Transtentorial herniation

Transtentorial herniation (TTH), also known as uncal herniation, is a type of brain herniation where part of the brain moves from its normal position across structures within the skull. This condition is a serious and often life-threatening event that occurs as a result of increased intracranial pressure (ICP), which can be due to various causes such as head injury, brain tumor, stroke, or inflammation of brain tissue.

Causes

Transtentorial herniation is most commonly caused by factors that lead to an increase in intracranial pressure. These can include:

• Head injury: Trauma to the head can cause swelling of the brain or bleeding within the skull, leading to increased pressure.
• Brain tumor: Tumors can grow to a size that they exert pressure on surrounding brain tissue or block the flow of cerebrospinal fluid (CSF), leading to increased ICP.
• Stroke: A stroke can cause brain swelling or hemorrhage, which increases intracranial pressure.
• Infection: Infections such as encephalitis or meningitis can cause inflammation and swelling of the brain or surrounding membranes.

Symptoms

Symptoms of transtentorial herniation can vary depending on the severity and speed of onset but may include:

• Changes in level of consciousness
• Pupil dilation, typically on one side
• Changes in breathing pattern
• Paralysis or weakness on one side of the body
• Headache
• Seizure

Diagnosis

Diagnosis of transtentorial herniation involves a combination of clinical assessment and imaging studies. Magnetic resonance imaging (MRI) or computed tomography (CT) scans are commonly used to visualize the brain and identify the presence of herniation, as well as to determine its cause.

Treatment

Treatment of transtentorial herniation is aimed at reducing intracranial pressure and addressing the underlying cause. This may involve:

• Medications to reduce brain swelling, such as mannitol or hypertonic saline
• Surgical intervention to remove the source of increased pressure, such as a tumor or hematoma
• Ventriculostomy to drain excess cerebrospinal fluid
• Supportive care in an intensive care unit (ICU) setting

Prognosis

The prognosis for individuals with transtentorial herniation varies widely and depends on the cause, severity, and speed of intervention. Early detection and treatment are critical for improving outcomes.

See also

• Brain herniation
• Intracranial pressure
• Head injury
• Brain tumor