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.
1. Uncal transtentorial herniation
2. Central tentorial herniation
3. Subfalcine herniation
4. Transcalvarial herniation
5. Upward transtentorial herniation (“reverse coning”)
6. Foraminal or tonsillar herniation (“coning”)
UNCAL TRANSTENTORIAL HERNIATION
- The uncinate process of the temporal lobe herniates into the anterior part of the opening of the tentorium cerebelli
- typically leads to
- Shift of brainstem and distortion of adjacent cisterns
- Dilatation of the contralateral temporal horn
- PCA territory infarct due to compression of the posterior cerebral artery as it crosses the tentorium
CENTRAL TENTORIAL HERNIATION
- symmetrical downward movement of the thalamic region through the opening of the tentorium cerebelli
- Displacement of the cingulate gyrus under the falx and across the midline.
- Aka external herniation
- Displacement of brain through a defect in the skull, such as a fracture site or following craniectomy.
- 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.
- Aka tonsillar herniation
- Downward herniation of the cerebellar tonsils into the foramen magnum
References and Links
FOAM and web resources
- Radiopaedia.org — Cerebral herniation