title: Nonlinear analysis of sensory organization test for subjects with unilateral vestibular dysfunction.
abstract: Vestibular disorder is the cause of approximately 50% of dizziness in older people. The vestibular system is a critical postural control mechanism, and posturography analysis is helpful for diagnosing vestibular disorder. In clinical practice, the sensory organization test (SOT) is used to quantify postural control in an upright stance under different test conditions. However, both aging and vestibular disorder cause declines of postural control mechanisms. The aim of this study was to enhance the performance of the SOT using a nonlinear algorithm of empirical mode decomposition (EMD) and to verify the differences of effects caused by aging and/or illnesses benefits to clinical diagnosis. A total of 51 subjects belonging to 3 groups--healthy-young, healthy-elderly and dizzy--were recruited for this study. New dynamic parameters of the SOT were derived from the center of pressure (COP) signals. EMD served as an adaptive filter bank to derive the low- and high-frequency components of the COP. The effects on four ratios of sensory analysis caused by aging and vestibular disorder can be investigated for the specific frequency bands. According to our findings, new SOT parameters derived from the component with the specific frequency band more sensitively reflect the functional condition of vestibular dysfunction. Furthermore, both aging and vestibular dysfunction caused an increase in magnitude for the low-frequency component of the AP-direction COP time series. In summary, the low-frequency fluctuation reflects the stability of postural control, while the high-frequency fluctuation is sensitive to the functional condition of the sensory system. EMD successfully improved the accuracy of SOT measurements in this investigation.
authors.affiliation: Research Center for Adaptive Data Analysis and Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan, Taiwan.
authors.forename: Jia-Rong
authors.initials: JR
authors.lastname: Yeh
authors.affiliation: Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan; National Yang-Ming University School of Medicine, Taipei, Taiwan.
authors.forename: Li-Chi
authors.initials: LC
authors.lastname: Hsu
authors.affiliation: Research Center for Adaptive Data Analysis and Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan, Taiwan.
authors.forename: Chen
authors.initials: C
authors.lastname: Lin
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: Research Center for Adaptive Data Analysis and Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan, Taiwan.
authors.forename: Men-Tzung
authors.initials: MT
authors.lastname: Lo
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D004856:Postural Balance / Q000502:physiology; D015837:Vestibular Diseases / Q000503:physiopathology*; D014724:Vestibular Function Tests