Spinal muscular atrophy (SMA) in children is a genetically based (inherited) neuromuscular disease that disrupts the ability of nerves to communicate with muscles. A child with SMA gradually loses control of most core muscle groups, which grow weak from lack of use. Nemours neuromuscular specialists offer many treatments and therapies to slow its progression and maximize function. Additionally, in 2016, there was a breakthrough in the treatment of SMA in children, allowing some children to live longer and reach developmental milestones. Nemours was on the forefront of the research leading to this discovery.
Four Types of Spinal Muscular Atrophy (SMA) in Children
There are four types of SMA, based on how severe the symptoms are and when they begin. Generally, the longer it takes for symptoms to start appearing, the less severe the disease will be.
- SMA type 1 (also called Werdnig-Hoffmann disease) is the most severe, with symptoms starting between birth and 6 months of age. These babies fail to sit or walk.
- SMA type 2 (or chronic infantile SMA), has more moderate symptoms, which start when a child is six to 18 months old. These infants can sit but not walk.
- SMA type 3 (Kugelberg-Welander disease or juvenile spinal muscular atrophy) has the mildest symptoms, which can start between 18 months and the teen years. These children do walk but have limitation and may lose skills over time.
- SMA type 4 develops more slowly, with symptoms usually starting after age 35, with slowly progressive limitation in walking.
How Spinal Muscular Atrophy (SMA) in Children Develops
Healthy muscles depend on nerve cells called motor neurons to tell them what to do. The motor neurons are located in the brain and spinal cord and carry these instructions from the brain, down the spine, to the muscle. The motor neurons depend on a special protein called SMN (“Survival of Motor Neurons”) to function properly.
Children with spinal muscular atrophy (SMA) lack the ability to make this essential SMN protein, because the gene for SMA that makes it possible to produce SMN is either defective or missing. Without sufficient SMN protein the motor neurons lose the ability to carry the brain’s instructions to the muscles. The muscles grow weak from lack of use and waste away (muscular atrophy). Thus the term “spinal muscular atrophy.”
Diagnosing Spinal Muscular Atrophy (SMA) in Children
Doctors who think a child might have SMA usually rely on various tests and imaging procedures to narrow down the diagnosis. These may include an electromyogram (EMG) and nerve conduction study.
In most cases, when SMA in children is suspected, the physician goes right to a genetic test (blood test) that checks to see if the gene responsible for producing the SMN protein is defective or missing.
Nemours Children's Hospital, Orlando
Locations & Doctors
For Appointments: (407) 650-7715
Hours: Monday–Friday, 8 a.m. to 5 p.m.
- photo ID
- medical and pharmacy insurance cards
- preferred pharmacy name and phone number
- names and dosage of all medications, including over-the-counter medication, your child is currently taking
- guardianship and custody papers, if a legal guardian rather than a parent accompanies your child
Bring these forms for your first appointment:
New Patient Forms
Returning Patient Forms
- Patient Presents Without Legal Guardian (PDF)
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Note: A parent or legal guardian must be with a child for a first visit.
Resources for Patients & Families
At Nemours Children’s Hospital in Orlando, your child will have the benefit of a team that includes some of the most accomplished pediatric SMA specialists in the world. Our SMA care is part of a comprehensive neuromuscular disease program that’s approved and supported by the Muscular Dystrophy Association (MDA) and the SMA Foundation.
It takes a team of pediatric professionals working together to care for a child with SMA. At NCH you’ll find doctors, counselors, nurses and staff who are uniquely qualified to provide this care, and who share a strong commitment to the long-term health and well-being of your child. Whatever form of this inherited disease your child has, our goal is simple: to treat each child as we would our own.
When you come to Nemours Children’s Hospital, you get a whole team of professionals devoted to your child’s care. Our experts treating SMA in children include:
- Physicians like the neurologists who establish the diagnosis, consider treatment options and help manage symptoms as SMA progresses. Also neuromuscular disease specialists in rehabilitation, orthopedics, pulmonology and gastroenterology.
- Therapists like the physical and occupational therapists who help your child remain as strong as possible and manage the activities of daily life. Also specialists in assistive technology to help with mobility and other devices that can help your child function independently.
- Dietitians who can provide nutritional support and advice.
- Geneticists to help families understand the genetic basis of SMA and offer counseling to make informed decisions about expanding their family.
At Nemours Children’s Hospital, our coordinated care team will work with your child to ease discomfort, build strength and preserve independent functioning for as long as possible. We treat SMA in children in a number of ways, including:
- Provide physical and occupational therapy to help preserve muscle tone and function.
- When appropriate, fit your child for orthotics (braces), mobility devices (such as a wheelchair and other assisting devices).
- Work with your family and caregivers to show you how to prepare nutritious meals that are easier to swallow and digest. If needed, we can also provide mechanical feeding systems to ensure that your child receives ongoing nutrition.
- Provide medication to help your child’s muscles function optimally.
- Support your child’s bone structure if orthopedic problems develop.
- Help your child avoid lung infections and related problems. If needed, we can offer breathing support devices.
- Provide counseling for your child and family members to help work through the challenges of caring for a loved one with SMA.
New treatments for SMA are being tested in clinical trials. Nemours Children’s Hospital (NCH) is one of only a handful of locations in the world that has been approved for participation in these studies.
The SMA program at NCH also participates in the Pediatric Neuromuscular Clinical Research Network for SMA, sponsored by the SMA Foundation, and works with other SMA experts at participating medical institutions. We also work with experts in Europe through SMA Europe, SMA REACH UK and TREAT-NMD.
We Value Your Involvement in Your Child's Care
We may know how to treat your child’s SMA, but no one knows your child better than you. That’s why we want you to be an active participant in the decision-making process for your child’s treatment. We’ll explain every step in easily understandable terms, present all options including alternative methods, and invite your input. We also maintain a physician hotline for families. If your child is undergoing treatment at Nemours Children's Hospital, you’ll be able to reach your Nemours neurologist or the physician on call anytime, day or night.