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Spinal Muscular Atrophy

Spinal muscular atrophy (SMA) is a disease that affects a child’s nervous system. It damages the nerve cells that control how muscles work. As a result, a child’s muscles gradually weaken and waste away.

SMA is a genetic disease. A child can get it only if he or she inherits the gene for it from both parents.

Types of spinal muscular atrophy

SMA has several types. Three of them affect children. Each has different symptoms. And each starts at a different age.

  • Type 1 is known as Werdnig-Hoffman SMA. It’s also called infantile-onset SMA. A child with this type usually has symptoms just after birth. An infant may have trouble moving, swallowing, and feeding. The infant may not be able to hold up his or her head. A child with this severe form of SMA usually dies within 2 to 6 years. Children with type 1 often die from breathing problems.

  • Type 2 is called juvenile or chronic SMA. A child with this type is often diagnosed at 6 to 18 months of age. The main symptom is muscle weakness throughout the body causing difficulty walking and standing. Children with type 2 may need help moving around. They may need a walker or wheelchair. They often live into adulthood. But they are more prone to respiratory infections.

  • Type 3 is the mildest form. It can affect children from 18 months old up to their teen years. The most common symptoms include clumsiness, difficulty walking and climbing steps, fine tremor, and muscle weakness. Children with type 3 often have trouble getting up from a sitting position.

Diagnosing spinal muscular atrophy

SMA is diagnosed after symptoms start and after testing is done. For instance, early signs of muscle weakness may point to the disease. Your child’s doctor will also do a physical exam and ask about your child’s medical history.

Other tests can confirm SMA. These include:

  • Blood tests. These check for the gene that causes SMA.

  • Muscle biopsy. The doctor takes a sample of muscle tissue to look at under a microscope.

  • Electromyogram. This test can find electrical problems in the muscles.

Treating spinal muscular atrophy

SMA can’t be cured. So finding early is important. Treatment may depend on your child’s age, his or her overall health, and the type of SMA he or she has.

Children with SMA may have problems breathing and swallowing. This is because the disease affects the muscles that control these functions. Children with severe cases are especially at risk for these problems. They may need a breathing machine or nutritional care.

Weak arm and leg muscles can make it hard for a child to walk and stand. A wheelchair or walker can help keep a child independent. Physical therapy and exercise can help, too. They can make it easier to move and stay flexible.

Many children with SMA also have scoliosis. Scoliosis is a condition that causes the spine to curve. A doctor may recommend special devices to help prevent this problem. Surgery may be needed to fix it.

© 2000-2017 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.