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Infusion therapy for spinal muscular atrophy (SMA) involves the use of medications delivered via needles or catheters. It functions to help manage symptoms and prevent progressive weakness and deterioration of your skeletal muscles.

Oral therapies, such as risdiplam (Evrysdi), are taken by mouth. Infusion therapies may be delivered directly into the body through your veins as intravenous treatments.

Some SMA medications are injected with a needle into the cerebrospinal fluid (CSF) at the low level of the spinal canal, beneath the spinal cord.

When considering your treatment options, it’s important to keep in mind that SMA infusions tend to come with a hefty price tag.

Shortly after the 2019 approval of onasemnogene abeparvovec-xioi (Zolgensma) — the only gene therapy approved for infantile-onset SMA — it was estimated to be the most expensive drug on the market, costing $2.125 million per patient.

While critics point to Zolgensma’s high price, it’s important to recognize that it’s a one-time treatment. Other injection therapies for SMA can cost up to hundreds of thousands of dollars per year, and patients generally need to take them on a regular basis, often for many years.

The good news? Some insurance companies do cover the cost of SMA therapies. The exact coverage depends on your policy, so it’s important to check the details with your carrier before starting any treatment for SMA.

You may also talk with your doctor about the possibility of participating in clinical trials, if interested.

Below are the types of infusion therapies currently available for the treatment of SMA.

Gene therapy infusions

Zolgensma is the first infusion approved by the Food and Drug Administration (FDA) for infantile-onset SMA (also called SMA type I). It’s a gene therapy that’s used for children ages 2 and under.

During the procedure, a healthy, functional human survival motor neuron (SMN) gene is injected to replace the missing or dysfunctional version.

Unlike other types of infusions delivered in clinical settings, Zolgensma is only given once. While many medications only help relieve symptoms, gene therapies make direct changes to the body to improve overall disease outcomes.

Spinal fluid injections

To date, there is one FDA-approved injection for SMA in both children and adults: nusinersen (Spinraza).

This treatment works by increasing the production of SMN proteins — something that people with SMA don’t produce enough of on their own — which are critical in preventing skeletal muscle weakness and wasting.

Other types of infusions for SMA

In addition to disease modification, other types of infusions are available to help treat the symptoms and complications of SMA.

For example, a 2020 study found that intravenous bisphosphonates (IV BP), an infusion typically used for the treatment of osteoporosis, was found to help prevent bone fractures in children with SMA.

Sold under the brand names Aredia and Zometa, BP infusions may help strengthen bones.

Infusion therapy is an effective treatment for SMA, especially when treatment starts at a young age.

However, it’s not yet known whether infusion therapies will help adult-onset SMA in the same way as infantile or childhood-onset subtypes of this progressive disease.

Zolgensma, for example, is only used in children under the age of 2 who have a diagnosis of infantile-onset SMA. So far, it has shown encouraging results, increasing the survival rate of those patients.

While Spinraza injections can be used in adults, the effects aren’t well understood in SMA type IV. This subtype develops after age 21. So far, Spinraza has shown the most promise in children between the ages of 2 and 12, but it has also been shown to benefit adults with SMA.


It’s also important to discuss the potential risks and side effects of infusion therapy with your doctor. Possible side effects can include liver damage, weakness, and injection site pain.

While BP infusions may decrease the risk of bone fractures, there have been reports of femur fractures as well as jawbone necrosis. However, these adverse events are considered rare.

Your doctor will help you weigh the benefits versus possible risks of SMA infusions.

Keep in mind that the effectiveness of any SMA treatment will vary between individuals. If your doctor recommends infusion therapy, the exact type will depend on your age, the type of SMA you have, and your overall condition.

While there’s no cure for SMA, infusion therapies can help manage symptoms, and prevent progressive weakness and deterioration of your skeletal muscles.

Zolgensma, which is only approved for children under age 2, is a gene therapy used to treat infantile-onset SMA.

There are also infusion therapy options for teens and adults with SMA, including Spinraza, as well as other types of injections that prevent complications from SMA.