stroke Flashcards
how long does Stroke last?
Symptoms lasting more than 24 hours or leading to death
when is a stroke classed as a TIa?
Symptoms lasting less than 24 hours classified as a Transient Ischaemic Attack (TIA)
what characterestic a key to the diagnosis of stroke?
Sudden onset
Focal neurological deficit
Of presumed vascular origin
Symptoms lasting more than 24 hours or leading to death
what factors are excluded as causing a stroke?
lesions associated with trauma, infection or tumour, retinal infarction and most cases of subarachnoid heamorrhage
what are the two types of stroke?
cerebral infarction
cerebral heamorrhage
which is more common stroke infraction or haemorrhage?
infarction is more common
85% of cases?
are the symtpoms or infarction and heamorrhage the same?
yes the symptos of both is the same if they occur in the same part of the brain
how can stroke differ in symptoms?
They differ because strokes can affect on different parts of the brain. Depending where the stroke takes place depends what symptoms you get
what occurs in cerebral infarction?
there is no oxygen going to the brain
what occurs in cerebral heamorrhage?
there is a bleed in the brain
how often is stroke caused by a haemorrhage?
15% of the time
how can you tell the difference between cereberal infacrtion or heamorrhage?
either by post mortem or by MRI scans
what is the pathophysiology of acute ischaemic stroke?
Initial reduction in cerebral blood flow
Alterations in cellular chemistry caused by the ischaemia
Cellular necrosis
when is acte ischaemic stroke reversible?
when necrosis of the brain has not occured. Once necrosis occurs it is irreversible
what percentage of oxygen consumption goes to the brain at rest?
20%
can brain strore oxygen?
no
what is the cerebral flood flow of the brain?
800 mL/min (15% cardiac output)
what is the average weight of the brain?
1400 g (2% body weight
what is the equation to flow?
Flow = pressure / resistance
what does CPP stand for?
cerebral partial pressure
what does CVR stand for?
cerebralvascular resistance
what does CBV stand for?
cerebral blood volume
what happens to the blood vessels in the brain if PaC02 increase?
this causes the blood vessels to dilate –> reduction in resistance and increase in blood flow –> occurs in occlusion of blood vessels
what is the substrate for energy metabolism for the brain?
only glucose 75-100 mg/min or 125 g/day
how is glucose metabolised in the brain?
Glucose is metabolised by the glycolytic sequence and the tricarboxylic acid cycle.
why do neurones need a constant supply of ATP?
For neurones to maintain integrity –> K+ inside and Na+ and Ca2+ outside the cell.
ATP cannot be stored
in aerobic respiration how many moles of ATP is produced by pyruvate?
36
in anerobic respiration how many moles of ATP is produced by pyruvate?
2
how many moles of pyruvate is produced by glucose? What is the name of the process and what is the byproduct?
produces 2m of Pyruvate
glycolysis is the reaction
2m of ATP produced
what is the first thing that is affected in cerebral ischemia?
electrical function is impaired
what is the importance of electrical function impairment stage?
the neurones stop working but are still intact. You see symptoms but the tissue is reparable. If you identify the stroke at this point recovery is very good
what is the stage after electical function is impaired?
the release of K and movement of water intraceullarly
what occurs in the stage of release of K and movement of water intraceullarly?
the tissues of the brain start to die and change in structure –> irreversible
what is the threshold of cerebral infarction where normal function still takes place?
50-20 ml/100mg/min
what is the threshold of electrical function is impaired
20-12 ml/100mg/min
what is the threshold of release of K and movement of water intraceullarly?
12-7 ml/100mg/min
when does cell death take place?
At brain function below 7 ml/100mg/min
what is the name of the area of the brain during cerebral infarction where the tissue has completely died?
core
what is occuring in the penumbra region of the brain?
electrical function impairment in that part of the brain has occured. There is symptoms relating to that part of the brain but you can still restore blood flow to this part of the brain and restore function
what is occuring in the oligemia region of the brain?
It is below the normal brain function threshold but the brain is still functioning
what occurs with time to the brain during cerebral infarction?
the core of the infarction grows –> so more dead tissue while the penumbra reduces in size
what happens to CPP and CBF as stroke occurs and symtoms begin?
they keep falling until full symptoms are present
what happens to oxygen extraction fraction as the symtpoms of stroke develops?
the oxygen extraction fraction rate increase
what are the two main causes of cerebral infarction?
thrombosis or embolism
what are the two type of thrombisis that causes ischaemic stroke?
large arteries (mainly extra-cranial) small arteries (mainly intra-cranial)
what are the two types of emobilsm that cause ischaemic stroke?
from the heart (cardiogenic embolism)
from proximal arteries (artery to artery embolism)
what is the most common cause of ischaemic stroke?
large vessel atheroscerosis
what is the most common cardiac cause of stroke?
