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
What are symptoms of posterior circulation stroke?
Involved anatomy
- brainstem/cerebellum/thalamus
- occipital and medial temporal lobes
Brainstem dysfunction
- coma, vertigo, nausea, vomiting, cranial nerve palsies, ataxia
- hemiparesis, hemisensory loss
- crossed sensori-motor deficits
- visual field deficits
What investigations might be done in suspected stroke?
Routine bloods - FBC, glucose, lipids, ESR
CT/MRI - infarct vs haemorrhage
ECG - ?AF, LVH
Echo - valves, ASD, VSD, PFO
Carotid Doppler - ?Stenosis
Cerebral angiogram/venogram - ?vasculitis
Hypercoagulable blood screen
Must search for aetiology in TIA (10% recurrence within 2 weeks)
What are some differential diagnoses for stroke?
Post-ictal states e.g. Todd's paralysis Hypoglycaemia Intracranial mass Vestibular disease Bell's palsy Functional hemiparesis Migraine Demented patients with UTIs
What are the usual terms used to describe different types of stroke?
TACS - Total anterior circulation
PACS - Partial anterior circulation
LACS - Lacunar stroke
POCS - Posterior circulation
What are the three aims of initial treatment in stroke? What are example treatments that help with this?
Restore blood supply
Prevent extension of ischaemic damage
Protect vulnerable brain tissue
E.g.
- aspirin
- stroke unit
- thrombolysis
- thrombectomy
Carotid endarterectomy is effective treatment in symptomatic ICA stenosis
What is the usage and exclusion criteria for use of TPA?
<4.5 hours of symptom onset
Disabling neurological deficit
Symptoms present >60 minutes
Consent obtained
Exclusion
- anything increasing haemorrhage probability e.g. blood on CT, recent surgery, recent bleeding episodes, coagulation problems
- BP >165 systolic or 110 diastolic
- glucose <2.8 or >22
What treatment is given for secondary prevention of stroke?
Anti-hypertensives - RRR >25% Antiplatelets - RRR 25% Lipid lowering agents - RRR 25% Warfarin for AF - RRR 66% Carotid endarterectomy
What is the prognosis of different stroke types, in terms of death/dependence at 6 months?
TACS - 96%
PACS - 45%
LACS - 39%
POCS - 38%
