Wearable sensors accurately detect FA in walking test, study shows
Researchers say results suggest 'promising utility' for sensors in clinical trials
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Sensors worn while walking at a natural pace can accurately distinguish people with Friedreich’s ataxia (FA) from those without the disease, according to a study.
Data from these sensors also showed that FA patients with greater step-to-step variability and irregular trunk movements during walking had more severe disease.
“Digital gait measures from wearable sensors were discriminative, reliable, and showed concurrent validity for evaluating ataxia severity during an instrumented walk test,” the authors concluded. “These results suggest promising utility of digital gait outcomes for use in [FA] clinical trials.”
The study, “Digital Gait Measures Discriminate People with Friedreich’s Ataxia from Healthy Controls,” was published in the journal Movement Disorders.
Gait ataxia refers to an uncoordinated walk with irregular steps, wide foot placement, and poor balance, resulting from impaired muscle coordination. In FA, it arises from genetic mutations that ultimately disrupt energy production in cells, especially in muscle cells.
Gait impairments among earliest signs of FA
Gait and mobility impairments are the earliest biomarkers of FA onset, typically occurring around age 11-13. Because of the condition’s relatively slow progression — patients generally need wheelchairs after 10-15 years — scientists can assess gait in those who are still able to walk.
Wearable inertial sensors are increasingly used to objectively measure, diagnose, and monitor gait ataxia. Placed at various locations on the body, these sensors offer a cost-effective, portable option that’s easy to use in both clinical and home settings and are more precise than traditional clinical rating scales.
A team led by scientists at the University of Chicago investigated whether wearable inertial sensors can accurately assess gait in people with FA.
“The goal of this study was to identify the digital gait measures most strongly associated with disease severity and most discriminative of individuals with [FA] from healthy controls,” the team wrote.
The researchers enrolled 24 FA patients and an equal number of healthy controls, matched by age. Each participant walked for two minutes at their own pace while wearing six sensors on the hands, feet, chest, and lower back.
Based on sensor data, the team identified the 10 measures that best distinguished people with FA from healthy individuals. All of these measures demonstrated excellent ability to differentiate between groups, with accuracies over 92%. Most of the strongest measures reflected increased step-to-step variability in walking.
A key measure that clearly differentiated groups was trunk transverse range of motion, which reflects upper-body twisting during walking, “highlighting the increased instability and irregularity of trunk movement of participants with [FA] during gait,” the researchers wrote.
FA patients with greater variable walking patterns and trunk instability tended to have more severe disease, as assessed by the modified Friedreich’s Ataxia Rating Scale Upright Stability Subscale.
The strongest links were seen for how much the trunk twists, the time spent with both feet on the ground, and how high the foot lifts during walking. Greater variability in these movements reflected worse FA impairment. Toe-out angle, reflecting inconsistent stride width, was moderately related to disease severity.
“These findings suggest that as motor function declines, as measured by clinical outcome measures, gait performance similarly worsens as evidenced by digital gait measures,” the team wrote.
Problems with gait variability, particularly the time spent with both feet on the ground and the height of foot lift while walking, also led to functional limitations in daily activities, as assessed by the FARS Activities of Daily Living Scale.
“This study has identified a set of digital gait measures highly sensitive to [FA]-related gait impairments during a single instrumented in-clinic walking assessment,” the team wrote. “Gait variability was highly discriminative and correlated with the current clinical outcome measures.”
The researchers noted that the study participants had “mild to moderate” disease.
“With the future development of disease-modifying therapies, we recommend that future studies use wearable technologies with a focus on early-stage disease,” they wrote. “Additionally, future studies should aim to collect larger cohorts of early-onset and later-onset participants to understand the characteristics of gait impairment and investigate potential discriminative ability between the two groups.”
