1.10 Acute Insults to the CNS: Stroke/TIA Flashcards
How long does neurological dysfunction have to persist to be considered a stroke?
At least 24 hours
List some non-modifiable risk factors for stroke
- Age
- Race
- Gender
- History of TIA/other conditions
- Genetics
List some modifiable risk factors for stroke
- Things that cause clots (diabetes, heart disease like AF, hypertension)
- Lifestyle factors (diet, exercise, alcohol, smoking)
Which is more common: haemorrhagic or ischaemic stroke?
Ischaemic (~85%)
What are the two kinds of ischaemic stroke?
Thrombotic and embolic
Where in blood vessels is it most common for atherosclerotic plaques to form that cause strokes?
Branches and curves in circulation
What is the most common cause of cerebral infarction?
Cerebral atherosclerosis
What are some common upstream causes of embolic stroke?
- Atrial fibrillation
- Infective endocarditis
- Recent MI
Which tends to have faster onset: thrombotic or embolic stroke?
Embolic
Compare and contrast large vessel disease and small vessel disease
- Usually multiple sites of infarction in SVD
- SVD occurs in smaller vessels (“end of the road”)
- SVD entails much smaller infarct(s)
What structures is small vessel disease most likely to affect?
Deep non-cortical structures: internal capsule, basal ganglia, brain stem
What is the most common risk factor for lacunar strokes in small vessel disease?
Chronic hypertension
Why are the resulting infarctions from small vessel disease called “lacunar” infarctions?
Because the process of healing results in small lake-like cavities
What syndromes can small vessel disease cause?
Think about the origin:
- Pure motor hemiplegia
- Pure sensory hemiplegia
- Dysarthria
What are some factors that influence the size of a cerebral infarction?
- Availability of collateral circulation
- Duration of ischaemia
- Magnitude of reduction in cerebral blood flow
Describe red infarcts. What causes them, and are they haemorrhagic or ischaemic?
- Often caused by embolic events (ischaemic, not haemorrhagic)
- After tissue is reperfused, tiny amounts of blood leak out of damaged vessels, resulting in petechial pattern
Describe pale infarcts. What underlying events are they usually associated with?
- Usually associated with thrombosis (non-haemorrhagic)
- Typical thrombosis -> loss of oxygen to tissue -> infarction
True or false: penumbra tissue can survive for many hours using collateral blood supply
True
Under what circumstances would it not be useful to reperfuse brain tissue with thrombolysis/thrombectomy?
If there is no penumbra, then reperfusion injury may cause more harm than good.
List some factors that can cause secondary injury following stroke
- Inflammation
- Excitotoxicity
- Loss of ion homeostasis
- Mitochondrial damage
- Disruption of blood brain barrier
Give two examples of conditions where reperfusion injury is more likely to occur?
- Embolic stroke
- Long-lasting ischaemic event
Describe the mechanism of reperfusion injury following embolic stroke
- During embolic stroke, the endothelial lining of the vessels may be damaged
- Upon reperfusion, this causes leakage of blood components into brain parenchyma (red infarct)
- Damaged endothelial cells release inflammatory mediators and generate free radicals, both of which lead to increased neuronal death
What is the typical duration of a TIA?
Less than 1hr
In terms of types of tissue damage, what is occurring in a TIA?
Penumbra without infarction
