Stroke and Risk Factors Flashcards by Lucy Jefford

What is a stroke?

A sudden onset of neurological deficit (loss of function) .

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How long does a stroke have to be present to be considered a stroke? (if that even makes sense).

24hrs

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What is the difference between a stroke and a transient ischemic attack?

Transient ischemic attack has the same symptoms as stroke but lasting less than 24hrs.

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What pathologically causes a stroke?

A blocked or ruptured blood vessel in the brain causing a failure of neuronal function leading (usually) to some deficit in brain function

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What are some of the causes of a stroke?

Blockage with thrombus or clot
Disease of vessel wall
Disturbance of normal properties of blood
Rupture of vessel wall (haemorrhage)

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What are strokes usually due to?

Infarction (85-90%)

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What is the difference between a haemorrhagic stroke and an ischaemic stroke?

Haemorrhagic- blood leaking in the brain
Ischaemic- not enough oxygen getting to the brain

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Where will there usually be an atheroma?

Bifurcation of arteries

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In which artery would a clot breaking off and embolising cause a stroke?

Internal carotid- if an atheroma and clot formed and the clot broke off, it would travel up to the brain.

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What is the condition in which a clot forms in the carotid artery and embolises to the brain known as?

Carotid disease

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Give another example of a type of stroke due to large vessel occlusion.

Cardioembolic stroke

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What is the commonest cause of cardioembolic stroke?

Atrial fibrillation

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Describe what happens to cause a cardioembolic stroke.

Clot forms in the left atrial appendage.
Clots travels up the aorta and into the cerebral vessels.

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Name two strokes caused by large artery disease.

Carotid artery disease
Cardioembolic stroke

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What is a small vessel artery disease?

When one of the smaller arteries branching off from a larger artery becomes occluded.

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What is lacunar stroke (small vessel artery disease) associated with?

Hypertension

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What is a rarer cause of large vessel artery disease?

Lining of the blood vessel tears

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What are some of the risk factors for a stroke?

Hypertension
Smoking
Diet
Exercise
Diabetes
Alcohol

What are some of the pathological causes of stroke?

Haemorrhagic
Small vessel disease
Large vessel disease (atherosclerotic cerebrovascular disease)
Cardiac embolism

What are some of the risk factors for haemorrhage?

Hypertension (60-70%)
Amyloid (15 -20%)*
Excess alcohol
Hypocholesterolaemia
Haemorrhagic transformation

*for interest- build up of protein (amyloid) in the organs

What is ischaemia the result of?

Failure of cerebral blood flow to a part of the brain.

What does transient mean?

Short, not permanent

What can ischaemia result in?

Various degrees of hypoxia

Is ischaemia transient?

It can be

What is it called when hypoxia becomes prolonged?

Anoxia (no oxygen)

What does anoxia result in?

Infarction

What does hypoxia do to the brain?

Hypoxia stresses the metabolic machinery of brain cells, which malfunction but are still alive

What happens in infarction?

Complete cell death leading to necrosis and therefore, the full cycle leading to a stroke has occurred.

After a completed stroke, what can cause further damage?

Oedema

What happens to cells when there isn't enough oxygen?

Cells cannot produce as much energy. Metabolism has to switch to anaerobic metabolism which greatly reduces ATP production and produces lactate

What can lactic acid do?

Lactic acid is an irritant, which has the potential to destroy cells by disruption of the normal acid-base balance in the brain.

What happens when the ATP-reliant ion transfer pump fails? (part of the ischaemic cascade).

Membrane becomes depolarised. Influx of calcium, and efflux of potassium.

If intracellular levels of calcium get too high, what does this trigger the release of? (part of the ischaemic cascade).

Glutamate- excitatory amino acid neurotransmitter

What does glutamate do?

Stimulates AMPA receptors and calcium-permeable NMDA receptors, which leads to even more calcium influx into cells.

What causes the release of glutamate?

High levels of intracellular calcium

What does excess calcium in the cell lead to? (part of the ischaemic cascade).

Overexcites cells and activates proteases, lipases and free radicals formed as a result of the ischaemic cascade.

What are proteases?

Enzymes which digest cell proteins

What do lipases do?

Enzymes which digest cell membranes

What can happen when phospholipases break down the cell membrane? (part of the ischaemic cascade).

It becomes more permeable so more ions and harmful substances enter cells

What happens when the mitochondria breaks down? (part of the ischaemic cascade).

Releases toxins and apoptotic factors

What do cells release if they go through necrosis? (part of the ischaemic cascade).

Glutamate and toxic chemicals

What can happen as a result of the loss of vascular structure as part of the ischaemic cascade?

Breakdown of the protective blood brain barrier and contributes to cerebral oedema, which can cause secondary progression of the brain injury.

Define excitotoxicity.

The toxic actions of excitatory neurotransmitters, primarily glutamate, where the exacerbated or prolonged activation of glutamate receptors starts a cascade of neurotoxicity that ultimately leads to the loss of neuronal function and cell death.

Define penumbra.

Reversibly injured brain tissue around ischemic core