Leukodystrophy

Leukodystrophies are hereditary diseases of the nervous system, characterized by the breakdown of the myelin sheath, which leads to the destruction of white matter in the brain. leukodystrophies are extremely rare diseases that are transmitted through an autosomal recessive and recessive, sex-linked type of inheritance. The disintegration of the membrane covering the brain and nerve fibers during leukodystrophy is widespread. In this case, the cerebral hemisphere and the cerebellum are usually symmetrically affected. The gray matter of the brain is less affected. The basis of leukodystrophy is a violation of the exchange of various lipids that make up the myelin sheath, which is accompanied by their accumulation in nerve fibers and in nerve cells. Leukodystrophy is caused by the genetic defect of enzymes involved in the metabolism of myelin. The products of impaired lipid metabolism accumulate not only in the brain, but also in internal organs due to widespread metabolic disturbances.

At present, the following main forms of leukodystrophy are distinguished:

1) Scholz's metachromatic leukodystrophy;

2) leukodystrophy Crab;

3) leukodystrophy of Gallevarden-Spatz;

4) Pelitseus-Merzbacher leukodystrophy;

5) Canavan-van Bogart-Bertrand disease;

6) Alexander's disease.

Rare and atypical forms of leukodystrophy .Metachromatic leukodystrophy was first described by Scholz in 1925. This form is characterized by an intense decomposition of myelin with an excessive accumulation of toxic products in the nervous system. The disease is associated with a generalized impairment of lipid metabolism, with the accumulation of them in the central nervous system, peripheral nerves and internal organs. The first symptoms of the disease appear more often at the age of 2-3 years, sometimes in the first year of life. Early signs of the disease are motor disorders: decreased muscle tone with decreasing tendon reflexes, valgus position of the feet, unstable gait, signs of cerebellar involvement, involuntary movements of the eyeballs. Later, convulsions join, the decrease in muscle tone is replaced by its excessive increase. Atrophy of the optic nerves comes rather late. Gradually, the disorders of higher cortical functions increase, the decline in intelligence progresses, speech is broken, vision and hearing decrease. In the final stage of the disease, there is an increase in body temperature due to brain damage, circulatory and respiratory disorders, tetraplegia, and decerebral rigidity. The lethal outcome occurs at the age of 3-7 years from the attachment of various infections.

Acute pediatric form Crab is one of the forms of leukodystrophy, which occurs primarily in the white matter of the brain and spinal cord. The first signs of the disease develop in infancy( 4-5 months) and are manifested by increased excitability, crying. Periodically, there are attacks of shrill cries, during which convulsions may appear. Often there is an increase in body temperature. The leading symptoms of damage to the nervous system are increased muscle tone, atrophy of the nipples of the optic nerves, hearing loss. The disease has a constantly progressive nature, there is a violation of blood circulation and breathing, increases the rigidity of muscles, frequent seizures, increasing dementia. In the final stage of the disease, severe circulatory and respiratory disorders develop, decerebral rigidity, and exhaustion of the body.

Gallowelden-Spatz's leukodystrophy is a special form of diffuse cerebral sclerosis. The disease was first described in 1922. The first symptoms of the disease appear at school age( 7-12 years) by the appearance of involuntary movements of facial muscles, trunk and extremities. In the future, muscle stiffness appears and grows first in the lower, then in the upper limbs, there is oligo- and bradykinesia, ataxic disorders often join, dementia grows. In some cases, convulsions occur. In the later stages, there are circulatory and respiratory disorders. The disease is slowly progressive and can last for many years.

Peliceus-Merzbaher's disease was first described in 1885. It can be transmitted through an autosomal recessive or sex-linked type of inheritance. The disease begins at an early age( 5-10 months) and is characterized by a slow progression. A triad of symptoms is typical: involuntary movements of the eyeballs, trembling of the head and impaired coordination of movements. In the future, there is an increase in muscle tone, a change in speech( its slowing down), a progressive decline in intelligence, an increasing atrophy of the optic nerve. In the late stage there are involuntary movements, Parkinson-like syndrome, and dementia increases. Beginning in early childhood, the disease is rapidly progressing, especially in the early years of a child's life. In the future, a bright gap can be observed for a long time. Occasional non-progressive forms of the disease are observed.

Canavan-van Bogart-Bertrand disease also belongs to leukodystrophy. It is assumed that the process of disintegration of the myelin sheath begins during the intrauterine life of the child. The first symptoms of the disease in most cases are detected already from the moment of birth. There is a drowsiness, the child moves little, the appetite is reduced. In some cases, the disease can begin with the appearance of seizures. Then, at the age of 2-6 months, there is a decrease in the tone of the muscles of the neck, an increase in muscle tone in the limbs, sometimes horeiform giperkinesis, atrophy of the nipples of the optic nerves, strabismus, involuntary movements of the eyeballs, an increase in the size of the head due to the accumulation of large amounts of fluid( hydrocephalus).Touching the child, a strong noise cause the condition of opisthotonus. The hearing, sight, and dementia quickly disappear. In the final stage of the disease, patients are in a state of decerebralization, immobilized, circulatory and respiratory disorders are expressed. Death occurs between the ages of six months to two years.

Alexander's disease is an extremely rare form of leukodystrophy. Characteristic manifestations of the disease are increasing hydrocephalus( a progressive increase in the size of the head due to accumulation of large amounts of fluid), dementia, motor disorders, convulsive attacks.