Brain herniation

[Dorothey Allen]

Brain herniation occurs when increased intracranial pressure causes the abnormal protrusion of brain tissue through openings in rigid intracranial barriers (eg, tentorial notch).
Because the skull is rigid after infancy, intracranial masses or swelling may increase intracranial pressure, sometimes causing protrusion (herniation) of brain tissue through one of the rigid intracranial barriers (tentorial notch, falx cerebri, foramen magnum). When intracranial pressure is increased sufficiently, regardless of the cause, Cushing reflex and other autonomic abnormalities can occur. Cushing reflex includes systolic hypertension with increased pulse pressure, irregular respirations, and bradycardia.
Brain herniation is life threatening.
Brain herniation is classified based on the structure through which tissue is herniated. Types include the following (see figure Brain herniation):

Transtentorial (uncal)
Subfalcine
Central
Upward transtentorial
Tonsillar