Spinal muscular atrophy-Causes symptoms and treatment

Spinal muscular atrophy-Causes symptoms and treatment

Spinal muscular atrophy, aka SMA, is a genetic condition that most often affects babies and children, and makes it hard for them to properly use their muscles. It happens because of the breakdown of the nerve cells in the spinal cord and brain. It is a sort of motor neuron disease where the brain stops sending messages to the other parts of the body to control muscle movement. So as the muscles don’t move, they get weaker and smaller (atrophy). As a result, the sufferer can have difficulty sitting without help, walking or controlling the movement of the head. In severe cases, they can also find it difficult to swallow or breathe. Here, we present more about the types, causes, signs and effective treatments of SMA.


Signs and Symptoms of SMA

Symptoms of SMA can vary from person to person. Some signs of the disease come earlier and are more critical than others. Generally, babies with SMA don’t know how to roll or sit at the expected age. While an older child suffering from SMA might fall more often from beds than the other kids of the same age group. Holding and lifting things is difficult for them. 

A curved spine (scoliosis) is often noticeable in kids with SMA. It occurs because of weak back muscles. In severe cases, the child might not walk or stand and may find it difficult to breathe or eat. 

What Are the Types of SMA?

There are mainly four types of SMA. The four types of Spinal muscular atrophy is based on the disease’s severity and the age when the signs start:

Type 1 SMA

This is the rarest and most severe form of AMA. The baby may develop it while you are still pregnant. This stage is also called infantile-onset SMA or Werdnig-Hoffmann disease. In this condition, the babies cannot move much in the womb and have weak muscle tone and joint and breathing issues. They may have floppy legs or arms. It affects infants from birth up to 6 months of age. Most of the babies do not survive due to breathing problems. 

Type 2 SMA

This type of SMA is called chronic infantile SMA, and it affects kids from 7 months to one and a half years old. The child may sit but cannot move without any support as it affects the legs more than the arms. These signs may range from moderate to severe. 

Type 3 SMA

The third type of SMA is called Kugelberg-Welander disease or juvenile SMA. Signs for this type start when children are 2-17 years old. This is the mildest type of SMA in children. The child can walk without any help but find it difficult to sustain the standing position due to weak leg muscles and thus may fall often. They might need a wheelchair in later life to move around. 

Type 4 SMA

This type of SMA occurs in adulthood. The symptoms start after age 35 and slowly get severe with time. As this kind of SMA develops very slowly, many people suffer from this unnoticed until years after signs start. In this type, the upper arms and legs get affected. Also, the sufferer may have symptoms, including twitching, weakness, or breathing problems.  

Causes of SMA

This is mainly a genetic disorder that is primarily passed down through families. If a child has SMA, they must have two copies of broken genes, one from each mother and father. The SMN1 gene is responsible primarily for most types of SMA. This gene does not create enough protein required for the motor neurons to function correctly. When the children grow up, they become the carrier of this disease and pass the broken gene to their own child. 

What is the Diagnosis?

Doctors may suggest the following testing for SMA:

Genetic testing: this is the primary and most common way to check for SMA. They test the variation or omission in the SMN1 gene. 

A Muscle Biopsy: Another way to diagnose SMA is to take a small muscle sample and check it under a microscope. 

What are the Treatment Options?

There were no treatments available for SMA a few years back. Only physiotherapy or other supportive care were used in India. In the last 3 years, three new treatment options for SMA have been approved. 

Zolgensma gene therapy

The doctors replaced the defective gene or the missing or non-working gene with the normal gene in this therapy. This normal gene synthesizes the SMN protein to halt disease progression. The treatment is good, and the results are promising if given in the first few months.


This is the first orally deliverable medicine to treat SMN. The study proves that this treatment increases the SMN protein in both the central nervous system and peripheral organs.

Nusinersen (or Spinraza™)

Approved in 2016, this treatment helps to increase the amount of protein in the body that is required from the SMN1 gene. It creates a sort of imitating gene- SMN2 gene that looks like the SMN1 gene and produces the same protein released by SMN1 gene. This is injected directly into the spinal canal. Four doses of this medicine are given to the patient for over 2 months and then every 4 months after that. As per the studies, the treatment has shown significant improvement in motor function, breathing, and survival. During the lumbar puncture procedure, it is required that the child stay still. Sometimes, the child may need anaesthesia to sleep during the process.

Remember that every individual who has this disease may have different symptoms or experiences. Although it slows down the person’s movement, it does not affect their intelligence in any way. They can still socialize and make friends.

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Author: Ahaana Sahay