11. Stroke / Cerebrovascular Accident Flashcards
What is a stroke?
Focal neurological disorder of abrupt onset due to pathological process in the cerebral blood vessels.
Disruption of blood supply to the brain (infarction) creates an area of brain damage (infarct). –> the brain takes up to 1/5 of the body’s blood supply
Attacks up to 1.9 million brain cells per minute.
How often do strokes occur, what are the effects?
1/6 people will have a stroke in their life.
1 stroke every 19 mins
Kills more women than breast cancer and more men than prostate cancer.
30% of stroke patients die within a year of their stroke.
Expected that by 2050, there will be one stroke every 10 minutes, and over 800 000 stroke survivors.
Around 500 000 Australians are living with the effects of stroke.
What are the economic costs of strokes?
2020: estimated cost in Australia was $6.2 billion in direct financial impact, and a further $26 billion in mortality and lost wellbeing.
Where in the brain do strokes occur?
Can happen anywhere
Strokes in the hind-brain (pons, medulla, cerebellum) are very severe: less likely to survive them, and if you do, neurocognition is not priority
Stokes in the midbrain tend to impact motor function (so neuropsychologists don’t play a big role in this)
The bulk of the brain (forebrain) where most people have strokes impacts cognition (relevant to neuros)
Discuss more neuroanatomy in terms of strokes
- clear lateralization (impacts left or right side) and we tend to see the effects (language skills vs visuospatial skills)
- distinguish between grey (outside) and white (inside) matter - strokes in white matter tend to be much smaller, show up as little dots on the brain but overtime can cause cognitive deficits
- white matter important for connectivity and communication (more likely to have slowness, inefficiency, problems with attention and concentration)
- grey matter: see more cortical deficits (speech, comprehension, memory, movement)
Discuss cerebral circulation - and the two main arteries
Cerebral circulation = movement of blood through blood vessels
- internal carotid artery (front of neck)
- vertebral arteries (through the back)
What are the 2 different blood supplies to the brain?
Anterior cerebral circulation system: itnernal carotid arteries –> anterior and middle cerebral arteries –> supplies blood to the front part of brain
Posterior cerebral circulation system: vertebral arteries –> basilar and posterior cerebral arteries –> supply blood to occipital lobes, brain stem, cerebellum
What is the role of the posterior communicating arteries?
Links the posterior circulation system to the anterior circulation system to create the ‘circle of Willis’
- engineered redundancy: if there’s an issue with this blood supply in the anterior part of the brain, the blood supplies can still communicate through the circle
- but only 35% of the population have a circle of Willis - if you don’t, it increases your chances of having negative effects of stroke
What do the vertebral and basilar arteries supply?
To the cerebellum, pons, medulla
Where does the anterior cerebral artery supply?
Inner parts of frontal lobe, parietal lobe, polar regions (PFC)
Where does the middle cerebral artery supply?
Grey matter of the frontal lobe, temporal lobe, and parietal lobe
Where does the posterior cerebral artery supply?
Inner parts and lower part of temporal lobe, the occipital lobe, the parietal lobe
What is the acronym for Stroke signs?
FAST!
Face (facial asymmetry - eye or mouth drooping)
Arms (motor impairment impacting contralateral side - i.e. left sided stroke = deficits on right side of body) –> ask person to raise both arms
Speech: changes in speech (slurred)
Time: 1.9 million brain cells dying per minute, i.e. call ambulance quickly
What are some other common symptoms
- dizziness
- loss of vision
- sensory impairment
- confusion
- severe headache
- difficulty swallowing
Outline a transient ischaemic attack
- relatively small bloodclot gets lodged in small blood vessel
- until it gets pushed through, it will cause these symptoms
- symptoms recover, but when the clot comes round again it causes the same symptoms
The build up of this causes damage to the brain - because these symptoms mean that part of your brain is not getting blood supply.
Transient ischaemic attacks are predictors for a big upcoming stroke - i.e. should go to hospital
What are some risk factors for stroke that you cannot control:
Age: >55, each decade your chance of stroke doubles
Sex: men are more likely to have a stroke at any one time, but at the end of life, more common in women
Family history: certain genetic mutations predispose someone to having more strokes (e.g. cadasil)
Race: people from Japan and Africa have higher likelihood of stroke
What are some controllable risk factors (lifestyle risk)
Hypertension / high blood pressure: puts more pressure on the blood vessel walls
Hypercholesterolaemia –> fatty deposits stick to the walls of the blood vessels and cause pathology
Cigarettes - increases blood pressure and releases chemicals which stick to the walls
Obesity - increases cholesterol, diabetes, blood pressure risk
Excessive alcohol consumption - increases blood pressure
What are some medical risk factors of strokes?
Cardiovascular disease: more likely to have the same type of disease in your brain
Atrial fibrillation - the chambers of the heart vibrating instead of beating rhythmically
Diabetes - the brain will be deprived of adequate sugar and oxygen (if not well managed)
Previous stroke or transient ischaemic attacks increase chances of having a stroke
What is atherosclerosis?
Pathological thickening and hardening of your arteries due to build up of fatty deposits in artery walls
- as you get older, they become thinner, rigid, hardened
- high blood pressure puts more pressure on these already compromised vessels
What are the 2 mechanisms of stroke:
Ischemia (deficient blood flow)
Haemorrhage (bleed)
Outline Ischaemia
Blood flow is deficient / absent due to obstruction in vessel (blood clot)
80% of strokes
Major risk factors = diabetes, hypercholesterolaemia, ischemic heart disease
What are the main causes of ischemic stroke?
Thrombus: clot formed in brain
Embolus: clot formed in body
What is a thrombotic stroke?
Most common cause of ischemia - blood clot formed in the brain!
Thrombus accumulates and becomes lodged in artery causing ischemia - may take hours to fully develop.
Thrombus in small arteries in white matter results in lacunar stroke - where you don’t see symptoms, but many will cause deficits.
But if its happening in grey matter in big blood vessels, there will be symptoms.
What is an embolic stroke?
Less common form of ischemia - accounting for only 20-30%.
Blood clot formed in the body that travels to the brain - usually originating from the heart. Becomes lodged in a cerebral artery causing ischemia.
Abrupt presentation (as clot is already formed)
