Genetic mutations lead to the development of spinal muscular atrophy

Spinal muscular atrophy refers to genetically determined diseases and is characterized by progressive muscle atrophy as a result of impaired peripheral innervation. In this case, a blockade of spinal cord impulses going to the muscle fibers occurs, which causes the termination of their normal development and functioning. Muscles of the trunk and proximal parts of extremities are more often affected. The disease develops in newborn children, but sometimes affects people of young age.

Causes of the development of the disease

The development of pathology is associated with a gene mutation that leads to a disruption of the synthesis of a specific protein involved in the vital activity of motor neurons of the spinal cord. They are an accumulation of cells that are localized in the anterior spinal segments and form the motor roots. The main function of neurons is the regulation of contractile activity, blood circulation, metabolic processes of muscle fibers.

If the protein synthesis fails, the motoneurons are gradually destroyed both in the right and left half of the spinal cord. Symmetrical spinal muscular atrophy refers to an important diagnostic feature.

As a result, the muscles do not receive signals from the central nervous system, they lose the ability to contract. This negatively affects the motor activity and the acquisition of the child's self-care skills. At the same time, sensitive innervation is preserved in full.

The disease is transmitted by autosomal recessive type, so it is extremely rare in the population. In order for pathology to develop in the body, it is necessary to carry the defective gene by both parents. In this case, most often they do not have manifestations of the disease, and mutual carrier does not always give the appearance of an ailment in a joint child. It is proved that every 40 people can contain in their genetic material mutations of a certain kind of chromosomes, which condition the carriage of a defective gene.

Manifestations of the disease

There are several forms of development of pathology, which differ in the age of the onset of the first symptoms, the severity of the course, and the duration of life.

The later the pathology develops, the better the prognosis for life and maintenance of self-service skills.

In any case, patients become disabled, requiring additional care and special means of transportation( strollers, walkers).Often patients are chained to a bed, their condition is complicated by stagnant processes in the lungs, which can lead to death.

Type 1( Vörding-Hoffmann disease)

Spinal muscular atrophy type 1 may be suspected even in the prenatal period with a slight stirring of the child in the second half of pregnancy. For half a year after birth, note the sluggishness, low activity of the newborn. At inspection do not show tendon reflexes( achilles, knee).

Muscles of the upper and lower extremities, trunk and head do not develop. Weakness and atrophy of muscle fibers leads to the inability of children to fully sit, crawl, get up on their feet. As the skeleton grows, deformation of bones occurs. For example, when a newborn is attempted to sit, the spine is not supported by the muscular back skeleton, which leads to the development of kyphosis.

Often reveal involuntary twitching of muscles, trembling fingers of outstretched arms. Muscular atrophy can visually be smoothed out by the excessive development of subcutaneous fat. Due to the underdevelopment of the intercostal muscles, the thorax acquires a flattened shape. The function of swallowing, sucking, and breathing suffers, as a result of which serious complications develop: aspiration and congestive pneumonia, exhaustion, respiratory failure.

The development of the mental sphere is satisfactory, since the brain regions are not subject to pathological changes.

This form of the disease is considered unfavorable for life, these children usually die within the first years after birth.

Type 2( intermediate form)

Spinal cord atrophy in case of type 2 disease occurs at the end of the first year of life, usually at 7-18 months of the child. The signs of pathology are not expressed sharply and develop gradually. As newborns mature, they are noted to have weak motor activity. Children prefer to lie, reluctantly move in space, significantly lag behind in physical development from their peers.

Muscles of the body and extremities are prone to involuntary contractions, note twitching of the tongue. Children are able to sit, get up on their feet, sometimes move slowly with outside help. Eating and breathing are usually not difficult, the tendon reflexes are poorly developed. The lifespan of such patients reduces frequent respiratory infections and severe congestive inflammation of the lungs as a result of sluggish motor activity.

Type 3( Kulenberg-Welander disease)

The first symptoms of an illness appear at the end of the second year of a child's life, sometimes the development of muscle atrophy begins during puberty. The disease is characterized by a slow progression. First, the upper muscle groups of the legs are atrophied, then the pathological process affects the arms, trunk, and neck.

Patients suffering from 3 types of illness are able to move: to get up, walk, climb the stairs. A characteristic sign of the disease is hypertrophy of the gluteus and gastrocnemius muscles. However, as the dystrophic changes in the anterior sections of the spinal cord increase, the tendon reflexes fade, indicating irreversible changes in muscle tissue.

Over time, motor activity is reduced, which causes patients to use wheelchairs. For a long time the ability to self-service is maintained, the pelvic functions are well developed( urination, defecation).Sensitive innervation in the disease does not suffer.

Therapeutic tactics

Treatment of spinal muscular atrophy is of a supporting nature and is carried out throughout the life of the patient.

Recovery can not be achieved, but only slow the development of pathology in the nervous and muscular tissues.

Therapeutic tactics include a set of measures aimed at preserving motor activity.

1. Drugs that normalize the nerve impulse - proserine, nivalin.
2. Nootropic drugs that improve blood circulation of nerve tissue - piracetam, nootropil.
3. Means that stimulate blood flow and metabolic reactions in muscle tissue - actovegin, potassium orotate.
4. Vitamin preparations with antioxidant properties - tocopherol, B vitamins, glutamic acid.
5. Physioprocedures that enhance the circulation of the affected limbs - paraffin, UHF, electrophoresis with proserin.
6. Massage - stimulates muscle activity, promotes the excretion of metabolic products.
7. Medical gymnastics - atrophy of the muscles of the back, arms, legs after exercise slows down.
8. Orthopedic assistance - the use of special devices that support the motor activity of the chest, upper and lower extremities.

In the terminal stages of the disease there are respiratory disorders that require the transfer of patients to artificial ventilation.

Spinal muscular atrophy is considered a serious genetic disease with a constant progression of the pathological process and an unfavorable prognosis.

In recent years, scientists from all over the world are conducting scientific research on the synthesis of a drug that can replace the missing neuronal protein. This is the only hope for patients to recover and significantly improve the quality of life.

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