8. Cerebrovascular Disease Flashcards
what are the 4 types of stroke
subarachnoid haemorrhage
primary intracerebral haemorrhage
ischaemic stroke
transient ischaemic attack
which is the most common type of stroke
ischaemic stroke (80% of cases)
what normally causes a subarachnoid haemorrhage
occurs when an aneurysm on the surface of the brain bursts and leaks
where does the bleeding occur in the subarachnoid haemorrhage
bleeding occurs in the space that surrounds the brain
where does the bleeding evolve from in a primary intracerebral haemorrhage
evolves from within the tissue of a brain
what normally causes primary intracerebral haemorrhage
hypertension or amyloid angiopathy
what happens in ischaemic stroke
a blockage prevents the flow of blood and oxygen to the brain
describe transient iscahemic attacks
also known as a mini stroke - symptoms only last for a short amount of time as the blockage preventing blood flow is only temporary
what structure ensures constant blood flow to the brain
the circle of Willis
what does NIHSS stand for
the national institute of health stroke scale
what does the NIHSS assess
the level of disability and neurological impairments on. scale from 0-42 0 with 42 the equivalent of death
on a CT scan, what is the white structure encasing the brain called
the cranial vault
how can a brain bleed be identified on a CT
the presence of a faint white line
what does infarction mean
the term for tissue injury that happens following reduced blood flow
what does ischaemia mean
reduced blood flow
how many strokes every year in the EU
1 million per year
give me a striking statistic on strokes
stroke is the second most common cause of death worldwide
name the 4 long-term complications associated with strong
increased long term mortality
physical, cognitive and behavioural impairments
chronic disability
recurrent stroke
increased risk of further vascular events
what is the biggest cause of stroke (what %)
atherothromboembolism = 50% of strokes
describe the Oxford vascular study as evidence for age as a risk factor
difficult to assess incidence of strokes. however, a longitudinal study directed by Oxford University found 75% of cerebrovascular diseases occurred in those aged 65+
what is a limitation of the Oxford vascular study
limited as numbers do not include possible, recurrent or suspected cerebrovascular events
name 3 races with an increased risk for stroke
black populations
maori and pacific islands
south asian populations living in the UK
why do black populations have an increased risk of stroke
due to comorbidities: increased risk of diabetes mellitus and hypertension
who do NZ people have a higher risk of stroke than
higher risk than europeans
why do south asian populations in the UK have a high risk factor for stroke
high prevalence of vascular disease due to genetic susceptibility, dietary and lifestyle factors
stroke as a result of atherosclerosis is high in rural china, what does incidence grow by each year?
stroke incidence rises annually at a rate of 8.7%
what factors make pregnant and postpartum females more prone to stroke
gestational hypertension
caesarean delivery
pre-eclampsia
- can all lead to aneurysm rupture as blood volume and cardiac output increase
women with gestational diabetes are how much more likely to have a stroke
6-9 fold
what does pre-eclampsia cause
endothelial dysfunction and impaired cerebral autoregulation
why is it interesting that the risk of perpiartuqm stroke is associated with caesarean delivery
perhaps this is because women at risk of stroke are encouraged to have a C-section. this would explain why incidence is higher in this group.
how many times more likely to suffer a stroke are people who take cocaine
6 x more likely
how does cocaine cause stroke
increases BP = could burst an aneurysm
cocaine promotes thrombotic strokes by causing hypercoagulable states
what evidence is there for a role of infections in preceding stroke
seasonal variation in stroke incidence and the fact that 10-35% of patients have an infection in the week preceding stroke
what chronic infections are associated with increased stroke risk
chlamydia pneumoniae
helicobacter pylori
name some modifiable risk factors for stroke
hypertension
psychosocial stress
smoking
how do these risk factors increase propensity to stroke
- promote the formation of atherosclerotic plaques
- these plaques in the brain compromise endothelial ability to regulate microvascular flow
why is it important that the brain is able to regulate microvascular flow
ensures that the brains energy supply matches demand - this can be mismatched when atherosclerotic plaques compromise this process
some of these risk factors can increase production of reactive oxygen species (ROS), what does this mean?
free radical superoxide inactivates nitric oxide resulting in a loss of vasoregulatory and loss of anti-aggregant effects
what are the two main zones of an ischaemic stroke
the core zone
the penumbra
what occurs in the core zone
rapid neuronal death and the death of supporting cellular elements e.g. glial cells
how do neurons and glial cells die in the core zone
the loss of oxygen and glucose results in an energy deficit.
this facilitates ionic imbalance and mitochondrial failure. activation of a series of enzymes results in the fast breakdown of cell structures and the loss of cellular integrity
what happens to the neurons in the penumbra
they remain viable for several hours. they will die if reperfusion is not established
what supplies neurons in the penumbra with their blood supply
collateral arteries
how can neurons in the penumbra be damaged even if blood flow is restored
they can face excitotoxicity = excess glutamate = calcium influx and production of free radicals.
what breaks down after ischaemic stroke and contributes to the oedema and bleeding into the infarcted area
the blood brain barrier
what molecule is involved in BBB breakdown
matrix metalloproteinases
what percentage of stroke patients go on to develop dementia in the months following stroke
~ 25%
what facilitates dementia formation post stroke
white matter lesions which interrupt neural pathways involved in cogntion
what is the term given for these small white matter lesions
leukoaraiosis
what happens when these white matter lesions form
they facilitate demyelination, axonal loss and microglial activation = neuronal loss involved in cognition
what is the development of dementia dependent on
the location and volume of the stroke and the presence of other cerebral pathologies
