Children with spinal muscular atrophy (SMA) often experience substantial gastrointestinal and nutritional issues.1 Impaired feeding correlates with failure to thrive and various comorbidities.2 Moreover, recent research has suggested that people with SMA have higher rates of metabolic abnormalities including metabolic acidosis, hyperlipidemia, hyper/hypoglycemia, and hyperleptinemia.3,4,5 Consequently, consensus guidelines published by the SMA Care Group recommend that an expert nutritionist should follow patients of every SMA type.6
The authors of the SMA Care Group guidelines suggest that a nutritionist and/or pediatrician should perform regular growth assessments; however, they acknowledge that standardized growth charts specific to children with SMA are not available. Children with SMA not only exhibit abnormalities in fatty acid metabolism, but they also have a higher fat mass and lower free fat mass than healthy peers.7 While children with SMA may have a low body mass index for their chronological age, they simultaneously have increased fat mass and could be considered overweight or obese.8 Given these caveats, some experts suggest using standardized growth charts to broadly monitor growth and note trends. If the healthcare professional suspects there is a growth or development abnormality not evident from standardized growth charts, specialized testing such as bioelectrical impedance analysis can be used to screen for excess adiposity.9
Conversely, children with clear growth failure should receive supplemental nutrition.6 Moreover, the patient should be assessed for swallowing or gastrointestinal problems that may interfere with feeding. The nutritionist has to strike a careful balance between adequate nutrition and overfeeding given the risk of obesity in many patients with SMA. While each patient is different, risk can be stratified in to groups. Young children with more severe forms of SMA who eat orally struggle to gain weight. However, sitters and walkers are at risk for overweight as they get older.8 Since there are practical limitations to using cardiovascular exercise and weight training to control body weight, dietary management becomes particularly important. Moreover, it is easier to prevent excess fat mass through diet than it is for SMA patients to lose excess weight once the fat mass has accumulated.
Nutritionists should carefully track fluid, caloric, macronutrient and micronutrient intake.6 Just as it is difficult to track growth using standardized growth charts, it can be difficult to establish caloric and nutrient standards for individual patients. The nutritionist must consider basal metabolic demands, but also the requirements for physical therapy, surgery, acute illness, chest physiotherapy, and the day-to-day use of adaptive equipment. Body composition and resting energy expenditure determinations may be helpful in this regard.10
Osteopenia and low bone mineral density are common among children with neuromuscular disorders, including spinal muscular atrophy.11 Higher vitamin D and calcium consumption is association with increased bone mineral density. d.12 As such, nutritionists should pay particular attention to vitamin D and calcium intake and monitor serum levels, as needed. Deficient patients require vitamin and mineral supplementation. Occasionally, patients with SMA may have pancreatic dysfunction and altered glucose metabolism13, which may be a feature of the acquired mutation4, but may be more common in children who develop obesity during the course of the disease.13 As such, children should be followed for glucose intolerance and insulin insensitivity from an early age, especially if they meet criteria for obesity.
1. Chen YS, Shih HH, Chen TH, Kuo CH, Jong YJ. Prevalence and Risk Factors for Feeding and Swallowing Difficulties in Spinal Muscular Atrophy Types Ii and Iii. J Pediatr. 2012;160(3):447-451.e441. doi:10.1016/j.jpeds.2011.08.016
2. Messina S, Pane M, De Rose P, et al. Feeding Problems and Malnutrition in Spinal Muscular Atrophy Type Ii. Neuromuscul Disord. 2008;18(5):389-393. doi:10.1016/j.nmd.2008.02.008
3. Kolbel H, Hauffa BP, Wudy SA, Bouikidis A, Della Marina A, Schara U. Hyperleptinemia in Children with Autosomal Recessive Spinal Muscular Atrophy Type I-Iii. PLoS One. 2017;12(3):e0173144. doi:10.1371/journal.pone.0173144
4. Bowerman M, Swoboda KJ, Michalski JP, et al. Glucose Metabolism and Pancreatic Defects in Spinal Muscular Atrophy. Ann Neurol. 2012;72(2):256-268. doi:10.1002/ana.23582
5. Tein I, Sloane AE, Donner EJ, Lehotay DC, Millington DS, Kelley RI. Fatty Acid Oxidation Abnormalities in Childhood-Onset Spinal Muscular Atrophy: Primary or Secondary Defect(S)? Pediatr Neurol. 1995;12(1):21-30.
6. Mercuri E, Finkel RS, Muntoni F, et al. Diagnosis and Management of Spinal Muscular Atrophy: Part 1: Recommendations for Diagnosis, Rehabilitation, Orthopedic and Nutritional Care. Neuromuscul Disord. 2018;28(2):103-115. doi:10.1016/j.nmd.2017.11.005
7. Poruk KE, Davis RH, Smart AL, et al. Observational Study of Caloric and Nutrient Intake, Bone Density, and Body Composition in Infants and Children with Spinal Muscular Atrophy Type I. Neuromuscular disorders : NMD. 2012;22(11):966-973. doi:10.1016/j.nmd.2012.04.008
8. Sproule DM, Montes J, Montgomery M, et al. Increased Fat Mass and High Incidence of Overweight Despite Low Body Mass Index in Patients with Spinal Muscular Atrophy. Neuromuscul Disord. 2009;19(6):391-396. doi:10.1016/j.nmd.2009.03.009
9. Sproule DM, Montes J, Dunaway SL, et al. Bioelectrical Impedance Analysis Can Be a Useful Screen for Excess Adiposity in Spinal Muscular Atrophy. J Child Neurol. 2010;25(11):1348-1354. doi:10.1177/0883073810365185
10. Bertoli S, De Amicis R, Mastella C, et al. Spinal Muscular Atrophy, Types I and Ii: What Are the Differences in Body Composition and Resting Energy Expenditure? Clin Nutr. 2017;36(6):1674-1680. doi:10.1016/j.clnu.2016.10.020
11. Khatri IA, Chaudhry US, Seikaly MG, Browne RH, Iannaccone ST. Low Bone Mineral Density in Spinal Muscular Atrophy. J Clin Neuromuscul Dis. 2008;10(1):11-17. doi:10.1097/CND.0b013e318183e0fa
12. Aton J, Davis RH, Jordan KC, Scott CB, Swoboda KJ. Vitamin D Intake Is Inadequate in Spinal Muscular Atrophy Type I Cohort: Correlations with Bone Health. J Child Neurol. 2014;29(3):374-380. doi:10.1177/0883073812471857
13. Davis RH, Miller EA, Zhang RZ, Swoboda KJ. Responses to Fasting and Glucose Loading in a Cohort of Well Children with Spinal Muscular Atrophy Type Ii. J Pediatr. 2015;167(6):1362-1368.e1361. doi:10.1016/j.jpeds.2015.09.023