Spinal muscular atrophy or SMA is generally identified by a lack of ability to use muscles. This condition mostly affects children and infants. When a child suffers from SMA, there is a breakdown of the nerve cells present in the spinal cord and the brain. As a result, the messages to control the movements of the muscles are no more sent by the brain.

Stages of spinal muscular atrophy
The types of stages and symptoms of spinal muscular atrophy are related. The symptoms of the condition are dependent on the type of spinal muscular atrophy.

SMA can be categorized under four different types. This is based on the developmental milestone the child is at when the condition develops. SMA type I and II can be most commonly found in children.

Type I or severe SMA
Also known as Werdnig-Hoffmann disease, this type of SMA is the most commonly diagnosed and the most severe form of the condition. The onset can be seen during birth or within the first few months after the child is born, between 0 and 6 months. This is an extremely progressive stage. 

Type II or intermediate SMA
The symptoms of this type of SMA can start to show when the child is anywhere between 7 and 18 months. How the condition progresses at this stage can also vary. The effects of this type can be seen more on the legs of the child. This stage of SMA can result in the inability of a child to stand.

Type III or mild SMA
Also known as Kugelberg-Welander or Juvenile Spinal Muscular Atrophy, the symptoms of this type of SMA can start to appear anywhere between 18 months and early adulthood. Patients suffering from type III are able to walk and stand. However, they might experience problems with standing up from a sitting position.

Type IV or adult SMA
This is a rare type of SMA that usually affects people by the time they are in their 20s or 30s. 

Symptoms of spinal muscular atrophy
The symptoms of the condition can vary based on the type of SMA. Hence, it is important to learn about both stages and symptoms of spinal muscular atrophy.

Type I symptoms
The symptoms at this stage include:

• Floppy legs or arms
• Difficulty swallowing
• Breathing problems

Type II symptoms
The symptoms of this type of SMA can range between moderate and severe, affecting legs more often. The child might need support to sit, walk, and stand. 

Type III symptoms
This is the mildest type of SMA. Standing and walking will not be a problem with children suffering from this type. However, climbing stairs, running, or getting up from a sitting position can be challenging. In later stages, wheelchair support might also be needed.

Type IV symptoms
The symptoms of this type include:

• Weakness of the muscles
• Breathing difficulties
• Twitching