Definition of Brain herniation:

A brain herniation is when brain tissue, cerebrospinal fluid, and blood vessels are moved or pressed away from their usual position in the head.

Causes, incidence, and risk factors:

A brain herniation occurs when something inside the skull produces pressure that moves brain tissues. This is most often the result of brain swelling from a head injury.

Brain herniations are the most common side effect of tumors in the brain, including:

• Metastatic brain tumor
• Primary brain tumor

A brain herniation can also be caused by:

• Abscess
• Hemorrhage
• Hydrocephalus
• Strokes that cause brain swelling

A brain herniation can occur:

• Between areas inside the skull, such as those separated by a rigid membrane called the "tentorium"
• Through a natural opening at the base of the skull called the foramen magnum
• Through openings created during brain surgery