Abstract
The effect of laser irradiation to alleviate pain was studied by thermography. The following apparatus was used for laser irradiation: GaA1As laser diode: wavelength 780 nm, power density 1.4 × 102 mJ/sec/cm2, continuous wave (SKL-101 Seirin-Kasei Co., Shimizu, Japan); for thermographic studies: Thermotracer (NEC-Sanei Co., Tokyo). One hundred twenty-four patients with pain were included in the study. Laser irradiation was performed for 120–300 seconds one to three times a week for an average of seven to eight times. The site of pain was studied before and after irradiation. Effective pain relief was obtained in 45 of 63 patients (71%) in the group with laser irradiation (group A) and in 8 of 61 patients (13%) in the group without laser irradiation (group B). A statistical difference was found between groups A and B (χ2 test = 42.4, p < 0.01). Thermography was carried out on 20 patients for a total of 92 times. In group A, 16 of 29 thermograms (55%) showed a rise of skin temperature after 1 minute and 8 of 18 (44%) after 5 minutes. Of 20 patients, 15 were measured successively for 5 minutes, of which 7 of 16 (43%) showed a continuous rise of skin temperature. Laser irradiation accelerated microcirculation, which may be due to direct action on the vasomotor nerve.
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