How Is Spinal Muscular Atrophy Treated?

Spinal muscular atrophy (SMA) is a genetic disorder where muscles become weak and waste away. It happens when spinal cord nerve cells die, causing important muscles to become inactive. It is the most common genetic cause of death in infants.^1,2

Symptoms and outcomes vary depending on the type of SMA. The most common and severe type is type 1, where symptoms begin during the first few months of life. Milder types affect older children and adults in different ways.^1,2

There is no cure for SMA and most treatments are supportive techniques. These are therapies that may delay or prevent complications and improve quality of life. There are also disease-modifying drugs approved by the U.S. Food and Drug Administration that may improve motor function and other health outcomes in people with SMA.

Treatment for SMA may combine supportive therapy with disease-modifying drugs. Supportive therapy focuses on nutrition and breathing support, improving mobility, and preventing complications of muscle weakness. A team of doctors will manage these treatments.

Disease-modifying drugs

Three disease-modifying drugs have been approved for people with SMA:¹

• SpinrazaⓇ (nusinersen)
• Evrysdi™ (risdiplam)
• ZolgensmaⓇ (onasemnogene abeparvovec-xioi)

These treatments work in different ways to increase the amount of “survival of motor neuron” (SMN) protein produced by cells. This helps rescue motor neurons to prevent muscle wasting.¹

These treatments can improve outcomes for people with SMA in ways not seen in the natural course of SMA. Starting treatment before symptoms begin seems to increase the chance of reaching motor milestones. However, these treatments are very expensive. Evrysdi is an oral liquid taken by mouth, but the others are more complicated to administer.^1-4

Talk to your doctor to determine if any are right for your child. Children under age 2 who do not rely on a ventilator are usually offered any of the 3 treatments. Children who depend on a ventilator may not benefit from these treatments. Children over 2 years old and adults with moderate symptoms should be offered Spinraza or Evrysdi.²

The choice between these is personal and depends on:²

• Cost and availability
• Ease of taking the drug
• Risks of side effects
• Preferences and priorities of the child and family

More research is studying these treatments in different cases. There are also other treatments currently in clinical trials for SMA.^1,5-8

Breathing or respiratory care

Breathing is a major cause of illness for people with SMA. Respiratory failure is the leading cause of death for children with type 1 and 2 SMA. Early respiratory support and regular monitoring can improve quality of life and life expectancy.²

Soon after diagnosis, parents should discuss respiratory care with a pulmonologist. This is a doctor who specializes in the lungs and breathing. The pulmonologist will:^9-11

• Evaluate breathing and cough function
• Offer tips to keep the airway clear
• Suggest equipment to support breathing, such as bi-level positive airway pressure (BiPAP)
• Suggest cough assistance devices
• Develop personal respiratory care goals
• Create a care plan to use during acute illnesses, like a cold or flu
• Eating and nutrition

People with severe types of SMA often have low body weight because of under-nourishment. This is usually because of difficulty swallowing and feeding. On the other hand, children with milder types of SMA have a higher risk for weight gain because of inactivity. Either case can worsen muscle weakness.¹²

Your care team will monitor your child’s growth and nutrient intake. A dietitian on the team can develop a personalized diet and feeding plan. This diet will include foods that reduce the risk of inhaling foods or drinks (aspiration) while ensuring the right nutrients. They can also suggest ways to avoid other digestive issues, such as acid reflux and constipation. If feeding by mouth becomes difficult, they can recommend using a feeding tube.^2,9

Movement and daily activities

Muscle weakness is the most common and obvious symptom of SMA. It ranges widely between people depending on disease severity.

Your care team will help you develop a plan to manage muscle weakness and improve mobility. Physical therapists and occupational therapists can:^9,12

• Evaluate range of motion, strength, and mobility
• Recommend stretching and other exercises to perform regularly
• Suggest tools or assistive devices to maintain posture or prevent complications, such as braces or wheelchairs
• Suggest when surgery is needed to manage joint problems

Preparing for illness

An important part of SMA management is planning for emergencies. Treatments may prevent or delay complications and emergencies. However, in people with severe types of SMA, acute and severe illnesses are unavoidable.

Talk to your care team to create a plan with management goals during medical emergencies.

This includes:¹⁰

• Plans for care given in the home for airway clearance and ventilation
• When to seek emergency help
• How to communicate with EMS and other emergency care providers
• Plans for transportation to a hospital, including what personal equipment to use during transport
• Goals for hospital care and when to discharge

An especially difficult discussion is how to proceed when non-invasive techniques cannot support breathing. Whether to maintain invasive support or switch to palliative (comfort-focused) care is a personal and emotional decision. Discussing this with your family and doctors before a crisis occurs can help prepare you and the care team.⁹