Longitudinal Changes In Sensorimotor And Mobility Function In People With Progressive Multiple Sclerosis

Abstract

PURPOSE: To determine whether changes in sensorimotor function and mobility are apparent between people with relapsing-remitting (RRMS) and progressive multiple sclerosis (PMS) after 1 year of baseline testing. METHODS: The percent change relative to baseline (i.e., % change = (visit 2 - visit 1)/visit 1)*100), for measures of sensorimotor function and mobility was calculated for 25 RRMS (22 women, 53.2±10.3 yrs) and 26 PMS (16 women, 60.3±8.7 yrs). Sensorimotor function measures included lower-extremity cutaneous vibration sensitivity, proprioception, and central motor drive. Mobility measures included the 25-Foot Walk Test at preferred and brisk speeds (25FWTpref, 25FWTbrisk), and the Timed-Up-And-Go (TUG). One-sample t-tests and pairwise comparisons were used to determine whether within- and between-group performance changed, respectively, relative to baseline. RESULTS: One-sample t-tests revealed that RRMS became less sensitive to vibration at the hallux (p=0.014, [5.4, 43.9]), improved 25FWTbrisk performance (p=0.018, [-17.5,-1.8], and tended to improve performance during the 25FWTpref (p=0.076, [-13.8, 0.7]) and TUG (p=0.053 [-14.8, 0.1]). Results for PMS demonstrated moderately decreased sensation to vibration at all but 1 site on the foot (Hallux: p=0.066, [-1.7, 49.8], Heel: p=0.084, [-2.9, 43.4]) and worsened performance for the 25FWTpref (p=0.090, [-1.4, 17.6]). Neither RRMS nor PMS demonstrated changes in lower-extremity proprioception or central motor drive measures for either one-sample t-tests or pairwise comparisons. Pairwise comparisons between the groups showed a larger % change (improved performance) from baseline to visit 2 in RRMS compared to PMS for all mobility tests (25FWTpref: p=0.015, [-26.2,-3.0], 25FWTbrisk: p=0.009, [-24.3,-3.7], TUG: p=0.048, [-26.5,-0.1]). CONCLUSION: Relative to RRMS, people with progressive forms of MS may increase the amount of time it takes to complete the 25FWT. Increased mobility impairment in PMS over a one year period may be explained by decreased sensation, especially related to cutaneous sensitivity at the plantar surface of the foot, which could impact perception of body orientation and foot-ground contact during the stance phase of gait, and thereby impair mobility performance by walking more cautiously at slower speeds.