Nutritional differences in neurologically impaired children

Abstract

OBJECTIVES:

To determine whether the recommended nutritional intake of moderately to severely neurologically impaired children is congruent with current growth parameter expectations.

METHODS:

Observational cross-sectional study at a children’s hospice and a tertiary care children’s hospital. Medically stable enterally fed children followed by the palliative care team underwent anthropometric assessment and chart review for diagnosis, intake and medications. Intakes, guidelines and recommendations were compared.

RESULTS:

Intakes were less than recommended. All children were <50th percentile weight-for-age, with many <3rd percentile. Fourteen of 15 were in higher percentiles for absolute and relative body fat.

CONCLUSIONS:

Recommended dietary intakes were not achieved by these children. Despite this, measures of body fat indicate adequate intake. Low weight values may reflect diagnosis-related growth stunting or decreased muscle mass and bone density from immobility. The Centers for Disease Control and Prevention (Georgia, USA) weight-for-age and body mass index are not suitable measures of adequate intake in this group of children.

Nutritional support in the care of neurologically impaired (NI) children focuses on improving nutritional status and quality of life (1). Nutritional requirements are variable in this population, tending to be lower than in normal children (2). Undernutrition is common due to oral feeding difficulties (3) and can lead to negative health effects and the increased use of health care (2,4–6). Artificial enteral feeding can improve nutritional status but can lead to unwanted complications, including overfeeding (4). The goal of nutritional support should be to achieve the correct balance of adequate nutrition with minimal complications.

NI children fed enterally lack the ability to communicate satiety, which may lead to overfeeding (7). They may experience nausea, vomiting, gastroesophageal reflux, excessive salivation and aspiration, in addition to long-term, excess body fat deposition. Other contributors to body fat may include medication side effects, limited mobility and low activity levels.

The negative consequences of excess fat are significant to all children, but there are additional problems specific to NI children. There may be increased work of breathing or restriction of already compromised motor function, and the provision of care may become more physically difficult for caregivers. In addition, increased body fat may further complicate medical and pharmacological management (8,9). Despite the prevalence of obesity in NI children, there is limited research documenting its natural history, making the effects in adulthood unknown (10,11).

The Canadian Pediatric Society (CPS) guidelines on nutrition in NI children recommend that when enteral nutrition is indicated, paediatric formula should be provided based on energy requirements estimated using the Krick, height-based or resting energy expenditure-based methods (12). Some calculations overestimate actual energy requirements; therefore, monitoring of weight changes in response to nutritional intervention is suggested (12).

Standard evaluation of nutritional status using weight-, height- and body mass index (BMI)- based standardized graphs is difficult in NI children. Alternative methods of height estimation were developed because these children are unable to stand unassisted and often exhibit severe scoliosis, contractures and involuntary movements (13). BMI calculations, which depend on accurate height, are less accurate when based on estimation.

Body composition can be estimated using anthropometric measurements (skinfold thickness, midupper arm circumference), to determine proportions of lean and fat body mass, although care must be taken when comparing values obtained from NI children with the general paediatric population (14,15). Upper body skin fold thickness measures appear to be preserved in the nonambulatory child with cerebral palsy compared with lower body skin fold thickness because of a significant reduction in leg muscle mass in this population (16). Annual nutritional assessment is recommended for all NI children, with more frequent assessments for young children and those at high risk (12).

We measured the nutritional status of a small group of NI children to determine whether there was congruence among published guidelines, dietitian recommendations and actual nutritional intake. If a trend is demonstrated, this information would serve as a basis for a larger study to guide recommendations for stable, moderately to severely NI children.

METHODS

The present prospective observational cross-sectional study was conducted between May and July 2011 at Roger’s House Children’s Hospice (RH, Ottawa, Ontario) and the Children’s Hospital of Eastern Ontario (CHEO), a tertiary care paediatric teaching facility in Ottawa, Ontario, following approval by the CHEO Research Ethics Board.

Children followed by the CHEO Palliative Care Outreach Team and admitted for respite care at RH during the study period were screened for eligibility. Children included were moderately to severely NI (equivalent to Gross Motor Function System Classification IV–V), relatively medically stable and receiving enteral nutrition via a gastric feeding tube (G-tube). Primary diagnosis included cerebral palsy, known genetic disorders, and known or presumed metabolic disorders. Patients could be enrolled only once in the study. Children were excluded if they had diagnoses that did not include neurological impairment, were exclusively orally fed, were admitted for end-of-life care or had circumstances that prevented their participation in the study (eg, in foster care).

Data collection included bedside assessment and review of the child’s RH and CHEO charts. The Krick and height-based methods recommended by the CPS guidelines and the Harris-Benedict and recommended dietary allowance (RDA) (multiplied by 0.8 for a wheelchair-bound child) methods recommended by local dietitians were used to calculate recommended intakes (12). Standard Centers for Disease Control and Prevention (CDC, Georgia, USA) growth charts were used to determine weight, height and BMI percentiles (17); National Health and Nutrition Examination Surveys were used to determine skinfold and midupper arm fat index percentiles (14). Calculated statures were derived from an average of tibial length and upper arm length stature estimates. Equations derived from children with cerebral palsy were used because all of the children in the present study face similar issues that affect skeletal development (abnormal muscle tone, lack of weight-bearing) (18,19).

