Spinal Muscular Atrophy (SMA)

What are the signs and symptoms of SMA?

SMA consists of a spectrum of disease and has been classified into 5 types.

SMA type 0

SMA type 0 is the most severe form of SMA.

Symptoms may include:

• Congenital hypotonia (decreased muscle tone)
• Severe joint contractures (joint shortenings)
• Digital contractures (finger or toe tightening)
• Facial diplegia (bilateral facial paralysis)
• Respiratory failure
• Possible fractures

SMA type 0 is typically fatal in the womb or shortly after birth due to the severity of the disease.

SMA type 1 (Werdnig-Hoffman Disease)

Symptoms of SMA type 1 have an onset between birth and 6 months of age. 

Symptoms may include:

• Hypotonia
• Muscle weakness (with facial muscles spared)
• Alert appearance
• Respiratory insufficiency (“belly breathing”)

SMA type 2

Symptoms of SMA type 2 have an onset between 6 and 18 months of age. 

Symptoms may include:

• Hypotonia
• Muscle weakness (with facial muscles spared)
• Alert appearance
• Normal cognition (process of acquiring knowledge and understanding through thought)
• Reduced or absent deep tendon reflexes over time

Milestones may include:

• A weak sitting (tripods)
• Poor roll and crawl
• Ability to stand but not walk without assistance

SMA type 3 (Kugelberg Welander Syndrome) and type 4

Symptoms of SMA type 3 have a typical onset of greater than 18 months, but age can range from 18 months to late teenage years depending on symptoms present. SMA type 4 is typically defined as onset in adulthood.

The range of symptoms and severity of type 3 and 4 symptoms ranges greatly among affected individuals. Symptoms may include:

• Hypotonia and muscle weakness that is symmetric and proximal
• Decreased or absent reflexes
• Troubling rising from the floor (gowers' sign)
• A different gait

What tests are used to diagnose SMA?

A blood test can be done to look for the genetic changes associated with SMA. It is important that the testing ordered can detect SMN1 deletions and sequence variants as well as SMN2 copy number. 

Why choose Children's Colorado for SMA testing?

Children's Colorado's Neuromuscular Program specialize in diagnosis and management of neuromuscular conditions like SMA. We're the only hospital in the region with this type of clinic. Children's Colorado is active in SMA clinical trials and is administering Spinraza.

What to expect from SMA genetic testing?

Genetic testing is done with a blood sample obtained by a pediatric phlebotomist (an expert who draws blood) at Children's Colorado. Results usually take about two weeks.

How do providers at Children's Colorado make a diagnosis?

SMA is typically suspected after obtaining a medical history and clinical examination by a provider at the hospital. If SMA is a suspected diagnosis, the neuromuscular care coordinator is introduced to the family to assist with coordination of testing and establish care in the Neuromuscular Program.

How is SMA treated?

We follow the consensus care guidelines that have been published for SMA. At each clinic visit we provide information about ongoing clinical trials (at our site and nationally) to all families.

Additionally, we have a dedicated inpatient team that helps with continuity of care between clinic and hospitalizations. Many individuals with SMA may require scoliosis surgery, and Children's Colorado has a nationally recognized high-risk spine pathway that reduces complications and recovery time.

Why choose Children's Colorado for your child's SMA treatment?

The Neuromuscular Program at Children's Colorado has more than 30 years of experience working with kids and young adults with SMA.

In addition to providing care based on consensus guidelines, the clinic team is active in clinical research for future treatments of SMA. Currently four of our Neuromuscular Program providers are serving on the medical advisory board of Cure SMA.

• Muscular Dystrophy Association (MDA)
• Cure SMA
• The Gwendolyn Strong Foundation