Feeding and swallowing are among the chief concerns for families and healthcare providers on non-sitters with spinal muscular atrophy (SMA).1 Bulbar muscle dysfunction affects the laryngeal and pharyngeal muscles, which can interfere with the ability to swallow and protect the airway.2,3 Moreover, bulbar dysfunction prevents adequate peak cough flows, so an affected individual is unable to clear their airway of secretions, debris, and partially swallowed food.4 These factors greatly increase the risk for aspiration and pneumonia in children with SMA.
Healthcare providers who are caring for a child with SMA who is a “non-sitter” should assess swallow function soon after initial diagnosis.1 Ideally, this swallowing evaluation involves a video fluoroscopic swallow study.1 Even if the child passes the swallow study, he or she should be followed closely for progressive changes that occurred during the course of the disease. If there is clinical suspicion of dysphagia such as weak suck, general fatigue, pneumonia, or “wet voice,” repeat swallow studies should be performed. Wet voice, it should be stated, indicates that the mucous membrane covering the vocal cords has been changed by aspirated particles.5 It is also important to keep in mind that in non-sitters, contracture of the masseter muscles often develops by one year of age.1 These contractures could interfere with the mechanics of chewing and swallowing and subsequently lead to malnutrition.
If the child with SMA fails the swallow study, a nasojejunal tube (NJ tube) should be placed for feeding purposes until a gastrostomy tube (G tube) can be inserted surgically. While it is not a settled issue, many experts recommend performing a Nissen fundoplication at the same time as G tube placement. The rationale to support this recommendation comes from the fact that patients with SMA have chronic gastrointestinal reflux and decreased GI motility. This, along with the risk of aspiration and pulmonary sequelae, support the use of a combined procedure.6
A dietitian should make caloric, fluid, macronutrient, and micronutrient recommendations based on the unique needs of children with spinal muscular atrophy. Nutrition labs can guide these decisions. Unfortunately, standardized growth charts do not provide a precise indicator of nutrition and growth in children with SMA, particularly in types I and II.7,8 Children with spinal muscular atrophy should meet with a dietitian every 3 to 6 months for reevaluation. Patients who have been prescribed specialized diets should meet with a dietitian on the more frequent side effect range (i.e., every three months).
Experts do not agree on a single nutritional regimen (e.g. elemental diet), but instead acknowledge that nutrition should be guided by individual patient need. On the other hand, fasting intended to prevent metabolic acidosis or fluctuations in blood glucose level should be avoided.1,9,10 As such, fasting during acute care should be kept to less than six hours at a time.1 Probiotics and agents that regulate bowel motility should be provided, and adequate hydration is an important part of maintaining gastrointestinal motility.
References
1. 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
2. Lunn MR, Wang CH. Spinal Muscular Atrophy. Lancet. 2008;371(9630):2120-2133. doi:10.1016/s0140-6736(08)60921-6
3. van den Engel-Hoek L, de Groot IJM, de Swart BJM, Erasmus CE. Feeding and Swallowing Disorders In pediatric Neuromuscular Diseases: An overview. Journal of Neuromuscular Diseases. 2015;2(4):357-369. doi:10.3233/JND-150122
4. Hadjikoutis S, Wiles CM. Respiratory Complications Related to Bulbar Dysfunction in Motor Neuron Disease. Acta Neurol Scand. 2001;103(4):207-213.
5. Warms T, Richards J. “Wet Voice” as a Predictor of Penetration and Aspiration in Oropharyngeal Dysphagia. Dysphagia. 2000;15(2):84-88. doi:10.1007/s004550010005
6. Durkin ET, Schroth MK, Helin M, Shaaban AF. Early Laparoscopic Fundoplication and Gastrostomy in Infants with Spinal Muscular Atrophy Type I. J Pediatr Surg. 2008;43(11):2031-2037. doi:10.1016/j.jpedsurg.2008.05.035
7. 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
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. Davis RH, Godshall BJ, Seffrood E, et al. Nutritional Practices at a Glance:Spinal Muscular Atrophy Type I Nutrition Survey Findings. Journal of Child Neurology. 2014;29(11):1467-1472. doi:10.1177/0883073813503988
10. Orngreen MC, Zacho M, Hebert A, Laub M, Vissing J. Patients with Severe Muscle Wasting Are Prone to Develop Hypoglycemia During Fasting. Neurology. 2003;61(7):997-1000.