical trials with LLLT, of which 18 included tendinitis. Three trials were excluded for lack of placebo control, of which one was comparative, another lacked patients with tendinitis in the treatment group, while the last unwittingly gave the placebo group active treatment. Four trials used too high power density or dose, and three did not expose the skin directly overlying the injured tendon. The remaining eight trials were included in a statistical pooling, where the mean effect of LLLT over placebo in tendinitis was calculated to 29.5% (19.5-39.0). LLLT with optimal treatment procedure/parameters can be effective in the treatment of tendinitis (Bjordal et al., 2000).

Laser Therapy in Epicondylitis

Epicondylitis is one of the tenoperiosteal lesions that can be distinguished from the intra-articular disease by the fact that passive movement of the related joint is full, albeit with pain. Strong static contraction of the affected muscle reproduces the pain, and there is tenderness at the tenoperiosteal junction (Copeman, 1978).

Lateral epicondylitis is termed ‘tennis elbow’ and is usually due to a traumatic lesion in the common extensor origin. This may be related to a poor back-hand style; sometimes a blow to the elbow seems to initiate symptoms, but often an extrinsic cause is lacking. The lesion can be troublesome for years, presumably due to repetitive irritation by use, and most disabling. Pain is induced by resisted radial deviation of the wrist or by a powerful grip, and an area of exquisite local tenderness is found over the lateral humeraepicondyle. Medial epicondylitis or ‘golfer’s elbow’ is less commonly affected and less severe, producing pain on ulnar deviation of the wrist (Copeman, 1978).

The effect of low level laser (GaAs) on lateral epicondylitis was investigated in a Norwegian double-blind, randomized, controlled study by Vasseljen et al. in 1992. Thirty patients were assigned equally to a therapeutic laser or a placebo laser group. All patients received eight treatments and were evaluated subjectively and objectively before, at the end of, and four weeks after treatment. Patients also completed a follow-up questionnaire on an average of five to six months after treatment. A significant improvement in the laser group compared to the placebo group was found on visual analog scale VAS (p= 0.02) and grip strength (p= 0.03) tests four weeks after treatment. In this study low level laser therapy was shown to have an effect over placebo; however, as a sole treatment for lateral epicondylitis it is of limited value. They suggested that further studies are needed to evaluate the reliability of their findings and to compare laser to other established treatment methods (Vasseljen et al., 1992).

In 1994 Krasheninnikoff et al. examined the laser effect in the treatment of lateral epicondylitis. Here, thirty-six patients with lateral epicondylitis of the elbow (19 women, 17 men, median age 48 yr.) were treated either with active laser or placebo, 18 patients in each group. The active laser was a Ga-Al-As; 30 mW; 830 nm low level laser. The study design was double blind and randomized. The treatment session consisted of eight treatments, two per week. Patients were irradiated on tender points on the lateral epicondyle and in the forearm extensors. Output power was 3.6 J/point. A follow up was performed by telephone, 10 weeks after the last treatment. No difference between laser and placebo was found on lateral elbow pain (Mann Whitney test, 95% confidence limits). On this basis, they concluded that low level laser offers no advantage over placebo in the treatment of musculoskeletal pain as lateral epicondylitis. They even went as far as to proclaim that further studies with low level laser treatment of musculoskeletal pain seem useless! (Krasheninnikoff et al, 1994).

Another team emerged as recently as 1998, Simunovic et al., with the opinion that among the treatment modalities of medial and lateral epicondylitis, low level laser therapy (LLLT) has been promoted as a highly successful method. They managed to come out with relatively good results from a study, whose aim was to assess the efficacy of LLLT using trigger points (TPs) and scanner application techniques under placebo-controlled conditions. This clinical study was completed at two Laser Centers (Locarno, Switzerland and Opatija, Croatia) as a double-blind, placebo controlled, crossover clinical study. The patient population (n= 324), with either medial epicondylitis (Golfer's elbow; n= 50) or lateral epicondylitis (Tennis elbow; n= 274), was recruited. Unilateral cases of either type of epicondylitis (n= 283) were randomly allocated to one of three treatment groups according to the LLLT technique applied: (1) Trigger points; (2) Scanner; (3) Combination Treatment (i.e., TPs and scanner technique). Bilateral cases of either type of epicondylitis (n= 41) were subject to crossover, placebo-controlled conditions. Laser devices used to perform these treatments were infrared (IR) diode laser (Ga-Al-As) 830 nm continuous wave for treatment of TPs and HeNe 632.8 nm combined with IR diode laser 904 nm pulsed wave for scanner technique. Energy doses were equally controlled and measured in J/cm² either during TPs or scanner technique sessions in all groups of patients. The treatment outcome (pain relief and functional ability) was observed and measured according to the following methods:

(1) short form of McGill's Pain Questionnaire (SF-MPQ);

(2) visual analogue scales (VAS);

(3) verbal rating scales (VRS);

(4) patient's pain diary; and

(5) hand dynamometer.

Fortunately, the treatments resulted in total relief of the pain with consequently improved functional ability which was achieved in 82% of acute and 66% of chronic cases, all of which were treated by combination of TPs and scanner technique. Thus, they concluded that this clinical study has demonstrated that the best results are obtained using combination treatment (i.e., TPs and scanner technique). They, herein, confirmed that good results are obtained from adequate treatment technique correctly applied, individual energy doses, adequate medical education, clinical experience, and correct approach of laser therapists. They, also, observed that under- and over-irradiation dosage can result in the absence of positive therapy effects or even opposite, negative (e.g., inhibitory) effects.

Initially, lateral epicondylitis can be treated with rest, ice, tennis brace and/or injections (Simunovic et al., 1998).

Treatment of Tennis Elbow

Although moderate sports are good for health, too much exercise gives damages to bones and muscles. If the excessive stress is repeated to a certain part of the elbow, bones or muscles, the part becomes inflamed and will lead to the pain. In case of the tennis elbow, the outside part is typically damaged. Injections are one of the most popular methods utilized, with a high success rate. However, when the condition is chronic or not responding to initial treatment, physical therapy is initiated. Common rehabilitation modalities utilized are ultrasound, photophoresis, electrical stimulation, manipulation, soft tissue mobilization, neural tension, friction massage, augmented soft tissue mobilization (ASTM) and stretching and strengthening exercise. ASTM is becoming a more popular modality due to the detection of changes in the soft tissue texture as the patient progresses through the rehabilitation process. Other new modalities include laser and acupuncture. As a last resort for chronic or resistant cases, lateral epicondylitis may undergo surgery. Scientific research has found that all these methods have been inconsistently effective in treating lateral epicondylitis. Therefore, further research efforts are needed to determine which method is more effective (Sevier and Wilson, 1999).

However, an early treatment by the low-level laser is very effective to eliminate the inflammation and the pain of such ailment. The 10mW laser is recommended to irradiate for 2 minutes at the most painful point (trigger point) and surrounding points 2 to 3 times a week. Low Level Laser therapy is said to be one of the most idealistic treatments for sports injuries, from the viewpoint of efficacy and safety (Zenba, 2001).

Laser Therapy in Painful shoulder syndrome

The shoulder joint mechanism is unique because of its great mobility. This is derived from four separate mechanisms:

1. The glenohumeral joint that provides 90˚ abduction and about 180˚ of internal and external rotation.

2. The sternoclavicular and

3. The acromioclavicular joints allow the clavicle to act as a mobile stabilizing strut during the remaining 90˚ of full elevation.

4. The scapula rotates against the chest wall, stabilized by various muscles including trapezius, rhomboids, levator scapulæ and serratus anterior. Such a mechanism is complex and a number of painful structures lie in close proximity. The diagnosis of shoulder pain is therefore dependent on a systemic examination based on a sound knowledge of applied anatomy (Copeman, 1978).

A Serbo-Croatian comparative study by Vlak et al to check the effectiveness of lasers and cryotherapy in the treatment of painful shoulder syndrome was carried on in 1994. The research comprised 60 patients, divided in two groups of 30 patients each. One group was treated by the cryotherapy procedures, the other by ten laser treatments, both having in addition individual therapeutic exercise for each patient. The difference in efficiency regarding both procedures were observed on the basis of objective measurable parameters (abduction, anteflexion, retroflexion, external and internal rotation, the distance between vertebræ prominens and styloid radii). Al, in view of anamnestic terms (pain both at rest and in motion) recorded before the treatment started and after the application of ten therapeutic procedures. The statistic results of data processing showed no significant difference in efficiency, regarding the objective parameters, between the two procedures treating painful shoulder syndrome. Nevertheless, laser treatment proved more efficient in reducing pain. In assessing the efficiency of both treatments there is a slight discrepancy as to the outcome between patients and the researchers: the patients found the laser treatment more efficient than cryotherapy, while the researchers’ evaluation was equal both procedures (Vlak et al., 1994).

Laser Therapy in Carpal Tunnel Syndrome

CTS is easily the most common entrapment neuropathy with a prevalence of 0.2-1%. It occurs when the median nerve is compressed by the flexor retinaculum at the wrist, producing characteristic nocturnal dysesthesias but occasionally progressing to sensory loss and weakness of thumb abduction. This condition is bilateral in half of patients and occurs with increased frequency in occupations associated with high levels of repetition and force (meatpackers, shellfish packing, musicians) (Katz et al., 1990).

Clinical results of a double-blind study by Weintraub 1996⁽¹⁾ of 11 patients afflicted with carpal tunnel syndrome who were treated with a diode-laser device showed that after six to 15 treatments, nine of the 11 patients experienced relief of pain and other associated symptoms as well as normalization of abnormal latencies. The patients all used a 30mW 830nm, a hand-held, battery-operated, nonsurgical laser device that employs the process of photo-biostimulation. Dr. Weintraub concluded that the results of his study support the efficacy and safety of laser-light treatment in carpal tunnel syndrome (Weintraub, 1996).

