Stroke Flashcards
when is risk of second stroke highest?
immediately after the first
3 main points defining stroke?
acute onset of symptoms (all strokes must be acute onset)
focal neurological signs and symptoms
due to disruption of blood supply
how is stroke diagnosis?
clinical diagnosis
scans just rule out other causes of similar presentation but can be normal even in stroke diagnosis
2 kinds of stroke?
ischaemic
haemorrhagic
most common stroke imaging?
usually CT
can be MRI
how many strokes are haemorrhagic?
10-15%
is haemorrhagic stroke same as intra-cranial haemorrhage?
no
intracranial haemorrhage can be different kinds, only an intracerebral haemorrhage is a stroke
types of intracranial haemorrhage?
extradural (extra cerebral)
subdural (extra cerebral)
subarachnoid (extra cerebral)
intracerebral (intra cerebral)
how do extra cerebral haemorrhages cause neuro damage?
due to compression not actual damage to brain tissue like in an intra cerebral
surgery more used for which type of haemorrhage?
extra cerebral as surgery can relieve pressure
why is surgery not really used in intracerebral haemorrhage?
surgery can remove the blood but cant undo the damage done to the brain tissue so not really worth the risk
when is surgery used in intra cerebral?
when pressure builds so much that it threatens life
only done to save life, cant fix disability
extravascular causes of haemorrhagic stroke?
not really a stroke but can cause intracerebral bleeding
eg bleeding into a brain tumour, abscess due to weakened blood vessel wall
blood related causes of haemorrhagic stroke?
not really a cause but can contribute
anticoagulants
strong antiplatelets
haemorrhagic diathesis
vessel wall related causes of haemorrhagic stroke?
hypertension
vasculitis (can cause ischaemic and haemorrhagic stroke)
vessel wall abnormalities (aneurysms, AVMs, amyloid etc)
most common cause of stroke overall?
hypertension
arteriosclerosis vs atherosclerosis?
can co-exist
arteriosclerosis = thickening of middle wall of artery
atherosclerosis = formation of atheromas (plaques, lipids etc) on lumen wall
what causes arteriosclerosis?
hypertrophy to deal with high pressure in system
why is arteriosclerosis a problem?
narrows lumen reduces compliance (not as elastic) of artery so when blood pressure surges it can rupture
2 main types of intra cerebral haemorrhage?
lobar (large)
deep parenchymal haemorrhage
causes of lobar haemorrhage?
hypertension
should look for underlying cause such as metastatic lesion in brain
where is metastatic lesion usually found in brain?
grey/white matter border
what does deep parenchymal haemorrhage often lead to?
intra ventricular haemorrhage (any bleed can cause intra ventricular haemorrhage if it bleeds into the ventricles)
how does deep parenchymal haemorrhage usually present?
LACS
doesnt generally affect the cortex
what can mimic stroke?
migraine
post seizure focal deficits (usually only last a few hours)
hypoglycaemia
acute presentations of chronic pathology such as space occupying lesion
demyelination
bells palsy
non-organic states (functional)
if stroke mimic excluded, how can type of stroke be determined?
imaging
anterior blood flow to the brain?
right = aorta > brachiocephalic trunk . common carotid > internal carotid
left =
posterior blood flow to brain?
vertebral arteries come off subclavian arteries and enter via foramen magnum and combine to become basillar artery?
what forms circle of willis?
common carotids branch to become 2 anterior cerebral and 2 middle cerebral arteries
basilar splits to become 2 posterior cerebral arteries
also have anterior and posterior communicating artery
where are the communicating arteries
anterior communicating joins the two anterior cerebral arteries
posterior communicating joins middle to posterior cerebral arteries
whats the point of circle of willis?
collateral circulation
does collateral circulation mean there wont be a stroke if one carotid artery is completely occluded?
no
if one carotid artery is taken out then blood supply will be significantly reduced and brain is v sensitive to lack of blood flow
even though there is collateral circulation, overall blood supply will still be significantly less
loss of blood supply must be acute for a stroke to happen, true or false?
