Lack of effect of pulsed low-intensity infrared (820 nm) laser irradiation on nerve conduction in the human superficial radial nerve

BACKGROUND AND OBJECTIVE: To investigate the effect of pulsed low-intensity laser irradiation on nerve conduction in the human superficial radial nerve and on temperature in the skin overlying the nerve. STUDY DESIGN/MATERIALS AND METHODS: Thirty-two healthy human volunteers were recruited and randomly assigned to either placebo, laser 1 (9.12 Hz), laser 2 (73 Hz), or control groups (n = 8 all groups). A GaAlAs laser diode (820 nm, 50 mW peak) was used to irradiate the skin overlying the right superficial radial nerve at three points (1.2 J per point; energy density, 9.55 J/cm(2)). Antidromic action potentials were recorded from the superficial radial nerve preirradiation and at 5, 10, and 15 minutes after irradiation. Skin temperature was monitored concomitantly by using two surface thermistor probes attached to the skin overlying the nerve. RESULTS: Repeated measures analysis of variance showed no significant differences between groups for negative peak latency nor skin temperature data after laser irradiation. CONCLUSION: This study has demonstrated that laser irradiation at the radiant exposure and pulsing parameters indicated did not produce any specific neurophysiologic effects in this model of nerve function.