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Degenerative diseases of the central nervous system.

Degenerative diseases of the central nervous system is a heterogeneous group of diseases characterized by a progressive loss of neurons with secondary changes in white matter and a concomitant glial-proliferative reaction. Most neurodegenerative diseases occur in the 5-6th decades of life and at a later age.

Atrophy of certain areas of the brain and spinal cord is determined macroscopically. Microscopically, the main changes are detected in neurons and their processes, are characterized by degenerative (dystrophic) processes, resulting in cell death. Changes in neurons are manifested by a variety of cytoplasmic and intranuclear inclusions, Alzheimer's neurofibrils, granulovacuolar degeneration, accumulation of lipofuscin, lipopigmented and neuroaxonal dystrophy. At the same time, glial and macrophage reactions, vascular changes, peculiar structures — plaques, spongy state of the brain — develop in combination.

Degenerative diseases of the central nervous system include: Alzheimer's disease, Peak's disease, Parkinson's disease, Huntington's chorea, amyotrophic lateral sclerosis. Similar morphological changes in the central nervous system are found in diseases with prion etiology. This is Creutzfeldt’s-Jakob disease (sporadic and new forms), Gerstmann-Streusler-Scheinker syndrome, fatal familial insomnia, Kuru.

Alzheimer's disease (Alzheimer's type dementia). Alzheimer's disease (a synonym for Alzheimer's type dementia) is a common form of primary degenerative dementia of late age, characterized by a complex of clinical and neuropathological signs. Moreover, reliable confirmation of the diagnosis is possible only with the help of data from a neuromorphological, usually post-mortem examination of the brain.

The current classification of Alzheimer's is based on the age principle. According to the ICD of the 10th revision [1992], two forms are distinguished: 1) Alzheimer's disease with a manifestation of up to 65 years of age (synonyms: type 2 Alzheimer's disease, presenile dementia of Alzheimer's type), since this form of dementia was described by A. Alzheimer in 1906, it is called pure Alzheimer's disease; 2) Alzheimer's disease with a late, that is, after 65 years, onset (synonyms: type 1 Alzheimer's disease, senile dementia of Alzheimer's type).

Alzheimer's disease ranks first among the causes of dementia in the elderly. The older the population, the greater the prevalence of Alzheimer's disease. So, it did not exceed 0.6% in the age group of 60–69 years, 3.6% - in 70–79 years, and among people older than 80 years, the prevalence of the disease reaches 15%. Women get sick more often than men.

The etiology and pathogenesis of Alzheimer's disease is not fully understood. Of great importance are genetic factors. The data of twin analysis, the study of the nature of inheritance and analysis of genes involved in Alzheimer's disease showed its heterogeneity. Family forms with early onset of Alzheimer's disease are inherited as an autosomal dominant trait associated with damage to one main gene. Such hereditary monogenic forms make up only a small part (up to 10%) of Alzheimer's cases. The remaining cases are sporadic forms that are heterogeneous. They can also be caused by mutations or polymorphisms in the genes, however, the pathogenic expression of the genetic disorder is influenced by other genes and / or environmental factors. Currently, 3 genes responsible for the development of early familial forms of the disease have been identified: on the 21st chromosome, the gene for the precursor protein of b-amyloid is located (APP - from the English.
Amyloid Precursor Protein), on the 14th and 1st chromosomes - genes encoding related membrane proteins - presenilins {presenilin 1 (PS1) and presenilin 2 (PS2), respectively}. The development of the sporadic form of Alzheimer's disease is closely related to the apolipoprotein E gene on the 19th chromosome.

The pathogenesis of Alzheimer's disease is associated with the following main disorders: firstly, extracellular deposits of β-amyloid, which is a product of APP secretion proteolysis [amyloid deposits usually form characteristic senile plaques (synonyms: “amyloid plaques”, “neuritic plaques”, “drusen” ") or appear in the walls of the vessels of the brain]; secondly, the formation in the bodies of nerve cells and their dendrites of Alzheimer's neurofibrils (intraneuronal plexuses), which are altered cytoskeletal components consisting of hyperphosphorylated tau protein.

The formation of senile plaques induces the expression of apoptosis inducer genes (c-jun), which leads to neuronal death. The death of neurons can be explained by the activation of calcium channels and the development of free radical oxidation of cell membranes. They also suggest the participation in the death of neurons of the classical complement cascade. An important role in the pathogenesis of Alzheimer's disease is probably played by the appearance of the apolipoprotein E - e4 allele (ApoE-e4). ApoE-e4 is a risk factor not only for Alzheimer's disease, but also for cerebral amyloid angiopathy and atherosclerosis. APOE can affect the aggregation and / or degradation of APP. The value of presenilins in the body is not clear, but they are determined in the endoplasmic reticulum and Golgi apparatus. Mutations of the PS1 and PS2 genes increase the production of P-amyloid, accelerate its aggregation and the formation of senile plaques.

