Defining optimal growth in cerebral palsy: comparing apples to apples?

Growth problems are common in children with cerebral palsy (CP). When children with CP are malnourished, there is a higher incidence of morbidity and mortality, combined with decreased social participation and quality of life. The etiology of growth impairment in CP is multifactorial with both treatable (malnutrition, feeding, endocrine) and non-treatable factors. In well-nourished children with hemiplegic CP, the affected side is smaller than the unaffected side, suggesting there are unknown factors affecting growth that may be intrinsic to CP. A better understanding of growth patterns and the etiologies of growth impairment in CP is imperative to improve the nutritional care of children with CP. Strand et al. provide valuable information on the growth patterns of children with CP from birth to 5 years of age in their prospective study comparing anthropometric measurements against Norwegian reference curves. The authors found that children with CP and normal birthweight without feeding problems have the growth potential of typically developing children. Those children small for gestational age, at Gross Motor Function Classification System (GMFCS) levels III–V, or with feeding difficulties had significantly reduced growth. These findings support earlier work showing the presence of feeding problems and level of motor impairment as contributors to poor growth. We found only minor limitations to the study not directly mentioned by the authors. In a typically developing child, brain growth is measured by sequential measurements of head circumference over the first 2 years of life. In their study, Strand et al. only provided head circumference measurements for the first 12 months. Another limitation is the absence of ‘mixed’ as a CP subtype for children with both dyskinetic and spastic features. Similarly, in another related paper Stanek et al. demonstrated that the growth of patients with quadriplegic CP was consistently lower than patients with diplegic or hemiplegic CP. This paper did not differentiate children by CP subtype. Comparisons of children with either dyskinetic or ‘mixed’ CP would have been interesting to include because they have significantly higher energy expenditure. We agree with Strand et al. in recognizing the difficulty obtaining reliable stature measurements. Improvements in study design could include the use of alternate height measures such as knee height and tibial length as well as a measurement of body composition including tricep skinfold and DXA. Early identification of feeding problems may provide an opportunity to intervene and improve growth potential. The development of a standardized screening tool that can be used by primary care providers to identify feeding problems may be helpful. In 2013, a uniform definition of pediatric malnutrition was created, and then endorsed by the American Academy of Pediatrics, to standardize nutrition assessment leading to earlier identification and treatment of malnutrition. The use of this definition has been widely adopted throughout the United States. While applicable to typically developing children, the strict application of this definition could lead to inaccurate diagnoses and inappropriate interventions in CP. Stanek et al. caution us not to use standard charts in growth assessment and suggest that growth be evaluated according to the CP subtype. Brooks et al. have established growth charts in CP using GMFCS levels. We agree with Stanek et al. that a large database of children with CP by subtype and GMFCS level may help decipher if one or both may be used to better delineate differences in growth. The multifaceted variables affecting growth in CP would make creating a uniform definition challenging. However, the current lack of guidelines for clinicians is likely resulting in the use of comparison standards to the general population which may lead to inaccurate assessment with unnecessary interventions or the acceptance that malnutrition is an inherent part of CP. The work by Strand et al. and Stanek et al. is vital to help us better understand the growth patterns in CP. This work provides the foundation to define optimal growth, which is necessary in order to standardize the assessment and treatment of growth impairment in individuals with CP.