stroke Flashcards
what is a stroke?
it is a neurological deficit (so loss of function in one part of the body), it has sudden onset and lasts more than 24 hours, and it is of vascular origin (meaning that its caused by blockage of a vessel)
what is the difference between stroke and transient ischaemic attack?
same symptoms but stroke is more than 24 hours and TIA is less
what are some of the causes of stroke
thrombus or clot
disease of vessel wall
disturbance of normal blood properties (e.g, too many WBC because of leukaemia, too many RBC and platelets)
haemorrhage
INFARCTION
what are the differences between haemorrhagic and ischaemic stroke?
haemorrhagic is caused by the rupture of a blood vessel which results in blood leaking around brain which also causes inflammatory reaction around area of bleeding
ischaemic is caused by a clot blocking the blood supply to an area of the brain which causes infarction
what parts of blood vessels tend to be higher risk for atheroma?
areas of bifurcation, such as at the common carotid when it splits into external and internal carotid as there is high turbulence in these areas
(think of when a river splits into two, a lot of turbulence)
what are some of the rarer causes of large vessel stroke?
carotid dissection (when wall of the vessel tears forming a thrombus which can break off and travel up the brain)
what are some of the risks of hypertension?
hypertension
smoking
waist to hip ratio
diabetes
ratio of apoB to apoA
where does haemorrhage usually occur and why does it occur?
in the small vessels
mostly occurs due to hypertension, amyloid, low cholesterol, and excess alcohol.
what is more dangerous, haemorrhage or ischaemic stroke?
haemorrhage
has a higher mortality rate and also has a greater level of dependancy if recovered (so more daily assistance needed)
what happens to the brain tissue in ischaemic stroke?
area of infarction occurs around the vessel as result of the blocking thrombus but also an area called penumbra which receives collateral blood flow and stays alive, usually outside the infarction
what is a risk of further damage after stroke?
oedema can occur as a result, depending on the size and the location of a stroke or secondary haemorrhage
oedema can put pressure and shift the midline of the brain which can also cause cell damage, but as it dies down its position can return to normal over time. in young patients, flap of scalp can be removed to allow the brain to swell out the way to reduce this.
list the important steps of ischaemic cascade at a molecular level?
Without adequate blood supply and thus lack of oxygen and glucose, brain cells lose their ability to produce energy - particularly adenosine triphosphate (ATP).
Cells in the affected area switch to anaerobic metabolism, which leads to a lesser production of ATP but releases lactic acid.
Lactic acid is an irritant, which has the potential to destroy cells by disruption of the normal acid-base balance in the brain.
when thinking about symptoms of stroke what should we consider?
should fit in with an artery territory and an area of the brain
symptoms should come on quickly and should make sense
what does the carotid system supply in the brain?
The carotid system supplies most of the hemispheres and cortical deep white matt
what does the vertebro-basilar system supply?
The vertebro-basilar system supplies the brain stem, cerebellum and occipital lobes
