Research

Use of information entropy measures of sitting postural sway to quantify developmental delay in infants

Joan E Deffeyes¹ , Regina T Harbourne² , Stacey L DeJong² , Anastasia Kyvelidou¹ , Wayne A Stuberg² and Nicholas Stergiou^1,3

¹  Nebraska Biomechanics Core Facility, University of Nebraska at Omaha, Omaha, NE, 68182, USA

²  Munroe-Meyer Institute, University of Nebraska Medical Center, Omaha, NE 68198, USA

³  Department of Environmental, Agricultural and Occupational Health Sciences, College of Public Health, University of Nebraska Medical Center, Omaha, NE 68198, USA

author email corresponding author email

Journal of NeuroEngineering and Rehabilitation 2009, 6:34doi:10.1186/1743-0003-6-34

Published:	11 August 2009

Abstract

Background

By quantifying the information entropy of postural sway data, the complexity of the postural movement of different populations can be assessed, giving insight into pathologic motor control functioning.

Methods

In this study, developmental delay of motor control function in infants was assessed by analysis of sitting postural sway data acquired from force plate center of pressure measurements. Two types of entropy measures were used: symbolic entropy, including a new asymmetric symbolic entropy measure, and approximate entropy, a more widely used entropy measure. For each method of analysis, parameters were adjusted to optimize the separation of the results from the infants with delayed development from infants with typical development.

Results

The method that gave the widest separation between the populations was the asymmetric symbolic entropy method, which we developed by modification of the symbolic entropy algorithm. The approximate entropy algorithm also performed well, using parameters optimized for the infant sitting data. The infants with delayed development were found to have less complex patterns of postural sway in the medial-lateral direction, and were found to have different left-right symmetry in their postural sway, as compared to typically developing infants.

Conclusion

The results of this study indicate that optimization of the entropy algorithm for infant sitting postural sway data can greatly improve the ability to separate the infants with developmental delay from typically developing infants.