Edema of the brain. Definition of cerebral edema. Causes (etiology) of cerebral edema. Pathogenesis of cerebral edema.
Edema of the brain The increase in its volume is due toaccumulation of fluid in the intercellular space. The increase in the volume of the brain due to the intracellular fluid is called swelling. From the point of view of pathophysiology, these conditions (edema and swelling) can often develop simultaneously and mutually change into each other, so from the clinical point of view it is perfectly permissible to interpret both these concepts as cerebral edema.
Edema of the brain refers to the secondary symptoms of the lesion. It can be local (local, perifocal) or generalized (diffuse).
Etiology of cerebral edema. Edema of the brain occurs in many diseases that affectnervous system: traumatic brain injury; stroke; tumors and abscess of the brain; encephalitis and meningitis; with hypoxia; with various forms of occlusive hydrocephalus; various syndromes of osmotic balance disturbance; common intoxications; infections; body burns; malignant hypertensive disease, etc. In the experiment and clinic it is proved that various etiological factors cause pathogenetically different forms of cerebral edema, but the mechanisms of its growth are identical.
Pathogenesis of cerebral edema. Distinguished four types of brain edema. vasogenic, cytotoxic, osmotic, hydrostatic (AN Konovalov, BA Kodashev, 1995).
1. Vasogenous edema of the brain associated with increased permeability of capillaries,as a result of which the liquid from the vessels partially passes into the interstitial space (into the white matter), causing an increase in its volume. Vasogenic swelling is usually perifocal. Most often they are observed with TBI, brain tumors, infectious allergic lesions of the central nervous system, hemorrhagic strokes, etc. (AN Konovalov, BA Kodashev, 1995).
2. Cytotoxic edema of the brain occurs with toxic (exo- or endogenous)impact on the brain cells, resulting in a disruption of normal cellular metabolism and changes the permeability of cell membranes. This type of edema occurs with various poisonings and with cerebral ischemia against ischemic stroke (AN Konovalov, BA Kodashev, 1995). Cytotoxic edema of the brain for 6-8 hours primarily due toreactivation of the ion pump, which can be achieved with the restoration of blood flow. If this does not occur, the edema becomes vasogenic in nature (BS Vilensky, 1986).
3. Osmotic edema develops in violation of the existing norma small osmotic gradient between osmolarity of the brain tissue (it is higher) and osmolality of the plasma. This species develops due to water intoxication of the central nervous system due to hyperosmolarity of the brain tissue. This type of edema is observed in metabolic encephalopathies (renal and hepatic insufficiency, hyperglycemia, etc.) (AN Konovalov, BA Kodashev, 1995).
4. Hydrostatic edema usually formed with a rapid increaseventricular pressure. The accumulation of fluid occurs in the periventricular zone, which is clearly revealed in computed tomography (AN Konovalov, BA Kodashev, 1995).