One of the rare diseases, SMA is a combination of the initials of the words Spinal Muscular Atrophy. SMA, which is the most common cause of death in infants, is a disease involving the muscles. In addition to being more common in Western countries, it is a genetically inherited disease.
What is SMA?
It causes loss of motor nerve cells in the spinal cord, leading to stiffness of the muscles near the center of the body, causing weakness on both sides. SMA has a progressive course and causes muscle wasting. Patients have more pronounced weakness in the legs and arms.
In SMA patients, SMN days do not produce protein. Therefore, the motor nerve cells cannot be nourished. As a result, voluntary muscles cannot perform their tasks.
There are 4 different types of SMA, also known as loose baby syndrome. Patients’ vision and hearing are not affected and there is no loss of sensation. However, in some patients, the muscles necessary for breathing or eating are affected, resulting in breathing and swallowing problems.
SMA, which is seen in children of parents who are carriers, is seen in every 6 thousand births in our country. The surrogate parents are not aware of the disease. There is a 25% chance of SMA in children of parents who have a defect in their genes.
SMA Symptoms
SMA symptoms vary according to the patients. The most characteristic symptoms include muscle weakness and atrophy. SMA, which is divided into four different types according to the age of onset of the disease and what it can do, shows different symptoms according to the types. Symptoms commonly seen in SMA patients include the following.
- Tongue twitching
- Difficulty sitting,
- Difficulty standing,
- Difficulty walking,
- Frequent falls,
- Don’t fall behind your peers,
- Cramp,
- Loss of ability to walk,
- Puny voice,
- Weak cough
- Feeding difficulties,
- Inability to maintain head control,
- Decreased reflexes,
- Weak weakness leading to a lack of motor development,
Types of SMA
SMA is divided into four different types. This classification is based on both the age of onset of the disease and the movements that it can perform. The fact that the disease occurs at an older age makes it milder.
SMA Type-1
Type-1 SMA, seen in babies younger than 6 months of age, is the most severe type of SMA. It first appears in late pregnancy when the baby’s movements slow down. Symptoms seen in SMA type 1 patients, also called hypotonic babies, include lack of head control, lack of movement and frequent respiratory tract infections. Infections that babies experience cause their lung capacity to shrink over time. This narrowing causes babies to need respiratory support. They also lack basic skills such as sucking and swallowing. At the same time, arm and leg movements are not seen. They also have lively eyes and can make eye contact. SMA Type-1 is the most common cause of infant death in the world.
SMA Type-2
In Type-2 SMA, which occurs in babies between 6 and 18 months of age, babies develop normally before the onset of the disease. They can hold their head and sit without support. But they cannot stand, walk or get up on their own. In addition, babies have tremors in their hands, weakness, weight loss and coughing. Some babies are also prone to scoliosis and frequent respiratory infections.
SMA Type-3
The symptoms of type-3 SMA are 18. starts after the first month of life. Their development continues until the first symptoms of the disease. However, their development is slower than their peers. With the progression of the disease, difficulties such as inability to climb stairs, difficulty in standing up, sudden cramps, frequent falls and inability to run begin to occur. Patients lose their ability to walk completely in advanced stages. Type 3 patients also have respiratory difficulties, but they are not as severe as type 1 and type 2.
SMA Type-4
The type of SMA that develops in adulthood is type 4. In this type, which is rarer than other types of SMA, patients rarely lose their ability to walk, swallow and breathe. SMA Type-4 patients have weakness in their arms and legs and curvature of the spinal cord. some patients also experience tremors and twitching. In SMA type-4 patients, symptoms spread slowly throughout the body.
How is SMA Diagnosed?
Since SMA affects nerve cells, it is usually recognized by the appearance of bilateral weakness and limitation of movement. If a physician is consulted with the symptoms seen in infants, nerve and muscle measurements are performed with EMG. If abnormal values are detected in blood tests, gene tests are performed.
SMA Treatment
There is not yet a definitive cure for SMA. However, research for a cure for the disease continues at full speed. However, different treatments are available to reduce the symptoms caused by the disease. With these applications, patients’ quality of life can be improved. In addition, patients need to be made aware of the care of SMA patients. Since type 1 and type 2 patients often die from lung infections, it is extremely important to clear the airways if their breathing is inadequate or inconsistent.
SMA Medicine
Nusinersen, known as the SMA drug, received FDA approval in 2016. The working logic of the drug is that the SMN2 gene aims to provide cell nutrition by increasing the production of the protein called SMN. This delays motor neuron death and reduces symptoms.
In our country, the drug, which was approved by the Ministry of Health in 2017, has been tested in only 200 patients worldwide.
Although there is no type distinction in the FDA approval, it has never been tried in type-4 patients. Since the side effects of this drug, whose costs are extremely high, are not known, it is not used in type-4 patients in our country. The Ministry of Health currently only approves its use in the treatment of type-1 SMA patients.
