Clinical Pain Abstracts:
LASER THERAPY IN POST
Abstract from the MALC conference Nov 96
Dr KEVIN C MOORE THE ROYAL OLDHAM HOSPITAL, OLDHAM,
Presented to the British Medical Laser Association "241"
Workshop and AGM
The Royal London Hospital
LASERS AND PAIN TREATMENT
K.MOORE Department of Anaesthesia,
The Royal Oldham
Hospital, Oldham, OL1 2JH, UK.
The clinical application of low incident power density
laser radiation for the treatment of acute and chronic pain
is now a well established procedure. This paper reviews the
currently available English speaking literature and
summarises a selection of serious scientific papers which
report a beneficial effect following the treatment of a wide
variety of acute and chronic syndromes whose main presenting
symptom is pain.
The Helium-Neon (HeNe) laser at a wavelength of 632.8nm
has proved very successful in promoting wound healing
particularly in indolent ulcers resistant to conventional
methods of therapy. However its limited depth of penetration
and low power output have rendered it less effective when
treating more deep seated causes of pain. The laser most
frequently used for pain therapy is the Gallium AIuminium
Arsenide (GaAlAs) diode emitting coherent light in the near
infra-red waveband, usually 820-840nm, and with a continuous
wave power output of some 60mW. The optoelectronic rationale
for choosing these parameters has been discussed by Moore
and Calderhead (1).
During the past 15 years experimental research has
greatly added to our knowledge of the response of tissue to
laser irradiation. Figure 1 summarises some 10 years work by
Karu (2) into the cellular response to photon energy.
Additional research at the Tissue Repair Research Unit at
Guy's Hospital, London has detailed the local tissue changes
followinq exposure to laser light. The current concept is
one of a dual response to laser bioactivation.
The immediate or primary effect is a local tissue
response to direct irradiation and comprises vasodilatation
with increased circulatory flow: enhanced lymphatic
drainage; increased neutrophil, macrophage and fibroblast
activity; and an improved metabolic function in depressed or
damaged cells. The delayed or secondary response consists of
a systemic effect caused by circulating photoproducts of
irradiation in the blood and lymphatic systems. Increased
plasma concentrations of certain types of prostaglandins,
enkephalins and endorphins have all been identified and most
probably play a major role in the mechanism of pain
ACUTE PAIN THERAPY
Acute trauma is invariably associated with a degree of
soft tissue injury comprising swelling, haematoma, pain,
reduced mobility and in the lower limbs impaired weight
bearing. Sporting injuries and domestic accidents usually
involve damage to muscles, joint ligaments and tendons.
Examples include a sprained ankle or wrist or a twisted
knee. More extensive soft tissue damage tends to result from
industrial crush injuries or road traffic accidents. In the
absence of bone fracture or other injury demanding priority
treatment laser therapy should be instituted at the earliest
opportunity. Kumar (3) reported a comparative study in 50
patients with inversion injuries of the ankle. He found that
compared to conventional physiotherapy the laser treated
patients showed a more rapid resolution of symptoms and an
earlier return to full weight bearing. Patients were treated
with a GaAlAs diode laser (830nm : 60mW) at 48 hour
intervals on a maximum of 3 occasions. A similar therapeutic
regime has been described for whiplash injuries of the
cervical spine (4). Ben Hatit and Lammens (5) used a
defocussed co2 laser to treat a variety of acute
musculoskeletal problems. The energy density varied between
40-70J/cm2. Patients were treated twice a week for up to 10
sessions. Pain was reduced by 70-90%.
Beneficial effects of laser therapy in acute small joint
inflammation in rheumatoid arthritis has been described by
Asada et al (6). Multiple joint irradiation using a GaAlAs
diode (830nm : 60mW) was applied for 15 seconds to each
point. Pain was reduced by up to 66% together with an
improvement in the measured range of movement (ROM).
In a similar report involving 938 patients with
osteoarticular pain Soriano (7) found pain attenuation of
88% when treating a variety of acute conditions such as
tenosynovitis, lumbago and cervical pain. He used a GaAs
diode (940nm . pulsed 10,000 Hz : average power 40mW) to
treat patients twice weekly for a maximum of 10 sessions.
The energy density delivered was 6-10J/cm2 per irradiated
Laser therapy has also proved helpful in reducing the
severity and duration of postoperative pain. In a
comparative study involving 20 patients undergoing elective
cholecystectomy Moore et al (8) reported a 50% reduction in
the postoperative pain experienced by the laser treated
patients together with a concomitant reduction in analgesie
CHRONIC PAIN SYNDROMES
Chronic painr as the name implies, may last for months or
years. Pain may arise as a result of damage caused by trauma
or surgery or be manifest as a symptom of a systemic disease
process. In later life pain due to musculoskeletal "wear and
tear" is very common. Finally neuralgic pain such as
postherpetic or trigeminal neuralgia can cause prolonged
problems to sufferers. A high percentage of patients
referred for laser therapy will have already shown little or
no response to conventional methods of treatment.
