Spinal muscle atrophy refers to a group of hereditary diseases that are usually known to affect the spinal cord and the nerve cells of the brain. According to some health specialists, these diseases generally affect patients by destroying the motor neurons which are responsible for various muscle activities, such as speaking, swallowing, and breathing. Most doctors categorize this group of diseases into four different types, as each of them generally affects patients of different ages.

The types of spinal muscle atrophy (SMA) are:

1. Type 1
Also known as Werdnig-Hoffmann disease, type 1 spinal muscle atrophy usually occurs in children aged between 3 to 6 months. Infants affected by this disease are born with not only breathing difficulties but also contractures. SMA type 1 generally comes with symptoms like problematic limb movements, feeling of pain or difficulty while swallowing, and an absence or lack of deep tendon reflexes. Affected children may develop a painful condition of the spinal cord known as scoliosis. Sometimes, they may not be able to perform normal motor functions, such as sitting, standing, or walking.

This type of spinal muscle atrophy (SMA) is also known to progress quite rapidly. As a result, if the condition is not treated properly, it may also lead to the death of patients within 12 to 18 months.

2. Type 2
Children affected by type 2 SMA are usually known to show symptoms when they are between 6 to 18 months. However, according to many child specialists, the symptoms may also occur earlier in some cases. Unlike type 1 SMA, children with type 2 SMA can sit independently, but they too are unable to walk or stand properly. If the disease is left untreated, the affected children may also lose their ability to sit without any support.

Apart from these problems, infants may also experience problems breathing and swallowing. However, among the types of spinal muscle atrophy (SMA), type 2 SMA is known to be much less deadly as it responds to the treatments quite well.

3. Type 3
Type 3 SMA affected children are generally known to show the symptoms between the ages of 18 to 19 months. This condition affects the muscles of the legs, rather than the spinal cord like the other types of spinal muscle atrophy (SMA). However, if the disease is treated properly, the affected children can walk without any support.

4. Type 4
This is the only type of SMA which affects adults. People affected by this disease generally develop the symptoms after the age of 21 years. The symptoms generally include mild muscle weakness, twitching, or breathing problems.

Among the types of SMA, type 1 is known to be quite deadly. Thus, if you see any symptoms of the disease in your child, visit the doctor as soon as possible.