Cerebral edema is an excess of fluid or water in the brain. The water can be intracellular or extracellular. Intracellular cerebral edema means that the water is between the cells within the brain. Extracellular cerebral edema means that the water is in excess in the spaces between the parts of the brain. Edema refers to swelling caused by fluid. Cerebral edema can be caused by a variety or factors and events such as, accident or injury to the head,, stroke, acute liver disease, allergic reaction, cardiac arrest or altitude changes (lack of successful altitude acclimatization).
Symptoms of cerebral edema are unconsciousness or decreased consciousness, disruption or loss of eyesight, headaches, hallucinations, illusions, psychotic behavior, coma and memory loss. If cerebral edema is untreated, it can be fatal. Bruce Lee, actor and martial arts expert died from cerebral edema.
There are different forms of cerebral edema and they are cause by different factors and conditions.
Vasogenic cerebral edema is caused by a breakdown in the endothelial junctions. These junctions are the walls of the blood brain barrier and are normally tight. The endothelial junctions when functioning typically allow proteins and fluid to pass from the circulatory system into the cerebral parenchymal extra-cellular space. When fluid cross the blood brain barrier it spreads and can occur quickly across the brain. This cerebral edema is usually caused by focal inflammation, trauma, tumors, hypertensive encephalopathy and cerebra ischemia. Dysfunction in the brain blood barrier is a combination of mechanisms that fail to work or are damaged such as impairment due to arterial hypertension or trauma. Tumors can cause the release of compounds that destroy the blood brain barrier such as histamine, free radicals, eicosanoids, bradykinin, arachidonic acid and excitatory neurotransmitters.
Cytotoxic cerebral edema
Cytotoxic cerebral edem is caused by an impairment in the metabolism of the cells that affects the sodium and potassium pumps in the glial cell membrane. Cells retain too much sodium and therefore too much fluid. Cytotoxic edema is present with a variety of intoxicants such as triethyltin, hexachlorophene, isoniazid and dinitrophenol. Other factors that can cause cytotoxic cerebral edema are Reye’s syndrome, early ischemia, encephalopathy, stroke, hypoxia, severe hypothermia, cardiac arrest, cerebral toxins and pseudotuor cerebri.
Osmotic edema is another type of cerebral edema. Osmolality of the cerebral-spinal fluid and the extra-cellular fluid is greater than plasma. Osmolality is a measurement of the concentration of particles in a fluid. Osmotic edema occurs when plasma is diluted by water intoxication (such as over ingestion of water), SIADH, or hemodialysis. The extra fluid leads to osmotic edema.
Hydrostatic edema is believed to be caused by pressure of the cerebral capillaries with an increase of fluids into the ECF. It is present in patients with severe hypertension.
Interstitial cerebral edema
Interstitial cerebral edema is caused when a blockage occurs in the hydrocephalus. The blockage is caused by a rupture in the cerebral spinal fluid brain barrier. Cerebral spinal fluid enters the brain and spreads throughout the extra-cellular space of white matter.
High altitude cerebral edema (HACE)
High altitude cerebral edema is usually fatal and is a symptom of attitude sickness. It is causes swelling of brain tissue due to fluid leakage after spending a week or more at a high altitude.
Treatment of cerebral edema depends on the classification, the health of the patient and any underlying factors.
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