Motor Deficit Severity Mediates Effects of Intellectual Function in Predicting Speech Motor Control in Children with Cerebral Palsy

Yu Fen Chuang,Chia Hui Chen,Chung Yao Chen,Katie Pei Hsuan Wu,Chia Ling Chen,Chia Ying Chung

doi:10.4172/2329-9096.1000445

Abstract

Objective: To elucidate whether motor deficit severity mediates effects of intellectual function in predicting motor speech functions in children with cerebral palsy (CP). Method: Twenty-five children with spastic CP aged 5-8 were classified into two groups, levels I-II (n=13) and levels III-IV(n=12) based on Gross Motor Function Classification System (GMFCS) levels. Predictor was the intelligence quotient (IQ). Speech outcome measures were Percentage of Consonants Correct (PCC) and Verbal Motor Production Assessment for Children (VMPAC). Pearson correlation analysis was used to investigate relationships between IQ and speech outcomes. A mediation analysis (a three-variable path model) was used to explain how GMFCS levels (the mediator) affect IQ to predict speech outcome. Results: Children with GMFCS levels I-II had greater scores in all IQ and all VMPAC sub scores, and PCC than those with GMFCS levels III-IV (p<0.05). Pearson correlation analysis showed that full IQ (FIQ) was correlated with all VMPAC scores (r=0.42-0.62, p<0.05), but not with PCC scores. The path model assumes path a from the predictor variable (FIQ) to the mediator (GMFCS levels), path b from the impact of the mediator (GMFCS levels) on the outcome variable (VMPAC), and two causal paths to the outcome variable (paths c and c'). Mediation analysis revealed that GMFCS level completely mediated the effect of FIQ when predicting global motor control (a=-0.027 ± 0.01, p=0.01; b=-17.910 ± 3.620, p<0.001; c=0.537 ± 0.235, p=0.032; c'=0.058 ± 0.192, p=0.766), focal motor control (a=-0.027 ± 0.01, p=0.01; b=-9.287 ± 2.441, p=0.001; c=0.315 ± 0.140, p=0.035; c'=0.067 ± 0.129, p=0.611), and average VMPAC (a=-0.027 ± 0.01, p=0.01; b=-10.976 ± 2.521, p<0.001; c=0.455 ± 0.154, p=0.007; c'=0.161 ± 0.133, p=0.241). GMFCS level partially mediated the effect of FIQ when predicting the VMPAC sequence (a=-0.027 ± 0.01, p=0.01; b=-5.732 ± 2.767, p=0.050; c=0.512 ± 0.135, p=0.001; c'=0.359 ± 0.146, p=0.023). Conclusion: Motor deficit severity mediates effect of intellectual functions on speech motor control. The findings allow clinicians to identify early motor speech problems in children with CP using the GMFCS level alone.

Highlights

The motor disorders that are symptomatic of cerebral palsy (CP) are often associated with other disturbances, such as sensation, perception, cognition, communication, and behaviour, as well as secondary musculoskeletal problems [1]
No significant differences existed between the demographic characteristics of the two CP groups in terms of Gross Motor Function Classification System (GMFCS) levels (Table 1)
Our findings provide valuable evidence that will help clinicians to identify motor speech problem early; this will allow timely intervention based on a patient's simple GMFCS level when treating children with CP

Summary

Introduction

The motor disorders that are symptomatic of cerebral palsy (CP) are often associated with other disturbances, such as sensation, perception, cognition, communication, and behaviour, as well as secondary musculoskeletal problems [1]. Motor speech problems in these children can adversely affect functional communication and diminish their quality of life [4]. Motor speech is a complex motor activity that involves the coordination and integration of respiratory, laryngeal and articulatory systems [5]. Motor speech problems associated with CP have been attributed to underlying neuromuscular control impairment that affects the speech mechanism [7]; these include impaired control of respiration, phonological and articulatory muscles [8]. Impaired oro-motor functions, such as poor oro-motor coordination, and poor tongue and lip movements, can cause speech production errors in children with CP. These speech production errors in children with CP include stopping, voicing, backing, fronting and de-affrication [9]

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Discussion

Conclusion