Bedside assessment included duplicate patient measurements obtained by a single observer, using one set of anthropometric tools (Defender body fat caliper, Sequoia Fitness Products, USA [14]). An assessment of muscle tone, activity level and presence of indicators of undernutrition (eg, bedsores, edema) was included (20).

Charts were reviewed for diagnosis, medications, nutrition plans, duration of enteral feeding and indicators of feeding intolerance. Each child’s caloric intake was recorded each day of their stay at the hospice, with inclusion of both oral and enteral nutrition if applicable. For children with variable intake, an average intake was calculated over the length of their stay (two to 18 days).

No bedside assessment data were missing and any missing chart review data were noted in the results.

RESULTS

Of the 37 children who received care at RH during the study period, 15 eligible children were enrolled (Table 1).

TABLE 1.

Patient demographics

Child	Sex	Age, years	Diagnosis	Length of stay in hospice, days	Length of G-tube feeds, years	Meds*
1	M	3	Cerebral palsy	6	3	1,2,6
2	M	4	Genetic	16	2	3
3	M	6	Genetic	4	5	6
4	M	9	Metab/neurodegen	3	>7	1,2,3,6
5	M	11	Metab/neurodegen	9	>7	1,2,3,4,5,6
6	M	15	Cerebral palsy	4	<1	1,6
7	M	16	Cerebral palsy	4	>7	1,2,3,4,6
8	M	16	Cerebral palsy	8	11	1,3,4,6
9	M	16	Metab/neurodegen	12	<1	1,2,3,4,5,6
10	F	2	Metab/neurodegen	4	<1	1,3
11	F	6	Genetic	4	3	1,2,4
12	F	6	Metab/neurodegen	18	6	1,2,3
13	F	9	Metab/neurodegen	5	8	1,2,3,4,6
14	F	10	Metab/neurodegen	15	5	1,4,6
15	F	11	Cerebral palsy	4	<1	1,3

^*Definitions of medications (Meds): 1 Antireflux medications including ranitidine, lanzoprazole, domperidone and others; 2 Laxatives; 3 Anticonvulsants including phenobarbital, lorazepam, carbamazepine and others; 4 Pain medication including nonsteroidal anti-inflammatory medications, opioids and antispasmodic medications; 5 Antipsychotic medications such as respiridone; 6 Other medications including vitamins, melatonin and others. F Female; G-tube Gastrostomy feeding tube; M Male; Metab/neurodegen Metatoblic/neurode-generative condition

The study population ranged from two to 16 years of age, with a median age of nine years. Nine of the children were male. The duration of G-tube use was more than two years for 12 of the children. There were five children with cerebral palsy, three with a known genetic disorder, and seven with a known or presumed metabolic disorder.

The majority of the children were on long-term pharmacother-apy, with many on medications that have been directly correlated with weight gain (n=10) and gastrointestinal side effects (n=13). These included anticonvulsant, antipsychotic, antispasticity, anti-depressant and antireflux medications. Seven children showed signs of feed intolerance during their index stay at RH (vomiting, gagging, increased secretions), and 13 of 15 children were on antireflux and/or anti-emetic medications, indicating longstanding issues with feeding intolerance. One child exhibited physical signs of undernutrition; this child had numerous severe decubitus ulcers.

Only five children had a registered dietitian (RD)-designed nutrition plan in their charts; most were acute-issue specific (post-pancreatitis). Only one included a recommended caloric intake, which was within 30 kcal/day of the RDA (multiplied by 0.8 for a wheelchair-bound child). Therefore, dietician-recommended intake using methods used by RDs at CHEO (80% RDA method) were calculated.

Figure 1 shows histograms of daily intake in kcal/kg/day above that recommended by each method of calculation. The number of patients is shown compared with the intake above the amount recommended in 10 kcal/kg/day gradations. Discrepancies were noted among the different methods for calculating energy requirements. Actual intake was less than calculated for: 10 of the 15 children (as calculated by the Krick method); all 15 children (height-based method); eight children (Harris-Benedict method); and 10 children (80% RDA method). A Wilcoxan signed rank test of intake above recommendations was performed for each method of calculation (Table 2). Despite the limited sample size of the population, the energy intake of the children was significantly lower than that calculated by the height-based method. The intake was also lower than calculated by the Krick and 80% RDA methods, although these comparisons did not achieve statistical significance in the small sample. The Harris method was not significanctly different, and it was noted that there is a wider variation in intake with more children at or above the intake recommended by this method.

Figure 1).

Histograms of intake above recommendations according to four methods. RDA Recommended dietary allowance

TABLE 2.

