Comparison of the effects on wound healing in rats using HeCd, Argon, HeNe and GaAlAs lasers was investigated. Our results showed that the acceleration in healing days was 15, 23, 29, 23 and 20% and the acceleration in size reduction was 32, 42, 50, 42, and 40% with 442 nm, 488-514 nm, 632nm, 780 nm, and 830 nm, respectively at the optimum incident dose of ≈ 20 J/cm², for a wound area of 0.39 cm² in 27-wk old rodents and three times per week treatment schedule. There were significant differences between the control group and the treated rats in each laser group used (p < 05). The results suggested that the HeNe laser at 632 nm was the most effective (6% ∼ 14% higher in healing days and 8% ∼ 18% higher in size reduction) in promoting wound healing amongst all the wavelengths used. The laser tissue penetration (transmission and absorption) were dependent on the laser wavelengths. The effects of wound healing acceleration were not apparently dependent on the laser tissue penetration depth. The wound healing acceleration was in proportion to the absorption spectrum of fibroblasts. There was no detectable temperature rise up to 150 J/cm² dose for an incident power density of up to 31.85 mW/cm².

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We discuss light-induced stimulation of biological activity in terms of crytosolic calcium ion concentration oscillations triggered by visible or infrared irradiation of the cells. In the visible region, endogenous or exogenous photosensitizers lead to the formation of reactive oxygen species (ROS) which stimulate the redox activity of the respiratory chain (RC). However, there is competition between photosensitization and intramolecular electronic-vibrational energy transfer from an endogenous photosensitizer to an enzyme of the RC, bringing this enzyme into an inactive configuration and thereby paralyzing the RC. Moreover, there is competition between stimulation of the redox activity of the RC by the ROS and a slower reaction of the enzymes of the RC with the ROS which again paralyzes the RC. The paralysis of the RC plays a dominant rôle in the case of ROS overproduction between reactivation of the ATPase ion pumps in the cell membranes and inhibition of the enzymes of the RC resulting from vibrational overtone excitation. Vibrational heating leading to similar effects may also be achieved by infrared laser-induced multiphoton excitation. Because of the negative influence of the competing processes, optimal irradiation conditions must be achieved to obtain photobiostimulation.

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The rôle of low reactive-level laser therapy (LLLT) in intensive pain management of postherpetic neuralgia (PHN) was evaluated in 31 patients with PHN. Patients had severe and/or persistent pain, and were admitted to our inpatient clinic for intensive pain management. Patients received two LLLT sessions daily, each for 10- 20 min. Fifteen patients also received either epidural, stellate ganglion or brachial plexus block as needed. Some patients were prescribed antidepressant drugs. Pain relief scores (PS) were obtained weekly using a linear analogue scale (0-10 ) with a score of 10 before treatment. The mean hospital stay was 46 ± 22 days. The PS in most patients decreased to a satisfactory level by the third hospital week. The mean PS at the first, second, third hospital week, and at discharge were 7 ± 2; 5 ± 2; 4 ± 2; and 3 ± 2, respectively. Although there was no patient who had slight pain or was pain free before admission, there were 23 patients in these categories at the final assessment. Our results indicate that LLLT is effective in the reduction of the pain of PHN, and LLLT has an important rôle in the management of PHN in the pain clinic. The efficacy of LLLT sometimes becomes more prominent when sympathetic blocks and/or antidepressants are combined in a timely and appropriate fashion.

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Seventy-one patients with acute cervical pain were randomized in two groups. Group A, 37 patients was irradiated with a pulsed GaAs diode laser, 904 nm, pulse width 200 nsec, pulse frequency 10,000 Hz peak power of 20 W, average power 40 mW, spot size 150 μm² in area (incident power density of approximately 26 W/cm²), and an angle of divergence of 6°. The laser was applied in the point technique with a dose of 4 J/cm² per point in the area of pain. Group B, 34 patients, was treated with sham irradiation with a deactivated laser system. Neither the patients nor the operator knew which group each patient was randomly assigned to. The use of analgesic drugs and physical therapy was excluded in both groups. Pain was evaluated through a linear colour scale. Laser treatment was considered effective when pain relief was more than 60%. The treatment was effective in 94.59% of patients in group A, and 38.24% of group B (P < 0.0019). The pain was relieved completely in 67.56% of patients in group A, and in 17.65% in group B. in patients in whom the response to the treatment was effective, the pain returned in the six months following treatment in 14.28% of group A but in 58.33 % of group B (P < 0.005). No side effects were observed These results suggest that GaAs laser radiation is an efficient and safe treatment for patients with acute cervical pain. Six years have passed since we incorporated the GaAs laser into our therapeutic arsenal and up to date we have irradiated more than two thousand patients with different kinds of pain and pain sites. The aim of this work is to evaluate the real therapeutic effect versus the placebo effect of laser therapy in patients with acute cervical pain in both the immediate effect and the possible latency of the pain relief with LLLT.

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A 59 year-old woman fell accidentally, and sustained bruising to her shoulder and left cheek two years before presenting at our pain clinic. She suffered from episodes of intermittent, sharp pain of the left cheek for three months after the accident, and this was then augmented by a continuous dull pain seven months after the accident. The usual diagnostic cranial examinations revealed no anatomically abnormal findings. As medication with antidepressants did not effectively attenuate the pain, she was referred to our clinic. We suspected that she was suffering from neuropathic pain secondary to her trauma, and we treated her with diode laser low reactive-level laser therapy (LLLT) using a GaAlAs 830 nm continuous wave system with an output power of 150 mW. Because the therapy was not effective, trigger point injection of an anesthetic (bupivacaine) was applied, which suceessfully attenuated the sharp pain, Subsequent combined treatment of conventional stellate ganglion block and antidepressant medication (desipramine) gave her a warm sensation on the pain region following LLLT. Three months after her admission, the intractable pain was successfully attenuated by the combination of diode LLLT and stellate ganglion block. As neuropathic pain is related to various mechanisms of neurotransmission and neuromodulation, a combination of treatment methods is recommended for successful attenuation of this type of intractable and difficult to treat pain.

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In the period of approximately 11 years between 1985 and 1995 64 patients suffering from allergic rhinitis (AR) visited the Department of Anesthesia, Matsuyama Red Cross Hospital for treatment. From these 64 patients, 32 clinical cases were studied for the case history, type and severity of the AR, and the efficacy of stellate ganglion block (SGB, n=20) and laser irradiation over the stellate ganglion (SGL, n=12) was evaluated. Treatment sessions were limited to a maximum of 20 over a maximum treatment period of one month. The lasers used were GaAlAs diode systems (60 mW and 120 mW, irradiation times of 10 min and 7 min, respectively, applied in contact pressure mode to the area over the stellate ganglion). The mean overall efficacy rate, (excellent plus good results) based on the improvement calculated on the pretreatment clinical score, was 60% (12 patients) for the SGB group and 100% (12 patients) for the SGL Group. The mean number of treatment sessions for the SGB Group was 13.9 ± 7.1 sessions and 6.8 ± 2.6 for the SGL group. Thus a better efficacy was obtained in the SGL group in a shorter period with fewer treatment sessions required compared to the SGB group. SGL using the GaAlAs diode laser at the parameters used in the present study was therefore concluded to be effective as a therapy for allergic rhinitis, and offers the additional advantages of being painless and easy to apply, side effect free and well-tolerated by all ages of patient.

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