Herniation Syndromes
- Central
Transtentorial
- Diffuse increased
supratentorial pressure causes downward displacement of
midbrain/diencephalon through tentorial incisura
- Change in mental status –
proceeds to Cheyne-Stokes respiration, paratonia, small reactive pupils,
decorticate posturing – proceeds to hyperventilation, decerebrate
osturing, midposition fixed pupils
- Subfalcine (Cingulate)
- Lateral shift of a cerebral
hemisphere forces cingulate gyrus under falx
- Compression of ACA and
internal cerebral vein result in infarction, further edema, worsening the
underlying pathologic process
- Tonsillar
- Posterior fossa mass causes
passage of cerebellar tonsils through foramen magnum
- Medullary compression causes
respiratory arrest
- Uncal
- Displacement of medial portion
of temporal lobe (uncus and hippocampal gyrus) over incisural edge
- Change in mental status and
ipsilateral pupillary dilatation – proceeds to hyperventilation,
decerbrate posturing, midposition fixed pupils
- Upward Transtentorial
- Upward displacement of
brainstem, anterior cerebellum, and posterior 3rd ventricle
from enlarging posterior fossa mass
- Chronic – Causes spasticity,
hydrocephalus
- Acute – Parinaud’s syndrome
with rapid LOC