Stroke Flashcards
How is a stroke defined?
A sudden onset of neurological dysfunction caused by an alteration in cerebrovascular blood supply
Characteristics of a stroke?
Rapid, acute onset
Focal neurological deficit: almost always some sort of hemiplegia
What is hemiplegia?
paralysis on one side of the body
What is hemiparesis?
Weakness on one side of the body
3 stroke classifications
Haemorrhage- 10-20%
Brain ischaemia (infarct)- 80-90%
TIA
What is a TIA?
Symptoms completely resolve within 24 hours.
Ischaemia without infarct
Causes of a TIA?
Usually microemboli (80%)
Temporary reduced blood flow e.g. massive postural hypotension or stenosed artery
How long does it take for clinical effects of a stroke to reach maximum?
Usually within 6 hours of onset
Prognosis
20% mortality in first 2 months, then roughly 10% per year
<40% of stroke (not TIA) patients make full recovery
Which brain arteries do arterial embolisms arise from?
Carotids, vertebral or basilar arteries
Heart valves in endocarditis (vegetations (clumps of blood cells and bacteria) form in heart)
How much does the blood flow to brain have to drop by for damage to occur?
50% of the normal value
What time of day are strokes most common?
Morning because the bp usually rises in the morning- this could dislodge an embolism
Risk factors for ischaemic stroke
hypertension (damages artery walls- increased risk of thrombus formation)
smoking (increases bp + damages artery walls)
exercise and diet
atrial fibrillation
diabetes (increases bp and atherosclerosis)
cholesterol (statins reduce risk by 1/3)
carotid artery stenosis
heart disease
valve disease
Risk factors for SAH?
hypertension
smoking
age
Risk factors for intracerebral haemorrhage?
hypertension
smoking
atrial fibrillation
obesity
cerebral aneurysm!
Anterior circulation stroke:
where is the thrombus coming from?
Affects which part of brain?
Likely from carotid system
Affects cerebral function
Features of an anterior circulation stroke?
Aphasia/dysphasia
Hemiparesis
Amaurosis fugax
Sensory loss (hemi)
Hemianopic visual loss
What is hemianopia?
loss of half of visual fields in one or both eyes
What is amaurosis fugax?
What causes it?
sudden loss of vision in one eye
Caused by infarct in the retinal artery
Posterior circulation:
where is the thrombus from?
Which part of brain is affected?
Vertebrobasilar arteries
Brainstem/cerebellum
Does a TIA cause a headache?
Not usually. This can be helpful to distinguish it from a migraine (migraine also has confusion and visual disturbance)
Immediate management for a TIA?
300mg aspririn
Causes of cerebral infarct?
Atherosclerosis
Disease of vessels in the brain
Valvular heart disease
Most common artery occluded in a stroke?
Middle cerebral artery (similar symptoms to internal carotid occlusion)
