Nutritional evaluation of the neurologically impaired child

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Background

The tasks required for nutritional surveillance are the same for children with and without NI: nutritional screening and assessment. Common questions facing clinicians caring for children with NI are outlined in Table 1.

Task: Screening

What is the best way to measure children with NI?

Weight measurement is a key element of standard paediatric care that can generally be performed in the office setting by using established techniques or by weighing caregiver and child together, then the caregiver alone, and calculating the difference. In contrast, height/length measurement may be impossible to obtain due to spasticity, contractures, or limited co-operation due to cognitive impairment. Body segment measurements (e.g., knee height, tibial length, ulnar length) correlate strongly with height/length and have been used to derive equations to predict height ^[1] or as a direct surrogate ^[2]-[5]. However, segmental body measures require specialized equipment, skills, and reference values which are often not readily available in the paediatrician’s office. Furthermore, while correlation is strong for group data, more recent analysis suggests that there are unacceptably wide differences between actual and predicted values for individuals ^[4]. Therefore, while length/height should be measured using standardized technique whenever possible, the use of segmental measures is not indicated.

Should standard or specialized growth charts be used?

What patterns of growth suggest malnutrition?

Growth charts are used to detect unusual patterns of growth, thereby targeting children for further assessment of health and/or nutritional status. Many congenital or genetic conditions are associated with slowed growth or small size. Using condition-specific growth charts typically results in fewer children being identified for further assessment. Condition-specific growth charts assume that altered growth is constitutional, but altered growth may also be caused by high-prevalence nutritional compromise, and both may occur together. In older children with Down Syndrome, for example, some evidence suggests that Centres for Disease Control and Prevention (CDC) growth charts for the general population more accurately identify children with high adiposity than DS-specific charts ^[6]. Although the use of standard growth charts in genetic or congenital conditions may over-identify children for further evaluation, this approach reduces the risk of missing individuals with a potentially modifiable growth impairment.

In conditions without a genetic basis, such as cerebral palsy (CP), growth patterns may be influenced significantly by clinical presentation as well as nutritional status. Recently developed growth charts specific to children with CP further describe the risk of morbidity, considering both weight and Gross Motor Functional Classification System (GMFCS) score ^[7]. For children with GMFCS scores of I to IV and V without feeding tubes, those with weights below the 20th %ile experienced increased comorbidities compared with heavier children. Children in GMFCS categories I and II had a comorbidity hazard ratio of 2.2 if their weights were below the 5th %ile, while for children in GMFCS categories III to V, the mortality hazard ratio was 1.5 when their weights were below the 20th %ile. These charts are readily available online (http://www.lifeexpectancy.org/articles/newgrowthcharts.shtml) and may help clinicians to identify children who require additional evaluation and support.

Are there specific questions that help identify children with NI at risk for nutritional compromise?

Unlike typically developing (TD) children, NI children have a high prevalence of feeding challenges ^[8]-[13] that may ultimately lead to medical complications (e.g., chronic lung disease due to aspiration) or malnutrition. Greater motor impairment ^[14] and parental report of concerns about difficulty eating and drinking should alert clinicians to children with significant risk for oromotor or nutritional impairment. Specifically eliciting information about duration of feeds, feeding aversion, coughing or choking with feeds, recurrent pneumonia, or chronic chest symptoms should help identify children requiring further feeding and swallowing evaluation.

Task: Assessment

What are the nutritional requirements for children with NI?

Nutritional intake is assessed by comparing actual intake with expected requirements. As there are no specific intake recommendations for children with NI, intake goals are based on the needs of healthy TD children. During infancy, energy requirements are similar for all infants. The differential energy requirements between children with NI and their typical peers tends to widen with age, due mainly to differences in physical activity (PA) levels and body composition (e.g., muscle and bone mass) ^[16]. Equations have been developed to predict intake requirements, but data increasingly suggest that their predictive accuracy is insufficient for clinical use ^[17]. Somewhat limited data further suggest that energy requirements for children with NI may be 16% to 31% lower than for TD children, with lower requirements associated with greater degrees of impairment ^[16]. With this information in mind, clinicians must exercise clinical judgment regarding a child’s estimated energy requirements, monitor intake and issues, and adjust as needed. There is limited information regarding micronutrient needs in this population, but they are generally assumed to be comparable to those of TD children.

Are there specific nutritional risks in the NI child?

