Brain herniations Flashcards
What is a herniation?
Abnormal movement of an organ through an opening
What causes brain herniation?
Increased intracranial pressure
secondary to tumours, bleeding, hydrocephalus, infection, cerebral oedema…
What are the four important types of brain herniation?
Cingulate / Subfalcine
Central
Uncal
Tonsilar
Which lobe is involved in a cingulate herination?
Most of them
Cingulate gyrus runs along the midline
What does the cingulate gyrus herniate underneath?
Does it move medially or laterally?
Falx cerebri (lining of dura running down the midline)
Medially
What structure may be damaged by a cingulate/subfalcine herniation?
Anterior cerebral artery
Which artery is most at risk of damage in a subfalcine herniation?
Anterior cerebral artery
Which part of the brain does the anterior cerebral artery supply?
Medial cerebral hemispheres - from frontal to parietal lobes
Corpus callosum
Caudate nucleus
Which symptoms are caused by a cingulate / subfalcine herniation?
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
Which lobe shifts in an uncal herniation?
Temporal lobe
In an uncal herniation, the temporal lobe passes through an opening in which structure?
Tentorium cerebelli
Which structures does the brain herniate through in
a) cingulate
b) uncal herniations?
a) Falx cerebri
b) Tentorium cerebelli
Which symptoms are caused by uncal herniation?
Dilation of ipsilateral pupil (compression of CN III)
Contralateral hemiparesis (compression of medullary pyramids, where motor fibres cross over, causes muscle weakness)
Which symptoms are seen in
a) cingulate
b) uncal herniations?
a) Contralateral leg weakness
b) Ipsilateral dilation, contralateral hemiparesis
In which herniation does the cerebellum pass through the foramen magnum?
Tonsilar herniation
Which
a) part of the brain
b) bony structure
is involved in tonsilar herniation?
a) Cerebellum
b) Foramen magnum
Which symptoms are caused by tonsilar herniation?
Cushing’s triad
Hypertension
Bradycardia
Irregular breathing
caused by compression of centres in the medulla
What congenital malformation, causing narrowing of the spinal cord, may tonsilar herniation be caused by?
Chiari malformation
Narrowing of the spinal cord which causes CSF blockage > increased ICP
What is a central herniation of the brain?
Downwards movement of brainstem towards the tentorium cerebelli
Which important space, containing venous blood, the internal carotid artery and a cranial nerve, is compressed in central herniation?
Cavernous sinus
Which cranial nerve travels in the cavernous sinus?
CN VI
Abducent nerve
What symptom is caused by compression of CN VI in a central herniation?
Diplopia
Which symptoms are caused by
a) tonsilar
b) central
herniations?
a) Cushing’s triad (hypertension, bradycardia, irregular breathing)
b) Diplopia
Which symptoms are caused by
a) tonsilar
b) subfalcine
c) uncal
d) central
herniations?
a) Cushing’s triad (hypertension, bradycardia, irregular breathing)
b) Contralateral leg weakness
c) Ipsilateral dilation, contralateral hemiparesis
d) Diplopia
