Gait Initiation and Fall Risk in Individuals with MS

Background: Mobility impairments and falls are common in individuals with MS.  Falls can occur at any time, but often result during transitions between positions such as the initiation of gait. To that end, dynamic balance tasks such as gait initiation offer a unique platform for the study of fall risk in MS.

Objectives: To investigate the association between gait initiation and fall risk in cognitive distracting and non-distracting conditions.

Methods: Thirteen individuals with MS (Age: 62.8yr±7.8yr, EDSS: median (IQR)=6.0(2.0)) participated in the investigation. Participants completed four (i.e. 2 baseline, 2 cognitive distraction) gait initiation trials on a 6.1 m pressure sensitive walkway.  Participants stood in place and started walking at a comfortable pace in response to an auditory cue.  During the cognitive distraction condition the participants recited alternating letters of the alphabet (e.g. A, C, E).  Gait initiation was indexed by time to take the first step following the auditory cue.  Participants also underwent a separate analysis of physiological fall risk as indexed by the physiological profile assessment (PPA). The PPA analyses performance in the areas of reaction time, leg strength, vision, proprioception and balance. The results of these assessments are combined for the calculation of an overall fall risk z-score with larger scores representing greater fall risk. Spearman correlations were used to examine the relationship with PPA.

Results: Overall, participants took between 0.68s and 1.11s to initiate a step during single task conditions and between 0.77s and 1.84s during dual task conditions.  PPA fall risk scores ranged from -0.03 to 3.46. There was a significant correlation between fall risk and step initiation in both the single task condition (r_s=0.65) and cognitive distraction condition (r_s=0.70).

Conclusions: The findings suggest gait initiation may represent a valuable outcome measure for understanding fall risk in MS and also highlight the association between cognitive distraction and fall risk. Ultimately, the relationship with physiological fall risk provides the possibility of gait initiation tasks being adapted as a marker of fall risk.