Walsh & Hoyt: Edema

A common response of the brain to a variety of insults is edema. Infections and inflammations of the CNS produce several types of edema: vasogenic, cytotoxic, interstitial, and hypo-osmotic. Some of these types can be distinguished by MR imaging. A variety of organisms produce toxins that can cause vasogenic cerebral edema. Bacteria are the most common organisms that produce such toxins. Clostridium botulinum, Clostridium tetani, and Corynebacterium diphtheriae all produce toxins capable of causing vasogenic cerebral edema. Other similar toxins include streptolysin O, the staphylococcal alpha-toxin, and the toxins produced by Shigella dysenteriae, Bacillus anthracis, Haemophilus pertussis, H. influenzae, and Escherichia coli. Release of cell wall fragments from Streptococcus pneumoniae also may produce vasogenic cerebral edema.