Edema is the medical term used to describe swelling. Swelling of the brain is referred to as brain edema or cerebral edema. There are several subtypes of cerebral edema which can have diverse mechanisms and causes. All types of cerebral edema are somewhat related, as one can sometimes lead to or facilitate another. Brain edema is a serious medical condition and can be life-threatening.
Vasogenic Edema
Vasogenic edema occurs due to changes in the blood brain barrier that increase cell permeability resulting in an increase in extracellular fluid volume, explains Stroke Center. "Principles of Neuroscience" notes that it is the disruption of the cerebral capillaries provides the underlying mechanism for vasogenic edema. Vasogenic edema can displace the brain hemisphere and, when severe, lead to cerebral herniation, notes Stroke Center. This type of edema is seen in trauma, tumors, inflammation and late ischemia, explains the University Health Network Brain Malformation Group, or UHN BrainAVM. The space between the cells enlarges due to fluid and, in later stages, the cells swell also. The cerebrospinal fluid, or CSF, is not increased, but the whole brain is affected.
Cytotoxic Edema
Cytotoxic edema describes intracellular swelling because of faulty ion pumps in the cell membrane which cause water accumulation that affects the whole brain, notes "Principles of Neuroscience." This type of edema is characterized by the swelling of cellular elements, according the Stroke Center, and can be observed in Reye's syndrome, hypothermia, early ischemia and intoxication. The blood-brain barrier remains intact and CSF is normal.
Osmotic Edema
Osmotic edema is an accumulation of excess water in the brain. This results from an abnormal osmotic gradient that increases the chemical potential of the plasma and causes water to enter the brain. With this type of edema, CSF formation is increased. This type of edema is seen in cases of excessive water intake or water intoxication and hemodialysis, according to UHN BrainAVM.
Hydrostatic Edema
Hydrostatic edema is seen in acute, malignant hypertension, notes UHN BrainAVM. It is caused by the direct transmission of pressure to cerebral capillaries resulting in the escape of liquids from blood vessels through pores or breaks in their cell membranes into the extracellular fluid. Only the white matter is affected; the CSF in unchanged. The blood brain-barrier remains intact. This form of cerebral edema is seen in acute, malignant hypertension.
Interstitial Edema
Interstitial edema occurs when there is an elevation of CSF pressure due to increased CSF. This condition is seen in cases of acute or obstructive hydrocephalus. Princeton Brain and Spine Care explains that obstructive hydrocephalus is a condition in which CSF accumulates in abnormal amounts. It occurs when the passage of CSF is obstructed. Only the white matter is affected and the blood brain-barrier remains undisturbed.
References
- Storke Center: Cellular Injury During Ischemia
- University Health Network Brain Malformation Group: Cerebral Edema
- "Principles of Neuroscience"; Eric Kandel, James Schwartz and Thomas Jessell. 2000.
- Princeton Brain and Spine Care: Obstructive Hydrocephalus
