Characterization of Compensatory Stepping in People with Multiple Sclerosis

Objective To characterize postural responses to forward and backward external perturbations in people with multiple sclerosis (PwMS), and to relate performance to commonly used clinical outcomes. Design Cross-sectional study. Postural responses were tested during large stepping and smaller feet-in-place perturbations in forward and backward directions. Setting University research laboratory. Participants PwMS (n=54) and age-matched controls (n=21) (N=75). Interventions Not applicable. Main Outcome Measures Center of mass displacement and step latency after external perturbations. Results PwMS exhibited larger center of mass displacements and step latencies than control participants in response to stepping perturbations (P=.003 and P=.028, respectively). Stepping deficits were more pronounced during backward stepping and were significantly correlated to increased severity on clinical measures (European Database for Multiple Sclerosis disability score and Timed 25-Foot Walk). Conclusions Compensatory stepping is impaired in PwMS and correlates with clinical disability. Measurement of backward compensatory stepping may be more effective at identifying postural dysfunction in PwMS than forward compensatory steps. Prolonged step latencies, large anticipatory postural adjustments, and multiple compensatory steps are especially altered in PwMS, suggesting possible targets for neurorehabilitation.