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Medicine

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Neurology

Question
2 out of 4
 

Which nerve is most commonly involve in uncal herniation?



A IIIrd
B VIth
C IXth
D XIIth

Ans. A

IIIrd

Types of cerebral herniation. (A) uncal; (B) central; (C) transfalcial; (D) foraminal.

Fig. Types of cerebral herniation (Ref. Hari-18th Ed., Fig 274-1, Pg 2248)

Uncal herniation

The uncus and the temporal lobe are forced through the cerebellar tentorium (tentorium that separates the cerebrum from the cerebellum)

1). It causes

Sequential compression occurs of the

- Ipsilateral third nerve

- Contralateral brainstem (later)

- Whole brainstem (eventually)

2). Physical signs

a. Early

i. I/L dilated pupils

ii. Signs of supratentorial mass lesions

b. Later

i. I/L hemiplegia

ii. Progressive ptosis & third n palsy

iii. Cheyne- stokes respiration

c. Still Later

i. Tetraparesis

ii. B/L fixed dilated pupils

iii. Erratic respiration

iv. Death