Cerebral edema description replies
Edema of the brain occurs in many diseases and requires urgent measures. Every doctor should be able to diagnose and treat it.
Under the edema of the brain is understood the excessthe accumulation of fluid in the extracellular space, and under its swelling - in cells. These processes are parallel, but sometimes one of them dominates. However, there are no clinical differences between them. Therefore, it is advisable to talk about swelling-swelling of the brain.
Increased in the volume of the brain begins to shift,filling all the reserve spaces of the cavity of the skull, penetrating into its natural cracks. The introduction of the hippocampal gyrus into the gap between the brain stem and the edge of the tentorial opening leads to compression of the upper part of the brain stem - temporo-tentorial wedging (see lecture: Tumors of the brain). In parallel, there is a dislocation of the edematous tonsils of the cerebellum into the large occipital foramen and the medulla oblongata is compressed (see ibid.). Both inclinations are very dangerous, because the vital functions are violated. All this dictates the need for emergency measures to combat swelling-swelling of the brain. And the sooner this treatment begins, the more successful it will be. Expressed, and even more so far gone swelling-swelling of the brain almost do not lend themselves to treatment.
The onset of edema of the brain can be explained by a violation of the function of capillaries and neurons. In capillaries, as is known, there are two types of pressure: oncotic. caused by the amount of blood protein and hydrodynamic. the term from the pulse blood pressure andvascular tone. In the arterial half of the capillary, the hydrodynamic pressure is higher than the oncotic pressure, which causes the liquid part of the blood to flow into the intercellular space-filtration. In the venous half of the capillary, the hydrodynamic pressure decreases, while the oncotic pressure remains practically unchanged. Therefore, the liquid returns from the intercellular space to the bloodstream - resorption (reabsorption). Normally, both processes are clearly balanced and ensure the exchange of gases and metabolic products between blood and tissues. The displacement of the equilibrium zone of pressure in the venous half of the capillary leads to excess filtration over resorption. This can be observed in the following cases:
- prolonged constant and uncontrolled arterial hypertension,
- compression of veins in zones around tumors, hematomas and abscesses,
- thrombosis of the sinuses or veins of the brain,
- with extracerebral causes of venous outflow from the cranial cavity: heart failure, pneumosclerosis and emphysema of the lungs,
- with hypoproteinemia: extensive burns, kidney failure, hunger,
- fat and air embolism of cerebral vessels,
- with pre- and postnatal asphyxia,
- drowning and altitude sickness,
- status epilepticus.
The described mechanism of cerebral edema is associated with a violation of the blood-brain barrier and therefore it is called vascular, vasogenic type.
Another important factor in the development of cerebral edema, or rather, its swelling, as already mentioned above, can be a violation of the glial cells of the brain. What processes contribute to this?
· Inflammation in the central nervous system: encephalitis, meningitis and brain abscess,
· Infectious diseases: pneumonia, diphtheria, dysentery, sepsis, fulminant
· Encephalopathy in children of the first 2 years of life,
· Allergic reactions: anaphylactic shock, Quincke edema, impotence encephalopathies, serum sickness;
· Metabolic disorders: alcoholic encephalopathy, parathyroid gland insufficiency, adrenal insufficiency;
· Intoxication: a) endogenous causes: uremia, eclampsia, renal, diabetic, hepatic coma; b) exogenous causes: poisoning with morphine, codeine, pachycarpine, hypnotics, phosphorus, arsenic, lead, hydrogen sulfide, leaded gasoline, carbon monoxide;
· Radiation injuries: ionizing radiation.
In all the above cases, the cause of excess water accumulation in glial cells is the damage to their membranes. Therefore, through them, potassium ions easily escape, and in their place and abundantly sodium ions are introduced. After them - the water is abundant. The cell increases in size - swelling. The described type of edema is called cytotoxic.
