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
signs and symptoms of stroke?
Motor (clumsy or weak limb)
Sensory (loss of feeling)
Speech: Dysarthria/Dysphasia
Neglect / visuospatial problems
Vision: loss in one eye, or hemianopia
Gaze palsy
IN STROKE MOST SYMPTOMS ARE OF LOSS OF SOME FUNCTION
what are some of the symptoms of a ACA occlusion?
paralysis of contra-lateral foot and leg
sensory loss over contra-lateral toes, foot and leg
impairment of gait and stance
symptoms of MCA?
Contra-lateral paralysis of face/arm/leg
Contra-lateral sensory impairment
Contralateral homonymous hemianopia
Gaze paralysis to the opposite side
Aphasia if stroke on the dominant (left) side
Unilateral neglect for half of external space if non-dominant stroke (usually right side).
where in the brain does small vessel stroke usually happen?
deep in the white matter, usually caused by a reduction in lumen in hypertensive patients
what are some of the symptoms of small vessel stroke?
Dysarthria - clumsy hand syndrome
Ataxic hemiparesis
what is the major danger associated with small vessel stroke?
if there is a small vessel stroke in an area where there are bundles of fibres packed together such as the pons will have major deficit.
(think of flowers in a vase)
name the stroke types?
TACS: Total anterior circulation stroke
PACS: Partial anterior circulation stroke
LACS: Lacunar stroke (small vessel)
POCS: Posterior circulation stroke (posterior blood vessels)
what are the 3 treatment categories for stroke?
protect the damaged brain before ischaemia becomes cell death
get rid of the clot and restore blood flow
prevent the clot happening in the first place
why are stroke units important?
allows patients to be looked after soon as possible, such as getting a therapist to help them physically recover
allows patients to get appropriate imaging and they can be given aspirin to help
can also receive assistance in eating and drinking if the stroke has impaired their ability to do so
what are the targets of acute stroke therapy?
Restore blood supply.
Prevent extension of ischaemic damage.
Protect vulnerable brain tissue.
Avoid reperfusion injury
Be non-toxic
what is the common treatment for thrombolysis and what is its complications?
alteplase
has to be given 10% then the rest as infusion over an hour
time is crucial with this treatment and risk of harm increases and benefit decreases over time (about 4 and a half hours of benefit after the onset of stroke)
what is the importance of radiological scans in stroke?
scans can help determine the state of the brain and figure out whether certain treatments will be a benefit or risk to the patient (such as giving thrombolytic drugs to a patient at a later stage can cause haemorrhage)
