Effects of Nd: YAG low power laser irradiation on the ulnar nerve

In our previous study, we have shown that low power laser irradiation of the stellate ganglion produces a rise in temperature in the bilateral facial skin. To clarify the mechanism behind this phenomenon, irradiation was performed on the ulnar nerve at the elbow joint. The sensation felt during irradiation was reported by the subjects. Changes in temperature of the hand dorsum were thermographically recorded. The evoked peripheral autonomic surface potentials (PASP) were also recorded. 77.3% of the subjects reported sensation changes in the hand; the temperature rose in both hands in 3 out of 5 subjects. The PASPs did not show marked changes in latency or amplitude. It is suggested that the effects of the irradiation are brought about mainly through the stimulation of the central nervous system.