The third mechanism of cerebral edema canserve as vasoactive substances released in large quantities in areas affected by the brain. This situation occurs in the focus of brain damage in trauma, encephalitis, ischemic injury of it - a heart attack. Toxic decay products of brain tissue and their metabolites (histamine, kinins, prostaglandins, etc.) paralyze the walls of small vessels - arterioles, capillary beds, venules. Increased permeability of paralyzed capillaries leads to the exit of almost the entire plasma into the interstitium - and this is the perifocal, local edema of the brain. In the lumen of the vessels, as well as the vasogenic edema, the mobility of erythrocytes sharply decreases, causing stasis and thrombosis. This, in turn, further worsens blood circulation - this is how one of the vicious circles of development of cerebral edema closes.
It is known that there is no reserve of energy in the brain. He receives it as a result of glycolysis. 90% of the latter is carried out by aerobic means - complete cleavage of glucose to water and carbon dioxide. This type of glycolysis is 18 times more effective than anaerobic (10%). The final products of which are pyruvic and lactic acids. By their level in liquor and blood, one can judge the state of glycolysis in the brain. Further, 10% of all energy generated in the brain, he spends on the normal operation of cell membranes. Contrary to the forces of natural osmosis, membranes should retain K ions in the cell, and Na in the intercellular space. With hypoxia of the brain, naturally, the percentage of anaerobic glycolysis begins to increase. There is a shortage of energy - an "energy crisis". The cell membranes, the potassium-sodium pump start to malfunction, which immediately leads to the release of K from the cell and the delay of Na in the intercellular space. In the liquor, and then in the blood accumulates an excessive amount of pyruvic and lactic acid. So hypoxia leads to swelling-swelling of the brain. In addition, excess Na in the intercellular space at any origin of edema of the brain causes accumulation of fluid in it, which leads to an extension of the pathway of diffusion of gases - brain hypoxia is increasing. Another vicious circle is coming.
Clinical picture edema-swelling of the brain is prettydistinctly emerges in patients whose cause of the complication was not the pathology of the brain itself. But it is difficult to isolate from the complex of symptoms of brain damage, complicated by its swelling-swelling (trauma, tumor, encephalitis, etc.). And, nevertheless, with edema of the brain there are general and local symptoms. First of all, it is obligatory headache. Sacral pathology of the brain, which resultedto his edema, it intensifies. When the edema was a complication of some other disease, it arises. A severe headache, as always, is accompanied by nausea and vomiting. Among other cerebral symptoms should be noted gradual fading of consciousness. This is a sign of the growing dislocation of the brain and, above all, temporo-tentorial (see lecture "Tumors of the brain"). Rapidly developing edema-swelling of the brain can manifest itself periodic psychomotor agitation. In children up to the age of three in cases of severe infections (pneumonia, for example), the edema of the brain is often accompanied by attacks of tonic convulsions, sometimes having the character of an epileptic status.
Focal symptoms of edema-swelling of the brain are reduced to:
- two-sided paresis of drainage nerves (VI),
- decrease in the corneal reflexes (V),
- extinction of abdominal (cremasterous) and knee-jerk reflexes.
Until the advent of computed tomography, there were no reliable means of confirming the edema of the brain. On slices computer tomograms around lesions (tumor, abscess,hemorrhage) clearly identified zones of reduced density. Such edema is called perifocal, and in cases of a tumor it can be called peritumose. The general edema of the brain is clearly visible in the form of finger-like zones of reduced density on sections through the large hemispheres on both sides. Excellent visible edema of the brain and on NMR tomograms in the form of a halo of increased signal around the hearthbrain damage. It is worth mentioning the extreme danger and therefore the inadmissibility of lumbar puncture with edema of the brain, as well as with intracranial hypertension of any other etiology.
This problem has not been solved so far, despiteour knowledge of many aspects of the pathogenesis of edema-swelling and the use of ever new and effective drugs in the fight against it. Above we have already mentioned the very modest successes in the treatment of a far-reaching general edema-swelling of the brain. We successfully treat its initial forms, our successes in the treatment of perifocal, peritumorous edema are undoubted. This dictates the need to foresee the possibility of a formidable complication and begin to vigorously treat it in the early stages.
