Spinal Muscular Atrophy Type 2
Diagnosis of Type II SMA is almost always made before 2 years of age, with the majority of cases diagnosed by 15 months. Children with this type may sit unsupported when placed in a seated position, although they are often unable to come to a sitting position without assistance. At some point they may be able to stand. This is accomplished with the aid of assistance or bracing and/or a parapodium/standing frame.
Swallowing problems are not usually characteristic of Type II, but vary from child to child. Some patients may have difficulty eating enough food by mouth to maintain their weight and grow, and a feeding tube may become necessary. Children with Type II SMA frequently have tongue fasciculation and manifest a fine tremor in the outstretched fingers.
Children with Type II also have weak intercostals muscles and are diaphragmatic breathers. They have difficulty coughing and may have difficulty taking deep enough breaths while they sleep to maintain normal oxygen levels and carbon dioxide levels.
Scoliosis is almost uniformly present as these children grow, resulting in need for spinal surgery or bracing at some point in their clinical course. Decreased bone density can result in an increased susceptibility to fractures. Major causes for concern include the Respiratory System, as once weakened it never fully recovers.