Evaluation of the postural stability of elderly persons using time domain signal analysis

Article type: Research Article

Authors: Rasku, Jyrki^{a; *} | Pyykkö, Ilmari^a | Juhola, Martti^b | Garcia, Melissa^c | Harris, Tamara^c | Launer, Lenore^c | Eiriksdottir, Gudny^d | Siggeirsdottir, Kristin^d | Jonsson, Palmi^{e; f} | Hoffman, Howard J.^g | Petersen, Hannes^h | Rasmussen, Cunoⁱ | Caserotti, Paolo^c | Toppila, Esko^j | Pajala, Satu^k | Gudnason, Vilmundur^{d; f}

Affiliations: [a] Department of Otorhinolaryngology, Tampere University Hospital, Tampere, Finland | [b] Deparment of Computer Sciences, University of Tampere, Tampere, Finland | [c] Laboratory of Epidemiology, Demography and Biometry, National Institute on Ageing, Bethesda, MD, USA | [d] Icelandic Heart Association, Kopavogur, Iceland | [e] Department of Geriatrics, Landspitali University Hospital, Reykjavik, Iceland | [f] Faculty of Medicine, University of Iceland, Reykjavik, Iceland | [g] National Institute of Deafness and Other Communication Disorders, Bethesda, MD, USA | [h] Department of Anatomy and Otorhinolaryngology, Landspitali University Hospital, Reykjavik, Iceland | [i] Department of Sport Sciences, University of Aarhus, Aarhus, Denmark | [j] Institute of Occupational Health, Helsinki, Finland | [k] Faculty of Sport and Health Sciences, Jyväskylä, Finland

Correspondence: [*] Corresponding author: Jyrki Rasku, Department of Otorhinolaryngology, Tampere University Hospital, Tampere, Finland. E-mail: jyrki.rasku@uta.fi

Abstract: A force platform is widely used in the evaluation of postural stability in man. Although an abundance of parameters are typically retrieved from force platform data, no uniform analysis of the data has been carried out. In general, the signal analysis does not analyze the underlying postural event, i.e., whether the signal consists of several small corrections or large excursions. In the present work, we studied the postural stability of 4589 elderly persons from Iceland on a force platform under visual and non-visual conditions during stance on a solid surface. We analyzed the internal relationship between frequently used time domain variables. In addition, we conducted a factor analysis using a subset of selected variables. Factor analysis yielded three components that can be considered different strategies for maintaining posture. In one control strategy, long swaying amplitues were pronounced, allowing the person to react when postural confidence limits are reached. In a second strategy, a high oscillation rate about the stationary point was the dominant characteristic of maintaining postural control. The third strategy appears to involve a short critical time period during which an open loop control changes into a closed loop that very rapidly controls excessive postural oscillations. The findings suggest that conventional parameters such as swaying velocity and amplitude alone do not provide sufficient information regarding a person's ability to maintain an upright stance.

Keywords: Force platform, postural control, variable, correlation, factor analysis

DOI: 10.3233/VES-120465

Journal: Journal of Vestibular Research, vol. 22, no. 5-6, pp. 243-252, 2012