In rheumatoid arthritis (RA) laser therapy can benefit
not only the pain of acute small joint inflammation but also
the more established chronic pain of the disease. Gartner
(9) in an excellent review article on rheumatology
considered some 18 papers published over a 10 year period.
A11 involved double blind trials of therapy with 5 having a
cross-over element. In considering the effect of laser
therapy in chronic rheumatoid and associated musculoskeletal
conditions all bar one of the reports noted a significant
improvement in pain. In his own work Gartner used a 904nm
infra-red laser to treat a variety of tendinopathies with a
better than 80% success rate in relieving pain. He compared
this to a similar rate of pain attenuation using anti
inflammatory drugs (NSAIDs) but noted that whilst laser
therapy was free of side effects some 20% of patients
treated with NSAIDs suffered unacceptable side effects of
medication. Asada and his colleagues (10) in a further study
of some 170 patients with rheumatoid arthritis used similar
laser parameters and treatment protocols to their earlier
reported work. The group achieved pain attenuation of up to
90% and improvement in ROM of up to 56%.
In a report of some 1000 treatments using a GaAlAs diode
laser (830nm : 60mw) for a wide variety of chronic pain
syndromes Moore (11) noted an overall reduction in pain
levels of some 70%. Trelles et al (12) used a similar diode
laser to treat 40 patients with degenerative joint disease
of the knee. They delivered 18J/cm2 to each of 4 points
round the knee twice a week for 8 weeks and reported a
significant pain reduction in 82% with improved joint
mobility. Li (13) used a 25mW combined COa/HeNe laser to
treat 90 patients with cervical spondylosis. Laser therapy
was administered to a variety of acupuncture points for 10
minutes daily for 2 periods each of 10 days with an
intervening rest period of 10 days. 90% of patients showed
symptom improvement with an excellent result in 43%.
Fender and Diffee (14) reported an interesting trial
involving patients suffering with chronic generalised
musculoskeletal pain. They irradiated the stellate ganglion
using a HeNe laser with an lnitial exposure of 6 minutes
(36J/cm2) gradually increasing over 4-6 weeks to a maximum
of 15 minutes (90J/cm2). They postulated a mechanism of
reduced sympathetic irritability causing a stabilisation of
the response loop and a breaking of the pain cycle. In
resistant cases they also treated segmental dermatomes and
site specific trigger points.
Patients suffering from postherpetic neuralgia (PHN) have
shown a good response to laser therapy. In a double blind
cross-over trial Moore et al (15) reported a mean reduction
in pain levels of 74%. Patients were treated with a GaAlAs
diode (830nm : 60mW) with the laser applied in contact mode
to the centre of each 2cm2 grid over the affected area
giving 24-30J/cm2 to each point. Treatment was given twice a
week for 4 weeks. Using an identical treatment protocol but
an extended regime of some 12 weeks Kemmotsu et al (16)
reported an end of treatment pain attenuation of 89%. Otsuka
and colleagues (17) used an 8.5mW HeNe scanner to treat the
acute rash of herpes zoster. Once the skin rash had subsided
treatment was continued using a GaAlAs laser (830nm : 60mW).
Within 1 month pain had been reduced by 76% with a final end
treatment improvement of 97%. The early introduction of
laser therapy produced a rapid resolution of acute herpes
zoster rash and a reduced incidence of PHN.
Laser therapy is effective for a wide variety of acute
and chronic pain syndromes. During the past 7 years the
Laser Therapy journal has featured some 30 papers on the
subject. The preferred laser i8 the GaAlAs diode emitting
light in the near infra-red usually at 830nm. The majority
of reports detail a power output of 60mW continuous wave.
Recently, however, researchers have been assessing the use
of higher output powers in the range of 150 - 300mW. In a
preliminary trial Yamada and Ogawa (18) compared the results
of treating PHN with 60mW and 150mW. They found that using
the higher output power reduced both the frequency and
duration of the treatment sessions and improved the pain
attenuation by some 25%. Ohshiro (19) has devised an
ingenious protocol for a computer controlled double blind
comparative trial which compensates for the placebo effect
of treatment and for patient and therapist bias. In a paper
comparing the therapeutic outcomes in 2 geographically
separate but otherwise identical clinics Shiroto (20)
described how a positive therapist attitude motivated by
enthusiasm and commitment can improve the results of therapy
There remains a need for more scientific studies based on
well constructed double blind comparative trials.
