Walsh & Hoyt: Cerebral Edema

Cerebral edema is an increase in brain volume caused by increased tissue water content. The causes of cerebral edema include an increase in intravascular pressure, damage to and increased permeability of the cerebral vascular wall, and a decrease in plasma colloid osmotic pressure. Aquaporins, a family of transmembrane proteins that selectively allow the passage of water through plasma membranes, also may be involved. Any of these phenomena alone or in combination can produce a net flow of water from the vascular bed into neural tissue. Although Klatzo separated cerebral edema into two types, vasogenic and cytotoxic, other investigators concluded that several types of cerebral edema can be distinguished, both pathologically and by certain neuroimaging techniques: (a) vasogenic, (b) cytotoxic from energy failure, (c) cytotoxic from poisoning, (d) hydrostatic, (e) interstitial, and (f) hypoosmotic. Vasogenic edema is the type most often produced by infections and inflammations of the CNS, although cytotoxic and interstitial edema also may accompany such disorders.