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Cerebral edema is most easily understood as a swelling of the brain because of excess water accumulation outside of, or within, the brain cells. Almost completely surrounded by the unyielding bony skull, the brain has little area to expand. Expansion within the area that it naturally has can cause injury and cellular death even as the brain seeks to release excessive pressure by expanding through the foramen magnum — the opening where the spinal cord enters the brain — in a process known as herniation. Treatment almost always involves attention to the primary disease or condition that has resulted in the increased intracranial pressure (ICP). First, however, treatment for cerebral edema often requires immediate measures to mechanically relieve the ICP, such as drilling a small hole as in ventriculostomy or removing part of the skull in decompressive craniectomy, along with the administration of osmolytic fluids to draw excess fluid from within the brain.
The primary cause of a patient's pathology will strongly influence aspects of his or her treatment for cerebral edema. Although patients experience a combination of causes for cerebral edema as the pathology cascades along known symptoms, cerebral edema generally has been divided into three subtypes: cytotoxic, vasogenic and interstitial, also called hydrocephalic. Depending on which subtype it is, steroids and osmolytic fluids might or might not be used. Steroids decrease swelling by decreasing overall tissue inflammation. Osmolytic fluids reduce intracellular water by drawing out excessive water using concentrated intravenous (IV) fluids.
Proper oxygenation, usually via a respirator, is a major treatment for cerebral edema. Brain cells that were injured by the original trauma or subsequent swelling require adequate oxygen to stay alive and to avoid releasing vasodilators that can further increase fluid in the area. Brain cells lacking adequate oxygen or recognizing too much carbon dioxide often release these natural vasodilators in an effort to increase their local blood flow, increase oxygen and decrease carbon dioxide. In situations involving cerebral edema, however, this reflexive action might result in even greater excess fluid and pressure.
Another form of treatment for cerebral edema is controlling the temperature of the brain and the rest of the body. Depending on the specific treatment facility's guidelines, hypothermic treatment might be started. In most cases, however, the goal is that of a normal body temperature, and prophylactic acetaminophen is often administered rectally. A febrile state — a condition in which the body's temperature significantly increases and causes various side effects — are to be avoided at all costs. The rationale behind these treatments is the theoretical assumption that feverish brain cells require more oxygen and therefore a greater volume of blood flow.
The treatment for cerebral edema often must be done with great care. Adequate blood volume and perfusion to the brain and brain cells is necessary to ensure proper oxygenation, but too much fluid can contribute to the edema. Osmolytic fluids might reduce intracellular cerebral edema, but too much of this type of infusion can result in systemic dehydration and decreased oxygen to the brain cells. Postural treatment for cerebral edema can decrease ICP while putting certain patients at risk for additional complications. The treatment for cerebral edema is thus almost always conducted in a neurological intensive care unit where careful monitoring can help avoid complications.
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