Spinal Muscular Atrophy (SMA)


Spinal muscular atrophy (SMA) is a condition with a wide clinical spectrum. Therefore, the coordinated efforts of a multidisciplinary treatment team are required to meet each patient’s needs.1

The specialists who work together to treat patients with SMA include neurologists, pulmonologists, gastroenterologists, orthopedists, and physical and occupational therapists. The multidisciplinary team may also include a palliative care specialist, nutritionist, and a genetic counselor.1

Patients should see their treatment team regularly to ensure that therapeutic approaches can be adjusted in line with their changing circumstances and the emergence of new treatments.

All care assessments and visits should be coordinated by a member of the team. This is usually the neurologist or pediatric neurologist.

Neurologists

SMA is characterized by alpha motor neuron degeneration due to low levels of survivor motor neuron (SMN) protein and, as a result, skeletal muscle atrophy.2 

A neurologist or pediatric neurologist is usually the first specialist that a patient with the disease will see. The neurologist will make and confirm the diagnosis of SMA and determine its type. The surest way of diagnosing SMA is by genetic testing.

Pulmonologists

SMA affects the respiratory muscles, so most patients have difficulty handling secretions. As a result, they experience recurrent pneumonia and sleep-disordered breathing.3

A pulmonologist can assess a patient’s respiratory function during a physical examination and with tests that include pulse oximetry, spirometry, and measurement of the end-tidal CO2, cough peak flow, and respiratory muscle strength.4

A pulmonologist should be involved in the treatment of patients with SMA and suggest the best therapeutic approach. This may include implementation of the following: cough assist, oral suctioning, use of nebulized bronchodilators, noninvasive ventilation with BiPAP, and tracheostomy/invasive ventilation.3

Orthopedic Surgeons

Muscle weakness in SMA can lead to skeletal problems and cause orthopedic complications [Link to SMA Comorbidities page] such as scoliosis, kyphosis, and contracture, which can exacerbate respiratory issues. Contracture and hip instability can limit mobility and cause pain. 

The orthopedist should work with the patient’s primary care physician to recommend the best treatments for musculoskeletal issues, such as spinal orthoses and scoliosis surgery. Scoliosis should be monitored every 6 months to 1 year.5 

Gastroenterologists

Muscle weakness in SMA can affect the voluntary muscles in the digestive tract, such as those used for chewing and swallowing. Patients may experience gastrointestinal problems, including dysphagia, aspiration, gastroesophageal reflux, constipation, abdominal distention, and delayed gastric emptying.6

A gastroenterologist can assess the health of the digestive tract and suggest the best treatment approach. This may include the use of proton pump inhibitors or histamine2 (H2) blockers to reduce discomfort. In more severe cases, a feeding tube may be suggested to ensure that the patient is getting adequate nutrition.

Dietitians

A dietitian can recommend nutrition plans and suggest nutritious foods that are safe to swallow according to speech therapy recommendations.6

Physical Therapists

Physical therapy [Link to SMA Therapies page] can help manage the skeletal deformities and respiratory complications of SMA through the use of stretching and range-of-motion exercises and strength training. Bracing and assistive devices may also maximize function.

Occupational Therapists

Occupational therapy in SMA aims to improve patients’ mobility and independence in the activities of daily living, such as bathing, dressing, grooming, and feeding. This can be achieved through the use of aids and adaptations such as walkers and wheelchairs or assistive technologies that the occupational therapist can prescribe.

Speech Therapists

Dysphagia and speech problems due to tongue, jaw, and throat muscle weakness in SMA can be addressed by a speech pathologist, who can design a therapy program.7 Speech pathologists can also recommend aids and devices that can improve communication.

Spinal Muscular Atrophy Palliative Care

The multidisciplinary team for SMA may include a palliative care specialist who focuses on ensuring that treatments match the patient’s life goals and provides help in overcoming challenges.1

Spinal Muscular Atrophy Genetic Counseling

Although almost all cases of SMA are caused by mutations in the SMN1 gene, various types of SMA can also be caused by mutations in other genes, such as IGHMBP2, UBA1, DYNC1H1, TRPV4, PLEKHG5, GARS, and FBXO38.8 Thus, families affected by SMA should be offered genetic counseling. A genetic counselor can interpret the results of any genetic tests and calculate the risk of passing the disease on to the next generation.1 Genetic counselors should also provide information on the possible options for future pregnancies, such as in vitro fertilization with a preimplantation genetic diagnosis or prenatal genetic testing. 

Reviewed by Michael Sapko, MD on 7/1/2021

References

  1. A guide to the 2017 international standards of care for SMA. Treat-NMD. Accessed June 8, 2021.
  2. D’Amico A, Mercuri E, Tiziano FD, Bertini E. Spinal muscular atrophy. Orphanet J Rare Dis. 2011;6:71. doi:10.1186/1750-1172-6-71.
  3. Schroth MK. Special considerations in the respiratory management of spinal muscular atrophy. Pediatrics. 2009;123(Suppl 4):S245-249. doi: 10.1542/peds.2008-2952K
  4. Chiang J, Mehta K, Amin R. Respiratory diagnostic tools in neuromuscular disease. Children (Basel). 2018;5(6):78. doi:10.3390/children5060078
  5. Scoliosis in SMA. SMA Foundation. Accessed June 8, 2021.
  6. Wang CH, Finkel RS, Bertini ES, et al. Consensus statement for standard of care in spinal muscular atrophy. J Child Neurol. 2007;22(8):1027-1049. doi:10.1177/0883073807305788
  7. Messina S, Sframeli M. New treatments in spinal muscular atrophy: positive results and new challenges. J Clin Med. 2020;13;9(7):2222. doi:10.3390/jcm9072222

Darras BT. Non-5q spinal muscular atrophies: the alphanumeric soup thickens. Neurology. 2011;77(4):312-314. doi:10.1212/WNL.0b013e3182267bd8

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