Does Instability during Standing Occur just after Transcutaneous Xenon Light Irradiation around the Stellate Ganglion?

Abstract

[Purpose] This study investigated whether instability during standing occurs just after transcutaneous xenon light irradiation around the stellate ganglion. [Subjects] Thirty healthy volunteers were the subjects. [Methods] The subjects underwent two experimental sessions: 1) 10-minute xenon light irradiation around the bilateral stellate ganglions in a comfortable supine position (Xe-LISG); and 2) 10-minute rest in the same position as Xe-LISG (control). After Xe-LISG and the control, they stood up immediately and maintained quiet standing for 1 minute. The low frequency power (LF) and ratio of LF to the high frequency power (LF/HF) based on R-R intervals, and the total length (LNG) and rectangular area (REC) of the excursion of the center of foot pressure during quiet standing were examined. [Results] Although no significant changes of HF and LF/HF were observed before and after the control, HF after Xe-LISG was significantly greater than that before Xe-LISG, and LF/HF after Xe-LISG was significantly lower than that before Xe-LISG. Additionally, although no significant difference was observed between REC after Xe-LISG and that after the control, LNG after Xe-LISG was significantly longer than that after the control. [Conclusion] These results suggest that Xe-LISG causes not only parasympathetic predominance and sympathetic suppression but also instability during standing just after Xe-LISG.