Spinal muscular atrophy

Spinal muscular atrophy is a heterogeneous group of hereditary diseases characterized by degenerative changes in special cells of the spinal cord that are directly involved in the movement. These diseases are accompanied by weakness and atrophy of skeletal muscles. The classical form of the disease was first detected in children in 1891. In 1956, a new form of spinal muscular atrophy with a later onset and a relatively benign course was described. Similar cases of the disease were previously described as benign muscular dystrophy with involuntary twitching of muscle fibers( externally manifested by subcutaneous flutter).Subsequent studies have shown that different forms of spinal muscular atrophy can occur in the same family.

At present, based on the age of onset and severity of the course, it is customary to isolate type III of infantile atrophy of muscular atrophy.

type I - Werdnig-Hoffmann.

II type - intermediate.

III type - Kugelberg-Welander.

In addition, the literature has descriptions of children's spinal muscular atrophy occurring in combination with underdevelopment of brain structures, congenital fractures, the formation of early respiratory failure, congenital heart disease, arthrogryposis. The latter disease is a congenital pathology of the musculoskeletal system, which consists in limiting the normal mobility in the limb joints due to muscle atrophy and the replacement of muscle fibers with connective and adipose tissue. With arthrogryposis, the child's characteristic posture arises: the upper limbs are pressed against the trunk, excessively unbent at the elbow joints, while the brushes are compressed into the fists, reminiscent of the appearance of the paw of the bird of prey. The lower limbs are bent in the hip joints and divorced in the sides, and in the knee joints they are, on the contrary, unbent. In addition, as a result of deformation of the joints, clubfoot is formed. The frequency of occurrence of this disease in the population on the average is 1 case per 10 000 children's population. Spinal muscular atrophy is transmitted by an autosomal recessive type of inheritance.

The age of appearance of the first signs of spinal muscular atrophy is different for different variants of this pathology. With type I spinal muscular atrophy, the first manifestations of the disease occur in the first months of life, with type II in the first years of life, and with type III disease at the age of 10-20 years.

In type I spinal muscular atrophy( Verdnig-Hoffmann type), the mother already during pregnancy can pay attention to the later and weak fecundity of the fetus. Since birth, the child has expressed a widespread decrease in muscle tone( syndrome "flaccid child").From the first months of life, weakness and atrophy of the muscles of the upper and lower extremities appear, with the subsequent involvement of the muscles of the trunk and neck. Such changes in the muscles lead to the fact that children can not sit. Muscular atrophy and twitching of muscle fibers are usually masked by a well-pronounced subcutaneous fat. A characteristic symptom is the small tremor( tremor) of the fingers of the elongated handles( fascicular tremor).Sometimes there are jerking of the muscles of the tongue. A typical sign is also the weakening or complete disappearance of tendon reflexes( knee, Achilles), restriction of normal mobility in the joint, deformation of the skeleton. Due to the weakness of the intercostal muscles, the baby's chest becomes flattened. As a result of muscle weakness, there is insufficient ventilation of the lungs, frequent respiratory infections attach, and a variety of respiratory disorders occur. The mental development of children does not suffer. To confirm the diagnosis of spinal muscular atrophy, a study of muscle tissue is performed, where the atrophy of muscle fibers is determined. The course of the disease is unfavorable. The lethal outcome occurs usually at the age of up to 2 years due to the defeat of the respiratory muscles and the occurrence of various complications from the lungs.

With spinal muscular atrophy of type II, the disease first appears somewhat later( in the first 1.5 years of a child's life) and is characterized by a slower course. The main feature is the child's inability to stand up. Lethal outcome with this form of the disease usually occurs at the age of more than two years.

With type III spinal muscular atrophy, the disease usually begins at the age of 2-5 years( sometimes from two to 17 years) and progresses very slowly. Weak muscles of the legs and pelvic girdle lead to difficulty walking, getting up, climbing the stairs. Gradually, the process extends to the upper limbs. Along with muscular atrophy, almost always there is a pronounced increase in the size of calf and gluteus muscles in varying degrees. Tendon reflexes( knee, Achilles) gradually fade. In the majority of patients, there is a distinct twitching of the fibers in the muscles of the shoulder and pelvic girdle, less often in the muscles of the lower leg and forearm. Limitation of mobility, deformations of the skeleton are not characteristic, but can develop in the late stages of the disease. Sick people long save the possibility of self-service.

The main signs that do not cause doubts in spinal muscular atrophy are the following:

1) autosomal recessive type of inheritance;

2) the appearance of the first signs of the disease in the first 6 months of life( type I), under the age of 1.5 years( type II) or after 1.5 years( type III);

3) weakness and symmetrical atrophy of muscles of the trunk and extremities( mostly lower);

4) involuntary twitching of the muscle fibers of the limbs, small trembling of the fingers;

5) characteristic changes on the electroencephalogram;

6) characteristic changes in muscle tissue( atrophy of muscle fibers);

7) absence of disorders of sensitivity and pelvic functions( stool, urination);

8) progressive course with an unfavorable prognosis for types I and II and relatively favorable for type III disease;

9) positive results in DNA testing.

Effective treatment of spinal muscular atrophy is absent. Widely used therapeutic exercise in order to prevent the development and correction of limb movement limitation, improve muscle tone, delay the development of atrophy, maintain motor activity. The following types of physiotherapeutic treatment are recommended: massage, physiotherapy( proserine electrophoresis, muscle stimulation, thermal procedures for the affected muscles).Also, the orthopedic correction of the affected limbs is beneficial. Drug therapy includes vitamins B, vitamin E, nootropics( nootropil, fesam, pyracetam) and agents that improve metabolism( actovegin, potassium orotate, phosphadene, cerebrolysin).

In 1968, the disease was first described, which was called bulbospinal muscular atrophy, or Kennedy's disease. It is transmitted along the X-linked( linked to the female sex chromosome) recessive type of inheritance. The disease manifests itself in men aged 40 to 60 years. It is characterized by progressive weakness and atrophy of the muscles of the hands, forearms, feet and shins( mainly upper extremities), the appearance of involuntary twitches of muscle fibers, a decrease in tendon reflexes( knee, Achilles).As the disease progresses, the following pathological signs develop: violation of swallowing, speech, atrophy and twitching of the muscles of the tongue and musculature around the mouth. Characteristic are also hormonal disorders, which manifest themselves as benign breast augmentation in men( gynecomastia), testicular atrophy, decreased potency and the ability of the sexually mature organism to produce offspring( fertility).

The course of the disease is slowly progressing. The social outlook is mostly favorable;