Cerebral Infarction Flashcards
What is the definition of a stroke?
Focal neurological deficit due to disruption of blood supply lasting more than 24 hours.
What percentage of strokes are ischaemic vs haemorrhagic?
85% Ischaemic
What are the physical causes of stroke?
Ischaemic
- large artery atherosclerosis
- cardioembolic e.g. AF
- small artery occlusion
- undetermined
- rare (arterial dissection, venous sinus thrombosis)
Haemorrhagic
- primary intracerebral haemorrhage (70%)
- secondary e.g. SAH, arteriovenous malformation
What are the risk factors for stroke (modifiable/non-modifiable)?
Modifiable
- hypertension (most important)
- diabetes (3x stroke incidence)
- smoking (2-3x stroke incidence)
- heavy drinking (2.5x)
- obesity
Non-modifiable
- previous stroke
- old
- male
- family history
- recent MI, AF
- OCP with high oestrogen content
- malignancy
In practice, what are the three main causes of localised interrupted blood supply?
Atheroma + arterial thrombosis causing ischaemia
Thromboembolism e.g. from left atrium causing ischaemia
Ruptured aneurysm of a cerebral vessel causing haemorrhage
Generally, changes in what three aspects of vasculature can cause disturbances?
Vessel wall Blood flow (including pressure) Blood constituents
What are two common sites of vessels rupturing causing haemorrhagic stroke?
Basal ganglia - microaneurysms form in hypertension
Circle of Willis - Berry aneurysms form in hypertension
What is a common cause of thromboembolism-stroke (excluding atheroma)?
Arrhythmias such as AF, thrombus in left atrial appendage breaks off and can embolise to aorta/carotid/further
In ICA thrombosis, where would you typically get ischaemia?
MCA territory
What can cause generalised infarctions? (not due to thrombus/embolism/haemorrhage)
Hypoxia
- flow but low O2: CO2 poisoning, near drowning, respiratory arrest
- inadequate supply - cardiac arrest, hypotension, brain swelling
- cyanide poisoning - can’t use O2
What pattern of infarction might be seen in hypotension induced infarction vs cardiac arrest?
Hypotension
- watershed infarct - central territories remain perfused, watershed zones poorly perfused - borders between main artery supply areas
Cardiac arrest
- largescale infarction due to complete perfusion loss - cortical infarction
Complex
- mix of various types - complex pattern
What might be some symptoms of ACA stroke?
Contralateral paralysis of face/arm/leg
Contralateral sensory loss over foot/leg
Contralateral impairment of gait/stance
What might be some symptoms of MCA stroke?
Contralateral paralysis of face/arm/leg
Contralateral sensory loss of face/arm/leg
Contralateral homonymous hemianopia
What might be some symptoms of right hemisphere stroke?
Left hemiplegia, homonymous hemianopia Neglect syndromes (agnosia) - Visual agnosia - Sensory agnosia - anoagnosia - denial of hemiplegia - prosopagnosia - failure to recognise faces
What are lacunar stroke symptoms?
Devoid of cortical signs - e.g. no dysphasia/neglect/hemianopia Pure motor stroke Pure sensory stroke Dysarthria - clumsy hand syndrome Ataxic hemiparesis