Herniation Syndromes

Question 1

Describe a subfalcine (cingulate) herniation

Answer 1

Brain tissue extends under the falx in the supratentorial cerebrum

Question 2

What lobe is affected in transtentorial descending (uncal) herniation?
Where does it perforate through?

Answer 2

Temporal lobe (medial side) pushes downwards through the posterior fossa

Question 2

What is the transtentorial central/downward bilateral deviation?
What parts of the brain herniate and where?

Answer 2

Downward displacement of the cerebral hemispheres anf basal nuclei compressing and displacing the diencephalon and midrain rostrocaudally through the tentorial notch

Question 2

Describe tonsillar herniation:
What herniates and where?

Answer 2

Cerebellar tonsils protrude below the foramen magnum compressing the medulla and upper cervical spinal cord

Question 3

Cingulate (subfalcine) herniation under falx cerebri may cause compression of what artery?

Answer 3

Anterior cerebral artery

Question 4

In central/downward transtentorial herniation what arteries may be ruptured by caudal (toward tail) displacement of the brainstem?

Answer 4

Paramedian basilar artery branches -> duret hemorrhages (usually fatal)

Question 5

Uncal transtentorial herniation causes what symptoms?

Answer 5

• Ipsilateral blown pupil (CN III compression) (early)
• Contralateral hemiparesis
• Coma (late)
• Later may cause Kernohan’s phenomenon

Question 6

What kind of herniation is Kernohan phenomenen seen with?

Answer 6

Uncal transtentorial herniation

Question 7

If Kernohan’s notch is on the right side where will the primary injury be?
Where will the symptoms of blown pupil be?
- USUALLY

Answer 7

• Primary injury Right side
• Blown pupil Left (on contralateral side)

Question 8

Describe Kernohan phenomenon

Answer 8

Misleading:
- Contralateral blown pupil
- Ipsilateral hemiparesis due to contralateral compression against Kernohan notch but fibres then cross over