Effect of noisy galvanic vestibular stimulation on center of pressure sway of static standing posture.

BACKGROUND: The vestibular system is involved in the control of standing balance. Galvanic vestibular stimulation (GVS) is a noninvasive technique that can stimulate the vestibular system. In recent years, noisy GVS (nGVS) using noise current stimulation has been attempted, but it has not been clarified whether it affects postural sway in open-eye standing.

OBJECTIVE: The purpose of this study was to clarify the influence of nGVS on the center of pressure (COP) sway measurement in open-eye standing postural control and identify the responders of nGVS.

METHODS: nGVS (0.1-640 Hz) was delivered at 0.4 and 1.0 mA over the bipolar mastoid. COP sway root mean square area, sway path length, medio-lateral (ML) mean velocity, and antero-posterior (AP) mean velocity before and during nGVS in an open-eye standing posture was measured.

RESULTS: nGVS at 0.4 and 1.0 mA significantly reduced sway path length, mean velocity. The stimulation effect of nGVS was also large in subjects with a long sway path. For subjects with high COP sway of Baseline, nGVS was effective even with stimulation for a short duration (5 s).

CONCLUSIONS: These findings suggest that nGVS improves postural sway in an open-eye standing posture among young subjects.