What is spinal muscular atrophy?

Spinal muscular atrophy is a genetic disorder that impacts voluntary muscle movement.

Although spinal muscular atrophy affects only one in every 6,000 to 10,000 people, one in every 50 people is a carrier of the condition.

There is not a cure for spinal muscular atrophy.

Common related conditions
Amyotrophic Lateral Sclerosis (ALS)

Types of spinal muscular atrophy (SMA)

Type 1

Type 1 spinal muscular atrophy is the most serious form of spinal muscular atrophy. This type typically affects babies under six months of age. Most babies with type 1 spinal muscular atrophy pass away in the first few years of life because of breathing problems.

Type 2

Type 2 affects babies ages seven to 18 months. It is typically less severe than type 1 and most children with type 2 spinal muscular atrophy live into adulthood. Children with this condition typically have issues with their legs and may have trouble standing or walking without assistance.

Type 3

Type 3 spinal muscular atrophy affects toddlers under the age of 18 months old. Most babies born with type 3 live a normal life span.

Type 4

Type 4 spinal muscular atrophy affects adults. Most adults who develop this condition do not experience serious symptoms and live a normal life span.

Causes of spinal muscular atrophy (SMA)

Spinal muscular atrophy is passed down from your parents in faulty genes. If both of your parents pass the faulty gene down to you, you will likely develop the condition. If only one parent passes the gene down, you will be a carrier of spinal muscular atrophy.

Risk factors for spinal muscular atrophy (SMA)

Risk factors for spinal muscular atrophy include:

  • Race — Caucasians are more likely to develop spinal muscular atrophy
  • Family history — spinal muscular atrophy runs in families, so if a family member has it, you are also more likely to develop the condition

Symptoms of spinal muscular atrophy (SMA)

Symptoms of SMA will vary depending on what type of spinal muscular atrophy you or your child has. The most common symptoms include:

  • Weak arms or legs
  • Trouble breathing
  • Trouble swallowing
  • Muscle tremors
  • Difficulty walking, sitting or standing up

Symptoms by type of spinal muscular atrophy include:

  • Type 1 patients have trouble sitting up, supporting their heads and problems swallowing and breathing.
  • Type 2 patients may have trouble standing, crawling or walking on their own.
  • Type 3 patients may have trouble going up and down stairs, running or getting up from a sitting position; these patients may need more advanced assistance as they age.
  • Type 4 patients have mild symptoms such as tremors, weak leg or upper arm muscles, breathing issues and/or twitching.

Diagnosis of spinal muscular atrophy (SMA)

It is challenging to diagnose spinal muscular atrophy because symptoms mimic other conditions. During an exam, your doctor will evaluate your symptoms and take a full medical history (and family history) to determine if you may have spinal muscular atrophy. Your doctor may also order other tests to confirm the diagnosis including:

  • Genetic testing — if your doctor suspects SMA, he or she will order a blood test to determine if you have faulty genes that indicate SMA. The blood test can diagnose types 1 - 4 chromosome 5-related SMA.
  • Imaging tests — imaging tests such as a CT scan (computed tomography scan) or MRI (magnetic resonance imaging) test to obtain images inside the patient’s body.
  • Electromyogram (EMG) — an EMG can evaluate the electrical activities of the nerves.

Treatment of spinal muscular atrophy (SMA)

There is not a cure for spinal muscular atrophy. The goal of treatment is to relieve symptoms and improve quality of life for patients who suffer from the condition. Treatment will involve a team of Mercy Health healthcare providers from a variety of specialties who will work together to develop the most appropriate treatment plan.

Treatment options for spinal muscular atrophy may include:

  • Medication — a prescription medication called Spinraza was approved in 2016 by the FDA to treat children with SMA; Spinraza can reduce the risk of death or permanent ventilator in infants with SMA.
  • Breathing treatments — people with SMA often have trouble breathing and need a mask, mouthpiece or machine to help them breathe.
  • Nutrition — if your child is not growing properly or has problems swallowing, a nutritionist may be able to help ensure your child gets the nutrition he or she needs to grow.
  • Physical therapy — physical therapy can help strengthen weakened muscles and joints. When necessary, a physical therapist may recommend braces, a wheelchair or other devices that can help your child move better.

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