Razi Journal of Medical Sciences

The purpose of this study were to 1) demonstrate the effect of infrared laser radiation on the sensory nerve latency of peripheral nerve, and 2) determine temperature changes in the tissue surrounding of the treated area. Fifty health subjects without an history of right and left upper extremity pathological conditions were divided into two groups: laser (n=30) and placebo (n=20) groups. Six 1 em blocks along 12cm segment of the subject's right and left superficial radial nerve recieved 70 second application of either the infared laser or a placebo. Antidromic sensory nerve conduction study was performed on the superficial nerve of each subject's right and left forearm. The infrared laser radiation was applied at the fixed intensity for six 1 em segments. Latency, amplitude, duration and temperature measurements were recorded before and after the test by EMG and thermometer. We assessed differences between pre test and post test latency, amplitude, duration and temperatuee with t-test for correlated and independent samples. The laser group showed a statistically significant increase in latency that corresponded to a decrease in sensory nerve conduction velocity. This finding provides the information about the mechanism of the reported pain relieving effects of the infrared laser. The irradiated site temperature showed no statistically significant increase in laser group when compared with placebo group.