Monitoring Exertion-Induced Changes in Gait Parameters in Patients with Relapsing-Remitting MS

Background: Gait disturbance is a common element of the physical disability caused by multiple sclerosis (MS), and deviations in gait parameters in MS have been noted in patients with early MS and no observable gait abnormality. Motor fatigue has been demonstrated in individuals with MS and generally does not correlate well with self-report measures of fatigue. Motor fatigue can also be measured via exertion-related alteration of gait parameters, and summarized in a Fatigue Index (FI).

Objectives: To validate the FI in patients with relapsing-remitting MS, low neurologic disability, no evidence of disease activity on DMT over the past year.

Methods: This is a prospective longitudinal study. We are reporting on baseline results only. The Computer Assisted Rehabilitation ENvironment (CAREN) system was used to monitor gait parameters including step length, width and height, leg circumduction, and knee flexion. Participants were asked to walk on a treadmill at a pre-specified speed (10% above comfortable speed) until they reached a Rate of Perceived Exertion score of 7 (Very Hard), then walk an additional 120 seconds for after-exertion recording. The Fatigue Index (FI) was based on mean and variation changes after exertion. Participants also completed the 2-Minute Walk (2MW) test, MS Walking Scale-12 (MSWS), Fatigue Scale for Motor and Cognition (FSMC), Center for Epidemiological Studies Depression Scale (CESD) and Neuro-QoL sleep score (NQoL-Sleep). Diffusion tensor imaging (DTI) was obtained on a subset of 10 participants.

Results: 29 patients (69% women, median age 46 years, median MS duration 10 years) were enrolled and completed baseline assessments. FI was only associated with CESD (Spearman r=-0.4), while before-exertion step length and step height were significantly correlated with MSWS (r= -0.4 for both), 2MW (r=0.5) and NQoL-Sleep (r=0.5). In before-after exertion comparisons, a significant increase was observed for circumduction on median values (p<0.0001) and area under the curve (p<0.001), while increased variation was detected on step length, step width, step height and circumduction. In the analysis of the DTI subgroup, some gait parameters, but not FI, were associated with DTI metrics.

Conclusions:

We were able to calculate the FI in 29 patients with RR-MS and low disability. Individual gait parameters

Exhibited better convergent validity and sensitivity to motor fatigue than the FI in patients with early MS and low disability