Plantar Hypoesthesia Alters Time-to-boundary Measures Of Postural Control

Abstract

PURPOSE: To identify the effect of diminished plantar cutaneous sensation on time-to-boundary (TTB) measures of postural control during double and single-limb quiet standing. METHODS: Thirty-two healthy young adults underwent ten minutes of ice immersion of the plantar aspect of the feet prior to balance testing. On a different day, the subjects did not receive this intervention prior to testing. A 2×2×2 vision (eyes open, eyes closed) by sensation (control, hypoesthesia) by gender (male, female) repeated measures design was used to analyze the TTB measures. RESULTS: In double limb stance, there were significant interactions between sensation and vision for the absolute TTB minimum (Abs. Min. TTB) (p=0.047) and the mean of TTB minima (Mean TTB) (p=0.017) in the anteroposterior (AP) direction. There was a significant increase in both measures after sensation was diminished with eyes closed (Abs. Min. TTBAP=13.23 ± 4.79s; Mean TTBAP=45.58 ± 13.82s) compared to the control (Abs. Min. TTBAP=11.29 ± 3.88s; Mean TTBAP=42.56 ± 12.14s), but not with eyes open. In single limb stance, the TTB absolute minimum and mean of TTB minima in the AP direction significantly increased with hypoesthesia regardless of vision (p<0.001). A gender by sensation interaction was found for the standard deviation of TTB minima (SD TTB) in the AP direction (p=0.04). Females had a significant increase in the SD TTBAP in the presence of plantar hypoesthesia (Hypo esthesia=6.74 ± 1.91s, Control=5.58 ± 1.69s) while there was no change in males. No significant differences were found in the ML direction for any of the TTB measures in double or single limb stance. CONCLUSIONS: Sensory information from the plantar cutaneous receptors appears to be most important in the maintenance of AP postural control.