Dynamical analysis of balance in vestibular schwannoma patients.

The analysis of the complexity of postural fluctuations is a recent method for assessing postural control. Complexity relates to the irregularity of the center of pressure time series and characterizes the ability of postural control to meet a changing environment. In our study, we used the sample entropy (SampEn) parameter to evaluate the complexity of postural sway velocity time series in patients with vestibular schwannoma (n=19) compared to healthy controls (n=20), using the sensory organization test.

Dynamical and stabilometric measures are complementary for the characterization of postural fluctuations in older women.

We investigate the complementarities of several measures extracted from center of pressure (COP) recordings during quiet standing, in older women. The selected variables include classical stabilometric measures (SMs) and several dynamical measures (DMs). The computed DMs quantify various features of the temporal structure of COP signals, including predictability, regularity and smoothness of the trajectories.

Characterizing the dynamics of postural sway in humans using smoothness and regularity measures.

We investigate human postural sway velocity time series by computing two dynamical statistics quantifying the smoothness (the central tendency measure or CTM) and the regularity (the sample entropy or SampEn) of their underlying dynamics. The purpose of the study is to investigate the effect of aging and vision on the selected measures and to explore the nature of postural dynamics by performing surrogate data tests. A group of 14 young subjects was compared to a group of 11 older healthy subjects in two visual conditions: with eyes open (EO) and with eyes closed (EC).

On the use of sample entropy to analyze human postural sway data.

We analyze the irregularity of human postural sway data during quiet standing using the sample entropy (SampEn) algorithm. By considering recent methodological developments, we show that the SampEn parameter is able to characterize the irregularity of the center of pressure fluctuations through the analysis of the velocity variable. We present a practical method to select the input parameters of the SampEn algorithm.

Dynamical structure of center of pressure fluctuations in elderly people.

This study investigates whether aging has an influence on the dynamics of the fluctuations of the displacement of the center of pressure (COP), during quiet standing. Two groups of healthy subjects were compared (11 young and 12 elderly) for two visual feedback conditions (eyes open and eyes closed). The data were analyzed using (i) classical stabilometric variables (length and surface) and (ii) recurrence quantification analysis (percentage of determinism and entropy), for the dynamical structure of COP signals.