Plantar or Palmar Tactile Augmentation Improves Lateral Postural Balance With Significant Influence from Cognitive Load.

Jacob Azbell,Hangue Park,Shuo-Hsiu Chang,Jaekwan Park,Marielle P K G Engelen

doi:10.1109/tnsre.2020.3037128

Abstract

Although it seems intuitive to address the issue of reduced plantar cutaneous feedback by augmenting it, many approaches have adopted compensatory sensory cues, such as tactile input from another part of the body, for multiple reasons including easiness and accessibility. The efficacy of the compensatory approaches might be limited due to the cognitive involvement to interpret such compensatory sensory cues. The objective of this study is to test the hypothesis that the plantar cutaneous augmentation is more effective than providing compensatory sensory cues on improving postural regulation, when plantar cutaneous feedback is reduced. In our experiments, six healthy human subjects were asked to maintain their balance on a lateral balance board for as long as possible, until the balance board contacted the ground, for 240 trials with five interventions. During these experiments, subjects were instructed to close their eyes to increase dependency on plantar cutaneous feedback for balancing. Foam pad was also added on the board to emulate the condition of reduced plantar cutaneous feedback. The effects of tactile augmentation from the foot sole or the palm on standing balance were tested by applying transcutaneous electrical stimulation on calcaneal or ulnar nerve during the balance board tests, with and without a cognitively-challenging counting task. Experimental results indicate that the plantar cutaneous augmentation was effective on improving balance only with cognitive load, while the palmar cutaneous augmentation was effective only without cognitive load. This result suggests that the location of sensory augmentation should be carefully determined according to the attentional demands.

Highlights

I N THE US alone, falls result in more than 2.8 million injuries treated in emergency departments annually, including over 800,000 hospitalizations and more than 27,000 deaths [1]
These results suggest that transcutaneous electrical nerve stimulation on the ankle and the wrist may work as an effective intervention for individuals with peripheral neuropathy to sense better on their feet and hands, respectively
Subjects’ Balance System Adapts to the New Ground Condition on the Balance Board, and Makes it Natural to Respond to the Board Sway Instead of the Body Sway. Another interesting fact that we found by the experimental results is that, the plantar cutaneous augmentation increased balance time with cognitive distraction, even though we did not augment the plantar cutaneous feedback based on the plantar pressure but based on the sway of the balance board

Summary

Introduction

I N THE US alone, falls result in more than 2.8 million injuries treated in emergency departments annually, including over 800,000 hospitalizations and more than 27,000 deaths [1]. Many of these falls are caused by balance deficit, which is the diminished ability to self-regulated balance. PN can result in seriously diminished sensory feedback on the plantar surface of the foot, and this sensory loss can induce detrimental changes in postural balance regulation, even in simple routine tasks, such as walking or standing, which can lead to dangerous falls [3]–[5]. Decreased plantar cutaneous feedback due to PN is a serious issue that needs to be addressed to ensure the safety and quality of life for those who are affected by it

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