And in a recent study by Branco and Naeser (1999) on the effect of LLLT in carpal tunnel syndrome, the outcome was really promising. The researchers’ objective was to record the outcome for carpal tunnel syndrome (CTS) patients (who previously failed standard medical/surgical treatments) treated primarily with a painless, noninvasive technique utilizing red-beam, low-level laser acupuncture and microamps transcutaneous electrical nerve stimulation (TENS) on the affected hand; secondarily, with other alternative therapies. The design of the study involved open treatment protocol, patients diagnosed with CTS by their physicians. The treatments were applied on a total of 36 hands (from 22 women, 9 men), ages 24-84 years, median pain duration, 24 months. Fourteen hands failed 1-2 surgical release procedures. The treatments were divided into: Primary treatment: red-beam, 670 nm, continuous wave, 5 mW, diode laser pointer (1-7 J per point), and microamps TENS (< 900 microA) on affected hands. Secondary treatment: infrared low-level laser (904 nm, pulsed, 10 W) and/or needle acupuncture on deeper acupuncture points; and, Chinese herbal medicine formulas and supplements were dispensed on case-by-case basis. Three treatments per week, 4-5 weeks. The outcome was measured against pre- and post-treatment Melzack pain scores; profession and employment status recorded. The results were significantly satisfying. Post-treatment, pain was significantly reduced (p < .0001), and 33 of 36 hands (91.6%) showed no pain, or pain reduced by more than 50%. The 14 hands that failed surgical release were successfully treated. Follow-up after 1-2 years with cases less than age 60, only 2 of 23 hands (8.3%) pain returned, but successfully re-treated within a few weeks. The researchers concluded that possible mechanisms for effectiveness include increased adenosine triphosphate (ATP) on the cellular level, decreased inflammation and temporary increase in serotonin. (Branco and Naeser, 1999)

Laser Therapy in Myofascial Disorders and Fibromyalgia

Regional myofascial pain syndrome is a localized soft tissue pain syndrome characterized by the presence of a trigger point within the muscle that, on palpation, results in severe local tenderness and radiation of pain into characteristic regions. Though the discomfort of the myofascial pain syndrome remains regional, it is usually more widespread than bursitis or tendinitis. It most commonly involves the lower back, neck, shoulder, or hip region. This syndrome is sometimes referred to as localized fibromyalgia (Bennett, 1993).

Fibromyalgia is a chronic (> 3 months) non-inflammatory and non-autoimmune diffuse pain syndrome of unknown etiology with characteristic tender points present on physical examination. In addition to diffuse chronic musculoskeletal pain, patients subjectively often have morning stiffness, severe fatigue, nonrestorative sleep, paraesthesiæ, and Raynaud’s phenomenon. Physical examination and pathologic investigation reveal no evidence of articular, osseous, or soft tissue inflammation or degeneration. It may occur alone or associated with a number of other disorders. It is sometimes referred to as generalized fibromyalgia or fibrositis (Bennett, 1993).

Tender points are specific regions on the surface anatomy that are exceedingly tender when point pressure (4 kg/cm²) is applied by the examiner. They are more sensitive to pressure than in control patients and when compared to other, nontender point sites (control points) in the same patient. They are 18 points (9 pairs) situated as follows:

1. Occiput: suboccipital muscle insertions.

2. Trapezius: midpoint of the upper border.

3. Supraspinatus: above the medial border of the scapular spine.

4. Gluteal: upper outer quadrants of buttocks.

5. Greater trochanter: posterior to the trochanteric prominence.

6. Low cervical: anterior aspects of the intertransverse spaces at C5-C7.

7. Second rib: second costochondral junctions.

8. Lateral epicondyle: 2 cm distal to the epicondyles.

9. Knee: medial fat pad proximal to the joint line.

The classification criteria for fibromyalgia require detection of 11 out of 18 tender points. They should exist both above and below the waist and be present for at least 3 months (Freundlich & Leventhal, 1993).

There was an Italian double-blind trial by Ceccherelli et al. (1989) in which a pulsed infrared beam was compared with a placebo in the treatment of myofascial pain in the cervical region. The patients were submitted to 12 sessions on alternate days to a total energy dose of 5 J each. At each session, the four most painful muscular trigger points and five bilateral homometameric acupuncture points were irradiated. Those in the placebo group submitted to the same number of sessions following an identical procedure, the only difference being that the laser apparatus was non-operational. The results showed a pain attenuation in the treated group and a statistically significant difference between the two groups of patients, both at the end of therapy and at the 3-month follow-up examination (Ceccherelli et al., 1989).

Also, the effect of low-level laser therapy (GaAlAs, 830 nm, continuous) for chronic myofascial pain in the neck and shoulder girdle was assessed in a double-blind randomized study with 36 female participants. Treatments were given six times during two weeks with a total effect of 4.5-22.5 J per treatment depending on the number of tender points. But, here, no significant effect was found, neither in pain relief nor in tablet intake between the laser and the placebo groups. However, none of the participants reported any side-effects (Thorsen et al., 1991). Then again the same author in a controlled cross-over study evaluated the effect of low level laser therapy (LLLT) evaluated again for myofascial pain in the neck and shoulder girdle. During a five weeks period, forty-seven female laboratory technicians received six laser and six placebo treatments to tender points in the neck and shoulder girdle. Surprisingly, subjects rated the placebo treatment significantly more beneficial than LLLT (p= .04). Again, there was no reduction in consumption of analgesics associated with either laser or placebo treatment. And, the results indicated no beneficial effect of LLLT for myofascial pain (Thorsenet al., 1992).

But, Douglas Ashendorf in an article published in 1993 commented on the ability of LLLT to mitigate fibromyalgic pain. In this pilot study, he mentioned that results had suggested that the pain relieving properties of LLLT had been the most consistent benefit. The duration of benefit had varied from one hour to one week, and seems to increase as treatment progresses. However, in no case had pain relief been permanent. Other areas of improvement were not as clear. Improvement in sleep was observed with some regularity although this was undoubtedly due in part to decreased pain. The "non-restorative" sleep complaints were less regularly improved. Improvement with regard to abnormal sensations in the limbs (paraesthesiæ and subjective swelling) appeared to be fairly consistent. Also, there were improvements in fatigue, mood and headache. Patients generally received treatment five days per week for three weeks and 1 to 2 days per week for another month. No patient had yet been tapered entirely. If no response to therapy was observed in 2 to 3 weeks, the patient appeared unlikely ever to benefit, and had left the study. All patients were also involved in a comprehensive stretching program either at home and/or in the researcher’s clinic. All patients had already undergone trials of low-dose antidepressants. Some had undergone trigger point injection therapy and/or various neurolytic (nerve blocking) procedures. In all cases, there was uniform patient dissatisfaction with the results of prior treatment. However, side effects of laser therapy encountered included brief episodes of the following: anxiety, dizziness, nausea, headache and sedation. In only one case did a patient find this objectionable enough to leave the study; in all other cases the frequency, intensity and duration of side effects decreased with time. There was no sensation associated with laser treatment, per se; all side effects occurred sometime after a treatment session had begun, or a short time after it had ended. Thus far, results have suggested that the pain relieving properties of LLLT had been the most consistent benefit. Accordingly, the author commented, cooperation between investigators, including a shared database and standardized treatment protocols, will be necessary to determine whether laser therapy should ultimately become a permanent part of our treatment for fibromyalgia. Other diagnostic groups were also being treated with LLLT outside of the fibromyalgia pilot study, including: myofascial pain syndrome, nerve root irritation from herniated discs and arthritis (discogenic and vertebrogenic radiculopathy), facet joint syndrome, reflex sympathetic dystrophy, bursitis, tendinitis, acute ligamentous strains, chondromalacia patellae, carpal tunnel syndrome and migraine headache disorder. Rheumatoid arthritis and diabetic neuropathy would have soon been added (Ashendorf, 1993).

Also, Laakso et al. (1995)⁽¹⁾ studied the effects of lasers on 56 people who suffered myofascial pain syndrome. Previous experiments linking endorphin release and lasers have only been done on rats. In this study, Laakso applied different doses and wavelengths of a laser diode to "trigger points" on the body and took blood samples measuring endorphin levels in these subjects and a control group. The control group reported some pain relief, most likely a placebo effect, but endorphins were present. However, those patients that underwent laser treatment reported pain reduction of up to 78%, and endorphins were present in their blood. Then she designed another study to analyze the effect of second daily infrared (IR) laser (820 nm, 25 mW) and visible red laser (670 nm, 10 mW) at 1 J/cm² and 5 J/cm² on chronic myofascial pain. Forty-one consenting subjects with chronic myofascial pain conditions exhibiting myofascial trigger points in the neck and upper trunk region underwent five treatment sessions over a two week period. All groups demonstrated significant reductions in pain over the duration of the study with those groups, which received infrared (820 nm) laser at 1 J/cm² and 5 J/cm² demonstrating the most significant effects (p < 0.001). Results indicated that responses to LLLT at the parameters used in this study are subject to placebo and may be dependent on power output, dose and/or wavelength (Laakso et al., 1995).

So, clinically, Low Level Laser Therapy (LLLT) has been used successfully in the treatment of chronic myofascial pain but many have questioned the scientific basis for its use. The reason maybe that many studies have been poorly designed or poorly controlled.

Laser Therapy in Low-back Pain and Intervertebral Disc

In 1989, the Japanese researcher Tatsuhide Abe published a case report about using LLLT in treatment of a herniated intervertebral disc. A 40-year-old woman presented with a 2-year history of lower hack pain and pain in the left hip and leg diagnosed as a ruptured disc between the 5th lumbar/lst sacral vertebræ. The condition had failed to respond to conventional treatment methods including pelvic traction, nonsteroid anti-inflammatory drugs and dural block anesthetic injections. MRI scans were made of the affected disc, showing it protruding on the left side through the dural membrane. The gallium aluminum arsenide (Ga-Al-As) diode laser (830 nm, 60 mW) was used in outpatient therapy. After 7 months of treatment, the patient's condition had dramatically improved, demonstrated by motility exercises. Surprisingly, this improvement was confirmed by further MRI scans, which showed clearly the normal condition of the previously herniated L5/S1 disc!! (Abe, 1989)

Then came again the veritable Basford with his colleagues from the Department of Physical Medicine and Rehabilitation, Mayo Clinic and Foundation, Rochester, Minnesota, USA in 1999 to assess the effectiveness of low-level laser therapy in the treatment of musculoskeletal low back pain. They conducted a double-masked, placebo-controlled, randomized clinical trial to ascertain the assumption. Sixty-three ambulatory men and women between the ages of 18 and 70yrs with symptomatic non-radiating low back pain of more than 30 days' duration and normal neurologic examination results. Subjects were bloc-randomized into two groups with a computer-generated schedule. All underwent irradiation for 90 seconds at eight symmetric points along the lumbosacral spine three times a week for 4 weeks by a masked therapist. The sole difference between the groups was that the probes of a 1.06 micron neodymium:yttrium-aluminum-garnet laser emitted 542mW/cm² for the treated subjects and were inactive for the control subjects. Eventually, the team found out that the treatment with low-level 1.06 micron laser irradiation produced a moderate reduction in pain and improvement in function in patients with musculoskeletal low back pain. Benefits, however, were limited and decreased with time. The authors advised that further research be warranted (Basford et al., 1999).

