Spinal muscular atrophy, or SMA, is generally observed in infants and young children. An inherited health disorder, SMA affects the muscles and nerves. Since the disease is degenerative, it causes progressive muscle decline, leading to mild or severe disability. While it is not preventable, it helps to learn all about it to seek timely diagnosis and treatment. To get started, here are some common causes, symptoms, and treatment options for spinal muscular atrophy.

Causes of SMA
The most common forms of SMA, that is, types 0 to 4, are caused by missing or mutated genes.
Under usual circumstances, a gene known as SMN1 releases the SMN protein, which helps the motor neurons to thrive and function properly. But in some cases, the SMN1 gene is mutated or is missing. This usually happens when a child has two copies of the malfunctioning gene, each inherited from one parent.

Therefore, those who have SMA are not able to make enough SMN protein. Subsequently, the motor neurons are unable to grow, and instead, they start to shrink and die out. The overall effect of this is the brain is unable to control most of the voluntary movements, typically involving movement in the neck, arms, head, and legs.

Along with SMN1, the SMN2 gene is also capable of producing a small fraction of the SMN protein. In most cases, a person can have about eight copies of the SMN2 gene. In such situations, the severity of SMA symptoms is decreased since the additional genes do the work of the missing SMN1 gene protein.

Symptoms of SMA
In the cases of spinal muscular atrophy types 0 to 4, the severity of the symptoms can range from mild to intense depending on the amount of functional SMN protein present in the motor neurons. The higher the amount of SMN protein, the later the onset of the symptoms will be. Also, the severity of the symptoms will be milder. In general, the symptoms vary depending on the type of spinal muscular atrophy.

Type 0
Known to be the rarest form of SMA, type 0 has some of the most severe symptoms. These symptoms usually develop during pregnancy. Consequently, the baby does not make enough movements when still in the womb. They are born with weak muscle tone, weak breathing, and joint problems.

Type 1
This type of SMA also has severe symptoms. Usually, a child with type 1 SMA is unable to support their head on their own. Also, they are unable to sit up independently even at the age when they normally would. Some children develop floppy arms and have difficulties with swallowing and breathing.

Type 2
Also known as chronic infantile SMA, type 2 is usually observed in toddlers who are between 6 to 18 months old. The intensity of symptoms can range from mild to severe. Children with type 2 SMA experience weakness in the muscles of their legs. Therefore, they are able to stand, walk, and sit up only with some assistance and help.

Type 3
Also known as Kugelberg-Welander disease or juvenile SMA, type 3 has the mildest symptoms. So, a child may be able to walk and stand without any assistance, but they may find it difficult to get up from a chair, run around, or climb the stairs. As they grow older, children with type 3 SMA require mobility aids and devices such as wheelchairs. Symptoms for this type start when children are between 2 and 17 years old.

Type 4
The symptoms of this type of SMA usually develop during adulthood. Some of the notable signs to watch out for include muscle weakness, twitching, and breathing problems. Most of the time, the muscles of the upper arms and legs are affected as they start to become weak.

Most of the symptoms last throughout the life of the person with SMA. In several cases, one does still have some mobility, and sometimes, the strength of the muscles and range of motion improves with exercise and therapy. In many instances, people with SMA may continue to work for several years despite the symptoms.

Management options
Spinal muscular atrophy does not have any cure. The treatment plans that are usually recommended by doctors are geared towards managing the symptoms, slowing down the disease, and improving the quality of life of the person with SMA. Often, these treatments and management options are developed depending on the type of SMA and the symptoms. Some of the generally recommended management options of SMA include the following.

Mobility devices
These include braces, support devices, and wheelchairs. Doctors recommended these to help a person with SMA maintain independence of movement for as long as possible.

Physical and occupational therapy and rehabilitation
These therapies are recommended to improve the flexibility and strength of the joints affected by SMA. In addition, physical and occupational therapy also help in slowing down the progression of muscle wasting. Besides this, therapies for speech, swallowing, and chewing also help in living with SMA. These ensure that the person is able to feed and breathe well without the risk of asphyxiation.

Ventilation assistance
When SMA affects the capability of a person to breathe, non-invasive ventilation is generally given to avoid the risk of apnea while sleeping. In some cases, assisted ventilation during the daytime may also be needed.