AF
why does AF increase the likely hood of having a ischaemic stroke?
dilation of Left atrium –> increaes the likely hood of the formation of a clot in the left atrium and then therefore emobilsm
when do you use aspirin?
you use it for ischemic stroke not for heamorrhage stroke
what is a secondary prevent for stroke?
to give antcoagulants
what is aspirin?
antiplatelet medicine
what does aspirin do?
Reduces the risk of clots forming in your blood
what is the acroynm used to identify someone havinga stroke?
F–> face
A–> arms
S–> speach
T–> time
Will MRI scan always show a stroke?
it will always show a heamorrhage stroke
However not always show a ischeamic stroke because at first the brain looks normal then takes a few hours for it to develop and be seen on a scan
what is the key secondary treatment for people with acute ischaemic stroke?
thromboylsis
what is thromboylsis?
is a clot busting mediction –> dissolves the clot to resume blood flow to the brain
what is the medication used in thromboylsis?
alteplase and it is injected
when should thrombolysis take place?
ASAP –> before 4 and 1/2 hours have passed
why should a scan of the brain be done before thrombolysis is administrated?q
To make sure it is a cerebral ischaemia and not heamorrhage. As it could make the haemorrhage worse
does thrombolysis work on all occlusions?
Thrombolysis is less effective on large occlusions
how offten does proximal anterior circualtion occlusion cause stroke? How often does this cause disability or death?
accounts for 18% - 25% of all ischaemic stroke but 60% - 70% of deaths or severe disability.
what is the definition of a TIA?
Neurological Deficit lasting less than 24 hours attributable to cerebral or retinal ischaemia
how often does TIA last for?
usually less than 60 minutes
do people recover from TIA and is there any brain damage?
person usually recovers from a TIA on there own but it does not mean there is no brain damage. IT does leave a scar on the brain
are the causes of stroke and TIA the same?
yes
what are the causes of TIA?
Carotid artery Disease/Large Artery Disease
Cerebral Small Vessel Disease
Cardiac Embolism
why do you distinguish between TIa and Stroke?
Distinction of research purposes
TIA indicates ischaemic pathology
TIAs represent a window of opportunity to treat
what type of stroke does TIA indicate?
ischeamic stroke
what can TIA indicate to in the future?
usually a stroke preceeds a TIA –> so can strart treatment to prevent this
how common are TIAs?
Incidence= 50/100 000 population
what other conditions can mimics the same symptoms of TIA?
Seizures Syncope Hypoglycaemia Migraine Acute confusional states
what occurs when there is TIa in anterior circulation?
Amarausis fugax
Dysphasia
Apraxia
Inattention
what is Apraxia?
loosing the ability to do motor functions that involve sequence of controlled learnt movements
what is inattention?
Right hemisphere –> visual/spatial awareness –> get a stroke here –> get inattention –> where they reject the left side of the hemisphere
what is AMARAUSIS FUGAX?
its painless transient monocular visual loss (i.e., loss of vision in one eye that is not permanent).
what occurs in TIa in posterior circulation?
Ataxia –>loss of balance
Diplopia –? double vision
Vertigo
Bilateral Symptoms
what is more common TIa in anterior or posterior circulation?
anterior –> only 1/3rd happen posteriorly and less easily recognisible
what symptoms can be present in TIA in either posterior or anterior circulation?
Visual field disturbance (e.g. hemianopia)
Hemiparesis
Hemisensory loss
Dysarthria
what arteries does anterior circulation of the brain involve?
the interal carotid arteries
what arteries does posteiror circulation of the brain involve?
vertebral arteries
what is used to predict what the risk is of developing a stroke after a TIA?
ABCD2
what does ABCD2 stand for?
Age 1……> 60 yrs
BP 1……> 140/90
Clinical features 2……unilateral weakness
1……speech disturbance
Duration symptoms 2…….> 60 mins
1…….10 – 59 mins
0…….
what type of scan is done to indicate TIA and why?
MRI because best at identifying events that already have happened in the brain
what preventions can take place to prevent a stroke?
Diet, exercise, aspirin, statins BP lowering, stop smoking, diabetic control
what is POLYPILL?
Combination of Statin Aspirin Antihypertensives Folic Acid
how effective is poylpill?
Reduce risk vascular events by 80%
if a TIA has occured and there is a fully occluded artery should Carotid Endarterectomy take place? Explain
No it shouldnt be –> the risk is much greater than resolving the occlusion. As the person has recovered clearly the circle of willis is adapted and strong enough to compensate for the occlusion and recover function in the brain
why is carotid occlusion not always bad in TIa?
the clot cannot move and means the patient has good collateral –> circle of willis that can keep blood flow going –> still need other secondary interventions
