Brain herniations

Question 1

What is a herniation?

Answer 1

Abnormal movement of an organ through an opening

Question 2

What causes brain herniation?

Answer 2

Increased intracranial pressure

secondary to tumours, bleeding, hydrocephalus, infection, cerebral oedema…

Question 3

What are the four important types of brain herniation?

Answer 3

Cingulate / Subfalcine

Central

Uncal

Tonsilar

Question 4

Which lobe is involved in a cingulate herination?

Answer 4

Most of them

Cingulate gyrus runs along the midline

Question 5

What does the cingulate gyrus herniate underneath?

Does it move medially or laterally?

Answer 5

Falx cerebri (lining of dura running down the midline)

Medially

Question 6

What structure may be damaged by a cingulate/subfalcine herniation?

Answer 6

Anterior cerebral artery

Question 7

Which artery is most at risk of damage in a subfalcine herniation?

Answer 7

Anterior cerebral artery

Question 8

Which part of the brain does the anterior cerebral artery supply?

Answer 8

Medial cerebral hemispheres - from frontal to parietal lobes

Corpus callosum

Caudate nucleus

Question 9

Which symptoms are caused by a cingulate / subfalcine herniation?

Answer 9

Contralateral leg weakness

legs map to areas of motor strip supplied by anterior cerebral artery, and remember motor pathways cross over so damage affects the opposite side

Question 10

Which lobe shifts in an uncal herniation?

Answer 10

Temporal lobe

Question 11

In an uncal herniation, the temporal lobe passes through an opening in which structure?

Answer 11

Tentorium cerebelli

Question 12

Which structures does the brain herniate through in

a) cingulate
b) uncal herniations?

Answer 12

a) Falx cerebri

b) Tentorium cerebelli

Question 13

Which symptoms are caused by uncal herniation?

Answer 13

Dilation of ipsilateral pupil (compression of CN III)

Contralateral hemiparesis (compression of medullary pyramids, where motor fibres cross over, causes muscle weakness)

Question 14

Which symptoms are seen in

a) cingulate
b) uncal herniations?

Answer 14

a) Contralateral leg weakness
b) Ipsilateral dilation, contralateral hemiparesis

Question 15

In which herniation does the cerebellum pass through the foramen magnum?

Answer 15

Tonsilar herniation

Question 16

Which

a) part of the brain
b) bony structure

is involved in tonsilar herniation?

Answer 16

a) Cerebellum
b) Foramen magnum

Question 17

Which symptoms are caused by tonsilar herniation?

Answer 17

Cushing’s triad

Hypertension

Bradycardia

Irregular breathing

caused by compression of centres in the medulla

Question 18

What congenital malformation, causing narrowing of the spinal cord, may tonsilar herniation be caused by?

Answer 18

Chiari malformation

Narrowing of the spinal cord which causes CSF blockage > increased ICP

Question 19

What is a central herniation of the brain?

Answer 19

Downwards movement of brainstem towards the tentorium cerebelli

Question 20

Which important space, containing venous blood, the internal carotid artery and a cranial nerve, is compressed in central herniation?

Answer 20

Cavernous sinus

Question 21

Which cranial nerve travels in the cavernous sinus?

Answer 21

CN VI

Abducent nerve

Question 22

What symptom is caused by compression of CN VI in a central herniation?

Answer 22

Diplopia

Question 23

Which symptoms are caused by

a) tonsilar
b) central

herniations?

Answer 23

a) Cushing’s triad (hypertension, bradycardia, irregular breathing)

b) Diplopia

Question 24

Which symptoms are caused by

a) tonsilar
b) subfalcine
c) uncal
d) central

herniations?

Answer 24

a) Cushing’s triad (hypertension, bradycardia, irregular breathing)

b) Contralateral leg weakness

c) Ipsilateral dilation, contralateral hemiparesis

d) Diplopia