SMA, or Spinal Muscular Atrophy, is a neurological disease that affects motor nerve cells in the brain and affects mobility, is usually diagnosed in infancy or early childhood, and can lead to death if not treated early. It is one of the biggest genetic causes of infant mortality worldwide and is a rare disease. With the defect of motor nerve cells in the spinal cord, voluntary muscles are also affected. This leads to loss of basic functions such as walking, eating and breathing. It is one of the diseases with symptoms such as progressive muscle weakness and muscle loss. Unfortunately, there is no definitive treatment for SMA. SMA is one of the most searched diseases on the internet in recent years.
In the human body, many of the nerve cells that control the muscular system are located in the spinal cord. In someone with SMA, signals are not transmitted from the motor nervous system to the muscles. In other words, this order does not work in a systematic way in SMA patients as in a healthy individual. This leads to restriction of the individual's movements and significantly reduces the quality of life.
WHAT ARE THE SYMPTOMS OF SMA DISEASE?
Symptoms of SMA disease may differ from person to person. The main symptom in all forms of the disease is weakness and wasting (atrophy) of voluntary muscles. The variability of the effects of the disease depends on the age and mobility of the person. The symptoms of the disease can be listed as follows:
- Muscle wasting and weakness
- Difficulty sitting and standing
- Inability to walk
- Difficulty moving the head
- Difficulty in sucking and feeding
- Decreased reflexes
- Cramping and numbness
- Frequent falls
- Inability to maintain balance
- Twitching of the tongue
- Hand tremor
WHO GETS SMA DISEASE?
A healthy individual has SM1 and SM2 neurons that encode the SMN protein. If these proteins are not encoded in a systematic order, they cause neurons to die. SMN protein is important for the function of muscles in the human body. If this protein is not produced, nerve cells lose their function. Damaged spinal cord motor neurons have difficulty controlling the patient's muscular system. In particular, the patient cannot move his/her legs, arms, neck muscles and head. The individual with SMA has difficulty in performing certain actions that are under the control of the motor nervous system, such as walking and sitting, and cannot perform these actions without help. In SMA disease, which causes damage to the muscular system in the body, the person does not have difficulty in using sensory functions such as vision, taste, smell, hearing and touch. Since the disease does not affect sensory functions, all of them are normal and as they should be.
WHAT ARE THE TYPES OF SMA?
There are 4 different types of SMA, which is a neurological disorder and is seen as rarely as 1/10,000 in the world. These types may vary from person to person as they differ according to the age and mobility of the patient. The earlier the disease occurs, the more difficult the effects and treatment process are for the patient. The 4 forms of SMA disease can be explained as follows:
Type-1 SMA:
It is the form of SMA with the highest number of infant deaths. It is the most severe and common type of Spinal Muscular Atrophy. It is usually seen in babies 6 months old or younger. Symptoms may begin while the baby is still in the womb. The baby shows minimal functioning in the womb. A person with type-1 SMA has difficulty feeding and respiratory distress. The disease progresses rapidly and causes complications. The disease can cause respiratory tract infection in the progressive process. The baby with narrowing of the lungs has to receive support from a respirator.
Type-2 SMA:
They have a milder disease compared to type-1 SMA patients. Symptoms of Type-2 SMA are usually seen in babies aged 6-18 months and everything progresses normally before this period. The patient can usually sit up and has no trouble moving his/her head. But he/she cannot move on his/her own. They have difficulty standing without support. Curvature of the spine (scoliosis) is possible. Symptoms such as trembling hands and inability to gain weight are observed.
Type-3 SMA:
This type is seen after the 18th month. From the 18th month until puberty, the patient may develop SMA symptoms. Respiration may be affected in this type, but the effect is not as severe as in the other two types. There is no problem in standing and walking, but there is muscle weakness and it may be difficult to perform functions such as sitting and standing. The patient lags behind in physical activities compared to his/her peers. As the disease progresses, running may be difficult and falls are common. In adolescence and adulthood, the patient may need to use a wheelchair.
Type-4 SMA:
Type-4 SMA, the 4th and final type, occurs when the disease occurs in adulthood. Type-4 is rare and progression is slow. These patients can usually walk and rarely need support. Muscle tenderness and weakness may be seen in the arms and legs. Rarely, breathing and swallowing difficulties are observed. Curvature of the spinal cord is also possible.
HOW IS SMA DISEASE DIAGNOSED?
The question of how SMA disease is diagnosed can be answered as follows: After listening to the medical history of the patient, the physician first examines the patient. Necessary laboratory tests such as blood tests, genetic tests and EMG nerve and muscle measurements are performed. If the parents notice abnormalities in the baby's movements, they should consult a physician. If the doctor suspects that the baby has SMA, the parents' suspected genes will be analyzed and a blood sample will be tested to confirm the diagnosis. Depending on the test results, the doctor will diagnose the patient. Spinal muscular atrophy is diagnosed when there are complaints such as restricted movement and weakness because it affects movement and nerve cells. SMA is a genetically transmitted disease. Even if the mother and father are not directly affected, they may be carriers and may not be aware of this condition. In case of genetic transmission from either parent, the disease may not occur, but it can be passed on as a carrier.
HOW IS SMA DISEASE TREATED?
There is no clear cure for SMA and the search for a cure is ongoing. However, the treatment of the disease today is aimed at minimizing the effects of the disease. "nusinersen", known as the drug for SMA, was approved by the Ministry of Health in 2017. This drug aims to produce protein from the SMN2 gene. The drug is only administered to SMA Type-1 patients, the type with the most severe disease. On the other hand, treatment approaches are applied to improve the patient's quality of life. In SMA Type-1 and SMA Type-2 patients with advanced lung infection, respiratory support is provided to the patient in cases such as inadequate or irregular breathing.
WHAT ARE THE COMPLICATIONS OF SMA DISEASE?
One of the main complications of Spinal Muscular Atrophy is a decrease in the ability to control the muscles. The patient has difficulty controlling especially the arm and leg muscles. The respiratory muscles are also damaged in this disease where muscles are particularly targeted. The limp air flow to the lungs is related to the weakness of the respiratory muscles.
Individuals with SMA should pay attention to their respiratory functions throughout their lives to prevent the disease from causing more serious problems and should especially pay attention to protection against infections.
Curvature of the spine (scoliosis) is a common complication in SMA patients and is a condition that requires intervention. Because the spine is an important building block of the human body and plays an important role in the movement function of the body. Scoliosis, which is caused by the weakening of the muscles supporting the spine, is a disorder that significantly reduces the quality of life of the individual and restricts the movement function.
The age of onset of SMA and the level of control of motor functions are related to how much available protein is present in motor neurons. If SMA is not due to a deficiency of chromosome 5 or the SMN protein, the severity of the disease and the affected muscles may vary from person to person. In contrast to the type associated with chromosome 5, these may affect distal muscles that are, at least initially, further away from the center of the body.
In chromosome 5-related SMA, the later the onset of symptoms and the more SMN protein present in the patient's body, the milder the course of the disease.
In the past, SMA was diagnosed in infancy, giving the patient an average life expectancy of two years. Today, medical experts recognize SMA as a process and believe that such estimates are not accurate.