SMA Type II (Chronic)
Diagnosis of Type II is almost always make before 2 years of age with the majority of cases diagnosed by 15 months. Children with this type may sit unsupported although they are usually unable to come to a sitting position without assistance. At some point they may be able to stand. This is most often accomplished with the aid of bracing and/or parapodium/standing frame.

Feeding and swallowing problems are not usually characteristics of Type II although in some patients this can occur and a feeding tube may become necessary.

Tongue fasciculations are less often found in children with Type II but a fine tremor in the outstretched fingers is common. Children with Type II are also diaphragmatic breathers.


Because of the range of progression seen in patients with Type II it is hard to tell how fast, if at all, the weakness will progress. Some children may learn to walk with the aid of bracing and may survive into adulthood. However, others, due to weakened chest and respiratory muscles may become increasingly weak with probable respiratory infections such as pneumonia. There are many cases in which the initial progressive weakness may remain the same, or there may be periods of worsening followed by long periods of stability. With such variables, age of death can vary greatly. It can take place as early as 3 years or not until adulthood.

Although not all children diagnosed with Type II develop respiratory weakness, respiratory failure is usually the cause of death following a bout of pneumonia or other respiratory infection.