true
outer brain layer?
grey matter/cortex
inner brain?
white matter
spots of grey matter - basal ganglia in inner brain
2 systems of blood supply in brain?
outer inch and a half supplied by large vessels which are branches from circle of willis
deeper structures supplied from same large vessels but via perforators from these large vessels
what would happen if middle cerebral artery is occluded?
loss of blood to large vessels branching from middle cerebral artery and perforators from these large vessels so both outer and inner affected
do large vessels communicate?
yes
ie if one large vessel occluded it might be ok (not if source of large vessels occluded such as middle cerebral artery)
do perforators communicate?
no
types of clot?
embolus (clot formed somewhere else which has broken off and travelled and occluded a smaller artery)
thrombus (clot formed at area of origin)
what usually causes a large vessel occlusion?
embolic
thrombus will gradually occlude a vessel so wont get symptoms due to collateral
embolus will cause a sudden occlusion so result in stroke
how quick does occlusion have to happen to cause stroke?
less than 3 months?
what causes perforator stroke?
usually thrombus (dont know why???) can get big embolus causing several perforators being occluded
perforator vs large vessel stroke?
perforator = deeper damage
large vessel = larger stroke
how does infarct show on imaging?
paler
how to clinically recognise large vs small vessel infarct?
large = usually cortical signs +/- physical disability as surface of brain affected small = no cortical signs, purely physical disability, might not even have any signs
cortical signs?
change in neuro functions served by (cortical areas) grey matter
due to damage of cortical areas such as visual cortex, motor cortex, somatosensory cortex, language cortex, auditory cortex and outer grey matter layer of brain in general
basically any problem with higher mental function (including cognitive and personality changes)
what is the internal capsule?
strip of white matter carrying info from motor and sensory cortex
deeper in brain so can be affected by small vessel/perforator infarct
which hemisphere is usually dominant?
left (contains communication centres)
examples of cortical signs from dominant hemisphere?
dysphasia (expressive or receptive) - often mixed dysphasia
agnosia (failure to recognise object despite holding it in their hand)
brocas and wernickes?
brocas in left frontal lobe
wernickes in left temporal lobe
brocas dysphasia?
expressive dysphasia
understand what other people are saying but cant form the words to speak
non-fluent
wernickes dysphasia?
fluent/receptive dysphasia
can speak fluently but its jibberish
cant really take meaning from language or what other people are saying
cortical signs from non-dominant hemisphere?
hemispatial neglect (loose all awareness of one half of the world) changes in personality sensory inattention (inability to identify simultaneous sensory stimuli, can be visual or sensory)
how can both a large and small vessel cause a dense hemiparesis?
large vessel can affect whole motor cortex
all information from motor cortex is concentrated in internal capsule so small vessel infarct can affect internal capsule causing dense hemiparesis (all body parts affected)
hemiparesis of one body part (eg leg) more likely to be what kind?
large vessel
oxfordshire classification?
classification of site of stroke based on clinical presentation (not imaging)
TACS?
total anterior circulation stroke
large vessel
features of TACS?
hemiplegia hemisensory loss visual loss cortical signs all 4
PACS?
partial anterior circulation stroke
large vessel
features of PACS?
cortical loss (Must be present) + at least one out of:
hemiparesis
hemisensory loss
visual loss
LACS?
lacunar stroke
AKA perforator stroke
features of LACS?
no cortical signs (cortex is spared)
only physical disability
POCS?
posterior circulation stroke
vertebro-basillar circulation
features of POCS?
ataxia can also have visual loss (hemianopia) as visual cortex is in occipital lobe vertigo can have dysarthria (not dysphasia) dysphagia diplopia LMN facial weakness anything basically which point to brainstem, cerebellum or occipital lobe
which strokes recover the best?
lacunar
smallest area of damage
brain has neuroplastic properties so brain can be able to re-set itself and learn new functions, esp when area of damage is small
