Peripheral neural system involvement in hypoalgesic effect of electromagnetic millimeter waves

In a series of blind experiments, using the cold water tail-flick test (cTF T) as a quantitative indicator of pain, the hypoalgesic effect of a single exposure of mice to low power electromagnetic millimeter waves (MW) was stu died. The MW exposure characteristics were: frequency = 61.22 GHz; incident power density = 15mW/cm(2); and duration = 15 min. MW treatment was applie d to the glabrous skin of the footpad. Exposure of an intact murine paw to the MW resulted in a statistically significant hypoalgesia as measured in t he cTFT. These mice were able to resist cold noxious stimulation in the cTF T more than two times longer than animals from the sham-exposed group, A un ilateral sciatic nerve transection was used to deafferent the area of expos ure in animals from one of the experimental groups. This surgery, conducted six days before the MW treatment, completely abolished the hypoalgesic eff ect of the exposure to MW,The results obtained support the conclusion that the MW - skin nerve endings interaction is the essential step in the initia tion of biological effects caused by MW. Based on our past and present resu lts we recommend that in order to obtain a maximum therapeutic effect, dens ely innervated skin areas (head, hands) need to be used preferentially for exposure to MW in clinical practice. (C) 2001 Elsevier Science Inc. All rig hts reserved.