The effect of relapsing-remitting Multiple Sclerosis on gait variability and regularity

Abstract

Multiple Sclerosis (MS) is an inflammatory and neurodegenerative autoimmune disease that destroys the myelin sheath of the central nervous system. Gait impairments are one of the most debilitating and concerning symptoms for PwMS that can significantly impact an individual’s quality of life. Gait changes in people with MS (PwMS) have often been quantified using basic spatiotemporal parameters; however, research into more complex measures of gait variability, such as the measurement of small fluctuations that occur during the gait cycle (e.g., fractal-scaling index (FSI)), and the measurement of the consistency of trunk-based acceleration waveforms (gait regularity), have been shown to provide deeper insights into gait deficits in other neurological conditions. This research has demonstrated the potential to provide better predictors for important clinical factors such as fall risk. The purpose of this study was to investigate the relationship between the aspects of gait variability and regularity in people with relapsing-remitting MS and to compare the results to a healthy, age- and sex-matched control group. Using a cross-sectional study design, thirty participants were recruited (13 MS (12F; 44.9 ± 14.0 years; Median EDSS (IQR): 2.5 (2.0 – 4.5)); 17 controls (15F; 40.3 ± 10.9 years). Each participant completed a ten-minute walking test at a self-selected speed around a 200m track. Gait patterns were assessed using a tri-axial accelerometer placed on the lower back. From the raw accelerometer data, gait variability was assessed as the coefficient of variation (COV) of step time and stride time, step regularity and stride regularity, and the FSI of stride time. PwMS were found to walk with significantly higher step time COV and lower anteroposterior (AP) step regularity and AP and mediolateral (ML) stride regularity than the control group. PwMS were also found to walk significantly slower and take shorter steps than the control group. Strong associations between the differences in speed and gait variability were also found. This association appeared to produce a powerful combined effect on the locomotor function of PwMS, but gait speed also appeared to partially influence the significant differences seen in gait regularity. The findings of this study suggest that PwMS walk with a significant amount of variability and demonstrate greater bilateral asymmetry and impairment of movement consistency during the braking and propulsive phases of gait than healthy controls. Future research is needed to better understand the relationship between MS, gait speed and measures of gait variability.