Brain Herniation

OVERVIEW

  • brain herniation is the displacement of part of the brain through an opening or across a separating structure into a region that it does not normally occupy.

TYPES

Supratentorial

1. Uncal transtentorial herniation
2. Central tentorial herniation
3. Subfalcine herniation
4. Transcalvarial hernaiton

Infratentorial

5. Upward transtentorial herniation (“reverse coning”)
6. Foraminal or tonsillar herniation (“coning”)

brain herniation

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UNCAL TRANSTENTORIAL HERNIATION

  • The uncinate process of the temporal lobe herniates into the anterior part of the opening of the tentorium cerebelli

CT Features:

  • Shift of brainstem and distortion of adjacent cisterns
  • Dilatation of the contralateral temporal horn
  • PCA territory infarct due to compression of the posterior cerebral artetry as it crosses the tentorium

CENTRAL TENTORIAL HERNIATION

  • symmetrical downward movement of the thalamic region through the opening of the tentorium cerebelli

SUBFALCINE HERNIATION

  • Displacement of the cingulate gyrus under the falx and across the midline.

TRANSCALVARIAL HERNIATION

  • Aka external herniation
  • Displacement of brain through a defect in the skull, such as a fracture site or following craniectomy.

UPWARD HERNIATION

  • So-called “reverse coning” can occur if an EVD is inserted for hydrocephalus due to a posterior fossa mass lesion. This leads to upwards transtentorial herniation of posterior fossa contents.

FORAMINAL HERNIATION

  • Aka tonsillar herniation
  • Downward herniation of the cerebellar tonsils into the foramen magnum

References and Links

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