One or both pupils may be dilated and fail to constrict in response to light. Vomiting can also occur due to compression of the vomiting center in the medulla oblongata. Severe headaches and seizures as a result of increased intracranial pressure are not uncommon. Cardiovascular and pulmonary symptoms may also be present as the brain loses function, but might also be associated with bleeding. They can include: hypertension, respiratory depression, arrhythmia and in severe cases cardiac arrest. Causes
Causes of brain herniation include:
Brain edema
Hematoma
Stroke
Tumour
Infection

Classification
The tentorium is an extension of the dura mater that separates the cerebellum from the cerebrum. There are two major classes of herniation: supratentorial and infratentorial. Supratentorial refers to herniation of structures normally found above the tentorial notch, and infratentorial refers to structures normally found below it. Supratentorial herniation1) Uncal (transtentorial)
2) Central
3) Cingulate (subfalcine/transfalcine)
4) Transcalvarial
5) Tectal (posterior)

Infratentorial herniation6) Upward (upward cerebellar or upward transtentorial)
7) Tonsillar (downward cerebellar)

Uncal herniation
In uncal herniation, a common subtype of transtentorial herniation, the innermost part of the temporal lobe, the uncus, can be squeezed so much that it moves towards the tentorium and puts pressure on the brainstem, most notably the midbrain. The tentorium is a structure within the skull formed by the dura mater of the meninges. Tissue may be stripped from the cerebral cortex in a process called decortication.The uncus can squeeze the oculomotor nerve (a.k.a.
Damage to the cardio-respiratory centers in the medulla oblongata will cause respiratory arrest and (secondarily) cardiac arrest. Investigation is underway regarding the use of neuroprotective agents during the prolonged post-traumatic period of brain hypersensitivity associated with the syndrome. See also
Second-impact syndrome

References


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