Spinal Muscular Atrophy (SMA) | Diagnosis & Treatments

How is spinal muscular atrophy diagnosed?

Spinal muscular atrophy (SMA) is sometimes difficult to diagnose, as symptoms can resemble other conditions or medical problems. Doctors usually diagnose SMA after a child has muscle weakness and decreased muscle tone.

If your clinician suspects SMA, they may use the following tests to diagnose the condition:

  • genetic blood tests, which can confirm the diagnosis of SMA
  • an electromyography (EMG) test that measures the electrical activity of a muscle or a group of muscles (in some cases)
  • a creatine kinase (CPK) test (to distinguish from other types of neuromuscular diseases, if necessary)

What are the treatment options for spinal muscular atrophy?

As yet, there is no complete cure for SMA. However, the discovery of the genetic cause of SMA has led to the development of several treatment options that affect the genes involved in SMA — a gene replacement therapy called Zolgensma, and two drugs, called nusinersen (Spinraza) and risdiplam (Evyrsdi). All three treatments were tested in clinical trials at Boston Children’s Hospital and elsewhere prior to their approval by the U.S. Food and Drug Administration (FDA).

You and your child’s care team will decide together the most appropriate treatment plan based on several factors:

  • your child’s age, health, and medical needs
  • SMA type
  • extent and type of symptoms
  • ability of your child to tolerate procedures and treatments
  • family preferences

Gene therapy for SMA (Zolgensma)

We provide the first gene replacement therapy approved by the U.S. Food and Drug Administration (FDA) for children with SMA younger than age 2 years — a promising treatment that delivers functional copies of the mutated gene to affected cells. Learn more about SMA gene therapy and the Boston Children’s Gene Therapy Program.

Risdiplam (Evrysdi)

Since 2016, Boston Children’s Spinal Muscular Atrophy Program has been actively involved in the key clinical trials for risdiplam (brand name Evrysdi), the first oral drug treatment for SMA. Risdiplam is the third treatment for SMA and was FDA approved in 2020 for use in children 2 months and older.

Our team is among the researchers involved in the ongoing FIREFISH trial, which provided some of the clinical information leading to ridsiplam’s FDA approval. This trial, and others we participate in, will continue to investigate risdiplam in participants for several years.

Nusinersen (Spinraza)

Our program was also involved in clinical trials of nusinersen (brand name Spinraza), the first drug treatment for SMA. We were the first hospital in the world to enroll an infant with type 1 SMA in the phase 3 ENDEAR trial in 2014.

Due to the success of clinical trials, the FDA approved the use of nusinersen for SMA in children and adults in 2016, and we began offering the drug to all eligible SMA patients. Our multispecialty SMA team helped to develop standardized ways to measure patients’ SMA symptoms and the changes in these symptoms over time. These results are being used to measure the effectiveness of nusinersen and other treatments.