Pediatric issues and vaccination

SMA is characterized by muscle weakness and atrophy resulting from progressive degeneration and irreversible loss of the anterior horn cells in the spinal cord (i.e., lower motor neurons) and the brain stem nuclei. The onset of weakness ranges from before birth to adulthood. The weakness is symmetric, proximal greater than distal, and progressive. Poor weight gain with growth failure, restrictive lung disease, scoliosis, joint contractures, and sleep difficulties are common complications of SMA.

Nutrition/gastrointestinal issues:

Bulbar dysfunction is universal in individuals with SMA I; the bulbar dysfunction eventually becomes a serious problem for persons with SMA II and only very late in the course of disease for those with SMA III. Gastrointestinal issues may include constipation, delayed gastric emptying, and potentially life – threatening gastroesophageal reflux with aspiration. Growth failure occurs due to gastrointestinal issues in SMA I patients. Non-ambulatory individuals with SMA II and III are at risk of developing obesity.

Respiratory:

Children with SMA I and II (and more rarely, type III) have progressive decline in pulmonary function due to a combination of weak respiratory muscles, reduced chest wall and lung compliance, and a reduction in alveolar multiplication. Respiratory failure is the most common cause of death in SMA I and II. Decreased respiratory function leads to impaired cough with inadequate clearance of lower airway secretions, hypoventilation during sleep, and recurrent pneumonia.

Orthopaedic:

Scoliosis, hip dislocation, and joint contractures are common complications in individuals with SMA. Scoliosis is a major problem in most persons with SMA II and in half of those with SMA III. Approximately 50% of affected children (especially those who are non – ambulatory) develop spinal curvatures of more than 50 degrees (which require surgery) before age ten years. Later in the disease course, non – ambulatory individuals can develop thoracic kyphosis.

Metabolic acidosis:

An unexplained potential complication of SMA is severe metabolic acidosis with dicarboxylicaciduria and low serum carnitine concentrations during periods of intercurrent illness or prolonged fasting.Whether these metabolic abnormalities are primary or secondary to the underlying defect in SMA is unknown. Prolonged fasting should be avoided to prevent this complication. Pre-symptomatic individuals should be monitored for the development of symptoms to determine appropriate timing to initiate targeted and/or supportive therapies. Individuals with SMA are evaluated at least every six months; weaker children are evaluated more frequently.

Multidisciplinary surveillance at each visit includes assessments of nutritional state, respiratory function, and orthopaedic status (spine, hips, and joints). Prolonged fasting should be avoided, particularly in the acutely ill infant with SMA.

Supportive Treatment of Manifestations in Individuals with Spinal Muscular Atrophy

Concerns Treatment/Referrals
1 Bulbar dysfunction leading to poor weight gain Growth monitoring, placement of gastrostomy tube and nutritional supplementation if needed.
2 Obesity Regular anthropometric and nutritional evaluations and dietary management.
3 Gastroesophageal reflux disease Antacids, proton pump inhibitors.
4 Bowel dysfunction (constipation) Stool softeners, prokinetics, osmotic agents, or laxatives as needed.
5 Respiratory insufficiency/ failure options Pediatric pulmonologist referral – Airway clearance techniques and secretion management; Noninvasive ventilation, such as BiPAP; Tracheostomy with mechanical ventilation if needed
6 Orthopaedic issues (Progress ive scoliosis or hip dislocation) Pediatric orthopaedician referral – Standard orthopaedic and surgical interventions as needed
7 Metabolic acidosis during intercurrent illness Supportive care with early intravenous fluids and glucose
8 Family support Coordinate care to manage multiple subspecialty appointments, equipment, medications and supplies. Ensure appropriate social support for families and to connect with local resources, respite and support. Training of caregivers for better management of patients.
9 Genetic counseling Screening in pre – symptomatic newborns, prevent recurrences in family and prenatal diagnostic facilities,

 

Vaccinations :

Children with spinal muscular atrophy are at increased risk of serious infections. The most important points to remember are as follows:

  1. These children should be offered all routine childhood vaccinations as recommended by Indian Academy of Paediatrics
  2. There should be special focus on pneumococcal and annual influenza vaccines (CDC 2019).
  3. Routine vaccinations should not be delayed in SMA patients and should be completed at appropriate age, even in COVID era, if possible to be given at home by competent health care worker with all precautions.
  4. The immunogenicity, efficacy and duration of pr otection of vaccines are lower than healthy children and hence if indicated higher antigen content or more doses may be required in these children.

Resources:

  1. Mercuri E, Finkel RS, Muntoni F, Wirth B, Montes J, Main M, Mazzone ES, Vitale M, Snyder B , Quijano – Roy S, Bertini E, Davis RH, Meyer OH, Simonds AK, Schroth MK, Graham RJ, Kirschner J, Iannaccone ST, Crawford TO, Woods S, Qian Y, Sejersen T, et al. Diagnosis and management of spinal muscular atrophy: Spinal Muscular Atrophy part 1: recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord. 2018;28:103 – 15.
  2. Chng SY, Wong YQ, Hui JH, Wong HK, Ong HT, Goh DY. Pulmonary function and scoliosis in children with spinal muscular atrophy types II and III. J Paediatr Child Health. 2003;39:673 – 6.
  3. Kelley RI, Sladky JT. Dicarboxylicaciduria in an infant with spinal muscular atrophy. Ann Neurol. 1986;20:734 – 6.
  4. Centers for Disease Control and Prevention (CDC). General Recommendations on Immunization. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR. 2019;60:1 – 61
  5. Prior TW, Leach ME, Finanger E. Spinal Muscular Atrophy. 2000 Feb 24 [Updated 2019 Nov 14].In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle ( WA): University of Washington, Seattle; 1993 – 2020.