A kinetic study of anticipatory postural adjustments in adults with and without spastic diplegic cerebral palsy

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A kinetic study of anticipatory postural adjustments in adults with and without spastic diplegic cerebral palsy


Author: Su, Yuen Wang
Title: A kinetic study of anticipatory postural adjustments in adults with and without spastic diplegic cerebral palsy
Degree: D.H.Sc.
Year: 2015
Subject: Human mechanics.
Cerebral palsied.
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Health and Social Sciences
Pages: xvi, 152 pages : illustrations
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2961709
URI: http://theses.lib.polyu.edu.hk/handle/200/8944
Abstract: Background: Anticipatory postural adjustments (APAs) are important for creating a stable postural base upon which focal movements can take place. Previous studies reported that children with CP exhibited APAs with high variability and had a reliance on APAs in the frontal plane. However, the knowledge of APAs in adults with CP is sparse. Physical activity is essential for APA development and is related to the Gross Motor Function Classification System (GMFCS) level for individuals with CP. In order to get a better understanding of the effects of physical activity level on APAs over the life course, an exploratory study of APAs in adults with CP was conducted. Objectives: We hypothesized that there were differences in APAs during performance of unilateral and bilateral standing reach task among high and low functioning adults with diplegia and age-matched adults with typical development (TD). Methods: A kinetic analysis was employed to study the characteristics of APAs in adults with CP. Consistency of APAs and their direction specificity together with six dependent variables derived from the center-of-pressure displacements in antero-posterior (COPAP) and medio-lateral directions (COPML) and vertical torque (TZ) were determined for individual participants in each task type. Results: Eleven middle-aged adults with diplegia at GMFCS level-II and level-III (CP-II and CP-III groups) and eight participants with TD (TD group) were recruited. APAs in TZ were commonly observed in the lower functioning CP-III group in the bilateral reach task where there was no significant difference in the latency and angular impulse of TZ between the CP-III and TD groups. Latencies of COPAP, COPML and TZ were found to be moving towards the anticipatory temporal range in the CP-III group during bilateral reaching. Peak magnitudes of COPML of both CP groups were significantly larger than that of the TD group during bilateral reaching (p<0.05, Kruskal-Wallis, post-hoc Dunn-Bonferroni). The pooled percentages of trials in which direction specificity was observed were 80% or above for the CP-II group while that for the CP-III group was lying between 60-80%. Compared to unilateral reaching, the CP-II group exhibited a significantly earlier onset of COPAP and TZ during bilateral reaching (p<0.05, Wilcoxon signed-rank test). Discussion: Consistent direction specific APAs was found in the higher functioning CP-II group during unilateral reaching. The CP-III group showed increased likelihood of APA emergence during bilateral reaching and APAs in TZ were commonly observed among its participants despite their low physical activity level. It is postulated that APAs may first emerge in TZ in the CP population. Reliance on premovement postural strategies in the frontal plane was retained during bilateral reaching among adults with CP at both GMFCS levels. The CP-II group showed an attenuation of APAs during bilateral reaching probably due to some of its participants had difficulty in clasping their hands. Our findings support the clinical practice of prescribing two-handed forward and one-handed across midline tasks for training low functioning CP. Further investigation is warranted to determine the cause-and-effect relationship between physical activity level and APA development in this population.

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