what happens when a muscle atrophies
When your child has SMA, there's a breakdown of the nerve cells in the brain and spinal cord. The brain stops sending messages that control muscle movement. When that happens, your child's muscles get weak and shrink, and he can have trouble walking and even sitting without help. In some cases he can have trouble swallowing and breathing. There are different types of SMA, and how serious it is depends on which type your child has.