A macroscopic examination of the brain by autopsy reveals a pronounced atrophy of the cerebral cortex. In some cases, the brain mass is less than 900 g. Pathognomonic changes in Alzheimer's disease are detected by microscopic examination. The most typical among them are the following symptoms:

• senile (neuritic) plaques - insoluble extracellular deposits of P-amyloid surrounded by dystrophically altered neurites and glial cells. Their diameter is from 5 to 100 microns. Sometimes plaques are localized around the vessels;

• Alzheimer's neurofibrils consist of densely spaced paired spiral filaments that form “strands” and are localized in dystrophically altered neurons. Neurofibrils are formed by tau (t) -protein, which is normally associated with tubulin. In Alzheimer's disease, tau protein hyperphosphates and, to a lesser extent, combines with microtubules. The unbound tau protein then spontaneously aggregates into insoluble filaments deposited in the cells;

• granulovacuolar neuronal degeneration is characterized by the appearance in neurons, most often of the ammonon horn, of rounded vacuole-like formations with a diameter of 3-5 microns, with a dense rounded core in the central part. The origin of these little bodies is unclear;

• reduction in the body volume of nerve cells, lipofuscinosis of neurons;

• vacuolization in the surface layers of the new cortex, characteristic of prion diseases, can occur in Alzheimer's disease;

• amyloid angiopathy, fibrosis and calcification, gliosis.

The duration of Alzheimer's disease ranges from 2 to 20 years. In the finale - dementia, severe disability with pelvic disorders. Death occurs most often from infectious diseases.

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Degenerative diseases of the central nervous system.

  1. Changes in the central nervous system during aging, degenerative processes and dementia (dementia)
    As a rule, the normal brain mass for adults up to the age of 65 is 1200–1600 g. After 65 years, the brain often decreases due to atrophic processes occurring in it, and the hemispheres somewhat recede from the bones of the skull. With a pathological study, you can see that the membranes of the brain (especially above the parietal zone) are thickened with a milky outflow. In the brain itself
    E.P. Richardson, M. Flint Beale, J. B. Martin (EPRichardson, M. Flint Beat, JBMartin) In the classification of diseases of the nervous system, a special group of pathological conditions is distinguished - degenerative, emphasizing that they are characterized by a gradual and steadily progressing death neurons, the reasons for which are not fully disclosed. To identify these diseases
  3. Metabolic diseases of the central nervous system
    Many metabolic diseases are inherited in an autosomal recessive manner, and some of them in an X-linked, recessive manner (see chapter 8). Hereditary metabolic defects disrupt the metabolism of many substances: lipids, carbohydrates, glycosaminoglycans (mucopolysaccharides), amino acids and trace elements. In some metabolic diseases, pathological changes begin with
  4. Demyelinating diseases of the central nervous system.
    Demyelinating diseases of the central nervous system are characterized by the predominant destruction of the myelin (Schwann) membrane with the relative preservation of the axon. Schwann cells form the Schwann membrane, or neurolemma, surrounding the axons and dendrites of the peripheral nervous system, cell bodies in the sensory ganglia and nerve fibers in the white matter of the central nervous system
  5. Viral diseases of the central nervous system.
    Viral meningitis is more benign than bacterial meningitis. Enteroviruses detect more than 70% of cases of viral meningitis. All representatives of enteroviruses cause meningitis, but most often Coxsackie viruses, ECHO and nonparalytic polio. In the study of cerebrospinal fluid, a lymphocytic composition is noted, and the level of protein and sugar does not significantly change. Macroscopic picture
  6. Systemic diseases of the central nervous system
    This is a group of diseases, many of which are family in nature and are accompanied by progressive degeneration of neurons and their processes of the central nervous system in certain areas. Patients are affected by sensory or motor (motor) systems with cerebellar ataxia and involuntary movements or dementia. Parkinson's syndrome (parkinsonism, trembling paralysis,
    The group of students to be transferred to special schools in most cases includes children who have undergone meningitis, encephalitis, meningoencephalitis and other forms of neuroinfection. In some cases, there are children with some form of damage to the nervous system as a result of syphilis, tuberculosis, and rheumatism. The causative agents of diseases are various types of microbes and
    There is a striking similarity between the central nervous system and the cardiovascular. In the latter, one subsystem (venous) returns blood to the heart, and the other (arterial) drives blood through the vessels from the heart. Similarly, the central nervous system (CNS) has two distinctly different types of nerves that are connected to the brain, and the brain, in turn, plays a paramount role in the central nervous system.
  9. Infectious diseases of the central nervous system.
    The classification of infectious diseases of the central nervous system takes into account the etiology, localization, nature of morphological changes, especially the clinical course of the lesion. By etiology, bacterial, viral, fungal, prion, and parasitic diseases are distinguished; according to the localization of inflammatory changes, meningitis (arachnoiditis, leptomeningitis, pachymeningitis); encephalitis; myelitis; encephalomyelitis; meningomyelitis;
  10. Infectious diseases of the central nervous system
    Infectious diseases of the central nervous system
  11. Diseases of the nervous system. Diseases accompanied by an increase in intracranial pressure. Cerebrovascular disease. Cerebral infarction. Spontaneous intracranial hemorrhage. Infectious lesions of the central nervous system. Alzheimer's disease. Multiple sclerosis.
    1. The earliest changes in neurons during blood flow arrest 1. cytolysis 4. microvacuolization 2. tigrolysis 5. wrinkling of neurons 3. hyperchromatosis 2. The most common causes of cerebral infarction 1. stenotic atherosclerosis 2. thromboembolism 3. true polycythemia 4. thrombosis 5. embolism fatty with a fracture of the tubular bones 3. Cerebral edema of the cytotoxic type occurs at 1.
    The central part of the nervous system includes the brain and spinal cord with their ganglia. Spinal ganglia — round bodies located along the spinal cord, to the right and left of it. They lie with the spinal cord inside the spinal canal. The number of ganglia corresponds to the number of segments. Histologically, the ganglia consist of stroma and nerve cells with their processes. Outside
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