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Infants born extremely prematurely (ie. <29 weeks gestation) or with extremely low birth weight (ie. <1000 grams) are at high-risk of major and minor motor sequelae that persist into the school years. Most of the research on the outcome of these high-risk infants has concentrated on the prevalence of major disability. The majority of high-risk children at school age have normal intelligence and no sensorineural disability. Despite this, these ???apparently normal??? high-risk children have a higher incidence of minor morbidities. Motor coordination problems are frequently reported, yet further investigation into the emergence of minor motor dysfunction, or its impact on academic achievement and everyday activities is seldom explored. The aim of this thesis was to provide a comprehensive investigation into motor dysfunction, which is commonly found in ???apparently normal??? high-risk children. This was addressed in a series of five studies that intended to provide insight into the emergence, prevalence, nature, and prediction of motor dysfunction in otherwise ???normal??? high-risk children. Study 1 examined the development of gross and fine motor skills from infancy to school age using a longitudinal cohort study design. ???Apparently normal??? high-risk children (n=58) were assessed with the Peabody Developmental Motor Scales at 18 months corrected age, 3 and 5 years. A significant proportion continued to have fine motor deficits to school age (64%), reflecting a persistent problem with fine motor skills throughout this period. The proportion of infants with gross motor deficits significantly increased from 18 months to 5 years (81.1%), particularly for the ???micropreemies???. Whilst there was no gender difference found, the development of gross and fine motor skills appeared to be influenced differently by the home environment. Study 2 examined the impact of motor dysfunction on performance at school age. The prevalence of Developmental Coordination Disorder (DCD) in ???apparently normal??? high-risk children was determined using a controlled cohort study design. In addition, the nature of DCD in this population was explored by testing sensorimotor abilities that possibly underlie the motor dysfunction. Fifty (50) high-risk children with IQ<85 and no identified sensorineural disability were assessed at 8 years of age along with a matched control from their respective class at school. The Movement Assessment Battery for Children and a battery of sensorimotor tests were administered. Results indicated a significantly higher prevalence of DCD (42%) in the high-risk group in comparison to the control group (8%). In relation to sensorimotor abilities that may influence motor performance, the high-risk group scored significantly lower on most of tests, however it was neurological ???soft signs???, postural praxis, and sequencing praxis that contributed to DCD in the high-risk group. Study 3 was designed to investigate the impact of motor dysfunction on a motor-based task performed within the school setting. Specifically, this study described handwriting skills in ???apparently normal??? high-risk children, determined the prevalence of handwriting dysfunction, and investigated sensorimotor abilities that may be associated with problematic handwriting. The high-risk cohort and matched controls described in study 2 were also administered a number of handwriting tests. High-risk children were found to have poorer handwriting legibility and speed in comparison to their classmates. The prevalence of handwriting dysfunction in the high-risk group was 46%, significantly higher than controls (18%). Hand preference, pencil grasp used, and pain whilst writing were comparable to the control group. The contribution of underlying sensorimotor abilities to handwriting dysfunction in the high-risk population however was not evident. By using the same subjects in studies 2 and 3, the co-morbidity of handwriting dysfunction with DCD could be determined. Of those high-risk children identified with DCD, 43% had co-morbid handwriting dysfunction. Study 4 explored the relationship between perinatal and environmental variables to Developmental Coordination Disorder and handwriting dysfunction in high-risk children. Perinatal and environmental variables of the 50 ???apparently normal??? high-risk children that participated in the previous study were analysed. Results indicated prolonged rupture of membranes (PROM) and retinopathy of prematurity (ROP) were significantly and independently associated with DCD, perhaps reflecting the impact of the antenatal infection process and visual development related to ROP on motor outcome in high-risk children. Perinatal variables were not associated with handwriting dysfunction, but high-risk males were more likely to have handwriting dysfunction. Maternal education and paternal occupation were associated with aspects of handwriting. Whilst handwriting is a motor-based activity, it appears to be influenced by environmental variables, similar to other academic areas for the high-risk population. Study 5 sought to determine whether a motor assessment at an earlier age could predict DCD in the ???apparently normal??? high-risk population at school age. Motor assessment at 12 months, 3 and 5 years for the high-risk subjects who participated in study 2 were analysed using Receiver Operator Curves (ROC curves). The 3 year assessment with the Peabody Developmental Motor Scales was the best predictor of DCD at 8 years, with the Griffiths Locomotor Scale at 3 years yielding a similar result. Findings suggest that high-risk children who scored below the specified cut-off points on 3 year motor assessments and who had a history of PROM or ROP were at greater risk of having motor-based problems that had the potential to interfere with functioning at school. |