Nevertheless the bulk of published work to date supports the
use of laser therapy for the treatment of pain. In a report
of the cost-effective benefits of using laser therapy to
treat PHN, Moore (21) noted that, compared with conventional
methods of treatment, the laser proved to be not only more
effective but more economical as well. The added advantages
of absence of side effects, non-invasive nature of therapy
and the ease of application ensured good patient acceptance
of the treatment modality.
1. MOORE & CALDERHEAD. The clinical application of
low incident power density 830nm GaAlAs diode laser
radiation in the therapy of chronic intractable pain : a
historical and optoelectronic rationale and clinical review.
Int.Jour Optoelectronics 6 : 503 520 1991
2. KARU. Photobiology of low-power laser therapy. Chur,
Swit2erland. Harwood Academic Publishers 1989.
3. KUMAR et al. A comparative study of low level laser
therapy and conventional physiotherapy for the treatment of
inversion injuries of the ankle. Lasers in Medical Science.
Abstract issue 298. 1988.
4. OHSHIRO. Low-reactive level laser therapy practical
application 103-110, Chichester, UK. John Wiley & Sons
5. BEN HATIT & LAMENS. Laser therapy with 10600
defocussed co2 laser. Laser Therapy 4 : 175-178 1992.
6. ASADA et al. Diode laser therapy for rheumatoid
arthritis : a clinical evaluation of 102 joints treated with
low-reactive level laser therapy (LLLT). Laser Therapy 1 :
7. SORIANO. The analgesic effect of 904nm gallium
arsenide semiconductor low level laser therapy (LLLT) on
osteoarticular pain : a report on 938 irradiated patients.
Laser Therapy 7 : 75-80. 1995.
8. MOORE et al. The effect of infra-red diode laser
irradiation on the duration and severity of postoperative
pain : a double blind trial. Laser Therapy 4 : 145-149.
9. GARTNER. Low-reactive level laser therapy (LLLT) in
rheumatoloqy : A review of the clinical experience in the
author's laboratory. Laser Therapy 4 : 107 115. 1992.
10. ASADA et al. Clinical application of GaAlAs 830nm
diode laser in treatment of rheumatoid arthritis. Laser
Therapy 3 : 77-82. 1991.
11. MOORE. LLLT for the treatment of chronic pain.
Frontiers in Electro-optics (Conference proceedings)
12. TRELLES et al. Infra-red diode laser in low reactive
level laser therapy (LLLT) for knee osteoarthrosis. Laser
Therapy 3 : 149-153. 1991.
13. LI. Laser Therapy for radicular cervical spondylosis.
Laser Therapy 4 151-153. 1992.
14. FENDER & DIFFEE. Physiological response in
chronic pain patients to a new LLLT protocol. Laser Therapy
4 169-173. 1992.
15. MOORE et al. A double blind cross-over trial of low
level laser therapy in the treatment of postherpetic
neuralgia. Laser Therapy (pilot issue) 7-9. 1988.
16. KEMMOTSU et al. Efficacy of low-reactive level laser
therapy for pain attenuation of postherpetic neuralqia.
Laser Therapy 3 : 71-75. 1991.
17. OTSUKA et al. Effects of helium-neon laser therapy on
herpes zoster pain. Laser Therapy 7 : 27-32. 1995.
18. YAMADA & OGAWA. Comparative study of 60mW diode
laser therapy and 150mW diode laser therapy in the treatment
of postherpetic neuralgia. Laser Therapy 7 : 71-74. 1995.
19. OHSHIRO et al. Critical considerations in protocol
design for a double blind trial on pain attenuation by laser
therapy. Laser Therapy 6 : 101-106. 1994.
20. SHIROTO et al. The importance of therapist education
and motivation on diode LLLT efficacy in pain therapy : a
comparative study. Laser Therapy 5 : 175-179. 1993.
21. MOORE. Cost effective benefits of the use of laser
therapy in the treatment of intractable postherpetic
neuralgia. Laser Applications in Medicine and Surqery 61-63
Bologna, Italy. Monduzzi Editore. 1992 .
FIGURE 1. Cellular Response to Laser Irradiation
CELLULAR RESPONSE TO LASER IRRADIATION
PHOTORECEPTORS ON MITOCHONDRIAL CHAINS
ELECTRON TRANSPORT CHAINS
PROTON MOTIVE FORCES
RESPIRATORY CHAIN ACTIVITY
OXIDATION OF NADH POOL
REDOX CHANGES IN MITOCHONDRIA AND CYTOPLASM
CELL MEMBRANE ACTIVITY
MEMBRANE TRANSPORT MECHANISMS
H+ ph Ca++ cAMP
DNA : RNA SYNTHESIS
GROWTH AND PROLIFERATION
LLLT_Clinical pain abstracts
LLLT Wound pictures