Understanding the Relationship Between Cutaneous Sensation, Balance, and Falls in People With Multiple Sclerosis

BACKGROUND AND PURPOSE: Falls remain an important and undertreated outcome in people with multiple sclerosis (PwMS). Understanding the paths through which neurophysiological changes contribute to altered balance and falls can improve our understanding of and ability to treat falls in this group. The purpose of this analysis was to assess the relationship between specific aspects of balance (reactive balance and sway) in PwMS and to assess whether balance deficits mediate relationships between neurophysiological changes (cutaneous sensation at the foot) and falls. METHODS: In this observational, cross-sectional study, cutaneous sensation, reactive balance, and standing sway data were collected in 121 PwMS and 48 controls. Correlation analyses assessed relationships between reactive and standing balance. Single and multiple mediator models determined the individual and joint mediating effect of sway and reactive stepping on the cutaneous sensation-falls relationship. RESULTS: Significant correlations were observed between reactive step latency (but not length) and multiple standing sway outcomes in PwMS. Statistically significant relationships were not observed in controls. Mediation models showed a significant mediating effect of reactive step latency and sway on the cutaneous sensation-falls relationship in PwMS. DISCUSSION AND CONCLUSIONS: Results indicate that the latency (but not length) of reactive stepping is related to standing sway, cutaneous sensation, and (via previous analyses) falls. Further, mediation analyses suggest that poor sensation leads to greater sway and slower reactive steps, which lead to greater fall risk. Together, these results inform links between balance outcomes and quantitatively confirm previous hypotheses regarding possible pathways through which sensory deficits contribute to falls.