Finally, 12 patients who had refractory low back pain problems related to spinal arthritis and complicated by herniated discs were treated with GaAs laser acupuncture. Nogier frequencies 2.82 and 146 were mainly used. Unfortunately, the used points were not indicated in the abstract. However, effectiveness was observed with immediate improvement in pain and muscle spasms. Elimination of pain medication and improvement in functional activities was progressive in 10 of the 12 patients. Two patients with spinal stenosis failed to maintain improvement for more than a brief period. One had a surgical relief of the stenosis and then responded with relief of post-operative symptoms (Kurland, 1999).

Treatment of Low Back Pain

Low back pain is said to be a characteristic illness to human beings that started to walk in the upright position. This is caused by poor posture, decline of muscular strength and fatness. In case the conventional therapy such as medical treatments or physical therapies are not effective to a low back pain patient, the low level laser therapy is recommended to take over (Zenba, 2001).

The low level laser can penetrate deep into the humbody, stimulate receptors of autonomous nervous system relieving the tension of sympathetic nerves and improve the blood circulation of the entire body and affected part and mitigates the pain very quickly. Compared with conventional treatments, the effect of low level laser irradiation will continue for several hours and can be accumulated. Points of irradiation are tender points or indurated parts, 20~30sec/point, 3~5 minutes in total, if possible daily irradiation is recommended for 3~4 days a week. Recently, the radicular sciatica, which is difficult to be affected by low level laser has been found to be cured by the repetition of very short time irradiation of high power laser (Zenba, 2001).

(VI) LASERS IN PAIN TREATMENT

LASERS IN PAIN TREATMENT

The use of Low Level Laser Therapy (LLLT) utilizing helium-neon (He-Ne) lasers has increased lately especially in pain control. New protocols are being developed aimed at a complex of primary and secondary symptomologies. One of these protocols is Stellate Ganglion Stimulation (SGS) that has shown a unique set of developments. Targeting the area of the stellate ganglion is showing great promise in the rehabilitation of patients with a history of chronic musculoskeletal pain syndromes, but several patients with preexisting psychological symptomology have exacerbated during the initial stages of utilization of this protocol. Patients with a history of psychological diagnosis for dysthymia, anxiety, post traumatic stress disorder or minor diffuse brain injury have shown an exacerbation of these symptomologies during the initial phases of stimulation treatment. Overall, response to this form of therapy seems to be positive but some patients require dermatomal and/or site-specific therapy to maximize outcome. With specific psychological treatment combined with a more conservative amount of stimulation initially, the increase in these symptoms shows a tendency to remit with the pain response. Continued research is currently focusing on the mechanisms for this type of response as well as protocol refinement to maximize its effectiveness (Scott and Difee, 1992).

A meta-analysis was undertaken by Gam et al. (1993) of low-level laser therapy (LLLT) on musculoskeletal pain. A literature search revealed 23 LLLT trials and of these, 17 were controlled trials. Ten were double blind and 7 were insufficiently blinded. Within the studies identified, pain was assessed by visual analogue scale (VAS) or by "some other indices of pain". Nine double-blind trials and 4 controlled trials presented results in a form that allowed pooling of data. In the double-blind trials, the mean difference in pain between LLLT and placebo was 0.3% [S.E.(d) 4.6%, confidence limits -10.3-10.9%]. In the insufficiently blinded trials the mean difference in pain was 9.5% [S.E.(d) 4.5%, confidence limits -2.9-21.8%]. It was concluded that LLLT has no effect on pain in musculoskeletal syndromes (Gam et al., 1993).

Really, there are many studies that devalue the laser effect in pain treatment. One such study is the one we have already mentioned in the low back pain section in which Basford et al. (1999) found no real effect of LLLT in pain treatment and that the analgesic effect of laser decreases with time. Another study is that American study conducted by Parris et al. in 1994. The aim of this study was to evaluate the effect of acute and repeated (5 days) treatment with various types of infrared (IR) diode lasers and probes (single- vs cluster-beam) on the pain response in rats with peripheral mononeuropathy produced by sciatic nerve ligation. Male Sprague-Dawley rats were anesthetized with sodium pentobarbital, and the mid-thigh was surgically exposed to reveal the sciatic nerve, around which four ligatures were loosely tied. On post-operative day 5, the skin over the sciatic nerve lesion was subjected to a 30-min daily local exposure from a 904-nm IR diode laser (700 Hz, average output power 10 mW) with a single-beam probe, a 830-nm IR diode laser (700 Hz) with either a single-beam (average output power 50 mW) or cluster-beam probe (average output power 15 mW), or placebo for 5 consecutive days. Two pain responses (foot-withdrawal time and the hind-paw elevation time) were measured on both sides using the radiant heat method on days 5 and 9. In addition, cold allodynia was measured on day 9 of treatment by placing the rats on a chilled metal plate (4° C) and measuring the duration of elevation of either of the hind paws. On day 9, the animals were sacrificed for collection of the samples of brain and lumbar spinal cord for the determination of the tissue concentrations of dynorphin A1-8-like immunoactivity (DYN) using specific radioimmunoassay (RIA). The hind-paw withdrawal and elevation times on the right side in all groups subjected to the various methods of IR laser irradiation did not differ significantly as compared with the placebo-treated group when measured on days 5 and 9 after surgery. No statistically significant differences in withdrawal response and elevation time of the unaffected left hind paw were noted either. The measurement of cold allodynia similarly failed to reveal any effect in laser-treated groups vs placebo. The RIA analysis found that tissue concentrations of DYN were significantly elevated in the spinal cord ipsilaterally to the ligation side, as compared with the contralateral side, in all rats with sciatic nerve ligation. All modalities of IR diode laser treatment did not produce any significant difference in the brain and spinal cord level of DYN on postoperative day 9 in all treatment groups. It is concluded that repeated IR diode laser treatment did not reduce hyperalgesia induced by sciatic nerve ligation in rats (Parris et al., 1994).

But, on the other hand, there is a Ga-Al-As diode system that produces low-energy red light (830 nm, 40 mW) that has been used for the treatment of many kinds of pain. The mechanism of action of this new laser irradiation for analgesia was studied in anesthetized rats in a study conducted in 1994 by Sato et al. In this study, the effect of laser irradiation of the saphenous nerve was studied by recording neuronal activity at the L4 dorsal root filaments after the injection of a chemical irritant, turpentine. Laser irradiation inhibited both the asynchronous firing that was induced by turpentine and increased part of the slow components of the action potentials. Thus, the laser irradiation selectively inhibited nociceptive signals at peripheral nerves, generally inhibiting neuronal activity associated with inflammation (Sato et al., 1994).

Also, Tam in 1999 conducted a study to confirm that the semiconductor or laser diode (GaAs, 904 nm) is the most appropriate choice in pain reduction therapy. The idea is that low-level laser acts on the prostaglandin (PG) synthesis, increasing the change of PGG2 and PGH2 into PG12 (also called prostacyclin, or epoprostenol). The last is the main product of the arachidonic acid into the endothelial cells and into the smooth muscular cells of vessel walls that have a vasodilating and anti-inflammatory action. In this study, treatment was performed on 372 patients (206 women and 166 men) during the period between May 1987 and January 1997. The patients, whose ages ranged from 25 to 70 years, with a mean age of 45 years, suffered from rheumatic, degenerative, and traumatic pathologies as well as cutaneous ulcers. The majority of patients had been seen by orthopedists and rheumatologists and had undergone x-ray examination. All patients had received drug-based treatment and/or physiotherapy with poor results; 5 patients had also been irradiated with He:Ne and CO2 lasers. Two-thirds were experiencing acute symptomatic pain, while the others suffered long-term pathology with recurrent crises. He used a pulsed diode laser, GaAs 904 nm wavelength once per day for 5 consecutive days, followed by a 2-day interval. The average number of applications was 12. He irradiated the trigger points, access points to the joint, and striated muscles adjacent to relevant nerve roots. In conclusion, he achieved very good results, especialin cases of symptomatic osteoarthritis of the cervical vertebræ, sport-related injuries, epicondylitis, and cutaneous ulcers, and with cases of osteoarthritis of the coxa. Finally, Tam concluded that treatment with 904-nm diode laser has substantially reduced the symptoms as well as improved the quality of life of these patients, ultimately postponing the need for surgery (Tam, 1999).

According to Japan Society of Laser Medicine, the pain relief effect of low level laser is scientifically confirmed to be a compound effect caused by the stimulation of nerves by the laser light.

1. The effect to peripheral nerves

The laser light stimulates peripheral nerves, which became excited by the stimulation of pain (depolarization) and stabilizes them(polarization) suppressing the generation of pain impulses.

2. The effect to central nerves

The laser light stimulates central nerves through acupuncture points or trigger points making to emit pain relief substances such as β-Endorphins and catecholamines.

3. The effect to sympathetic nerves

The laser light stimulates sympathetic nerves making relieve the strain of blood vessels and improve the blood circulation. Thus it suppresses the generation of pain substances.

4. The effect to blood

The laser light directly stimulates the blood and improves the blood circulation and leads to emit chemical mediators (Japan Society of Laser Medicine, 2001).

