Brain herniation Health Article

Definition

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

Alternative Names

Herniation syndrome; Transtentorial herniation; Uncal herniation; Subfalcine herniation; Tonsillar herniation; Herniation - brain

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

Symptoms

• Cardiac arrest (no pulse)
• Coma
• Irregular breathing
• Irregular pulse
• Loss of all brainstem reflexes (blinking, gagging, pupils reacting to light)
• Progressive loss of consciousness
• Respiratory arrest (no breathing)

Signs and tests

A neurological exam shows changes in alertness (consciousness). Depending on the severity of the herniation, there will be problems with one or more brain-related reflexes and cranial nerve functions.

Patients with a brain herniation have irregular heart rhythms and difficulty breathing consistently.

Treatment

Brain herniation is a medical emergency. The goal of treatment is to save the patient's life.

To help reverse or prevent a brain herniation, the medical team will treat increased swelling and pressure in the brain. Treatment may involve:

• Placing a drain placed into the brain to help remove fluid
• Corticosteroids such as dexamethasone, especially if there is a brain tumor
• Medications that remove fluid from the body such as mannitol or other diuretics, which reduce pressure inside the skull
• Placing a tube in the airway (endotracheal intubation) and increasing the breathing rate to reduce the levels of carbon dioxide (CO2) in the blood
• Removing the blood if bleeding is causing herniation