Measuring Gait Stability in People with Multiple Sclerosis Using Different Sensor Locations and Time Scales

Abstract

The evaluation of local divergence exponent (LDE) has been proposed as a common gait stability measure in people with multiple sclerosis (PwMS). However, differences in methods of determining LDE may lead to different results. Therefore, the purpose of the current study was to determine the effect of different sensor locations and LDE measures on the sensitivity to discriminate PwMS. To accomplish this, 86 PwMS and 30 healthy participants were instructed to complete a six-minute walk wearing inertial sensors attached to the foot, trunk and lumbar spine. Due to possible fatigue effects, the LDE short (~50% of stride) and very short (~5% of stride) were calculated for the remaining first, middle and last 30 strides. The effect of group (PwMS vs. healthy participants) and time (begin, mid, end) and the effect of Expanded Disability Status Scale (EDSS) and time were assessed with linear random intercepts models. We found that perturbations seem to be better compensated in healthy participants on a longer time scale based on trunk movements and on a shorter time scale (almost instantaneously) according to the foot kinematics. Therefore, we suggest to consider both sensor location and time scale of LDE when calculating local gait stability in PwMS.

Wearable inertial sensors are highly sensitive in the detection of gait disturbances and fatigue at early stages of multiple sclerosis

“…Assessments took place in the Klinikum Bayreuth GmbH, Department of Neurology. Both MS patients and healthy participants had to complete a walking test that required them to cover a distance of 25 feet repeatedly throughout a maximal assessment period of six minutes as enduring and fast as possible (6-min 25-ft walk [ 3 , 6 ]). A cone was placed three feet away from each endpoint of the 25-foot distance and participants circle the cones to make their turn back toward the 25-foot distance.…”

“…To exclude effects of acceleration and deceleration the first and the last 25 feet distance, as well as the first and the last 2.5 m of each 31 feet distance between the cones were excluded from the following analysis [ 6 , 22 ]. To calculate gait parameters (i.e.…”

“…They found that MS patients had a significantly greater reduction in walking speed over the course of the 6-min walk, which coincided with a significantly greater increase in step time and double support. Comparable results can be observed in gait analysis using wearable inertial sensors [ 6 , 14 – 16 ]. However, to the best of our knowledge, the progression of distinct temporal gait parameters throughout the test duration, as obtained by wearable inertial sensors, has not been investigated so far.…”

“…Multiple sclerosis (MS) is often associated with a decline in walking ability and balance control [ 1 – 6 ]. Moreover, around 40 % of people with MS report walking problems that negatively affect their quality of life [ 7 ].…”

“…With the appearance of electronic walkways and wearable inertial sensors, it has become possible to measure additional gait parameters in a clinical setting, e.g. step length and width or step time [ 6 , 9 , 10 , 13 – 15 ]. For example, Socie et al examined temporal gait parameters during the 6-min walk in MS patients and healthy participants using an electronic walkway [ 9 ].…”