Brain herniation

Baback Arshi MD (

Dr. Arshi of the University of Illinois at Chicago College of Medicine has no relevant financial relationships to disclose.

Matthew Lorincz MD PhD, editor. (Dr. Lorincz of the University of Michigan has no relevant financial relationships to disclose.)
Originally released February 10, 1995; last updated December 17, 2018; expires December 17, 2021

This article includes discussion brain herniation, caudal transtentorial herniation, central herniation, cingulate herniation, subfalcine herniation, tentorial herniation, tonsillar herniation, transtentorial herniation, uncal herniation, and upward herniation. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.


The author describes the anatomical basis, physical mechanisms, and clinical presentations of brain herniation. Included in the discussion of management of brain herniation is an update on the medical and surgical interventions used for treatment.

Key points


• The Monro-Kellie doctrine states that the skull is a fixed space with 3 components: brain, blood, and CSF; and when the volume of one increases, there is a compensatory decrease in the other components.


• Per the Monroe-Kellie doctrine, brain herniation occurs when there is a space-occupying lesion that overcomes the available volume in the intracranial vault, thus causing herniation of the normal contents out of the cranium.


• Transtentorial herniation is associated with the clinical triad of coma, ipsilateral pupillary dilatation, and hemiparesis of the contralateral side due to compression of the cerebral peduncle.


• Acute brain herniation is a medical emergency, often requiring a combination of medical and surgical treatments.

Historical note and terminology

During the 17th century, the human body began to be viewed as a system of subunits and independent compartments. This eventually led to the first human anatomical descriptions that mapped the body into different organs and tissues. As a result of this "subunit" or "compartment" theory, the Latin term herniation was employed to describe the protrusion of a portion of an organ or tissue through an abnormal passage. In the brain, herniation occurs when the total volume of the intracranial vault is overcome, leading to herniation of brain out of the intracranial vault.

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