Effect of Non-polarized Near-infrared Ray Irradiation on Pressure Pain Threshold, Tactile Perception Threshold and Temporal Summation of Thenar Eminence

Effects of non-polarized near-infrared ray irradiation on pressure pain threshold, tactile perception threshold and temporal summation were examined. The subjects were 10 healthy adults. All subjects were participated in both irradiation and control groups. The irradiation group, non-polarized near-infrared rays were applied to thenar eminence of non-dominant hand. The control group was not irradiated. Pressure pain threshold, tactile perception threshold and temporal summation were measured before and after irradiation. The pressure pain threshold value showed a significant increase after non-polarized near-infrared ray irradiation in the irradiation group, but the tactile perception threshold and visual analogue scale value reflecting the temporal summation did not change in the both groups. It was suggested that non-polarized near-infrared ray irradiation increased the pressure pain threshold. On the other hand, it was considered that non-polarized near-infrared ray irradiation does not affect the tactile perception threshold and the temporal summation.