Supportive Therapy

The SMA treatment team also includes rehabilitation professionals such as respiratory, physical, occupational, and speech therapists. Rehabilitation treatment involves care related to positioning, mobility, activities of daily living, stretching, and use of adaptive equipment to maximize functioning and QOL.1

Respiratory therapists are key health care professionals involved in the care of patients with SMA.10 Respiratory assessments should include pulse oximetry and capnography, along with an assessment of cough effectiveness. Also, patients with SMA types 1 and 2 often require airway support, including noninvasive positive pressure ventilation, continuous positive airway pressure, or tracheotomy ventilation. Parents of children with these airway support devices will require extensive education. Part of respiratory management for this patient population includes chest physiotherapy and mechanical cough assistance.

Patients with SMA type 3 may have a higher risk for complications during acute illness and should be monitored closely for any signs of respiratory impairment.10 Because of the high risk for respiratory complications, patients with SMA should receive annual influenza (after 6 months of age) and pneumococcal vaccinations. In addition, for the first 24 months, infants diagnosed with SMA should receive therapy to prevent respiratory syncytial virus infection (palivizumab).


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Orthopedic professionals involved in SMA care help manage associated scoliosis, which is more common in SMA types 1 and 2.1,2 Patients may have chest deformity and hip instability that require treatment by an orthopedic specialist.2 Patients with limited mobility are at higher risk for osteoporosis and vitamin D deficiencies related to disuse and may experience fragility fractures.

The multidisciplinary team caring for patients with SMA includes speech therapists and nutritional specialists, who help to manage impaired swallowing and dysphagia.1,10 Regular growth and development assessments, including weight, height, and length measurements, are essential to help guide nutritional status. Additional gastrointestinal issues commonly include gastroesophageal reflux, constipation, and delayed gastric emptying, which may require surgical or pharmacologic interventions. Maintenance of a healthy weight is critical for patients with SMA because extra weight reduces mobility and increases the risk for comorbidities such as high blood pressure and diabetes and can exacerbate respiratory and orthopedic issues.1,2 Nonambulatory patients are at high risk for obesity because of a lack of physical activity.2

Spinal muscular atrophy is a complex disease requiring lifetime management involving a multidisciplinary team of health care providers. It also requires effective communication between the health care team, the patient, and their family as much of the care for patients with SMA types 1 and 2 is provided in the home. Although SMA types 3 and 4 may be less severe, patients and their health care providers need to be aware of how to manage this chronic disorder and optimize QOL. Knowing the essential assessments for monitoring disease progression, treatment outcomes, and potential complications is key to proactively caring for patients with SMA.

Delayed Diagnosis of SMA Type 3: A Case Study

Clay, a 12-year-old budding athlete, presents to his pediatrician having met every developmental milestone up to this point but showing subtle changes in leg strength. His mother notices changes in his running stride. In addition, he has fallen, both on and off the field, and has difficulty pedaling a bike.

At age 13 years, Clay notices a slight tremor in his hands during meals. The tremors are worse with purposeful activity. He is diagnosed with essential tremor by his pediatrician.

At age 16 years, Clay presents with progressive weakness in his legs. He struggles to get up from a kneeling position on the lacrosse field. His pediatrician observes physical changes, but Clay blames his weakness on a lack of conditioning.

That same year, obvious atrophy is apparent in his upper thighs and his pediatrician notes a difference in the muscular tone of his quadriceps versus his lower legs. At this point, 4 years after the initial visit to the primary care provider for the concern of a change in strength, Clay is referred to a pediatric neurologist.

At the initial appointment, the pediatric neurologist reviews developmental milestones, and Clay’s mother explains the history of falling, hand tremors, change in running stride, and inability to pedal a bike or get up from a kneeling position. Clay continues to deny that anything is wrong, saying he does not notice any physical changes. During the exam, the neurologist notes markedly impaired quadriceps strength and hypotonic reflexes in Clay’s lower extremities. The neurologist expresses concern that the patient may have a degenerative muscular disorder and orders laboratory tests, including creatine kinase, which is elevated to 4 times the normal level.

The neurologist refers the patient to the Mayo Clinic for further evaluation by a neuromuscular specialist. After the second specialty consult, EMG is scheduled to rule out SMA. The EMG findings suggest a neurologic source of the muscular weakness, which narrows down the differential diagnosis. The final and definitive diagnosis for SMA is obtained from blood work showing an SMN1 gene mutation and 4 SMN2 copies.

This case provides an example of diagnostic delays in a patient with SMA type 3 who met all infant and childhood milestones and developed progressive weakness in adolescence.

Mellisa Hall, DNP, AGPCNP-BC, FNP-BC, is a professor of nursing and chair of the Master of Science in Nursing Program at University of Southern Indiana College of Nursing and Health Professions, in Evansville, Indiana; Jennifer Titzer Evans, DNP, RN, NC-BC, is an associate professor of nursing and program chair of the undergraduate nursing program at the University of Southern Indiana.

References

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  2. Prior TW, Leach ME, Finanger E. Spinal muscular atrophy. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews. University of Washington; 1993-2021. Updated December 3, 2020. Accessed June 30, 2021. https://www.ncbi.nlm.nih.gov/books/NBK1352/
  3. Butchbach ME. Copy number variations in the survival motor neuron genes: implications for spinal muscular atrophy and other neurodegenerative diseases. Front Mol Biosci. 2016;3:7. doi:10.3389/fmolb.2016.00007
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  5. Kraszewski JN, Kay DM, Stevens CF, et al. Pilot study of population-based newborn screening for spinal muscular atrophy in New York state. Genet Med. 2018;20(6):608-613. doi:10.1038/gim.2017.152
  6. Chien YH, Chiang SC, Weng WC, et al. Presymptomatic diagnosis of spinal muscular atrophy through newborn screening. J Pediatr. 2017;190:124-129.e1. doi:10.1016/j.jpeds.2017.06.042
  7. Arnold WD, Kassar D, Kissel JT. Spinal muscular atrophy: diagnosis and management in a new therapeutic era. Muscle Nerve. 2015;51(2):157-167. doi:10.1002/mus.24497
  8. Centers for Disease Control and Prevention. Assessment Timed Up & Go (TUG). Accessed June 30, 2021. https://www.cdc.gov/steadi/pdf/TUG_Test-print.pdf
  9. London Health Sciences Centre. Critical Care Trauma Centre. Assessment of motor function. Accessed June 30, 2021.  https://www.lhsc.on.ca/critical-care-trauma-centre/assessment-of-motor-function
  10. Finkel RS, Mercuri E, Meyer OH, et al. Diagnosis and management of spinal muscular atrophy: part 2: pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord. 2018;28(3):197-207. doi:10.1016/j.nmd.2017.11.004
  11. Spinraza (nusinersen) injection, for intrathecal use. Prescribing information. Biogen; 2020. Accessed June 30, 2021.  https://www.spinraza.com/content/dam/commercial/spinraza/caregiver/en_us/pdf/spinraza-prescribing-information.pdf
  12. Zolgensma (onasemnogene abeparvovec-xioi) suspension, for intravenous infusion Prescribing information. AveXis; 2021. Accessed June 30, 2021. https://www.novartis.us/sites/www.novartis.us/files/zolgensma.pdf
  13. Evrysdi (risdiplam) for oral solution. Prescribing information. Genentech; 2020. Accessed June 30, 2021. https://www.gene.com/download/pdf/evrysdi_prescribing.pdf