Cerebral Edema

Cerebral edemaorcerebral œdemais excess accumulation of fluid in the intracellularor extracellularspaces of the brain. Causes Cerebral edema can result from brain traumaor from nontraumatic causes such as ischemic stroke, cancer, or brain inflammation due to meningitisor encephalitis). [ 1 ]The blood–brain barrier(BBB) or the blood– cerebrospinal fluid(CSF) barrier may break down, allowing fluid to accumulate in the brain's extracellular space. Altered metabolismmay cause brain cells to retain water, and dilution of the blood plasmamay cause excess water to move into brain cells. Fast travel to high altitude without proper acclimatizationcan cause high-altitude cerebral edema (HACE). Symptoms Certain changes in morphologyare associated with cerebral edema: the brain becomes soft and smooth and overfills the cranial vault, gyri(ridges) become flattened, sulci(grooves) become narrowed, and ventricular cavitiesbecome compressed. Symptoms include nausea, vomiting, blurred vision, faintness, and in severe cases, seizuresand coma. If herniationoccurs, respiratory symptoms or respiratory arrestcan also occur due to compression of the respiratory center. Research Many studies of the mechanical properties of brain edema were conducted in the 2000s, most of them based on finite element analysis(FEA), a widely used numerical method in solid mechanics. For example, Gao and Ang used the finite element method to study changes in intracranial pressure during craniotomy operations. [ 2 ]A second line of research on the condition looks at thermal conductivity, which is related to tissue water content. [ 3 ] Types Four types of cerebral edema have been identified: [ 4 ] Vasogenic Vasogenic edema occurs due to a breakdown of the tight endothelial junctions that make up the blood–brain barrier. This allows intravascular proteins and fluid to penetrate into the parenchymal extracellular space. Once plasma constituents cross the barrier, the edema spreads; this may be quite rapid and extensive. As water enters white matter, it moves extracellularly along fiber tracts and can also affect the gray matter. This type of edema may result from trauma, tumors, focal inflammation, late stages of cerebral ischemiaand hypertensive encephalopathy. Mechanisms contributing to blood–brain barrier dysfunction include physical disruption by arterial hypertensionor trauma, and tumor-facilitated release of vasoactiveand endothelialdestructive compounds (e.g. arachidonic acid, excitatory neurotransmitters, eicosanoids, bradykinin, histamine, and free radicals). Subtypes of vasogenic edema include: Hydrostatic cerebral edema This form of cerebral edema is seen in acute, malignant hypertension. It is thought to result from direct transmission of pressure to cerebral capillarieswith transudationof fluid from the capillariesinto the extravascular compartment. Cerebral edema from brain cancer Cancerous glial cells( glioma) of the brain can increase secretion of vascular endothelial growth factor(VEGF), which weakens the junctions of the blood–brain barrier. Dexamethasonecan be of benefit in reducing VEGF secretion.