Laser Therapy in Acute Pain

Concerning the subject of acute pain, with a history of hours or at most a few days, has a sudden onset either from injury or a sudden attack of a pathological disease such as appendicitis. The pain is sharp and very often extremely uncomfortable, sometimes causing loss of consciousness. Acute pain is nearly always accompanied by inflammation and swelling and the cause is usually apparent; the affected area can be seen on a thermogram as an area or areas of elevated skin temperature. Treatment such as surgical and pharmaceutical intervention is therefore able to be quickly given, with a corresponding immediate reduction in the degree of the pain attack. However, in the case of a broken bone, for example, the pain continues even after the operation to reduce, set and immobilize the fracture: the natural healing processes of the body also cause pain of their own, such as the pressure pain associated with edema formation, which is the part of the body's natural immobilization mechanism. After an operation such as appendectomy, although the stabbing pain of appendicitis is gone, the patient has undergone an invasive surgical procedure with the resulting pain from the incision and its closure. In cases like these, the physiotherapist comes into his or her own to get the patient back to a normal and useful life as quickly as possible. The operation wound is itself an abnormal condition for the body, and more precise multi-layer closures approximate the cut tissues better, thereby speeding up the reparative processes and helping to minimize scarring. In this situation LLLT may offer a speedy and noninvasive method of both controlling the pain and speeding up the reparative processes.

The keynote of acute pain therapy is the recognition of the physical abnormality that is causing the pain, and restoring the injured or diseased tissues to their normal condition as quickly as possible. The role of LLLT becomes of tremendous importance in assisting restoration of the system to its normal condition, thereby fulfilling the double role of speeding up the repair processes including the natural recovering powers of the injured tissues, while at the same time enhancing the body's autoanalgesic powers (RianCorp Pty Ltd, 2001).

An English trial was designed by Moore et al. in 1992 to test the hypothesis that LLLT reduces the extent and duration of postoperative pain. Twenty consecutive patients for elective cholecystectomy were randomly allocated for either LLLT or as controls. The trial was double blind. Patients for LLLT received 6-8-min treatments (GaAlAs: 830 nm; 60 mW) to the wound area immediately following skin closure prior to emergence from general anesthesia. All patients were prescribed on demand postoperative analgesia (IM or oral according to pain severity). Recordings of pain scores (0-10) and analgesic requirements were noted by an independent assessor. There was a significant difference in the number of doses of narcotic analgesic (IM) required between the two groups. The controls group to LLLT group ratio was 5.5: 2.5. No patient in the LLLT group required IM analgesia after 24 h. Similarly the requirement for oral analgesia was reduced in the LLLT group; controls to LLLT ratio was 9: 4. Control patients assessed their overall pain as moderate to severe compared with mild to moderate in the LLLT group. Thus, the results justified further evaluation on a larger trial population (Moore et al., 1992).

But concerning acute pain in the orthopedic complaints, the Irish Mulcahy et al. (1995) conducted a prospective, double blind trial of low level laser therapy (LLLT) in musculoskeletal injuries to assess its efficacy. They assigned patients with a variety of painful skeletal soft tissue conditions to one of two treatment groups, treatment from a functional machine or placebo treatment from an inactive machine. Both machines were identical and both appeared functional. The operative status of each machine was unknown to both the therapist and the patient. Here, the results suggested that LLLT has no significant therapeutic effect and acts primarily as a placebo (Mulcahy et al., 1995).

Also, to test the efficacy of low-level laser therapy on lateral ankle sprains as an addition to a standardized treatment regimen, a Dutch trial was conducted by de Bie et al. in 1998. In this study, high-dose laser (5 J/cm²), low-dose laser (0.5 J/cm²), and placebo laser therapy (0 J/cm²) at skin level were compared. It was designed as a randomized, double-blind, controlled clinical trial with a follow-up of 1 year. Patients, therapists, assessors, and analysts were blinded to the assigned treatment. After informed consent and verification of exclusion criteria, 217 patients with acute lateral ankle sprains were randomized to three groups from September 1, 1993 through December 31, 1995. Twelve treatments of 904nm laser therapy in 4 weeks as an adjunct to a standardized treatment regimen of 4 weeks of brace therapy combined with standardized home exercises and advice were given. The laser therapy device used was a 904nm Ga-As laser, with 25-watt peak power and 5,000 or 500Hz frequency, a pulse duration of 200 msec, and an irradiated area of 1 cm². Pain and function as reported by the patient were registered. The results showed that the intention-to-treat analysis of the short-term results had shown no statistically significant difference on the primary outcome measure, pain (p = .41), although the placebo group showed slightly less pain. Function was significantly better in the placebo group at 10 days (p = .01) and 14 days (p = .03) after randomization. The placebo group also performed significantly better on days of sick leave (p = .02) and at some points for hindrance in activities in daily life and pressure pain, as well as subjective recovery (p = .05). Thus, in this particular study, they concluded that neither high- nor low-dose laser therapy is effective in the treatment of lateral ankle sprains (de Bie et al., 1998).

Laser Therapy in Chronic Facial, Head and neck pains

Chronic pain may have a history of at least several weeks, and in some cases, years. The typical chronic pain condition will most likely have started as an acute condition, and due either to lack of correct therapy, or to the complete lack of any kind of treatment at all, the complex interaction of the various injured systems results in the condition which is the cause of chronic pain. By its very nature, chronic pain cannot be easily or quickly treated. The longer it is left, the more deep-rooted it becomes, and the more it spreads to related anatomical regions. As a typical example, an ignored painful condition in the fingers may gradually involve the entire upper exand spread to the shoulder, neck and head. The pain however gradually lessens in time, to be replaced with a numbness in the affected extremity, followed by a palsy-like condition accompanied by attacks of abnormal sensitivity such as "pins and needles': this is a worst-case example, but it can easily happen with lack of appropriate treatment.

The mechanisms of chronic pain are complex. The most modern research points to an 'habituation' of the neural pathways to pain transmission, resulting in spontaneous neuron firing and irregular synthesis of nociceptive transmitter substances. Chronic pain can involve the vascular, lymphatic, neural and humoral systems singly or in combination. An old muscle injury may gradually turn fibrotic: this in turn constricts the neighboring blood and lymphatic vessels and may compress both afferent and efferent nerves. It is a vicious circle. Without the blood and lymphatic system to bring in the necessary tissue scavengers and collagen lysing agents the fibrosis becomes more and more pronounced. In the meantime the affected nerves transmit and receive with impaired efficiency, and the blood supply to and from the area distal to the obstruction is diminished. The patient may begin to feel coldness below the affected area, with associated pain. Thermography will typically reveal abnormally low skin temperatures in the distal affected region. As the lymphatic system gradually backs up, the tissues proximal to the obstruction are not properly drained, and muscles may begin to exhibit some of the side effects of local lactic acidosis, and the condition gradually spreads.

Chronic pain patients, who cannot often actually 'see' what is wrong with them, tend to have 'tried everything', and very often have a less trusting attitude to their treatment than the acute pain patient who can see why they feel pain. In LLLT, there is a double problem for the laser therapist to overcome: therapy of the actual chronic pain condition itself, and the psychological barrier which the patients may automatically erect between themselves and the therapist. One part of the patient really wants the treatment to succeed, because the pain and related complaints are interfering with their business and social lives; and the other part tells them that this 'new treatment' is no better than any they have had before. The answer lies in patient education (RianCorp Pty Ltd, 2001).

Post-herpetic neuralgia is a significant and severe disability that afflicts some patients following the acute manifestation of the disease despite what may be considered adequate pharmacological treatment at the time of onset of the vesicular rash. Surgery in general has little to offer in this condition although dorsal route entry zone lesions may be appropriate in some situations. Low level laser therapy has been of value in a small series, to date, of cases that the treatment has been used on. This has been both in the early phase soon after the vesicles have cleared and often late, many years after the onset of the pain. Reported is a good improvement rate in approximately 60% of cases. The treatment is non-invasive and consideration of initial laser therapy is advocated (Yaksich et al, 1993).

The efficacy of low level laser therapy (LLLT) for pain attenuation in patients with post-herpetic neuralgia (PHN) was evaluated by the Japanese Kemmotsu et al. (1991) in 63 patients (25 males. 38 females with an average age of 69 years). Patients were managed at the researchers’ pain clinic over the preceding four years of 1991. A double blind assessment of LLLT was also performed in 12 PHN patients. The LLLT system was a gallium aluminum arsenide (Ga-Al-As) diode laser (830 nm, 60 mW continuous wave). Pain scores (PS) were obtained using a linear analog scale (LAS) 1 to 10 before and after LLLT. The immediate effect after the initial LLLT was very good (PS: 3) in 26, and good (PS: 7-4) in 30 patients. The long-term effect at the end of LLLT (the average number of treatments 36 + 12) resulted in no pain (PS: 0) in 12 patients and slight pain (PS: 1-4) in 46 patients. No complications attributable to LLLT occurred. Although a placebo effect was observed, decreases in pain scores and increases of the body surface temperature by LLLT were significantly greater than those that occurred with the placebo treatment. Thus, their results indicated that LLLT is a useful modality for pain attenuation in PHN patients and because LLLT is a noninvasive, painless and safe method of therapy, it is well acceptable by patients (Kemmotsu et al., 1991).

Low level laser therapy near the stellate ganglion is a new method introduced to alleviate the neuralgic pain. In another Japanese case study by Ohtsuka et al. in 1992, such treatment was given for a 68-year-old female with post-herpetic neuralgia, suffering from burning pain in the right forehead for 11 years. Stellate ganglion block and supra-orbital nerve block with oral medication were not effective to relieve this pain. The laser irradiation induced warm sensation in her face followed by an excellent pain relief. Thermograms illustrated a remarkable increase from 30.6ºC to 31.5ºC in temperature of her right face. The irradiation near the right carotid artery also had the similar effect. Therefore, the results imply that the irradiation with low level laser of the stellate ganglion and/or the carotid artery increases a facial blood flow and relieves facial neuralgia (Ohtsuka et al., 1992).

