Cerebral Infarction Flashcards
define stroke
a sudden onset of focal or global neurological symptoms caused by ischaemia or haemorrhage lasting more than 24 hours
what are the three most common causes of ischaemic stroke?
> large artery thrombosis
cardioembolic
small artery occlusion
what can cause haemorrhagic stroke?
> primary intracerebral haemorrhage
> secondary intracerebral haemorrhage: subarachnoid, arteriovenous malformation)
describe the ridiculously simple pathophysiology of ischaemia
> failure of cerebral blood flow to part of the brain
results in varying degree of hypoxia
hypoxia stresses brain metabolism and if its prolonged = anoxia
anoxia leads to infarction
what can further damage result form after infarction in a stroke?
> oedema (dependent on size and location)
> secondary haemorrhage
what is ischaemic penumbra?
area surrounding ischaemic event which will have reduced blood flow. ischaemic core will die no matter what you d but the penumbra could be saved?
name some non-modifiable risk factors for stroke?
> previous stroke
being old
being male
family history
what is the most important modifiable risk factors for stroke?
hypertension
why is hypertension a risk factor in stroke?
> chronic worsens atheroma (virchows) and affects small arteries
majority of hypertension is poorly managed
what is small artery lipohyalinosis?
hypertrophy of the blood vessel wall and resultant lumen diameter loss in small arteries
by how much does diabetes mellitus increase stroke risk?
3 fold
what is the increased risk of cerebral infarction in smokers?
2 fold increase
what is the affect of lipids on stroke risk?
increased serum lipids increase vessel wall atheroma as in creased plasma levels of low density lipoprotein results in excessive amounts of LDL within the arterial wall
what are some modifiable risk factors?
> alcohol > obesity > inactivity > impaired cardiac function > oral contraceptives with high estrogen content > hypercoagulable states
where are border zone anastomoses?
between peripheral braches of anterior, middle and posterior cerebral arteries
name some symptoms of anterior cerebral artery occlusion
Contra-lateral:
> paralysis of foot and leg
> sensory loss over foot and leg
> impairment of gait and stance
what are symptoms of middle cerebral artery occlusion dominant side?
> contralateral: - paralysis of face/arm/leg - sensory loss face/arm/leg - homonymous hemianopia > gaze paralysis to the opposite side > aphasia on dominant side > dysphasia
what can an ophthalmic artery blockage be?
a warning stroke.
often a curtain coming down over the vision
describe the symptoms of a middle cerebral artery occlusion on non-dominant hemisphere
> contralateral hemiplegia > homonymous hemianopia > agnosia: neglect symptoms: - visual agnosia - sensory agnosia -anosagnosia - prosopagnosia
what is anosagnosia?
denial of hemiplegia
what is prosopagnosia?
failure to recognise faces
what sort of stroke affects the basal ganglia?
lacunar stroke
name lacunar stroke syndromes
> pure motor stroke
pure sensory stroke
dysarthria- clumsy hand syndrome
ataxic hemiparesis
what stroke is devoid of cortical signs
lacunar strokes
what does the posterior circulation of the brain supply?
> brain stem
cerebellum
thalamus
occipital and medial temporal lobes
what are some symptoms of brainstem dysfunction?
> coma > vertigo > nausea and vomiting > cranial nerve palsies > ataxia > hemiparesis > hemisensory loss > crossed sensori-motor deficits > visual field deficits
what should ischaemic stroke therapies do?
> restore blood supply
prevent extension of ischaemic damage
protect vulnerable brain tissue
who works on a stroke unit?
> nurses > physiotherapists > speech and language therapists > OT's > dietician > psychologists > orthoptist
name 4 classifications of stroke
> total anterior circulation stroke
partial anterior circulation stroke
lacunar stroke
posterior circulation stroke
what stroke classification will have brainstem signs?
posterior circulation stroke
what stroke must have hemianopia?
lacunar stroke
what stroke type will most likely have death or dependence at 6 months?
total anterior stroke
what is the criteria for TPA use?
> < 4.5 hour symptom onset
disabling neurological deficit
symptoms present >60 minutes
consent obtained
what would exclude IV TPA use?
> anything increasing possibility of haemorrhage - blood on CT - recent surgery - recent bleeding episode - coagulation problems > BP >185 systolic or >110 diastolic > glucose <2.8 or >22mmol/L
what is a warning sign of stroke?
TIA
what is a treatment for symptomatic internal carotid artery stenosis?
carotid endarterectomy
what are the investigations for stroke?
> routine blood tests > CT/MRI head scan > ECG > ECHO > carotid Doppler ultrasound (stenosis) > cerebral angiogram > hypercoagulable blood screen
what is the secondary prevention for stroke?
> antihypertensives > antiplatelets > lipid lowering agents > warfarin for AF > carotid endarctectomy
