Definition of Cerebral herniation

Cerebral herniation: The abnormal protrusion of brain tissue through an opening when there is increased intracranial pressure (when the brain is under increased pressure). The increased pressure may be due to a number of causes including inflammation of the brain (as in meningitis), a tumor, hemorrhage, and edema (swelling of the brain). The tonsils of the cerebellum, for example, may be forced from their normal position (within the posterior fossa of the skull) through the foramen magnum into the vertebral canal. This is usually fatal.

Source: MedTerms™ Medical Dictionary
http://www.medterms.com/script/main/art.asp?articlekey=25065
Last Editorial Review: 6/14/2012