SMA Topics for Healthcare Providers

The following topics and resources may be helpful to healthcare providers who are providing care to individuals with SMA.

About SMA

Spinal muscular atrophy (SMA) is a genetic neuromuscular disease characterized by weakness of the skeletal and respiratory muscles. SMA is a rare disorder occurring approximately 1 in 11,000 births, and about 8 million Americans are genetic carriers. SMA is caused by a missing gene called the survival motor neuron 1 (SMN1); this is the gene that encodes the SMN protein. The SMN protein is critical to the health and survival of the nerve cells in the spinal cord responsible for muscle contraction (motor neurons).

Diagnosing Spinal Muscular Atrophy

SMA is often diagnosed on a clinical basis by how the child appears physically. The diagnosis may be suspected when children are noted to be weak or to have a delay in their developmental milestones, have low muscle tone, difficulty holding their head up, rolling over, sitting independently, standing or walking later than would be expected. A thorough medical history is performed, and a primary care provider may order genetic testing through a blood sample. A child may be referred to a pediatric neurologist who will also perform an examination and order genetic testing.

Early diagnosis can make a difference. Learn the signs to identify pediatric muscle weakness and neuromuscular disease. Child Muscle Weakness includes clinical resources and videos for healthcare professionals such as, how to learn about early identification of muscle weakness, view a motor surveillance tool, and download a screening and referral algorithm.

The Types of SMA

There are four primary types of SMA: type I, II, III, and IV. The type of SMA is based on the onset and highest physical milestones achieved. It is important to note that no two people with SMA have the same experiences. Decisions about care and treatment should be made according to each person’s needs.

Type I

Type I, also known as Werdnig-Hoffman disease, is the most severe and common. It is usually diagnosed during an infant’s first six months. Babies with SMA type I face many physical challenges, including muscle weakness, trouble breathing, coughing and swallowing. They may need breathing assistance or a feeding tube. Type I is often fatal early on in lifer. 60% of all SMA cases are type I.

Type II

Type II is usually diagnosed after six months of age, but before two years of age. Children with this type have delayed motor milestones, and display a range of physical abilities. Individuals affected by SMA type II can typically sit up without help, however some may need assistance getting into a seated position, but they are unable to walk and will require a wheelchair.

Type III

Type III, also called Kugelberg-Welander disease or juvenile SMA, is usually diagnosed after 18 months of age, but before three years of age. SMA type III can be diagnosed as late as the teen years. Individuals affected by SMA type III are initially able to walk, but have increasingly limited mobility as they grow, and eventually may need to use a wheelchair.

Type IV

SMA type IV is very rare. The onset of the disease is usually in adulthood, and it leads to mild motor impairment. While symptoms can begin as early as age 18, they usually begin after age 35.

The Genetics of SMA

SMA is caused by a mutation in the survival motor neuron gene 1 (SMN1). In a healthy person this gene produces a protein, called survival motor neuron (SMN) protein that is critical to the function of nerves that control our muscles. Without it, the nerve cells cannot properly function and die, leading to debilitating and often fatal muscle weakness.

A second gene also has a role in producing SMN protein. This is called survival motor gene 2 (SMN2), often called the SMA "backup gene." Most of the SMN protein produced by SMN2 lacks a key building block that is normally produced by SMN1. However; people with more copies of SMN2often have a less severe form of SMA than those with fewer copies.

It must be noted, however that the number of copies of SMN2does not reliably predict what type of SMA an individual will have or how weak their muscles will become. The determination of the type of SMA is based upon the physical milestones achieved.

Much of the research into SMA focuses on how SMN2 could be prompted to make more protein, or to make a complete protein. This could lead to new treatments that compensate for the loss of SMN protein caused by the SMN1mutation.

Complications of SMA

Though no treatment has yet been approved, proper care can improve quality of life for those with SMA. Patients with SMA often have impaired cough, respiratory insufficiency, dysphagia, gastroparesis, constipation, and evolving orthopedic issues including scoliosis.

