How Spinal Muscular Atrophy (SMA) Is Treated

Treatments for the genetic disorder spinal muscular atrophy (SMA) include two approaches—disease-modifying therapy and symptom control. Spinraza (nusinersen) and Zolgensma (onasemnogene abeparovec-xioi) are the two treatments that are approved for preventing SMA from worsening, and they are considered disease-modifying treatments.

In addition to these disease-modifying therapies, other important aspects of managing SMA include at-home approaches such as respiratory care, optimization of motor control with physical therapy, and the use of devices to support the spine and muscles. Sometimes surgery may be needed to manage serious complications of SMA.

Disease Management 

SMA disease-modifying treatment has advanced substantially with the approval of two treatments: Spinraza in 2016 and Zolgensma in 2019. The prognosis and disease progression of SMA may be improved with these treatments. Keep in mind that because these medications are relatively new, the long-term outcome is not yet known.

If you or your child has SMA, you would have your disease-modifying treatment administered by a physician in a supervised setting.

Spinraza

Spinraza was approved by the U.S. Food and Drug Administration (FDA) in 2016. This medication is taken by intrathecal injection, a procedure in which the medicine is injected directly into the spinal fluid with a needle. This procedure must be done by a trained physician.

Treatments are injected as three loading doses every two weeks, followed by a fourth loading dose after one month. After the four initial loading doses, you would receive an injection of Spinraza every four months.

According to the manufacturer, the recommended dosage of Spinraza is 12 milligrams (mg), or 5 milliliters (mL), per administration.

Spinraza works by stimulating production of the SMN protein, a protein that is deficient in SMA. Replacement of SMN protein with this procedure helps the motor neurons in the body to function properly, preventing the disease from progressing.

Zolgensma

Zolgensma was approved by the FDA in 2019 for use in babies under two years old who have infantile-onset SMA.

It is used as a one-time intravenous (IV—injected in a vein) treatment. According to the manufacturer, the recommended dosage of Zolgensma is 1.1 × 1014 vector genomes (vg) per kilogram (kg) of body weight.

This medication is a type of gene therapy. It works by delivering a normal copy of the SMN gene (which is altered in SMA) into the blood through a non-infectious virus. The normal gene replaces the altered SMA gene so the body can produce SMN protein.

Both of these therapies have been studied in SMA, with promising results. You would have to discuss your specific situation with your doctor to decide which therapeutic plan is right for you or your child.

Other medications are in development for the treatment of SMA, including Risdiplam, a type of gene therapy.

Strategies for managing complications of SMA with at-home approaches, physical therapy, and prescriptions may be necessary even if you use disease-modifying therapy. It is important that you maintain close follow up with your doctor so that any issues that you may develop, such as breathing problems or infections, can be managed promptly.

Home Remedies and Lifestyle

Living with SMA requires lifestyle adjustments that affect the whole family. Often, family members need to learn how to assist with mobility.

Additionally, family members may need to assist with using at-home therapies. Respiratory devices are the most important and frequently used at-home tools in SMA.

Respiratory Devices

There is a range in the types of respiratory care used in managing SMA. Some devices provide oxygen or minimal airway pressure and can be easily used at home. Many people who have mild breathing problems with SMA only need to use breathing assistance while sleeping or during times when breathing is especially difficult, such as during an infection.

If your breathing becomes more impaired as your disease progresses, it may become necessary to advance to increasingly supportive and consistent respiratory care. Machines that provide full breathing assistance can aid with inspiration (breathing in) and expiration (breathing out) when respiratory muscles are very weak. Sometimes oxygen is provided through a respiratory machine as well.

Supportive Splint or Brace

If you or your child has developed musculoskeletal complications such as scoliosis or contractures, a brace or other supportive device may be necessary to hold the body in a comfortable and safe position.

You may need a brace or splint to support your arms, wrist, leg, or ankle. These should be custom fit to your size and needs. Using supportive devices can help you optimize your ability to get around safely and use your limbs (arms and legs).

If you have developed scoliosis, you may need an external back brace to support you and to prevent your spine from curving. With advanced SMA, you may need to secure your position in a wheelchair to prevent your back from leaning to one side, which can exacerbate scoliosis.

Wheelchair or Walker

You may need an assistive device to help you get around. There is a range of support that you can use, depending on your muscle control. Options include a cane, a walker, a wheelchair, or a mobilized wheelchair.

Physical and Occupational Therapy

Often, the effects of the motor limitations of SMA can be improved with interactive physical exercises and rehabilitative therapy approaches.

While physical therapy techniques cannot repair the nerves or muscles or reverse muscle atrophy, you can learn to optimize your motor strength, control, and coordination.

You can also learn to avoid injuries by learning how to control your weight and your limbs as well as possible. Therapy can often help prevent muscle contractures.

Goals and types of therapy used in SMA include:

  • Muscle strengthening and coordination: Consistent physical therapy with a therapist is often combined with exercises that you can learn to do at home. Consistently moving your muscles can help minimize muscle atrophy and maximize muscle control.
  • Swallowing safety: Sometimes choking can be a risk with SMA. Working with a specialist to learn to control swallowing muscles can prevent complications like aspiration pneumonia and choking.
  • Respiratory management: Because the muscles that control breathing are often weakened in SMA, exercises that help you to strengthen and control these muscles can be an important part of managing your condition.

Breathing exercises may include the use of a device at home. You may be instructed to take a certain number of deep breaths every day with a device that measures inspiratory and expiratory volume (how deep you breathe in and out). Your doctor or therapist may work with you to create targets and goals that you can measure with your respiratory device.

Passive muscle movements: If you or your child has severely diminished muscle strength, passive movements may be necessary. A family member or a therapist would move your muscles on a regularly scheduled basis to prevent contractures and pressure sores from developing.

Surgeries and Specialist-Driven Procedures

In some circumstances, surgery may be beneficial for the treatment of complications of SMA. There are several procedures that can help in managing the effects of this condition.

Procedures that may be needed to manage complications of SMA include:

Botulinum toxin: In situations when muscle stiffness is interfering with mobility, injections of botulinum toxin, a powerful muscle relaxant, may help. Often, oral muscle relaxants cause intolerable side effects, while injections can concentrate the effects of the medication towards the areas that need it most, with fewer side effects.

Release of contractures: When muscle contractures are painful or interfere with mobility, a surgical procedure to release contractures can be helpful in some situations.

Spine surgery: Scoliosis can be very severe in SMA, and the bony structural changes can impinge on the chest area, potentially impairing breathing. Spine surgery to surgically repair scoliosis may be necessary for some circumstances. Sometimes a supportive device, such as a rod, is surgically placed near the spine to support it and help keep it straight.

Tracheostomy: In some situations, the most effective way to manage breathing problems in SMA is with the use of a tracheostomy. This is a surgical procedure that involves the placement of a breathing tube directly in the throat. The tube may be attached to a mechanical device that aids with breathing.

Complementary and Alternative Medicine (CAM)

Alternative medicine is not considered an effective approach for disease modification or for preventing the complications of SMA. It is important that you discuss any treatment that you are interested in with your doctor to ensure that you do not expose yourself to anything that is not beneficial or that could be harmful to your overall health.

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Article Sources

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