Brain Herniation Syndromes

Subfalcine Herniation

• Description: Brain tissue extends under the falx in the supratentorial cerebrum.
• Clinical Signs:
  • Small reactive pupils
  • Contralateral leg paralysis

Transtentorial Descending Herniation (Uncal Herniation)

• Description: Medial temporal lobe pushes downward into the posterior fossa through the incisura.
• Clinical Signs:
  • Ipsilateral pupil dilation
  • Contralateral hemiparesis
  • Decerebrate posturing

Transtentorial Bilateral Herniation (Central Herniation)

• Description: Caused by the downward displacement of cerebral hemispheres and basal nuclei.
• Clinical Signs:
  • Medium-sized fixed pupils
  • Stupor and coma
  • Decorticate posturing
  • Cheyne-Stokes respirations
  • Diabetes insipidus

Transtentorial Ascending Herniation

• Description: Infratentorial mass effect protrudes upwards compressing the midbrain.
• Clinical Signs:
  • Nausea and vomiting
  • Progressive stupor

Tonsillar Herniation

• Description: Cerebellar tonsils protrude below the foramen magnum compressing the medulla and upper cervical spinal cord.
• Clinical Signs (Cushing Reflex):
  • Hypertension
  • Bradycardia
  • Dyspnea
  • Respiratory arrest

Transcalvarial Herniation

• Description: Rare, usually due to penetrating injuries to the head and skull leaving a defect/opening for herniation.
• Clinical Signs:
  • Vary based on whether brain tissue was involved
  • Location of involvement also affects symptoms