Pathology Of Cerebro-vascular Disease Flashcards
Which 3 arteries supply the brain
Anterior cerebral artery
Middle cerebral artery
Posterior cerebral artery
Which arteries supply brainstem and cerebellum
Vertebral and basilar arteries
What is a stroke (WHO definition)
Focal neurological deficit (loss of function affecting a specific region of the CNS) due to disruption of blood supply
What causes a stroke
Interruption of oxygen and nutrients causing damage to brain tissue
Caused by changes in:
- vessel wall (e.g. atheroma)
- blood flow (including blood pressure) (e.g. decreased blood flow)
- Blood constituents (e.g. thrombosis of arteries and rarely veins)
In practice what are the 3 main causes of localised interrupted blood supply
Atheroma + thrombosis of artery causing ischaemia
Thromboembolism (e.g. from left atrium) causing ischaemia
Ruptured aneurysm of a cerebral vessel causing haemorrhage
What is a transient ischaemic attack
Transient symptoms lasting <24hrs due to reversible ischaemia
Tissue is still viable
What is a stroke infarct
Long-standing symptoms lasting >24hours due to irreversible ischaemia causing localised brain death (infarct)
If infarction then there will be permanent damage to neurones - neurones do not regenerate
What is a regional cerebral infarct (what does it look like)
Localised area of brain death
Classically wedge-shaped reflecting arterial perfusion territory
Soft and then become cystic
What is the outcome of a thromboembolism
Thrombosis in left atrium breaks off and embolises to aorta and possibly the carotid arteries
Causes an Ischaemic stroke similar to atheroma/thrombosis
Why do cerebral arteries have thin walls
Dont want too much muscle in cerebral arteries as you don’t want them to contract - cerebral blood flow has to be protected
Thin walls become an issue with hypertension
How does a ruptured vessel wall cause ischaemia
Ruptured vessel wall causes haemorrhage - any vessel which is bleeding goes into spasm which decreases the blood flow distally
Double blow as bleeding combined with spasm increases distal ischaemia
Where are the 2 common sites of ruptured vessels causing haemorrhagic stroke
Basal ganglia - microaneurysms form in hypertensive patients
Circle of Willis - berry aneurysm forms in hypertensive patients (doesnt cause many problems unless you have hypertension - results in rupture)
What are the 3 causes of hypoxia (with examples)
Low O2 in blood (hypoxia with intact circulation of blood e.g. carbon monoxide poisoning, near drowning, respiratory arrest)
Inadequate supply of blood (flow of blood not occurring e.g. cardiac arrest, hypotension, brain swelling)
RARELY: inability to use O2 (e.g. cyanide poisoning)
What is a watershed infarct
Ischaemic lesion along the border of zones between the territories of two major arteries
What causes a watershed infarct
Hypotension
What causes a cortical infarction
Cardiac arrest
(If patient lives long enough grey matter becomes thinner as seen in photo)
What causes a complex pattern infarction
Complex cases involving different mechanisms
