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Inertial sensors on the feet, rather than lumbar sensor only, increase sensitivity of spatio-temporal gait measures to longitudinal progression in ataxia

Lookup NU author(s): Dr Javad SarvestanORCiD, Dr Silvia Del DinORCiD, Dr Lisa AlcockORCiD


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BACKGROUND AND AIM: The optimal number of inertial sensors for gait analysis is a trade-off between data quality and patient convenience and feasibility. 1-sensor systems (1S) have proven to deliver reliable information for average values of gait speed or step length. However, for measures of spatio-temporal gait variability shown to be sensitive in ataxia, 1S systems often showed less reliability and sensitivity compared to 3-sensor (3S) systems which include two sensors at the feet. Here, we compare specificity, reliability and longitudinal sensitivity of ataxic-specific gait variability assessed by 3S vs 1S with state-of-the-art algorithms for both conditions1,2. METHODS: We captured longitudinal gait data of 55 ataxia subjects and 44 healthy controls, using a constrained walking condition (2*25 m straight in self-selected speed) and assessed at baseline, 1-year and 2-years follow-ups using 3 Opal APDM Sensors (1 lumbar spine, 2 feet). For 1-sensor analysis, only the pelvis OPAL sensor was used, analysed with algorithms developed in project Mobilise-D, successfully characterizing gait of PD patients. We analysed spatio-temporal gait variability (stride length, stride duration) in terms of specificity, test-retest reliability and sensitivity to longitudinal change in both sensor conditions.RESULTS: Specificity in discriminating healthy controls and ataxia subjects reveals higher effect sizes with 3S, which is caused by generally increased variability of healthy subjects with 1S (effect sizes: stride duration var: (3S) =0.75; (1S) =0.55; stride length var: (3S) =0.82, (1S) =0.35). In addition, test-re-test reliability reveals higher values for 3S (stride duration var: ICC=0.73; stride length var: ICC=0.81) compared to 1S (stride duration var: ICC=0.43; stride length var: ICC=0.61). In 1S, longitudinal changes are not detectable in temporal, but in spatial gait measures after one year (stride length variability: effect size rprb=0.31) and increased after two years (e.g. stride length variability: rprb=0.46)However, longitudinal analysis in 3S shows higher effect sizes in 1-year and 2-years follow-up (stride length variability: effect sizes rprb=0.34; rprb=0.53). CONCLUSIONS: While at least a part of the variability measures are sensitive to longitudinal change also in the 1S condition, effect sizes of change as well as reliability are higher in the 3S condition. This indicates an additional benefit from feet sensors – at least with current algorithms - to determine spatio-temporal gait variability in ataxia, given the necessity of high effect sizes and test-re-test reliability in upcoming intervention trials in this rare disease.1. Ilg et al Real-life gait assessment in degenerative cerebellar ataxia: Toward ecologically valid biomarkers. Neurology 20202. Del Din, et al "Validation of an accelerometer to quantify a comprehensive battery of gait characteristics in healthy older adults and Parkinson's disease: toward clinical and at home use." IEEE journal of biomedical and health informatics (2015)

Publication metadata

Author(s): Ilg W, Seemann J, Sarvestan J, Del Din S, Synofzik M, Alcock L

Publication type: Conference Proceedings (inc. Abstract)

Publication status: Published

Conference Name: International Society of Posture and Gait Research - ISPGR

Year of Conference: 2023

Acceptance date: 11/04/2023

Publisher: International Symposium on Posture and Gait Research