In another study, Hashimoto et al. (1997) evaluated the effects of laser irradiation on the area near the stellate ganglion on regional skin temperature and pain intensity in patients with post-herpetic neuralgia. A double blind, crossover and placebo-controlled study was designed to deny the placebo effect of laser irradiation. Eight inpatients (male 6, female 2) receiving laser therapy for pain attenuation were enrolled in the study after institutional approval and informed consent. Each patient received three sessions of treatment on a separate day in a randomized fashion. The treatment scheme was as follows: Three minutes irradiation with a 150 mW laser (session 1), 3 minutes irradiation with a 60 mW laser (session 2), and 3 minutes placebo treatment without laser irradiation. Neither the patient nor the therapist was aware which session type was being applied until the end of the study. Regional skin temperature was evaluated by thermography of the forehead, and pain intensity was recorded using a visual analogue scale (VAS). Measurements were performed before treatment, immediately after (0 minutes) then 5, 10, 15, and 30 min after treatment. Regional skin temperature increased following both 150 mW and 60mW laser irradiation, whereas no changes were obtained by placebo treatment. VAS decreased following both 150 mW and 60 mW laser treatments, but no changes in VAS were obtained by placebo treatment. These changes in the temperature and VAS were further dependent on the energy density, i.e. the dose. Results demonstrated that laser irradiation near the stellate ganglion produces effects similar to stellate ganglion block. Here, their results clearly indicated that they are not placebo effects but true effects of laser irradiation (Hashimoto et al., 1997).

Bearing in mind that most post-herpetic neuralgias can be extremely painful conditions, which in many cases prove resistant to all the accepted forms of treatment, they are frequently most severe in the elderly and may persist for years with no predictable course. On such basis, Moore et al designed a trial. In (2000). It was a double blind assessment of the efficacy of low level laser therapy in the relief of the pain of post herpetic neuralgia with patients acting as their own controls. Admission to the trial was limited to patients with established post herpetic neuralgia of at least six months duration and who had shown little or no response to conventional methods of treatment. Measurements of pain intensity and distribution were noted over a period of eight treatments in two groups of patients, each of which received four consecutive laser treatments. The results demonstratea significant reduction in both pain intensity and distribution following a course of low level laser therapy (Moore et al., 2000).

Neurogenic facial pain has been one of the more difficult conditions to treat, but the introduction of laser therapy now permits a residual group of patients hitherto untreatable to achieve a life free from or with less pain. The English Professors P.F. Bradley and Rehbini (1994)⁽¹⁾ reported their method of employing LLLT in treatment of head, neck and facial pain as follows: They employ lasers which are compact and low priced because they use diode technology. According to Bradley and Rehbini:

The two most frequently used modalities are:

1. Near Infra Red Gallium Aluminum Arsenide 820nm.

This is the most widely applicable wavelength due to its deep penetration in tissue.

2 Visible Red Helium Neon 632.8nm or Diode 660nm.

There is evidence that red light is well absorbed by chromophores in nerve tissue and epithelium particularly, although its penetration is less than near infrared. Commonly used pulsed in acupuncture techniques.

Mechanisms of Pain Relief:

Also, there is experimental evidence for:

1. Effects on nerve: changes in sodium potassium ATPase have been reported and microneuronography has demonstrated damping action on fine non myelinated fibers.

2. Energization of depleted enzymes e.g. super-oxide dismutase.

3. Elevation of endorphin levels has been reported after treatment of trigger zones in muscle (Bradley and Rehbini, 1994)..

Laser in Acupuncture

The National Institutes of Health recently recommended acupuncture as an effective tool for the treatment of various health problems. Acupuncture is an old technique but has been popular in the United States only since 1972. Its history, theories, and indications are not well known to the medical community.

In 1998, Ceniceros and Brown reviewed the literature to gather information on the history, techniques, physiology, indications, adverse effects, and opposing views to acupuncture. The mechanism by which acupuncture works involves neurotransmitters and adrenocorticotropic hormones. It appears to be effective in the treatment of pain, nausea, and drug detoxification and in stroke victims. Studies suggest acupuncture is no more effective than placebo. Acupuncture side effects have rarely been reported. Among the various methods of application techniques in low level laser therapy (LLLT) (HeNe 632.8 nm visible red or infrared 820-830 nm continuous wave and 904 nm pulsed emission) there are very promising "trigger points" (TPs), i.e., myofascial zones of particular sensibility and of highest projection of focal pain points, due to ischemic conditions. The effect of LLLT and the results obtained after clinical treatment of 243 patients (headaches and facial pain, musculoskeletal ailments, myogenic neck pain, shoulder and arm pain, epicondylitis humeri, tenosynovitis, low back and radicular pain and Achilles tendinitis) to whom the "trigger points" were applied were better than anyone had ever expected. According to clinical parameters, it has been observed that the rigidity decreases, the mobility is restored (functional recovery), and the spontaneous or induced pain decreases or even disappears, by movement, too. LLLT improves local microcirculation and it can also improve oxygen supply to hypoxic cells in the TP areas and at the same time it can remove the collected waste products (Ceniceros and Brown, 1998).

The normalization of the microcirculation, obtained due to laser applications, interrupts the "circulus vitiosus" of the origin of the pain and its development (circulus vitiosus = muscular tension↔ pain → increased tension → increased pain, etc.). Results measured in acute pain, diminished more than 70%; in chronic pain more than 60%. Clinical effectiveness (success or failure) depends on the correctly applied energy dose. Over/underdosage produces opposite, negative effects on cellular metabolism. But, there are no negative effects on the human body and the use of analgesic drugs could be reduced or completely excluded. LLLT suggests that the laser beam can be used as monotherapy or as a supplementary treatment to other therapeutic procedures for pain treatment (Simunovic, 1996).

To establish whether there is evidence for or against the efficacy of acupuncture in the treatment of neck pain, a systematic literature review was undertaken of studies that compared needle or laser acupuncture with a control procedure for the treatment of neck pain. Two reviewers, White and Ernst (1999), independently extracted data concerning study methods, quality and outcome. Overall, the outcomes of 14 randomized controlled trials were equally balanced between positive and negative. Acupuncture was superior to waiting-list in one study, and either equal or superior to physiotherapy in three studies. Needle acupuncture was not superior to indistinguishable sham control in four out of five studies. Of the eight high-quality trials, five were negative. In conclusion, according to the authors, the hypothesis that acupuncture is efficacious in the treatment of neck pain is not based on the available evidence from sound clinical trials (White and Ernst, 1999).

There are two kinds of response by acupuncture. One is local and another is to enhance the homeostasis of the body. This response occurs after one or three minutes after stimulation (sometimes ten minutes). Kazushi Nishijo in 2001 ⁽¹⁾investigated the relation between the stimulation at hand to enhance homeostasis and the irradiation at local points by a laser. He stimulated at one point of right back of the body and checked the reaction at left side of the body. He made two kinds of test in a double blind trial.

Case1: Firstly, he made a stimulation to enhance the homeostasis and secondly made a local stimulation.

Case2: Firstly, he made a local stimulation and secondly made a stimulation to enhance the homeostasis.

There were no differences immediately after the treatment. However a difference appeared after one minute, evidently differed after three minutes. It is clearly more efficient to make a local stimulation first and then make a stimulation to enhance the homeostasis. This response to enhance the homeostasis is one of most typical effects of traditional acupuncture treatment and he could confirm that 1mW laser has the same ability as the old method.He also stated that this effect can never be realized by high power laser irradiation (Nishijo, 2001).

(VII) LASERS IN TISSUE REGENERATION

Effects of Low-Level Laser Irradiation on Wound Healing

Results from the earlier, largely uncontrolled studies indicated that low-level laser light may promote better wound healing in humans. For example, Mester and associates (1973) found that wound healing appeared to be accelerated in six patients with skin ulcers treated with an He-Ne laser. Electron micrographs of tissue from the wound sites showed that the stimulation of healing was possibly primarily due to the activation of collagen production. Subsequently, other studies have pointed to normalization of the humoral immune responses, as measured by serum complement activity and immunoglobulin levels, as the mechanisms responsible for the improved healing; this suggests that laser modulation of immune mechanisms may also play a role in enhancing healing (Mester et al., 1976 & 1978). It should be noted, however that the cases studied represented a broad spectrum of leg ulcers of varying causes and in general studies consisting of such relatively small numbers of cases are difficult to control. It should also be noted that nonirradiated areas of the ulcers showed changes identical to, although less marked than, those seen in the irradiated area (Mester et al., 1973). These observations indicate either that the ulcers healed spontaneously even in areas not subjected to direct laser irradiation or that the laser irradiation had systemic effects affecting sites not directly exposed to laser irradiation (Bosatra et al., 1984).

In 1998, Webb et al. conducted some experiments to assess the stimulatory effect of 660-nm low level laser energy on hypertrophic derived fibroblasts and the possible mechanisms for increase in cell counts. The experiments investigated the effect of a 660 nm, 17 mW laser diode at dosages of 2.4 J/cm² and 4 J/cm² on cell counts of two human fibroblast cell lines, derived from hypertrophic scar tissue and normal dermal tissue explants. Estimation of fibroblasts utilized the methylene blue bioassay. For a result, post-660 nm-irradiated hypertrophic scar fibroblasts had very significantly higher cell counts than controls (Webb et al., 1998).

Also, in 1998, Lowe et al. mentioned that the use of low level laser and monochromatic light diodes as a therapeutic modality has become popular in a variety of clinical applications, including the promotion of wound repair. But, they also mentioned that despite this, the clinical evidence base for such application remains sparse; in contrast, recent studies have demonstrated a number of quantifiable photobiological effects associated with such therapy. In their present study, the effect of low level monochromatic light irradiation (MLI) at various radiant exposures upon a radiation-impaired wound model in murine skin was investigated. Male Balb/c mice (n = 50; age matched at 10 weeks) were randomly allocated to five experimental groups (n = 10 each group). In Group 1, mice were left untreated; in Groups 2-5, a well-defined area on the dorsum was exposed to 20 Gy X-ray irradiation. At 72 hours postirradiation, all mice were anaesthetized and a 7-mm-square area wound was made on the dorsum. All wounds were videotaped alongside a marker scale until closure was complete. In Groups 3-5, mice were treated with MLI (0.18, 0.54, and 1.45 J/cm², respectively) three times weekly using a GaAlAs 890 nm multidiode (n = 60) array unit (270 Hz; maximum rated output, 300 mW; Anodyne, Denver, CO). Subsequently, the area of each wound was measured from video using an image analysis system (Fenestra 2.1), and results were analyzed using repeated measure and one-factor ANOVA statistical tests. As a result, the X-ray irradiation caused a significant delay (P = 0.0122) in healing by day 7. MLI at 0.18 J/cm² and 0.54 J/cm² had no effect upon the rate of wound closure. However, a highly significant (P = 0.0001) inhibition occurred following MLI irradiation at 1.45 J/cm² by day 16. These findings provided little evidence of the putative stimulatory effects of monochromatic light irradiation in vivo, but, rather, revealed the potential for an inhibitory effect at higher radiant exposures (Lowe et al., 1998).

