Quantifying six-minute walk induced gait deterioration with inertial sensors in multiple sclerosis subjects.

BACKGROUND The six-minute walk (6MW) is a common walking outcome in multiple sclerosis (MS) thought to measure fatigability in addition to overall walking disability. However, direct evidence of 6MW induced gait deterioration is limited by the difficulty of measuring qualitative changes in walking. OBJECTIVES This study aims to (1) define and validate a measure of fatigue-related gait deterioration based on data from body-worn sensors; and (2) use this measure to detect gait deterioration induced by the 6MW. METHODS Gait deterioration was assessed using the Warp Score, a measure of similarity between gait cycles based on dynamic time warping (DTW). Cycles from later minutes were compared to baseline cycles in 89 subjects with MS and 29 controls. Correlation, corrected (partial) correlation, and linear regression were used to quantify relationships to walking and fatigue outcomes. RESULTS Warp Scores rose between minute 3 and minute 6 in subjects with mild and moderate disability (p<0.001). Statistically significant correlations (p<0.001) to the MS walking scale (MSWS-12), modified fatigue impact scale (MFIS) physical subscale, and cerebellar and pyramidal functional system scores (FSS) were observed even after controlling for walking speed. Regression of MSWS-12 scores on Warp Scores and walking speed explained 73.9% of response variance. Correlations to individual MSWS-12 and MFIS items strongly suggest a relationship to fatigability. CONCLUSION The Warp Score has been validated in MS subjects as an objective measure of fatigue-related gait deterioration. Progressive changes to gait cycles induced by the 6MW often appeared in later minutes, supporting the importance of sustained walking in clinical assessment.

[1]  John Lach,et al.  Toward Detection and Monitoring of Gait Pathology using Inertial Sensors under Rotation, Scale, and Offset Invariant Dynamic Time Warping , 2015, BODYNETS.

[2]  S. Chiba,et al.  Dynamic programming algorithm optimization for spoken word recognition , 1978 .

[3]  M. Sutliff.  Contribution of impaired mobility to patient burden in multiple sclerosis , 2010, Current medical research and opinion.

[4]  F. Horak,et al.  Body-worn motion sensors detect balance and gait deficits in people with multiple sclerosis who have normal walking speed. , 2012, Gait & posture.

[5]  N. Larocca.  Impact of Walking Impairment in Multiple Sclerosis , 2011, The patient.

[6]  Eamonn J. Keogh,et al.  Exact indexing of dynamic time warping , 2002, Knowledge and Information Systems.

[7]  Jeffrey A. Cohen,et al.  Diagnostic criteria for multiple sclerosis: 2010 Revisions to the McDonald criteria , 2011, Annals of neurology.

[8]  Pavlos Protopapas,et al.  Supporting exact indexing of arbitrarily rotated shapes and periodic time series under Euclidean and warping distance measures , 2008, The VLDB Journal.

[9]  C. Fowler,et al.  Urinary symptoms and the neurological features of bladder dysfunction in multiple sclerosis. , 1993, Journal of neurology, neurosurgery, and psychiatry.

[10]  P. Feys,et al.  Comparison of the 2- and 6-minute walk test in multiple sclerosis , 2011, Multiple sclerosis.

[11]  Dimitrios Hatzinakos,et al.  Gait recognition using dynamic time warping , 2004, IEEE 6th Workshop on Multimedia Signal Processing, 2004..

[12]  J. Kurtzke.  Rating neurologic impairment in multiple sclerosis , 1983, Neurology.

[13]  A J Thompson,et al.  Measuring the impact of MS on walking ability , 2003, Neurology.

[14]  F. Horak,et al.  Body-worn sensors capture variability, but not decline, of gait and balance measures in multiple sclerosis over 18 months. , 2014, Gait & posture.

[15]  P. Calabresi,et al.  Longitudinal relationships among posturography and gait measures in multiple sclerosis , 2015, Neurology.

[16]  Carlo Pozzilli,et al.  Assessing walking disability in multiple sclerosis , 2012, Multiple sclerosis.

[17]  R. Motl,et al.  Evidence for the different physiological significance of the 6- and 2-minute walk tests in multiple sclerosis , 2012, BMC Neurology.

[18]  Jeffrey A. Cohen,et al.  Evaluation of the six-minute walk in multiple sclerosis subjects and healthy controls , 2008, Multiple sclerosis.