The mechanism by which laser phototherapy (Low Level Laser Therapy - LLLT) induces analgesia in the treatment of chronic pain is not understood. To investigate a possible role for opioids in this treatment, a double-blind, placebo-controlled study was designed to compare the effect of two dosages (1 J/cm² and 5 J/cm²) of an infrared (IR) laser (820 nm), a visible red laser (670 nm) and a near-monochromatic light emitting device (660 nm, 30 nm bandwidth) on trigger points. Fifty-six consenting subjects with chronic pain conditions exhibiting myofascial trigger points in the neck and upper trunk region underwent six experimental sessions over a two week period. Blood samples were withdrawn before and after treatment on three of six appointments. Plasma was assayed for β-endorphin (radioimmunoassay, RIA) and adrenocorticotropic hormone (ACTH ∼ two-site immunoradiometric assay, IRMA) to assess opioid response. ACTH was shown to have a cumulative response to treatment with 1 J/cm² infrared laser (p < 0.001) and 5 J/cm² red laser (p < 0.05) responding significantly. β-endorphin was noted to be significantly elevated between days one and four (p < 0.05) in subjects who received IR (5 J/cm²) laser. Results indicated that the analgesic response to phototherapy may be mediated through hormonal/opioid mechanisms, and that responses to LLLT are dose and wavelength dependent. A mechanism by which peripheral stimulation using LLLT may elicit activity in the central pathways is proposed.

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The efficiency of infrared (IR) diode low reactive-level laser therapy (LLLT) has been reported in a variety of pain complaints. In order to ascertain if LLLT is particularly effective in a given pain group, 115 informed and consenting patients in two institutions (Toho University and Keio University, Tokyo, same ambient environmental parameters in treatment rooms) were assigned to groups according to the aetiology of their pain condition. Each patient's name was placed against a number, and a randomization computer program selected either real or sham (placebo) irradiation for each number, and thus each patient. The computer directly controlled the laser system appropriately, and stored the information on disc for retrieval after the trial was finished. The computer was located remotely from the treatment room. Neither the patient nor the therapist knew if they were in the real or placebo group: in placebo therapy, only laser emission was absent, the visible and audible emission indicators behaving exactly as in “real” treatment. The laser used was a gallium aluminium arsenide (GaAlAs) diode laser, 60 mW output, 830 nm, continuous wave. The laser was applied in the contact technique, with an incident power density of ≅ 3 W/cm², total exposure time per session of from 5-10 min (energy density ≅ 900 ∼ 1800 J/cm²). There were three groups: the extremity joint pain (35), cervical pain (39) and lumbar pain (41) groups. This gave a total of 115 patients (53 female, 62 male, ages from 18∼82, mean age 49.2 ± 15.3). 82% of those who received real treatment in the total population reported effective pain relief, compared with 42% of those who were assigned to receive sham treatment. Following the trial, the data were analyzed statistically applying the χ² and Fisher’s tests, giving a value of χ² = 21.328 (df=1), with a value for p = ‹ 0.0001 at a level of confidence of less than 1%, a statistically significant difference for the real versus the placebo treatment. There were no statistically significant differences in the results between the individual pain groups in the two sites. No adverse side effects were reported. It was concluded that diode laser therapy, at the parameters used in the trial, was both safe and effective for alleviation of pain in the groups treated.

