Pathology of Cerebrovascular Disease: Ischaemia and Hypoxia Flashcards
Which artery is the middle cerebral artery a continuation of?
Internal carotid artery
Ischaemia?
Lack of blood flow
Hypoxia?
Lack of oxygen
What can ischaemia often lead to?
Hypoxia
What causes a stroke?
Disruption to blood supply of brain. This leads to an interruption in oxygen and nutrient supply to brain causing brain tissue damage
The interruption of supply of oxygen to the brain can be caused by changes in which things?
- Changes in vessel wall
- Changes in blood flow
- Changes in blood constituents
What could cause a change to the vessel wall and disrupt blood flow?
Atheroma
Vasculitis
Outside pressure e.g. spinal cord compression, strangulation
What could cause a change to the blood constituents and disrupt blood flow?
Thrombosis of arteries
Bleeding due to anticoagulation
Reduced platelets and clotting factors
In practice, there are three main causes of localised interrupted blood supply. List them.
- Atheroma and thrombosis of an artery
- Thromboembolism
- Ruptured aneurysm
What would atheroma and thrombosis do to the artery?
Narrows it
What are the components of thrombosis?
Platelets and fibrin
If there was atheroma and thrombosis of an artery, what could this cause?
Ischaemia
If there was internal carotid artery thrombosis, in which area would there be ischaemia?
Middle cerebral artery region
->middle cerebral artery is a branch of the internal carotid arteries
When are ischaemic symptoms classified as transient?
If they last less than 24hrs
When are ischaemic symptoms classified as longstanding?
If they last more than 24hrs
If there is transient ischaemia, what happens to the brain tissue?
Still viable as this process is reversible
If there is longstanding ischaemia, what happens to the brain tissue?
Infarct as death to brain tissue due to irreversible ischaemia
Anoxia?
Total loss of oxygen
What can hypoxia/anoxia of the brain lead to?
Infarction
Is infarction reversible?
No as neuronal damage is permanent and neurons do not regenerate
Which cells in the brain have a role in inflammation and act as the macrophages in the brain?
Microglial cells
What is the name given to the CNS version of fibrosis?
Gliosis
Which heart related condition is it more common to get thrombosis?
Atrial fibrillation
If there is a thrombosis in the left atrial appendage and it breaks off, where will it embolise to?
Aorta and potentially carotid arteries
What does thromboembolism cause?
Ischaemia
Which type of stroke would thromboembolism or atheroma/thrombosis lead to?
Ischaemic stroke
In which condition are the thin walled arteries of the brain more likely to rupture?
In those with hypertension
->this is why hypertension is the biggest risk factor for strokes!!!!
What would a ruptured vessel in the brain lead to?
Haemorrhage and ischaemia
->as reduced blood flow to part after the rupture as all blood leaking through the rupture
What are the two common sites of ruptured vessels causing haemorrhagic stroke?
Basal ganglia
Circle of Willis
Which type of aneurysm forms in hypertensive patients in the basal ganglia?
Microaneurysms
Which type of aneurysm forms in hypertensive patients in the Circle of Willis?
Berry aneurysm
A berry aneurysm in the Circle of Willis can give rise to what?
Subarachnoid haemorrhage
When may there be a generalised interrupted blood supply, potentially causing hypoxia?
-Low oxygen in blood
-Inadequate supply of blood
In which situations would there be low oxygen levels in blood?
Carbon monoxide poisoning, near drowning, respiratory arrest
In which situations would there be an inadequate supply of blood?
Cardiac arrest
Hypotension
Brain swelling
What name is given to zones of infarction at interface of artery perfusion territories?
Watershed infarcts
What does complete loss of perfusion and oxygen* lead to?
*e.g. someone has had a cardiac arrest and all blood flow stops
Cortical necrosis
Which type of infarction could someone get if they had hypotension?
Watershed infarction
