What is brain herniation, and how do doctors treat it?

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Brain herniation happens when brain tissue, cerebrospinal fluid (CSF), and blood move from their usual position inside the skull and create increased pressure within it.

It may occur due to a head injury, brain tumor, or stroke.

There are five different types of brain herniation, depending on the affected part of the brain:

• Subfalcine: The cingulate gyrus, an arch-shaped section of the brain, pushes against the falx cerebri, a crescent-shaped section between the left and right sides of the brain. This is the most common type of brain herniation.
• Transtentorial or uncal: A mass may squeeze the medial temporal lobe under and across a membrane called the tentorium.
• Central: Both temporal lobes shift through an opening in the tentorium, called the tentorial notch.
• Tonsillar herniation: A mass in the infratentorial area of the brain forces the cerebellar tonsils, small structures at the base of the brain, through the foramen magnum, an opening in the skull.
• Upward herniation: A mass in the infratentorial area of the brain compresses the brain stem.

Some types of brain herniation, such as subfalcine herniation, may not initially present with severe symptoms. A person may experience:

• headaches
• nausea and vomiting
• altered mental status, such as confusion

Other symptoms of brain herniation may include:

• dilated pupils
• unequal pupil sizes, where one pupil may be more dilated than the other
• weakness in the lower limbs or on one side of the body
• altered mental state, such as confusion or unusual change in alertness
• fluid buildup in the brain, which may cause headaches, nausea, and vision problems
• abnormal body posture — for example, the head arched back with the arms and legs straight out, or bent arms, clenched fists, and straight legs
• the inability to move the eyes up or down
• frequent urination
• changes in breathing, such as hyperventilating
• respiratory arrest, which is when a person stops breathing

Swelling in the brain can cause pressure within the skull, resulting in brain tissue shifting from its usual position into surrounding areas. This movement may occur due to:

• trauma to the brain through a head injury
• a brain tumor
• bleeding in the brain
• infections affecting the brain
• stroke
• a buildup of fluid in the cavities of the brain

Healthcare professionals need to diagnose brain herniation quickly to begin treatment as soon as possible. They will likely do this by:

• assessing any symptoms
• taking a medical history
• using imaging tests, such as CT scan or MRI scan, to identify any shift in brain structure or masses and to determine the type of herniation
• checking for any signs of complications

Treatment for brain herniation may include the following:

• surgery to remove a mass, such as a tumor or an abscess
• sedatives and pain relief medication
• ventilation to help any breathing problems
• drainage of the CSF from the brain
• osmotherapy with drugs, such as mannitol, to reduce fluid buildup and pressure in the skull
• corticosteroids to reduce swelling
• hyperventilating a person to reduce pressure in the skull
• therapeutic hypothermia, which is when doctors use cooling devices to reduce a person’s body temperature to help reduce brain swelling
• induced coma to reduce blood flow in the brain
• decompressive hemicraniectomy, which is a type of surgery that removes part of the skull to allow more space for the brain and reduce compression

Complications of brain herniation may include:

• hydrocephalus, which is a buildup of fluid on the brain
• high pressure on the blood vessels, which may cause a stroke
• issues affecting the cranial nerves

If brain herniation progresses, it may lead to:

• an altered state of consciousness
• abnormal posturing, such as a rigid body or unusual body positions
• respiratory arrest, which can be fatal

Certain factors may affect the outlook for people with brain herniation. These factors include:

• the person’s age
• the level of consciousness
• the type of herniation
• if a person has multiple traumas
• which symptoms are present
• where in the brain the bleeding occurs, if there is a hemorrhage
• the level of oxygen in the tissues of the body
• low blood pressure
• the level of pressure within the skull

The immediate diagnosis and treatment of brain herniation are essential to improve a person’s outlook and maximize their likelihood of recovery.

An important part of treating brain herniation is the prompt treatment of any primary injuries and secondary conditions, such as high blood pressure or infection.

Brain herniation is a severe condition in which brain tissue, CSF, and blood shift position to surrounding areas of the brain, increasing the pressure within the skull.

Brain herniation may occur as a result of swelling in the brain, which may be due to a head injury, stroke, bleeding in the brain, or a brain tumor.

Brain herniation can be life threatening, and immediate medical attention will be necessary.

The treatment options may include surgery to remove a mass, medications to reduce swelling and pressure within the skull, and the drainage of any fluid buildup.