Brain herniation is a potentially deadly side effect of moderate/severe TBI that occurs when a part of the brain is squeezed across the fixed structures within the skull, through a defect in the skull (from an open skull fracture or penetrating wound), or through the hole in the base of the skull where the spinal cord connects with the brain.

In the combat or trauma setting, herniation can result due to mass effect from intracranial bleeding or increased intracranial pressure caused by swelling associated with TBI.

Brain herniation typically presents with one or more of the following signs and symptoms:

-Abnormal body posturing, a characteristic positioning of the limbs indicative of severe brain damage

-Decreased level of consciousness

-One or both pupils may be dilated (i.e., blown) and fixed (i.e., fail to constrict in response to light)

-Vomiting

-Severe headaches

-Seizures

-Cardiovascular and respiratory symptoms including respiratory depression, hypertension, and bradycardia (Cushing’s sign)

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Signs of impending brain herniation must be addressed as soon as possible and are an indication for urgent evacuation to a higher level of medical care.

More advanced treatments and interventions are addressed in the TACEVAC phase of TCCC.