And to evaluate the efficacy of low-level laser irradiation for the induction of wound healing of a diabetic neuropathic foot ulcer, Andreas Schindl et al. (1999) reported a case of a man with insulin-dependent diabetes mellitus, sensory neuropathy, macroangiopathy and microangiopathy, who had been suffering from an ulcer of his first left toe accompanied by osteomyelitis for 6 weeks. After a total of 16 sessions of low-level laser therapy using a 670-nm diode laser administered within a 4-week period, the ulcer healed completely! During a follow-up period of 9 months, there was no recurrence of the ulcer even though the patient's metabolic condition remained unstable. Although laser therapy was not applied as a monotherapy, the present observation suggests that it might constitute a useful side-effect-free alternative treatment modality for the induction of wound healing of neuropathic ulcers in diabetic patients (Schindl, A et al., 1999).

In addition, Schindl, M. et al. (1999), explained in an article published in the same year that chronic skin ulcers still represent a therapeutic challenge in dermatology. Among the various non-invasive treatment modalities used for the improvement of impaired wound healing, low-level laser irradiations are gaining an increasing body of interest. In another study, they used low-level laser irradiations delivered by a 30 mW helium-neon laser at an energy density of 30 J/cm² three times weekly for the induction of wound healing in ulcers of diverse causes. In the present study, twenty patients with the same number of ulcers, which had previously been treated by conventional wound care for a median period of 34 weeks (range: 3-120 weeks) without any significant evidence of healing, were included. Concerning the underlying disorders, patients were divided into four groups: diabetes, arterial insufficiency, radio damage and autoimmune vasculitis. In all ulcers, complete epithelization could be induced by laser therapy. No amputation or any other surgical intervention was necessary and no adverse effects of any kind were noted during low-level laser treatment. Regarding the different diagnoses, a statistically significant difference was noted (P = 0.008): ulcers due to radio damage healed significantly faster than those caused by diabetes (6 weeks [range: 3-10 weeks] vs. 16 weeks [range: 9-45 weeks], P = 0.005). Wound healing in autoimmune vasculitis (24 weeks [range: 20-35 weeks]) required longer than in radiodermatitis, although the difference was not significant. In addition to the diagnosis, wound size was found to be an important factor influencing the duration of wound closure (P = 0.028), whereas duration of previous conventional treatment (P = 0.24) and depth (P = 0.14) showed no effect. Obviously, their results indicate that low-level laser irradiation could be a valuable non-invasive tool for the induction of wound healing in recalcitrant ulcers, and that healing time is correlated with the ulcer cause and size (Schindl, M. et al., 1999).

And to top this, a wound healing study by Simunovic et al. in 2000 on rabbits suggested that 4 J/cm² was the optimal dose. A clinical study was performed on 74 patients suffering from injuries of soft tissue upon traffic accidents and sport activities. Two types of lasers were used: 830 nm for Trigger point treatment and a combined 633/904 for scanning, both applied in monotherapy. Clinical parameters studied were redness, heat, pain, swelling, itching and loss of function. Wound healing was accelerated 25-35% in the laser group compared to the control group. Pain relief and functional recovery was significantly improved in the laser group as well (Simunovic et al., 2000).

Effects of Low-Level Lasers on Epidermal Wound Healing

An essential component of cutaneous wound healing is the regeneration of the epidermis, particularly in pigs and humans, in whom wounds do not contract to the same extent as rodent wounds do. However, only a few studies have carefully examined the rate of the epidermal healing in laser treated wounds. An early study conducted by Braverman and colleagues (1989) showed that the relative epidermal thickness was somewhat enhanced in the He-Ne laser treated areas, as compared with the epidermal thickness of unexposed tissue, but the difference was not statistically significant. Nevertheless, this study showed that low-level lasers might have effects on epidermal components. However, the comparison between the treated and untreated wounds was performed in the same animal, making it possible for systemic effects to also have been responsible for increasing the epidermal growth on the untreated contralateral wounds, and thus obscuring the true magnitude of the laser effect (Braverman et al., 1989).

Effects of Low-Level Lasers on Cell Proliferation

Several studies have examined the effects of low-level laser irradiation on the growth and replication of a variety of cell types (Mester et al., 1971; Kovacs et al., 1974; Mester et al., 1974; Namenyi et al., 1975; Abergel et al., 1984; Bard and Elsdale, 1986; Lam et al., 1986; Ohta et al., 1987; Hallman et al., 1988; Marchesini et al., 1989; Young et al., 1989; Pourreau-Schneider et al., 1989; Noble et al., 1992 and van Breugel et al., 1992). These studies are important because the proliferation of fibroblasts or other cell types may play a major role in the reparative processes, such as wound healing, that could be accelerated by laser irradiation. Most of the studies reported on so far have shown that low-level lasers may affect the rate of proliferation of the cells in vitro. However, there are criticaldifferences in terms of the response to different lasers and the magnitude of the effect produced. For example, Ga-As laser irradiation was noted in one study to suppress DNA replication in human skin fibroblast cultures (Lam et al., 1986 and Abergel et al., 1984). The DNA replication, measured by radioactive thymidine incorporation, was found to be already inhibited by approximately 80% after exposures in 1 day to ~0.3 J/cm² (Lam et al., 1986).

Immune Modulation of Cells by Low-Level Lasers

Some of the studies of wound healing have shown that various aspects of humoral immunity may be altered in laser-treated animals. This has been indicated by the systemic effect seen in studies in which contralateral wounds were used as controls. Some earlier studies also showed that complement and immunoglobulin levels might be normalized in the serum of patients with leg ulcers treated by low-level laser irradiation (Mester et al., 1976 & 1978). This has been further borne out by the finding that the serum lipid peroxidase levels were normalized in mice with burn wounds treated by the He-Ne laser (Zhang et al., 1992).

Effects of Low-Level Lasers on Other Regenerative Processes

Neural Regeneration

Several other facets of tissue regeneration have been examined in the context of low-level laser irradiation (Rochkind et al., 1989 and Belkin and Schwartz, 1989). One of these is the recovery of injuries in the peripheral and central nervous system. One study (Rochkind et al., 1989) examined the effects of He-Ne laser radiation on injured sciatic nerves as well as on bilaterally inflicted crush injuries and revealed that healing appeared to be far more accelerated in the laser-treated group than in control, nonirradiated group. A systemic effect was also found in the spinal cord segments corresponding to the crushed sciatic nerves. The findings from these studies indicated that bilateral retrograde degeneration of the motor neurons of the spinal cord, which is expected after bilateral crush injury of peripheral nerves, is greatly reduced in patients who undergo laser treatment (Arndt et al., 1997).

Angiogenesis

Two studies involving the use of a rabbit ear chamber model, which allows the growth of blood vessel in response to laser irradiation to be directly observed, have shown that He-Ne laser irradiation may cause an increase in neovascularization during wound healing. However, the precise mechanisms of neovascularization and the effects of laser energy on vascular endothelial and smooth muscle cells have not been studied in further detail (Kovacs et al., 1974: 3 references).

(VIII) treatment with low level laser

Wavelength, Output and dosage of Low Level Lasers in physical medicine

The effect of Low Level Laser is photochemical (like photosynthesis in plants). Red light aids the production of ATP thereby providing the cell with more energy which in turn means the cell is in optimum condition to play its part in a natural healing process. Shorter wavelengths (600nm-700nm) are absorbed within a couple of mm by hemoglobin, longer wavelengths (1,000nm + )are absorbed by fat and water (Alternative Medicine, 2001).

The main indications of LLLT in Physical Medicine are:

JOINT CONDITIONS

PAIN

NON HEALING WOUNDS AND ULCERS

ACUPUNCTURE

LLLT devices are typically delivering 2 mW - 200 mW (0.2 -> 0.02 Watts). The power density typically ranges from 0.05W/Cm² → 5 W/Cm². Gas lasers (such as helium neon) for this therapy is not so popular a semi-conductor lasers. Helium Neon (HeNe) works quite well but has many disadvantages when compared to the modern semi-conductor GaAlAs diode type systems. Helium neon lacks power, is large, wears out, fragile, requires high voltage, and is quite expensive. Semi conductor types (as GaAs 904 nm, GaAlAs 780-820-870 nm and InGaAlP 630-685 nm) are quite the opposite in all he above cases. HeNe laser with a power output of 3.5 mW has a greatest active depth of 6-8 mm depending on the type of tissue involved. A HeNe laser with an output of 7 mW has a greatest active depth of 8-10 mm. A GaAlAs probe of some strength has a penetration of 3.5 cm with a 5.5 cm lateral spread. A GaAs laser has a greatest active depth of between 20 and 30 mm (sometimes down to 40-50 mm), depending on its peak pulse output (around a thousand times greater than its average power output). If you are working in direct contact with the skin, and press the probe against the skin, then the greatest active depth will be achieved

Power: Power is expressed in watts (W); however LLLT device outputs are so low the tend to be expressed in milli-watts (mW). Powers for constant lasers and Average Powers for pulse lasers are typically 3 -100 mW. More power means shorter treatment times

Power density: Power Density (Pd) expressed in W/Cm² or mW/Cm². This is an essential parameter. Pd (W/Cm²) = Total power (W or mW) / Size of beam (Cm²). Power density, indicating the degree of concentration of the power output, has also increasingly proved to play a major role. It is measured in watts per square centimetre (W/cm²). Some studies have concluded that the power density may be of even greater significance than the dose.

