Balance Training With a Vibrotactile Biofeedback System Affects the Dynamical Structure of the Center of Pressure Trajectories in Chronic Stroke Patients.

Kentaro Kodama,Kazuhiro Yasuda,Nikita A Kuznetsov,Yuki Hayashi,Hiroyasu Iwata

doi:10.3389/fnhum.2019.00084

Kentaro Kodama, Kazuhiro Yasuda + Show 3 more

Open Access

https://doi.org/10.3389/fnhum.2019.00084

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Abstract

Haptic-based vibrotactile biofeedback (BF) is a promising technique to improve rehabilitation of balance in stroke patients. However, the extent to which BF training changes temporal structure of the center of pressure (CoP) trajectories remains unknown. This study aimed to investigate the effect of vibrotactile BF training on the temporal structure of CoP during quiet stance in chronic stroke patients using detrended fluctuation analysis (DFA). Nine chronic stroke patients (age; 81.56 ± 44 months post-stroke) received a balance training regimen using a vibrotactile BF system twice a week over 4 weeks. A Wii Balance board was used to record five 30 s trials of quiet stance pre- and post-training at 50 Hz. DFA revealed presence of two linear scaling regions in CoP indicating presence of fast- and slow-scale fluctuations. Averaged across all trials, fast-scale fluctuations showed persistent dynamics (α = 1.05 ± 0.08 for ML and α = 0.99 ± 0.17 for AP) and slow-scale fluctuations were anti-persistent (α = 0.35 ± 0.05 for ML and α = 0.32 ± 0.05 for AP). The slow-scale dynamics of ML CoP in stroke patients decreased from pre-training to post-BF training (α = 0.40 ± 0.13 vs. 0.31 ± 0.09). These results suggest that the vibrotactile BF training affects postural control strategy used by chronic stroke patients in the ML direction. Results of the DFA are further discussed in the context of balance training using vibrotactile BF and interpreted from the perspective of intermittent control of upright stance.

Highlights

Following a stroke, a complex interplay of sensory, motor, and cognitive impairments may interfere with balance (de Haart et al, 2004)
To examine whether vibrotactile BF training affect the center of pressure (CoP) dynamics in chronic stroke patients, the detrended fluctuation analysis (DFA) was applied to CoP trajectories data in the ML and AP directions
To the best of our knowledge, this is the first study to describe changes in the dynamical structure of CoP trajectories resulting from vibrotactile feedback training

Summary

Introduction

A complex interplay of sensory, motor, and cognitive impairments may interfere with balance (de Haart et al, 2004). Stroke patients commonly show increased postural sway and asymmetric weight distribution while standing (Mansfield et al, 2013; Hendrickson et al, 2014). Impaired balance decreases mobility and increases fall risk in elderly stroke patients (Lamb et al, 2003). We previously found that a 4 week vibrotactile BF training did not induce significant changes on several center of pressure (CoP) measures (i.e., sway area, path length) in chronic stroke patients (Yasuda et al, 2018). We apply detrended fluctuation analysis (DFA; Peng et al, 1994) to characterize the effects of this BF training in stroke patients. DFA offers an additional perspective on postural control dynamics in comparison to traditional CoP metrics because it examines control processes across multiple time scales (Eke et al, 2002; Seuront, 2009).

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