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The Shiroto Ciinic in Goshogawara has been studying the efficacy of low reactive-level laser therapy (LLLT) in pain attenuation using the 830 nm GaAlAs diode laser since 1984, and the authors and colleagues have presented regular updates in this journal and at various national and international congresses, including the last three ILTA meetings. The current study covers the period from April 1984 to February 1993 (106 months) and details 15,641 cases in 8,844 patients with a follow-up period of over 1 year. The clinic currently uses the Luketron® laser therapy system, researched and developed by the Japan Medical Laser Laboratory and Matsushita Electric Company, and marketed by Mochida Pharmaceutical Company. Laser energy at 60 mW, 830 nm in continuous or switched wave is easily delivered by a hand-held probe used in contact with the target tissue, with usual exposure times per session varying from 5 to 30 seconds, although treatment times of up to 3 minutes may sometimes be used. Our average effective rates are consistently around 84%, but in common with other reports it is noted that the efficacy varies, with some pain entities resistant to LLLT. 3 years ago the principal author (CS) opened an annexe to his main Goshogawara clinic in Nakasato, about 30 minutes away by car. The overall efficacy rate in 1992 with the same LLLT techniques as the main clinic was surprisingly poor, however, at 75%. The therapists' attitude and level of enthusiasm were reviewed and improved by more careful staff education, and after a further year the overall efficacy had risen to 89.7%. In spring of 1993, in the main hospital, a former in-patient ward area was remodelled to provide a new laser therapy facility with an open, spacious and warm environment, and a decor relying on natural wood and greenery in which 6 laser therapists can work to a selection of appropriate back-ground music (BGM). In addition to laser therapy, another 3 types of conventional pain attenuation system are used, thus employing patients’ waiting time to the maximum efficiency. Although LLLT remains the treatment method of choice by a large majority of the patients, a questionnaire completed by over 100 patients 3 months after the remodelling shows that the pleasant environment combined with the use of appropriate conventional methodologies can enhance the efficacy of LLLT, so the psychosomatic aspects of the therapy area must also be taken into account in addition to careful staff training and patient education.

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Thirty-six cases of subclinical mastitis and forty-six cases of various reproductive disorders (persistent corpus luteum [28], quiescent ovary [12], silent heat [5], and pyometra [1]) in dairy cattle were treated with low level laser acupuncture (LLLA) using a GaAlAs semiconductor diode laser (wavelength 830 nm, output 80 mW, contact mode of application). The efficacy of LLLA for subclinical mastitis, measured as a decrease in somatic cell count (SCC) of ≥ 100,000, was 80.6%. SCC decreased significantly from an average of 767,000 before LLLA to an average of 547,000 a month after LLLA (p < 0.005). The efficacy of LLLA for reproductive disorders, measured as the recurrence of heat within 1 month after beginning LLLA, was 80.4% (78.6% for persistent corpus luteum, 75% for quiescent ovary, 100.0% for silent heat and 0.0% for pyometra). The results suggest that low level laser acupuncture can be used as an alternative therapy for subclinical mastitis and reproductive disorders, excluding pyometra, in dairy cattle.

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This experiment was performed to confirm the hypotheses that (a) LLLT had a biostimulative effect on all kinds of cells and that (b) there would be differences in the growth of cells irradiated by different types of pulsed laser. 360 samples were used in this study. The samples were randomly divided into 6 groups according to the pulse type: quasi continuous type (CW), pulse 1 (P1), pulse 7 (P7), pulse 9 (P9), pulse 15 (P15) and sham-irradiated control (Co) groups. Energy fluences of all experimental groups, P1, P7, P9, P15 and CW were 2.12, 2.12, 6.37, 57.32 and 31.85 mJ/cm², respectively. All samples were each irradiated for 1 minute at 0, 12, 25, 36, 48 and 60 hours. Ten samples of each group were sacrificed at 0 and every 12 hours and then the optical density of all samples was measured with a spectrophotometer. Significant differences were seen amongst the groups depending on the pulse type with which they were irradiated. An increase in the number of cells was markedly stimulated with laser irradiation in P7 and P9 groups, and inhibited in CW, P1, and P15 groups, compared with the controls. It is, therefore, suggested that specific laser pulses could be recommended to have a biostimulative effect on specific tissue or cells, while the biostimulative effect is dose dependent.

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The 10th Congress of the ISLSM was held in Bangkok, Thailand from 12-17th November, 1993. Of the 1000 delegates attending some 600 were from the host nation which demonstrated the keen interest that exists in the medical use of Laser in Thailand. For those involved in the application of low power laser energy (otherwise known as LLLT) there were 6 scheduled sessions during which aknowledged experts from around the world presented a wide variety of informative papers which did much to stimulate delegates’ interest and promoted some lively and highly educational discussions both inside and outside the lecture theatres. For obvious reasons, I will limit my report on the meeting mostly to the LLLT sessions, which took place over 3 days.

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