Various types of equipment may be used, from respiratory support during sleep, e.g. BiPAP and mucus clearance devices, to gastrostomy tubes, to wheelchairs, and braces. Cognitive development is usually not affected. Usual primary care practice, especially care coordination, family support, as well as routine pediatric care immunizations, developmental surveillance, and monitoring of growth contribute to the overall well-being of this child and their family.

Care Management

In 2007 the Journal of Child Neurology published the "Consensus Statement for the Standard of Care in Spinal Muscular Atrophy" and the "Family Guide to Consensus Statement for Standard of Care in Spinal Muscular Atrophy." In the Family Guide to Consensus Statement, the Patient Advisory Group for the International Coordinating Committee for Clinical Trials provides the following recommendations for care management of SMA.

  1. Confirm the diagnosis of illness: A simple blood test can confirm whether or not the child has a mutation that causes SMA. If it is a positive gene test then the child’s diagnosis is confirmed. Although, 5% of children with the symptoms of SMA can have a negative SMN gene test and may require additional diagnostic testing. These tests can include an electromyography study (EMG), nerve conduction study (NCS) and/or a muscle biopsy and blood tests to help rule out other forms of muscle disease. If a positive test is confirmed then it is important for families to discuss these results with their doctor or genetic counselor. Individualized planning for patients is very important, to help the family understand and prepare for daily life as well as how to respond to medical emergencies that they could encounter in the course of the child’s life.
  2. Manage breathing problems: Respiratory problems are primary causes of illness and the most common cause of death for children with SMA type I and II. It is important to learn about maintaining a clear airway for all SMA patients, discuss breathing and support options with the medical team as well as develop a care plan with the medical team to prevent any issues, and work with the medical team to develop a care plan for responding to acute illness, such as a cold or flu to minimize the effects of respiratory infection.
  3. Manage feeding and nutrition issues: Patients with SMA are more susceptible to suffering from under- or over-nutrition and this can impact a child’s life. It important for the medical team, including nutritionists, dieticians, and/or therapists specializing in speech to monitor the child’s growth and work with the family to develop a personalized feeding and nutrition for the child. The medical team should work with the family on solutions for any swallowing, gastric reflux, or constipation issues. It is important for the medical team to monitor any eating or digestive problems if they arise that could lead to aspiration pneumonia and work with the family.
  4. Manage movement and daily activities: Muscle weakness in SMA will vary for each individual depending on the disease severity. Physical therapists, occupational therapists, speech therapists and/or rehabilitation specialists are the experts who can help the family and the rest of the medical team design the best care plan for the child. A physical therapist can design an individualized physical therapy plan to support function and help slow additional complications. It is also important to consult with the medical team about evaluation from an orthopedic specialist.
  5. Prepare for illness: It is important for families to plan for how to prevent emergencies. When an emergency occurs it is important to have a knowledgeable healthcare team’s support. Families should share their plans and management goals with all healthcare professionals involved in the care of their child.

Resources for Healthcare Providers

There are a number of resources available on our Cure SMA website:

On the Medical Advisory Council (MAC) page, you can learn more about experts on our advisory board.

On the Educational Resources page, you can learn about existing education opportunities on SMA.

On the Support and Care Publications page, you can download all of our Care Series Booklets.

Within this area, we encourage you to download our new Care Series booklet Learning about Clinical Trials. This booklet was developed with expert reviewers including many on our Medical Advisory Council. The booklet discusses the clinical trial process and important considerations about participation. As a member of the care team healthcare providers are in a unique position to inform families of the clinical trial opportunities that exist, and to help them walk through the process as they decide if participation is right for them.

On our Medical Issues page, you can download the full Consensus Statement for the Standard of Care as well as the family version. Within this same section, we have pages developed on the most significant medical issues that SMA patients and individuals face. Additional resources, guidelines/protocols, and presentations can be found on the following pages: palliative care, breathing, orthopedics/musculoskeletal issues, nutrition, and equipment.

If an individual has been newly diagnosed, we encourage you to refer them to our Newly Diagnosed section. In this area, we can connect you with resources that we provide to families directly.

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