Children with reduced energy requirements may have associated insufficient micronutrient intake ^[18]-[20]. Children who require anti-epileptic drugs (AEDs) for seizure disorders may be at increased risk for specific micronutrient deficiency. Folate and vitamin B12 levels appear to be low in some children on AEDs, which may be associated with hyperhomocysteinemia ^[21] and increased long-term cardiovascular risk. Also, a large body of evidence has documented the association between prolonged AED use and impaired bone health, including greater risk for fracture, rickets, and osteomalacia ^[22][23]. The mechanisms are unclear and biochemical changes are inconsistent, but children with low energy intake for age or receiving AEDs should have regular monitoring of vitamin, mineral, and trace element levels, and receive supplements when indicated. Specific biochemical measures and testing intervals must be determined individually because no standard recommendations exist.

What tools are most useful for assessing nutritional status?

Growth can be considered as the sum of increases in fat mass (FM) and lean mass (LM) consisting of bone, muscle, and organs. Increases in LM occur with normal growth, while disproportionate increases in FM contribute to metabolic dysregulation and increased health risks. In children with NI, non-nutritional factors such as genetics and altered weight-bearing significantly impact the acquisition of LM and, thus, the relationship between nutrition and growth measurements. Weight is the indicator most commonly measured and tracked, but linear growth is more strongly correlated with accretion of lean tissue and organ (including brain) growth ^[24].

The challenges in measuring linear growth have led to the suggestion that body composition be included in the assessment of children with NI ^[25][26]. Although technology-based body composition tools (e.g., dual energy x-ray absorptiometry (DEXA) or bioimpedance analysis (BIA)) are accurate and relatively easy to use, they are not universally available. Estimation of body fat from skinfold (SF) measurements has been shown to be inaccurate in children with cerebral palsy (CP), likely due to altered distribution of body fat ^[27][28]. However, one study ^[29] has proposed modifications to equations based on two SF measurements that show good agreement with DEXA values ^[25][30], making this a reasonable option for use in the clinic setting. Although SF measurements are not routine in the paediatrician’s office, the technique is easily learned, can be reliably performed with practice, and requires only the purchase of a SF caliper, which is relatively inexpensive and available. The World Health Organization has prepared a training video demonstrating techniques for accurate measurement of all anthropometric measures, including SF, which is available online (https://www.youtube.com/watch?v=UVcEZoCDV20).

Summary

• Weight should be measured using standard techniques. Height should be measured using standard techniques if possible, but when impossible due to contractures, spasticity, or limited cooperation, segmental measures are not indicated.
• For most conditions, the use of condition-specific growth charts does not improve the ability to identify children at risk for nutrition-related morbidity.
• For children with CP, the use of GCFMS-specific growth charts (http://www.lifeexpectancy.org/articles/newgrowthcharts.shtml) may improve the ability to identify children at risk for nutrition-related morbidity or mortality.
• Children with NI who have a history of oral aversion, long duration of feeds, feeding aversion, coughing or choking with feeds,  recurrent pneumonia, or chronic chest symptoms, should be evaluated for both nutritional compromise and feeding safety.
• Energy requirements are similar to those of TD children during infancy, but decrease beyond the first year due to differences in PA and body composition. There is no accurate way to predict a child’s requirements. Individualized estimates followed by monitoring and adjustment as needed is the most effective approach.
• Children with low energy intake for age or those receiving AEDs should have regular monitoring of vitamin, mineral, and trace element levels and supplementation when indicated.
• Body composition assessment can add valuable information when monitoring the nutritional status of children with NI. For children with CP, this can be achieved using skinfold measurements and validated equations.

Acknowledgements

This practice point has been reviewed by the Hospital Paediatrics Section Executive, Community Paediatrics, and Mental Health and Developmental Disabilities Committees of the Canadian Paediatric Society.

CANADIAN PAEDIATRIC SOCIETY NUTRITION AND GASTROENTEROLOGY COMMITTEE

Members: Linda M. Casey MD, Eddy Lau MD (Board Representative), Catherine M. Pound MD (Chair), Ana M. Sant’Anna MD, Pushpa Sathya MD, Christopher Tomlinson MB, ChB, PhD
Liaisons: Becky Blair MSc RD, Dietitians of Canada; Patricia D’Onghia MPH RD, Health Canada; Tanis R. Fenton PHD RD, Dietitians of Canada; Laura Haiek, Breastfeeding Committee for Canada; Deborah Hayward, Bureau of Nutritional Sciences, Health Canada; Sarah Lawrence MD, Canadian Pediatric Endocrine Group
Principal author: Linda M. Casey MD

References

Disclaimer: The recommendations in this position statement do not indicate an exclusive course of treatment or procedure to be followed. Variations, taking into account individual circumstances, may be appropriate. Internet addresses are current at time of publication.