Wilcoxon signed rank test of intake above recommendations

Method	Median (IQR)	P
Krick	−5.6 (−15.9 to 4.8)	0.08
Height-based	−23.2 (−29.7 to −17.8)	<0.001
Harris	−2.1 (−10.4 to 8.2)	0.85
80% RDA	−4.5 (−15.1 to 1.45)	0.06

IQR Interquartile range; RDA Recommended dietary allowance

Weight and BMI values for each child were assigned to a percentile according to the standard CDC growth chart data tables.

All 15 children had a weight below the 50th percentile for their age (only two children were >25th percentile), with nine children below the 5th percentile (Figure 2). Using weight for height-age, 14 of 15 children were below the 50th percentile. BMI values were similarly low, with only one child above the 25th percentile.

Figure 2).

Percentiles for common anthropometric measurements in neurologically impaired children. BMI Body mass index

Two-site, skinfold thickness was used as a representative of the absolute amount of body fat present on the limbs (triceps skinfold) and trunk (subscapular skinfold). Eleven children were above the 25th percentile for two-site, skinfold thickness; only two children were below the 5th percentile.

Midupper arm fat index is affected by the amount of lean body mass, making it a relative measure of body fat composition. Eleven children measured above the 25th percentile for midupper arm fat index and no child was below the 5th percentile.

DISCUSSION

The estimates of energy requirements suggested by CPS guidelines and by local RDs did not match the nutrition received by our sample of moderately to severely NI children. RD-recommended methods (Harris and 80% RDA methods) were closest to estimating the actual intake, possibly because these methods were used in their original nutritional planning. Highly variable amounts of nutrition are being given, often with fewer calories than suggested.

Despite low weight, measures of body fat were reassuring in most children. Similar to normal children, an assumption is made that to fall in the ‘average’ range for fat is the goal for children with NI. Because of muscle wasting, due in part to disuse, using normal body weight in these children would mean that the muscle mass present in normal children would be replaced by fat. In a previous study (16), weight-for-height and limb anthropometric composition were examined in tube-fed children with cerebral palsy compared with normal children and orally-fed children with cerebral palsy. In this study, it was noted that skinfold thickness may overestimate fat in areas of higher muscle wasting (such as the legs for nonambulatory children with cerebral palsy). Midupper arm fat areas did not show this overestimation and was, thus, used to estimate body fat content in our sample. Weight-for-age on CDC growth charts is a poor measure of nutritional status in this population. Developed for use in typically growing children, they show every child in our study population weighing less than average, with 13 children falling below the 25th percentile. BMI values are similarly affected. Diagnosis-specific growth curves are available for some common genetic syndromes (21–23); however, they do not exist for the children with rare genetic disorders or the known or presumed metabolic disorders encountered in our study population. Prescriptive growth charts published for children with cerebral palsy are the best resources available to enable health care providers to better monitor nutritional status in these children (23). Low weight alone is not significantly associated with morbidity in a severely NI child, unless the child is below the 20th percentile for weight (24). Only two of our children with cerebral palsy and three of our children without cerebral palsy fell below the 25th percentile according to these charts.

The children in the present study were underweight according to standard percentiles, but lack of weight bearing leads to decreased density of both skeletal muscle and bone (25–27). The fixed nutrient/energy ratio of the formulas given to these children in combination with long-term anticonvulsant medications may also contribute to bone disease (28,29). A decrease in lean body tissue was seen in the midupper arm fat index measurements. The two-skinfold and midupper arm fat index percentiles for these children ranged from the 10th to the 90th percentile, with most values falling between the 25th and 50th percentiles.

It has been proposed that a normal body weight should not be the goal for NI children; a more appropriate goal is a ‘sufficient’ body weight (16). Attempts to increase nutritional intake because of perceived undernutrition may cause accumulation of excess body fat (30).

During the present study, many parents and care providers volunteered that they were rebuked by medical professionals for not feeding their children enough. Not only may this be untrue, it increases parental guilt about underfeeding their child. In one case, a child’s dietician withdrew herself from the care team because she felt uncomfortable with how little formula the child was being fed.

The present pilot project was limited by time and patient availability, and inclusion criteria designed to describe children with similar nutritional needs limited the numbers further. Many of the individual syndromes included present in a similar fashion and, because of nutritional impairment, have similar approaches to augmenting nutrition and similar secondary effects due to these interventions. The heterogeneity of our study population gives our results the potential for generalization to other populations of NI children. This would need to be demonstrated in larger, more comprehensive studies involving similar populations.

CONCLUSION

The children in the present study did not receive the amount of nutrition recommended by CPS or RD guidelines. Despite this, they had reassuring measures of body fat content. The midupper arm fat measures, which appear to be the most objective measures of body fat composition in this group of children, were all above the 5th percentile. Prescriptive growth charts for children with cerebral palsy may be validated for other children with rare genetic, metabolic or neurodegenerative conditions that lead to similar nutritional challenges. The common practice of attempting to achieve normal weight percentiles on CDC growth charts with nutritional supplementation does not take into account measures of body fat and may overestimate nutritional needs in this group of children. This overestimation may lead to unintended side effects including feeding intolerance, physical discomfort and increased difficulty in providing care. The present small study supports a larger, population-based study in children with similar nutritional challenges.