Stroke Flashcards
define apoplexy
cerebrovacular accident.
what 2 drugs are commonly used to prevent stroke in high risk patients
aspirin and statins
define stroke
Sudden onset
Focal neurological deficit
Of presumed vascular origin
Symptoms lasting more than 24 hours or leading to death
define TIA
Symptoms lasting less than 24 hours classified as a Transient Ischaemic Attack (TIA)
How can you distinguish between a TIA and a stroke
the length of time it lasts
what is the difference between serous and sanguinous cerebra apoplexy
serous-cerebral infarction
sanguinous- cerebral haemorrhage.
do haemorrhages and infarcts present in the same way
Yes
how are haemorrhages and infarcts distinguished
CT scan
pathophysiology of acute ischeamic stroke.
initial reduction in cerebral blood flow
alterations in cellular chemistry caused by ischaemia (lack of blood flow)
cellular necrosis- reversibility depends on the level of cellular necrosis which occur.s.
what is the average cerebral blood flow
800ml/min (15% cardiac output)
what is the average brain weight
1400g (2% body weight)
what percentage of body oxygen does the brain consume
20%
what is the equation that links flow pressure and resistance
flow=pressure /resistance.
does the ability to extract oxygen increases or decrease as the oxygen content decreases
increase
how to blood vessels adapt to accommodate more blood flow when vessels become occluded
Blood vessel dilates to accommodate more blood flow when they become occluded
what is the sole substrate for energy metabolism of the brain
glucose
why doe neurones require ATP
to maintain integrity (K+ inside and Na+ and Ca2+ outside the cell).
Cerebral metabolism
1 glucose- 36 ATP via TCA
1 glucose- 2ATP via anaerobic respiration.
what are the thresholds of glucose levels for a stroke
20
20-12
20- normal but blood flow is subnormal
20-10- stroke symptoms are nerves stop working, but they still maintain structure
what are the 3 regions of an infarct called and how are they distinguished
CORE- below 10 (glucose level)
PENUMBRA- 20-12
OLIGOEMIA- 20
Define capacitance
pipes allowing blood to flow into the head e.g. carotids and vertebral arteries
define resistance
vessels within the brain which have muscles so they can constrict and dilate depending on blood flow.
what are the primary homeostatic mechanisms to prevent resistance
- Blood vessels which are resistant dilate to increase the cerebral blood flow
- Blood flow will eventually start to decrease as mechanism 1. has been used to it’s max
- Next steps involves oxygen extraction
- Only when this no longer occurs do get symptoms of stroke.
what are the 2 main causes of an ischaemic stroke
bloot clot- thrombus- intracranial of extra-cranial
embolism (cardiogenic embolism)
cardiogenic factors which increase there risk of blood clots
cardiac embolism endocarditis left ventricle flops due to heart attack. atrial fibrillation. atherosclerotic thrombi emboli
Is aspirin a effective method for secondary stroke prevention
Yes
what anticoagulant is given to precent stroke
warfarin
why is it important to take both early scan but also a late scan
Early scans for ischemia are normal therefore it is important that you take a scan after 24hrs to see if there has truly been any damage.
Is stroke a medical emergenecy
If treated within 1 hour of stroke risk of survival increases- suggest stroke is a medical emergency.
what treatment is given once you have diagnosed the patient has had a stroke
thrombolytics
what is a Stentriever, and how does it work.
Place stent across occlusion: leave in position for 10 min
Reperfuse brain
‘Relax’ and plan your strategy
Most clot will lyse naturally or improves efficacy of IV tPA
Withdraw stent with smaller clot ‘core’
clot comes out on stent as you push the wire through the clot and pull it out.
what specific blood circulation stroke results in 18% - 25% of all ischaemic stroke but 60% - 70% of deaths or severe disability.
Proximal anterior circulation large vessel occlusion
what does the acronym FAST stand for
Face
Arms
Speech
Time
