title: Complexity of human postural control in subjects with unilateral peripheral vestibular hypofunction.
abstract: Complexity is a new measure for identifying the adaptability of a complex system to meet possible challenges. For a center of pressure (COP) time series, the complexity measure represents the stability of postural control. In this study, multiscale entropy (MSE) was used to evaluate the complexity of COP time series in six test conditions of sensory organization test (SOT). Complexity index (CI) is defined as the summation of entropies with coarse-graining scales 1-20 by MSE. A total of 51 subjects belonging to 3 groups - healthy-young, healthy-elderly and dizzy - were recruited in this study. The COP signals in both anteroposterior (AP) and mediolateral (ML) directions were analyzed respectively. According to our results, the CI of AP-direction COP time series is significantly correlated to the equilibrium score, which represents the stability of postural control in SOT. The AP-direction sway is significant larger than the ML-direction sway, particularly in the test conditions with sway-surface. In additions, the CI of AP-direction COP for the healthy-elderly and dizzy groups are significantly lower than those for the healthy young group in the test conditions 1-4. The CI of ML-direction COP for the healthy-elderly group is significantly lower than those for the healthy-young and dizzy groups under test conditions 3 and 6. These results show that the complexity loss is a common status of AP-direction COP time series for both healthy-elderly and dizzy groups, and the complexity of ML-direction COP time series for subjects with unilateral vestibular dysfunction is higher than that for the healthy-elderly group specifically under test conditions 3 and 6.
authors.affiliation: Research Center for Adaptive Data Analysis, National Central University, Taoyuan, Taiwan; Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan, Taiwan.
authors.forename: Jia-Rong
authors.initials: JR
authors.lastname: Yeh
authors.affiliation: Research Center for Adaptive Data Analysis, National Central University, Taoyuan, Taiwan; Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan, Taiwan.
authors.forename: Men-Tzung
authors.initials: MT
authors.lastname: Lo
authors.affiliation: Taiwan Textile Research Institute, New Taipei City, Taiwan; National Yunlin University of Science and Technology, Graduate School of Design, Yunlin, Taiwan.
authors.forename: Fu-Ling
authors.initials: FL
authors.lastname: Chang
authors.affiliation: Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan; National Yang-Ming University School of Medicine, Taipei, Taiwan. Electronic address: lchsu@vghtpe.gov.tw.
authors.forename: Li-Chi
authors.initials: LC
authors.lastname: Hsu
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology; D001696:Biomechanical Phenomena; D004244:Dizziness / Q000503:physiopathology*; D019277:Entropy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D063165:Neurotology / Q000379:methods; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure; D013624:Taiwan
keywords: Center of pressure; Complexity; Multiscale entropy; Sensory organization test; Unilateral vestibular dysfunction