Dynamic Stability during Gait Is Altered in Persons with Multiple Sclerosis Who Have a Falls History Compared to Non-Fallers and Healthy Controls

Background: Persons with multiple sclerosis (PwMS) walk with slower, shorter, and wider steps and spend more time in double-support phase than age matched healthy controls, however contradicting evidence exists relating these changes to fall risk. Some studies report that PwMS who are fallers walk slower than non-fallers but with similar step widths while other studies show fallers walk with wider steps but with similar velocity. The disagreement may be due to spatiotemporal measures (e.g. step length, width, and time) of gait being reflective of ‘fear of falling’ rather than actual instability during gait. 

Objectives:  The present study examined dynamic stability measures that explicitly identify features of gait which may contribute to trip-related and balance-related falls rather than being reflective of fear of falling.

Methods: Twenty seven healthy controls and 55 PwMS were enrolled. PwMS were classified as non-fallers if they did not experience a fall in the previous 6 months (n=28) and as fallers if they has 2 or more falls in the previous 6 months (n=27). It was expected that compared to non-fallers and healthy controls, the fallers would adopt a more cautious gait strategy, display increased gait variability, and have poor center of mass control during gait. For the data collection, all subjects walked on a treadmill at their self-selected preferred pace for 3 minutes while motion of their trunk and legs was collected. Several dynamic stability measures during gait were calculated including margin of stability, variability of trunk motion, and gait symmetry. 

Results: PwMS in the faller group showed altered margin of stability and variability of trunk relative to healthy controls and to PwMS in non-faller group. These results generally agree with the hypothesis that the fallers group would have altered gait variability as indicated by increased trunk variability and that fallers would have worse center of mass control which is indicated by altered margin of stability during gait. 

Conclusions: These findings indicate that it’s not just the presence of MS that causes gait changes, but that there is a specific influence of falls history on the gait pattern of PwMS. The specific physiological mechanisms behind these dynamic instabilities are unknown; however it is likely that sensorimotor conduction delays, cognitive impairment, muscle weakness, and spasticity could all contribute. Future studies examining gait in PwMS must consider the falls history of the individual in addition to their disease status.