Stroke territories Flashcards
What are the 2 main group that stroke can be divided into?
- Ischaemic
- constitutes about 85-90% of water - Haemorrhagic
What are 2 overlapping areas of Ischaemic group?
- Thromboembolic
- Haemodynamic
Interplay between them in stroke setting
When does Ischaemia occur?
When the blood flow through one or more your coronary arteries is decreased
Perfusion drops to a certain threshold
Nutrient supplied to the brain, oxygen and glucose, drops to a critical level
What is the consequence of nutrients dropping to a critical level?
- Decoupling of potassium-ATPase pump of the cell
What are 2 major processes of de-coupling of potassium-ATPase pump?
- Influx of calcium into the cells
2. Release of glutamate into the synaptic cleft
What leads to further increase in intracellular calcium and ventral cellular death?
Attachment of NADPH receptors which is a irreversible process
Further increase in intracellular calcium
Ventral cellular death - end result of ischaemic process
What is the most vulnerable to the effect of blocked artery?
Tissue closest to the blocked artery
Become infarcted tissue
What can be supported for longer by collateral circulation?
Surrounding tissue away from area of infarction
What happens to the tissue if blood supply is reversed?
Will recover
If occlusion persists - get infarcted tissue
The lower the perfusion areas, less time is needed before infarction occurs
What are 2 parameters that infarct are dependent on?
- Severity of blood supply
2. Duration
What is the most used modality in acute setting?
CT
Looking for signs of acute stroke
What is CT scan used to look for?
To exclude haemorrhage
What looks at major blood vessels?
- CTA
2. Angiogram
What is intraluminal thombus in a vessel?
Looking for dense MCA
What happens when you lose perfusion?
Lose grey matter interface
Anterior circulation is lost in that area
What is the posterior circulation constituted by?
Vertebral-basilar circulation
What is anterior circulation constituted by?
Anterior middle cerebral arteries arising from termination of internal carotid arteries
Where does midline anastomosis occur?
between anterior circulation and anterior communicating arteries
There is further anastomosis communication of the anterior and posterior by the posterior communicating arteries
What are the 3 major arterial territories?
- Middle cerebral artery (MCA) -largest
- Anterior cerebral artery (ACA) - paramedially
- Posterior cerebral artery (PCA) - posteriorally
What has invariable supply from anterior circulation by recurring arteries of hebru?
Caudate
What is supplied by MCA?
Some of the lenticulate striate
What is difficult in their supply?
Middle deep grey structures