Treatment, of course, must be pathogenetic. Despite the seemingly morphological identity of swelling-swelling of any origin, they are different. Different, if only because there is no universal means of their treatment. They respond in different ways to drug therapy. Nevertheless, there are effective measures and medicines common, for any of them (points 1-5) and individual (items 6-7).
- In order to improve the outflow of blood from the head, you need to raise the head and chest of the patient with the help of the head restraint.
- It is necessary to ensure free and full breathing.
- The output of plasma from the vascular bed (filtration)leads to a thickening of the blood and a difficulty in its circulation, stasis and thrombosis. It is necessary to improve the rheological properties of the blood. To this end, it is customary to introduce reopoligyukin, trental and some other drugs that, by increasing the same charge of erythrocytes and capillary walls, which improves blood circulation.
- Given that in the swelling-swelling zone, the vesselsare paralyzed, the blood flow in them is considerably slowed down, it is possible to resort to the narrowing of the vessels (vasoconstriction) in the remaining relatively safe zones of the brain. Such a redistribution of blood flow will strengthen it in the disaster zone, improve regional gas exchange. You can achieve what you want in two ways. Either the introduction of vasoconstrictors, or periodic short-term hyperventilation. The latter method is often used at the time of operations on the brain.
- In the treatment of edema of the brain of any etiology is requiredstrengthening the blood-brain barrier to reduce the filtration of blood plasma into the intercellular space. For this purpose, tocopherol acetate is used in injections in high doses and nootropil or piracetam, lucetam, vitamin E, antioxidants.
- Edema of the brain, as a result craniocerebral trauma best suits osmodiuretics (mannitol ). First, intravenously injected with a large dose of the drug - 1-1.5 grams per kilogram of the patient's weight, and then every 4-6 hours for 0.5 grams per kilogram of weight. In response, an abundant diuresis occurs up to 2-3 liters. It is necessary to measure the volume of excreted urine in order to return an adequate amount of fluid to the bloodstream. What can you do to fill the volume of the circulating fluid? First of all, this is reopoliglyukin. On the one hand, it will fill the volume of circulating fluid, on the other hand it improves the rheology of blood. It is also very appropriate infusion of blood plasma or albumin, which will increase the volume of reabsorption of fluid from the interstitium. Blood loss shows blood transfusion. The volume of the circulating fluid can be filled with Labouri solution - otherwise a polarizing mixture consisting of 10% glucose, potassium chloride and simple insulin. On the one hand, this mixture replenishes the volume of the circulating fluid, on the other hand it gives "raw materials" for replenishing the energy resources of the brain. But if the patient has hyperglycaemia, the introduction of a polarizing mixture is not indicated. It is necessary to take into account the amount of liquid that is drunk or injected into the probe.
- Edema of the brain for bulk processes in the cranial cavity (tumor, abscess, hematoma), which initially has a local overturning character, is well removed glucocorticoids. dexazone, prednisolone and others.
It is worth emphasizing the practical inefficiency intreatment swelling-swelling of the brain lasix (furosemide), hypertonic solutions of glucose and sulphate magnesia. Mindful of the delay of sodium in the interstitium and brain cells in the described pathology, physiological and hypertonic solutions of table salt are contraindicated in these patients. In doubtful cases, their introduction should be preceded by the study of blood electrolytes. With a normal sodium content in the blood can, and with a reduced even need to enter a physiological saline solution into the bloodstream.
These are the main ways to combat the terrible complication of many diseases - edema-swelling of the brain.
CONTROL QUESTIONS TO THE TOPIC:
- Describe the mechanisms of the pathogenesis of swelling and swelling of the brain. Give
- List the causes of swelling and swelling of the brain, dividing them into
- Treatment of edema-swelling of the brain in cases of craniocerebral trauma and "volumetric processes" of the brain.