Cerebral palsy (CP) describes a group of permanent movement disorders that are attributed to disturbances in the developing foetal or infant brain (1). Growth and nutrition concerns are widespread in children with CP, despite the primary impairment being gross motor function (2). Studies of populations of children with CP have indicated that malnutrition is prevalent (3-8), with the potential to persist into adulthood (9). A significant contributing factor to suboptimal growth is poor nutritional status, due to an inadequate dietary intake, often exacerbated by altered energy requirements (2, 10). Poor growth and malnutrition in this population is related to poorer health, lower societal participation, increased healthcare utilisation and decreased survival (2). Conversely, the prevalence of overweight and obesity is an increasing health concern amongst many children with CP (11, 12). Nutritional management strategies are essential to prevent malnutrition, manage overweight and obesity, and maximise or stabilise growth and nutritional status. Currently, minimal data exists regarding basic nutritional parameters in preschool aged children with CP.
The overall aim of this thesis was to investigate energy balance and body composition in a group of preschool aged children with CP. The primary outcome was to determine the energy requirements of children according to functional ability, motor type and distribution, and compared to typically developing children (TDC) and published estimation equations. Secondly, differences in body composition between children with CP were evaluated according to functional ability, and compared to TDC. Finally, the relationships between energy intake, macronutrient intake and body composition were determined.
Eighty five children with CP aged 1.4 to 5.1 years, representing all gross motor functional abilities (I=42, II=10, III=13, IV=9, V=11) and 16 similarly aged, TDC participated in this cross-sectional study. Measurements obtained included details of functional ability, motor type and distribution, anthropometry, total energy expenditure (TEE), body composition, dietary intake and a clinical feeding evaluation. Due to time and financial constraints, isotopic data relating to TEE measurements were available for 32 children with CP and all 16 TDC. Nevertheless, these numbers allowed adequate statistical analyses.
Results: Energy intake assessment
The validity of dietary assessment methods used previously in children with CP was questionable. Evaluation of a modified three-day weighed food record in the current research confirmed the record accurately measured energy intake in preschool aged children with CP. When evaluating the bias in energy intake as a percentage of TEE, all bias was minimal (4.3 % to 16.8 %) and less than published data detailing typical within-subject variability in day-to-day energy intake (19 %) (13).
Results: Total energy expenditure and energy requirements
Children with CP had significantly lower TEE levels and hence energy requirements when compared to TDC (5200 ± 1286 kJ/day vs 6411 ± 755 kJ/day, p<0.05). Energy requirements decreased as functional ability declined, therefore marginally ambulant and non ambulant children had significantly lower energy requirements when compared to ambulant children (4359 ± 1000 kJ/day vs 6040 ± 953 kJ/day, p<0.05). Differences in fat free mass (FFM) and ambulatory status accounted for 67 % of the variability in energy requirements (p<0.01). There was a trend towards lower energy requirements with increasing number of limbs involved. Published population specific estimation equations consistently underestimated energy requirements in the non ambulant children with CP by 22 %.
Results: Body composition and functional ability
In the study cohort, there was a trend towards decreasing fat free mass index (FFMI) and increasing body fat (%) as functional ability declined. This reached statistical significance in children who were marginally ambulant or non ambulant (p<0.05). Ambulant children were similar to TDC in all body composition parameters. Non ambulant children had the lowest values of FFMI (11.4 ± 1.4 kg/m2) and highest body fat percentages (24.6 ± 10.7 %) of all participants. Changes in body composition have the potential to persist throughout childhood and impact negatively on overall health.
Results: Dietary intake and body composition
Children with CP had a lower energy intake compared to TDC (4236 ± 1090 kJ/day vs 5152 ± 1047 kJ/day, p<0.05), which decreased as functional ability declined. In contrast, the macronutrient composition of the diet was similar for all children. Energy intake was positively correlated to FFMI in both children with CP (r=0.36, p<0.01) and TDC (r=0.57, p<0.05). There were no significant relationships between any other dietary intake or body composition variables. Consequently, confirmed differences in body composition cannot be entirely attributed to the nutrient composition of the diet.
Altered energy requirements, body compositions and energy intakes are evident in preschool aged children with CP across the spectrum of functional abilities when compared to TDC. The important outcomes detailed in this thesis will assist in clinical practice when determining energy intake, energy requirements and body composition in this population. Future research is required to build on these findings and examine contributing factors, such as physical activity levels. In particular, longitudinal examination of energy balance and body composition is recommended.