Dynamic posturography and gait time: markers of functional decline in patients with multiple sclerosis and mild disability

BACKGROUND: Balance and gait disorders are common in people with multiple sclerosis (MS) and appears even in MS individuals with minimal impairment or without clinical signs, becoming more pronounced in those with significant disease progression. However, little is known about the decline in balance control in patients with mild disability. Posturography is the gold standard objective measure of postural balance in MS, being able to detect even minimal impairments. Therefore, our aim was to examine if dynamic posturography detect longitudinal postural balance decline. METHODS: We evaluated relapsing-remitting MS patients with mild disability, according to Expanded disability status scale (EDSS 0-3,5). After 18 months, all patients was contacted to return to the final evaluation. Postural balance control was evaluated through the Modified Sensorial Organization Test (mSOT), at Dynamic Posturography and the walking time was measured by Timed 25 foot walk test (T25FW). All patients were properly evaluated by MS neurologists at both moments of study analysis. We compared all measures at the baseline and after 18 months, individually. We also analyzed the postural control changes according to the EDSS subgroups. RESULTS: 89 MS patients was evaluated at baseline and 79 completed the study. 40 healthy subjects was included in control group. We did not find differences between age and sex in both groups. Median time of the disease was 4.9 years (SD±3) and the median score of EDSS was 1,21 (SD±0,93). We found significant differences between baseline and after 18 months considering some variables: patients that had relapse during the period or changed the medication worsened the EDSS score in 0.34 points (p= 0.006), increased the walking time in 0.34 seconds (p=0,012); patients with new positive gadolinium lesions between sessions increased EDSS score in 0.94 points (p=0.001), increased the walking time in 0.99 seconds (p < 0.001) and worsened static and dynamic balance control mSOT (p < 0,001). We also observed strong correlations between increased EDSS and increased gait time (rho 0.760, p=0.001), worse static balance control (rho= -0,536, p=0,032) and worse dynamic balance control (rho= - 0.660, p=0.005). As the degree of disability increases (EDSS), performance in all balance and gait tests worsens (0 < 0.001). CONCLUSIONS: MS patient\'s performance at Posturography and gait tests worsened as the disease progresses, even patients with mild disability. These changes characterize functional decline and are related to disease activity. The evaluations used in our study may be complementary to characterize the accumulation of disabilities in the early stages of the disease. For this reason, Posturography evaluation and gait timed tests may be considered markers of functional decline in patients with multiple sclerosis (AU)