Dose: The most important parameter in LLLT is always the dose. By dose (D) is meant the energy (E) of the light directed during a given session of therapy. The energy is measured in J (joules). The dose of 1 J = 1 Watt of irradiation during 1 Sec. Dose ( J ) = Average Power (Watt or mWx1000) of the laser device X Time of irradiation (Sec). In other trials by dose (D) is meant the energy (E) of the light directed at a given unit of area (A) during a given session of therapy. The energy is measured in J (joules), the area in cm², and, consequently, the dose in J/cm². Assuming that the power (P) output of the laser probe remains constant during treatment, the energy (E) of the light will be equal to the power multiplied by the time (t) during which the light is emitted. Sometimes, however, the power output is not constant, such as when the laser is pulsed or modulated. This enables distinguish average power and maximum power. In these lasers the maximum power is always greater than the average power. If the laser output is not constant and Average power is not indicated by supplier, to calculate the average power needed this equation is used: Average Power (mW) = Maximum power (mW) X [Duration of impulse / 1 sec] X [Frequency of impulses] (Alternative Medicine, 2001).

For the light source of low level laser therapy, usually the wavelength of around 800nm is adopted because of its highest permeability to the body, which is brought about by the least absorption by water and haemoglobins. It is already confirmed by researchers that the laser light of 10~100mW can penetrate 30~50mm inside of human bodies. When the nature of 630nm red laser and 780~830nm infrared laser is compared, the infrared laser is said to be more effective for the removal of pain, which is brought about by its high penetration to human bodies. On the other hand, the red laser is said to be more effective for the healing of wounds and ulcers, which is brought about by its high absorption by skins. Clinically, they are utilized in different applications. The relation between the wavelength of laser and its efficacy is not yet clarified and remains as one of the most important themes for research in future together with the clarification of receptors which absorb photons. However, we should be careful about the selection of output, because there is no direct relation between the output of the equipment and its efficacy. Especially in case of Oriental medicine, the strong stimulation is said to act as "discharge" and could worsen the illness of a patient who is in the condition of "void" (Japan Society of Laser Medicine, 2001).

Kinds and Uses of Low Level Lasers in Physical Medicine

The main types of laser on the market are Infrared, HeNe (now being gradually replaced by the InGaAlP laser), GaAs anGaAlAs. They can be installed in separate instruments or combined in the same instrument (Swedish Laser Medical Society, 2001).

* The Infrared Laser: Infra-red energy is absorbed in the cell membrane, where it induces a photophysical reaction which directly mediates the membrane potential, resulting in the intra and extra cellular transport of photoproducts. The ultimate photoresponse is cellular proliferation. The cellular mechanisms are immediate, and are followed by secondary local reactions as the photoproducts interact with surrounding cells and tissue, producing such documented effects as enhanced blood and lymphatic flow, and photomediated neural reponses. The local reactions are followed by systemic effects as the photoproducts are carried by the blood and lymphatic systems around the body, and the photomediated neuroresponses take effect. The 904 nanometer wavelength of the Infrared models is especially effective in the treatment of:

1. Slow healing skin wounds

2. Fibrous lesions

3. Sprained and strained ligaments

4. Tendon injuries

5. Muscle soreness (RianCorp Pty Ltd, 2001).

* The HeNe laser or InGaAlP laser is used a great deal in dentistry in particular, as it was the first laser available. The HeNe laser has now been used for wound healing for more than 30 years. One advantage is the documented beneficial effect on mucous membrane and skin (the types of problem it is best suited to), and the absence of risk of injury to the eyes. An optimal dosage when using a HeNe laser for wound healing is 0.5-1.0 J/cm² around the edge of the wound and approximately 0.2 J/cm² in the open wound. HeNe lasers are used to treat skin wounds, wounds to mucous membrane, herpes simplex, herpes zoster (shingles), gingivitis, pains in skin and mucous membrane, conjunctivitis, neuralgia, etc. It should be noted that HeNe fibers couldn’t be sterilized in an autoclave. The alternative is to use alcohol to clean the tip, or to cover it with cling-film or a thermometer sleeve. HeNe lasers cost somewhere between US $3,000 and $4,000, depending on their power output and the quality of their fibers. InGaAlP lasers of the same power cost usually about half as much and can be had with considerably higher output.

* The GaAs laser is excellent for the treatment of pain and inflammations (even deep-lying ones), and is less suited to the treatment of wounds and mucous membrane. Prices are usually between US $3,000 and $6,000 for output power between 4 and 20 mW. A GaAs laser needs an integral output meter that shows that there is a beam and its strength in milliWatts - this is necessary because the light this type of laser emits is invisible. Protective glasses for the patient may be appropriate in view of the invisible nature of the light. In older systems the power output of conventional apparatus follows pulsation. This means that a GaAs laser with an average output of 10 mW when pulsing at 10,000 Hz only produces 1 mW when pulsed at 1,000 Hz, and at 100 Hz only 0.1 mW. If we, therefore, want to administer treatment at low frequencies around e.g. 20 Hz (for the treatment of pain), the output power is, clinically speaking, unusable. However, there are GaAs lasers with "Power Pulse", which means that the power output is held constant at all pulse frequencies. This would be of interest to a physiotherapist, for example, when one considers that the GaAs laser has the deepest penetration of the common therapeutic lasers. Large doses can be administered to deep-lying tissue over a short period of time. A GaAs multiprobe can also shorten treatment times for conditions involving larger areas (neck/shoulders). The GaAs laser is, like GaAlAs and InGaAlP lasers, a semiconductor laser. A purely practical advantage of this type of laser is that the laser diode is located in the hand-held probe. This means that there is no sensitive fiber-optic light conductor, which runs from the laser apparatus to the probe, but just a normal, cheap, robust electric cable. Optimum treatment dosages with GaAs lasers are lower than with HeNe lasers. The GaAs laser is most effective in the treatment of pain, inflammations and functional disorders in muscles, tendons and joints (e.g. epicondylitis, tendinitis and myofascial pain, gonarthrosis, etc.), and for deep-lying disorders in general. As mentioned above, GaAs is not thought to be as effective on wounds and other superficial problems as the HeNe laser (InGaAlP laser) and GaAlAs laser. GaAs can, nevertheless, be used successfully on wounds in combination with HeNe or InGaAlP, but the dosages should be very low - under 0.1 J/cm².

* The GaAlAs laser has become increasingly popular during the 1990s. As it is very easy to run electrically, small rechargeable lasers have been put on the market, which are not much larger than an electrical toothbrush. (They can run on normal or rechargeable batteries.). 20-30 mW laser diodes are now relatively cheap and the GaAlAs laser gives "a lot of milliWatts for the money". Recently, GaAlAs lasers have appeared on the market with an impressive output of over 400 mW. Many GaAlAs lasers have well-designed, exchangeable, Sterilizable intraoral probes. Output meters are essential because the light from this type of laser is largely invisible. The price tag for a GaAlAs laser of around 30 mW can be between US $3,000 and $4,000, excluding value added tax. Price differences depend on factors such as output, ergonomics, and standard of hygiene, to name but a few. GaAlAs lasers of 300-500 mW are in the range $4,000-$6,000.

*Therapeutic laser treatment with carbon dioxide lasers has become more and more popular. This does not require instruments expressly designed for that purpose. Practically any carbon dioxide laser can be used as long as the beam can be spread out over an appropriate area, and that the power can be regulated to avoid burning. This can always be achieved with an additional lens of germanium or zinc selenide, if it cannot be done with the standard accessories accompanying the apparatus. There are small, portable CO2 lasers on the market today - even battery-driven ones - producing up to 15 watts, which is more than enough power output! Prices in the range of $10,000-$25,000. It is interesting to note that the CO2 wavelength cannot penetrate tissue but for a fraction of a mm (unless focused to burn). Still, it does have biostimulative properties. So the effect most likely depends on transmitter substances from superficial blood vessels. Conventional LLLT wavelengths combine this effect with "direct hits” in the deeper lying affected tissue (Swedish Laser Medical Society Website, 2001)..

Following is a simple scheme of the uses of laser in the field of physical medicine with the recommended methods of treatment. This scheme has been excerpted according to the best systems used in laser clinics in USA, Canada and Russia

IN RHEUMATOLOGY

INDICATIONS:

Arthrosis.

Arthritis.

Osteochondrosis of the spinal column.

Arthralgia.

CONTRA-INDICATION:

Cancer.

Blood diseases.

EFFECTS:

Anti-inflammatory

Analgesic

Immunomodulation

Regenerative

Improves microcirculation

ADVANTAGES OF LASER THERAPY:

Relieves pain quickly

Increases joints flexibility

Prolongs anti-inflammatory effect

Reduces drug intake

EXAMINATION REQUIRED:

CBC..

Blood test (Total protein, C-reactive protein).

X-ray of joints (in specific cases).

COURSE OF TREATMENT:

Combination of traditional medication with laser therapy.

Intra-venous laser treatment (6 - 8 sessions).

External laser treatment (10-14 sessions).

Laser acupuncture (10-14 sessions).

The course should be repeated every four (4) to six (6) months.

IN NEUROLOGY

INDICATIONS:

Neuritis.

Neuralgia.

Radiculitis.

Osteochondrosis of the spinal column.

Decreased blood circulation in the brain.

Post stroke conditions.

CONTRA-INDICATION:

Cancer in the brain.

Blood diseases.

Decompensated conditions.

Three (3) months after stroke

EFFECTS:

Anti-inflammatory.

Analgesic.

Immunomodulation.

Improves microcirculation.

ADVANTAGES OF LASER THERAPY:

Relieves pain quickly.

Accelerates rehabilitation.

Prolongs anti-inflammatory effect.

Improves quality of life.

Improves workability and rest.

Decrdrug intake.

EXAMINATION REQUIRED:

CBC, Blood test.

X-ray (in specific cases).

COURSE OF TREATMENT:

Combination of traditional medication with laser therapy.

