Effect of 670 Nm Laser Beam on the Action Potentials of Sural Nerve in Healthy Individuals

Abstract

Introduction: Low Level Laser (LLL) is being used in physiotherapy for pain relief in various pathologies and particularly on peripheral nerve entrapments. In the present study, the effect of LLL on the electrophysiological parameters of sural in humans was investigated. The results might be used as a basis for further clinical research in abnormal conditions. Methods and Materials: Thirty-eight normal men voluntarily participated in the current study and 670 nm LLL beam was applied to the left sural nerve at 5 points for 10 sessions. The electrophysiological parameters such as onset latency, peak latency, negative peak amplitude, peak to peak amplitude, and duration were measured before and after the application of LLL (0.5, 1.5 & 2.5 J/cm² energy density). Results: Overall, 670 nm laser beam increased the latency and reduced the nerve conduction velocity (NCV). In addition, LLL beam decreased the amplitude of action potentials. Among the various values of energy densities, application of 2.5 J/cm² had the most effective results ( P < 0.001). Conclusion: These results might suggest that 670 nm laser beam could affect the latency and reduce the NCV in sural nerve of human. Probably, LLL affects the bioelectric and bioenergetic properties of the neural biomembrane. These findings might have clinical signlificance in non-surgical treatment of entrapment syndromes, such as carpal, tarsal syndromes and trigeminal entrapment in human. Further investigations are needed to elucidate the effects of LLL beam on the human peripheral nerves in pathological conditions. Keywords: Low-level laser, Sural nerve, Electrophysiology, Pain