What is SMA disease? What are the symptoms and treatment methods of SMA disease?

SMA , also known as Spinal Muscular Atrophy , is a rare disease that causes muscle loss and weakness. The disease, which affects mobility by affecting many muscles in the body, significantly reduces peoples quality of life. SMA, which is considered the most common cause of death in babies, is more common in western countries. In our country, it is a genetically inherited disease that is seen in approximately one baby in 6 thousand to 10 thousand births. SMA is a progressive disease characterized by muscle loss, originating from motor neurons called movement cells.

What is SMA disease?

It is a genetically inherited disease that causes loss of spinal motor neurons, that is, motor nerve cells in the spinal cord, causing bilateral weakness in the body, with involvement of proximal muscles, that is, close to the center of the body, leading to progressive weakness and atrophy, that is, muscle loss. Weakness in the legs is more pronounced than in the arms. Since the SMN gene in SMA patients cannot produce any protein, motor nerve cells in the body cannot be fed and as a result, voluntary muscles become unable to function. SMA, which has 4 different types, is also known as "loose baby syndrome" among the public. In SMA, which in some cases even makes eating and breathing impossible, vision and hearing are not affected by the disease and there is no loss of sensation. The persons intelligence level is normal or above normal. This disease, which is seen once in every 6000 births in our country, is seen in the children of healthy but carrier parents. SMA may occur when parents continue their healthy lives without being aware that they are carriers, and when this disorder in their genes is passed on to the child. The incidence of SMA in children of carrier parents is 25%.

What are the symptoms of SMA disease?

Symptoms of Spinal Muscular Atrophy may vary from person to person. The most common symptom is muscle weakness and atrophy. There are four different types of the disease, classified according to the age of onset and the movements it can perform. While the weakness seen in type-1 patients on neurological examination is general and widespread, in type-2 and type-3 SMA patients, the weakness is seen in proximal, that is, muscles close to the trunk. Typically, hand tremors and tongue twitching may be observed. Due to weakness, scoliosis, also called spinal curvature, may occur in some patients. The same symptoms can be seen in different diseases. Therefore, the patients history is listened to in detail by a specialist neurologist, his/her complaints are examined, EMG is performed and laboratory tests and radiological imaging are applied to the patient when deemed necessary by the physician. With EMG, the neurologist measures the effect of electrical activity in the brain and spinal cord on the muscles in the arms and legs, while a blood test determines whether there is a genetic mutation. Although symptoms vary depending on the type of disease, they are generally listed as follows:

• Weak muscles and weakness leading to lack of motor development
• Decreased reflexes
• Tremors in hands
• Inability to maintain head control
• Feeding difficulties
• Hoarse voice and weak cough
• Cramping and loss of walking ability
• Falling behind peers
• Frequent falls
• Difficulty sitting, standing and walking
• Tongue twitching

What are the types of SMA disease?

There are four different types of SMA disease. This classification represents the age at which the disease begins and the movements it can perform. The older the age at which SMA shows its symptoms, the milder the disease is. Type-1 SMA, whose symptoms are seen in babies aged 6 months and younger, is the most severe one. In type-1, slowing of baby movements may be observed in the last stages of pregnancy. The biggest symptoms of type-1 SMA patients, also called hypotonic babies, are lack of movement, lack of head control and frequent respiratory tract infections. As a result of these infections, babies lung capacity decreases and after a while they have to receive respiratory support. At the same time, arm and leg movements are not observed in babies who do not have basic skills such as swallowing and sucking. However, they can make eye contact with their lively gaze. Type-1 SMA is the most common cause of infant death in the world.

Type-2 SMA is seen in babies aged 6-18 months. While the babys development was normal before this period, symptoms begin during this period. Although type-2 patients who can control their heads can sit on their own, they cannot stand or walk without support. They do not verify on their own. Tremors in the hands, inability to gain weight, weakness and cough may be observed. Type-2 SMA patients, in whom spinal cord curvatures called scoliosis can also be seen, frequently experience respiratory tract infections.

Symptoms of type-3 SMA patients begin after the 18th month. In babies whose development was normal until this period, it may take until adolescence for SMA symptoms to be noticed. However, his development is slower than his peers. As the disease progresses and muscle weakness develops, difficulties such as difficulty standing up, inability to climb stairs, frequent falls, sudden cramps, and inability to run are encountered. Type-3 SMA patients may lose their ability to walk in later ages and need a wheelchair, and scoliosis, that is, curvatures of the spine, may be observed. Although the breathing of these types of patients is affected, it is not as intense as in type-1 and type-2.

Type-4 SMA, known to show symptoms in adulthood, is less common than other types and the progression of the disease is slower. Type-4 patients rarely lose the ability to walk, swallow and breathe. Spinal cord curvature can be seen in the type of disease in which weakness can be seen in the arms and legs. In patients who may be accompanied by tremors and twitching, the muscles close to the trunk are usually affected. However, this condition gradually spreads throughout the body.

How is SMA disease diagnosed?

Since spinal muscular atrophy disease affects movement and nerve cells, it is usually noticed when bilateral weakness and limitation of movement occur. SMA occurs when parents decide to have a baby without being aware that they are carriers, and the mutated gene is passed from both parents to the baby. If there is a genetic inheritance from one of the parents, carrier status may occur even if the disease does not occur. After parents notice abnormalities in their babies movements and consult a physician, nerve and muscle measurements are performed using EMG. When abnormal findings are detected, suspicious genes are examined with a blood test and SMA is diagnosed.

How is SMA disease treated?

There is no definitive treatment for SMA disease yet, but studies are continuing at full speed. However, the patients quality of life can be increased by applying different treatments to reduce the symptoms of the disease by a specialist physician. Raising awareness of the relatives of the patient diagnosed with SMA about care plays an important role in facilitating home care and increasing the patients quality of life. Since type-1 and type-2 SMA patients usually die due to lung infections, it is extremely important to clean the patients airways in case of irregular and inadequate breathing.

SMA disease medicine

Nusinersen, which received FDA approval in December 2016, is used in the treatment of infants and children. This drug aims to increase the production of a protein called SMN from the SMN2 gene and provide cell nutrition, thus delaying motor neuron deaths and thus reducing symptoms. Nusinersen, which was approved by the Ministry of Health in our country in July 2017, has been used in less than 200 patients worldwide in a few years. Although the drug received FDA approval without distinguishing between SMA types, there are no studies on adult patients. Since the effects and side effects of the drug, which has a very high cost, are not fully known, it is considered appropriate to use it only for type-1 SMA patients until its effects on adult SMA patients are clarified. For a healthy and long life, do not forget to have your routine check-ups by your specialist physician.