Intra-venous laser treatment (6 - 8 sessions).

External laser treatment (10-14 sessions).

Laser acupuncture (10-14 sessions).

The course should be repeated every four (4) to six (6) months

IN SPORTS TRAUMAS

INDICATIONS:

Arthrosis, arthritis, arthralgia.

Sprained joints and muscles.

Contusions and dislocations.

Pain syndromes.

Meniscus.

Tennis elbow.

Golf shoulder.

Tendovaginitis.

Myositis.

EFFECTS:

Anti-inflammatory.

Analgesic.

Regenerative.

Increases blood oxygenation.

ADVANTAGES OF LASER THERAPY:

Accelerates rehabilitation.

Relieves pain quickly.

Increases physical and psychological stability.

Increases tolerance to physical exercise.

Conducive to drug free sports results.

Undetectable stimulating effect.

EXAMINATION REQUIRED:

CBC.

X-ray (in specific cases).

COURSE OF TREATMENT:

Combination of traditional medication with laser therapy.

Intra-venous laser treatment (5 - 7 sessions).

External laser treatment (5-10 sessions).

Laser acupuncture (7-12 sessions)

Repeated course on the eve of the tournament.

LASER IN ACUPUNCTURE

Laser acupuncture is stimulation of the acupuncture points and zones. Laser acupuncture is applied to the same zone and points as traditional acupuncture. The usage of lasers for acupuncture is (Alternative Medicine, 2001):

Red (0,63-0,68 nM)	Infrared (>0,74 nM)
56%	44%

LASER ACUPUNCTURE APPLICATIONS:

Internal diseases.

Neurology.

Surgery, traumatology, orthopedics.

Skin diseases.

Pediatrics.

Gynecology.

Dentistry.

EFFECTS:

Anti-inflammatory, analgesic

Immunomodulation

Regenerative

Improves microcirculation

Increases blood oxygenation

Improves quality of life

ADVANTAGES OF LASER THERAPY:

Quick pain relief

Free from side effects

Not harmful to the skin, sterile

Perfectly combines with traditional acupuncture

Increases the effect of other forms of treatment

No contra-indications

(LA has a deeper penetration ability up to 5-7 cm compared to traditional acupuncture).

EXAMINATIONS REQUIRED:

CBC, blood test (in specific cases).

X-ray (in specific cases).

COURSE OF TREATMENT:

Combination of laser acupuncture with external laser therapy (8-12 sessions).

For greater effect should be repeated 2-3 times in two weeks period.

Time of laser application at one point:

On the body 10-30 sec. Total time 3-4 minutes.

On the ear 5 -10 sec. Total time 1 minute.

One laser session 10-12 points.

The usage of average power for acupuncture:

1-3 mW	3-10 mW	10-30 mW	>30 mW
9%	44%	26,5%	20,5%

The usage of power density for acupuncture:

25-75 mW/cM^2	75-300 mW/cM^2	300-1000 mW/cM^2	>1000 mW/cM^2
9%	45%	27%	19%

The usage of dose for acupuncture:

0,1-0,5 J	0,5-1 J	1-3 J	>3 J
20%	27%	28%	25%

SIDE EFFECTS OF LASER THERAPY⁽¹⁾

Can therapeutic lasers damage the eye?

The following factors are of importance regarding the eye risk of different lasers:

1. The divergence of the light beam. A parallel light beam with a small diameter is by far the most dangerous type of beam. It can enter the pupil, in its entirety, and be focused by the eye's lens to a spot with a diameter of hundredths of a millimeter. The entire light output is concentrated on this small area. With a 10 mW beam, the power density can be up to 12,000 W/cm²

2. The output power (strength) of the laser. It is fairly obvious that a powerful laser (many watts) is more hazardous to stare into than a weak laser.

3. The wavelength of the light. Within the visible wavelength range, we respond to strong light with a quick blinking reflex. This reduces the exposure time and thereby the light energy which enters the eye. Light sources, which emit invisible radiation, whether an infrared laser or an infrared diode, always entail a higher risk than the equivalent source of visible light. Radiation at wavelengths over 1400 nm is absorbed by the eye's lens and is thus rendered safe, provided the power of the beam is not too high. Radiation at wavelengths over 3,000 nm is absorbed by the cornea and is less dangerous.

4. The distribution of the light source. If the light source is concentrated, which is often the case in the context of lasers, an image of the source is projected on the retina as a point, provided it lies within our accommodation range, i.e. the area in which we can see clearly. A widely spread light source is projected onto the retina in a correspondingly wide image, in which the light is spread over a larger area, i.e. with a lower power density as a consequence. For example: a clear light bulb (which is apprehended as a more concentrated light source) penetrates the eye more than a so-called "pearl" light bulb. A laser system with several light sources placed separately, such as a multiprobe (the probe is the part of the laser we hold and apply to the area to be treated: a single probe means there is only one laser diode in the probe, as opposed to a multiprobe, which has several laser diodes) with several laser diodes, can, seen as a whole, be very powerful but at the same time constitute a smaller hazard to the eye than if the entire power output was from one laser diode, because the diodes' separate placement means that they are reproduced in different places on the retina.⁽¹⁾

* A GaAlAs laser with a wavelength of 830 nm, an output of 1 mW and a well collimated beam (1 mrad divergence) is classified as laser class 3B⁽²⁾ as it is judged to be hazardous to the eye. The reason for this is partly the collimated beam, and partly the wavelength, which is just outside the visible range and hence provokes no blink reflex in strong light.

* A HeNe laser with a wavelength of 633 nm, an output of 10 mW and divergent beams (1 rad divergence, which corresponds to a cone of light with a top angle of about 57°) is classified as laser class 3A⁽³⁾ because, owing to its divergence, it cannot damage the eye.

With the recent advent of "high power low level lasers", i.e. GaAlAs lasers in the range 100-500 mW there is another story. These lasers are indeed dangerous for the eye and should only be used by qualified persons and with proper protective measures taken. Thus, the use of protective eyeglasses for the therapist is advisable only if he is subjected to significantly prolonged exposure. Also, it is not advisable to carry out prolonged applications near important glandular organs, especially the thyroid and some plexuses as the carotid and the celiac plexuses (Leung et al, 1983). There is also a slight problem with accumulation of static electric charge by the therapist with the handheld unit. However, this is more easily dissipated by wearing of the operators non-insulating footwear and washing their hand by the end of each treatment.

Can LLLT cause cancer?

The answer is no. No mutational effects have been observed resulting from light with wavelengths in the red or infrared range and of doses used within LLLT. Then what happens if we treat someone who has cancer and is unaware of it? Can the cancer's growth be stimulated? The effects of LLLT on cancer cells in vitro have been studied, and it was observed that they could be stimulated by laser light. However, with respect to a cancer in vivo, the situation is rather different. Experiments on rats have shown that small tumors treated with LLLT can recede and completely disappear, although laser treatment had no effect on tumors over a certain size. It is probably the local immune system, which is stimulated more than the tumor.

The situation is the same for bacteria and virus in culture. These are stimulated by laser light in certain doses, while a bacterial or viral infection is cured much quicker after the right treatment with LLLT.

What happens if we use a too high dose?

We will have a biosuppressive effect. That means that, for instance, the healing of a wound will take longer time than normally. Very high doses on healthy tissues will not damage them. There have been some clinical reports and cell study reports that have shown that you can overtreat using laser therapy. In these instances the healing will be regressed, not aided. Sometimes patients feel lightheaded, or have an increase in pain. This outcome is reversible. Some patients are more sensitive than others, it is better to start with a lower treatment dosage in the first instance. The device handbook should provide treatment guidelines for specific conditions (RianCorp Pty Ltd, 2001).

Does LLLT cause a heating of the tissue?

Due to increased circulation there is usually an increase of 0.5-1 centigrade locally. The biological effects have nothing to do with heat. GaAlAs lasers in the 300-400 mW range may cause a noticeable heat sensation, particularly in hairy areas (Swedish Laser Medical Society Website, 2001).

CONTRA-INDICATIONS OF LASER THERAPY

We should not treat cancer, for legal reasons. Pregnancy is not a contra indication, if used with common sense. Pace makers are electronical, do not respond to light but certain care should be taken since the electronic circuits of the laser system may interfere with the operation of the pacemaker (Karu and Letokhov, 1981). In general, the most valid contra indication is lack of medical training. However, sometimes certain patients are advised not to be treated with laser; among them are the epileptics and cardiac (Bolognani et al, 1985) and (Foster & Palastagna, 1988). In skin infections, when treated in contact, the treatment head (probe) must be sterilized with a suitable solution after placing on infected skin.

Also, particular care should be taken in the following cases:

*Patients with left ventricular insufficiency under treatment for poor peripheral circulation, since laser treatment may produce a dangerous overload on the central venous system (De Min et al., 1985).

*Patients with recent heart attacks (Zhong & Wang, 1983).

*The abdominal area of pregnant women due to the possibility of undesired effects on the fetus.

The following should never be irradiated:

*The eyes due to the possibility of retinal or conjunctival problems (Leung et al., 1983).

*The thyroid glands due to the possibility of increased hormone secretion (Mester, 1985).

*The male external genitalia due to the possibility of interaction with the cells of the germinal line or the endocrine portion of the testes (Jayasurya, 1984).

*The cutaneous or subcutaneous bacterial infections, although there is a lack of any scientific proof of positive interaction between such bacteria and laser beam (Bassleer et al., 1985).

*The growth cartilage in children due to the possibility of stimulation though such hypothesis has not yet been well documented in a scientific research (Walker, 1983; Gallico et al., 1984 and Dyson & Young, 1985).

(IX) SUMMARY AND CONCLUSION

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 owner’s 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 1960’s. 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 patient’s 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 21^st century, we shall see to where the laser beam can reach.

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110.Moore, Kevin C.; Naru Hira; Parswanath S. Kramer, Copparam S. Jayakumar and Toshio Ohshiro (2000): “Double blind crossover trial of Low Level Laser Therapy in the treatment of post herpetic neuralgia.” Laser Therapy; © 2000 by John Wiley & Sons, Ltd.

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THE ARABIC SUMMARY