Ischaemic Stroke Flashcards
what is the stroke classification system?
bamford/oxford classification
what is a total anterior infarct (TACI) defined by?
contralateral hemiplegia or hemiparesis
AND
contralateral homoymous hemianopia
AND
higher cerebral dysfunction (e.g. asphasia, neglect)
what does a total anterior circulation infarct (TACI) involve?
anterior and middle cerebral arteries
what is a partial anterior circulation infarct (PACI) defined by?
2 of:
contralateral hemiplegia or hemiparesis
contralateral homonymous hemianopia
higher cerebral dysfunction (e.g. asphaia, neglect)
OR
higher cerebral dysfunction alone
what does a partial anterior circulation infarct (PACI) involve?
anterior or middle cerebral artery
what is a lacunar infarct (LACI) defined by?
- pure motor stroke
- pure sensory stroke
- sensorimotor stroke
- ataxic hemiparesis
NO visual field defect, higher cerebral dysfunction or brainstem dysfunction
what does a lacunar infarct (LACI) involve?
small deep perforating arteries, typically supplying internal capsule or thalamus
what is a posterior circulation infarct (POCI) defined by?
- cerebellar dysfunction
- conjugate eye movement disorder
- bilateral motor/sensory deficit
- ipsilateral cranial nerve palsy with contralateral motor/sensory deficit
- cortical blindness/isolated hemianopia
what does a posterior circulation infarct (POCI) involve?
vertebrobasilar arteries and associated branches (supplying the cerebrellum, brainstem and occipital lobe)
what area of the brain do the anterior cerebral arteries supply?
medial and supero-medial edge of the cortex, along the falx cerebri
what area of the brain does the middle cerebral artery supply?
hemisphere (cortex and white matter)
what is the typical presentation of the occulsion of the left middle cerebral artery?
dysphasia
what are the clinical features of an acute basilar artery occulsion?
‘locked-in syndrome
- quadriparesis (complete loss of movement)
- preserved consciousness
- preserved ocular movements - typically only vertical gaze
name posterior stroke syndromes
- locked-in syndrome
- lateral pontine syndrome
- lateral medullary syndrome/wallenberg’s syndrome
- medial midbrain syndrome/weber’s syndrome
what artery occlusion leads to locked-in syndrome?
basilar artery
what artery occulsion leads to lateral pontine syndrome?
anterior inferior cerebellar artery
what artery occlusion leads to weber’s syndrome (medial midbrain syndrome)?
branches of the posterior cerebral artery that supply the midbrain
what are the clinical features of the wallenberg’s syndrome (lateral medullary syndrome)?
DANVAH
* Dysphasia
* ipsilateral Ataxia
* ipsilateral Nystagmus
* Vertigo
* Anaesthesia (ispilateral facial numbness and contralateral pain loss on the body)
* ipsilateral Horner’s syndrome
what are the clinical features of weber’s syndrome (medial midbrain syndrome)?
- ipsilateral oculomotor nerve (CN III) palsy
- contralateral hemiparesis
what is the scoring system used to recognise stroke in the emergency setting?
ROSIER
what is the most common artery infarct in thromboembolic strokes?
middle cerebral artery territory
what artery occulsion leads to wallenberg’s syndrome (lateral medullary syndrome)?
posterior inferior cerebral artery
what are the clinical features of lateral pontine syndrome?
- ataxia
- dysarthria
- dysphagia
- ipsilateral horner’s syndrome
- ipsilateral loss of pain and temperature sensation on the face
- contralateral loss of pain and temperature sensation over the contralateral body
AND ipsilateral facial paralysis (CN VII) OR hearing loss (CN VIII)
wallenberg’s syndrome + facial paralysis or deafness
what is wernicke’s area responsible for?
understanding of speech
what is broca’s area responsible for?
fluent speech
what type of dysphasia would an infarct in wernicke’s area lead to?
receptive dysphasia
typically present with a patient speaking in ‘word salad’ as a result of their impaired understanding
patient can express but not understand
what type of dysphasia would an infarct in broca’s area lead to?
expressive dysphasia
patient retains their understanding of speech but is having difficulty producing words of their own
patient can understand but not express
what is the definition of an ischaemic stroke?
sudden onset focal neurological deficit of vascular aetiology, with symptoms last >24 hours (or with evidence of infarction on imaging)
what precentage of strokes are ischaemic?
85%
what are the causes of an ischaemic stroke?
- intracranial small vessel atherosclerosis
- large vessel atherosclerosis (e.g. carotid artery stenosis)
- cardio-embolic pathology (e.g. AF)
- primary vascular causes (e.g. vasculitis and arterial dissection)
- haematological causes (e.g. prothrombotic states)
what are the risk factors for ischaemic stroke?
- age
- male sex
- family history of ischaemic stroke
- hypertension
- smoking
- diabetes mellitus
- atrial fibrillation
- weaker risk factors = hypercholesterolaemia, obesity, poor diet, oestrogen-containing therapy, migraine
what is the mnemonic for acute management of ischaemic stroke?
DR ABCDE
airway protection and aspiration precautions are very important
what should be performed with suspected stroke?
CT head should be performed on arrival to distinguish ischaemic from haemorrhagic stroke
what is the most sensitive test for confirming ischaemic infarct?
diffusion weighted MRI - used if the diagnosis is unclear
what is the medical management of acute stroke?
alteplase (tissue plasminogen activator)
what is the criteria for giving alteplase?
within 4.5 hours of symptoms onset with no contraindications to thrombolysis
what are the contraindications to thrombolysis?
- recent head trauma
- GI or intracranial haemorrhage
- recent surgery
- acceptable BP
- platelet count
- INR
when can mechanical thromboectomy be performed?
- within 6 hours of symptom onset in anterior circulation strokes
- within 12 hours of symptom onset in posterior circulation strokes
what is the recommended aspirin dosing?
- no hyperacute treatment = aspirin 300mg OD for 2 weeks
- hyperacute treatment = aspirin started 24 hours post-treatment following repeat CT head
what investigations are commenced post-acute ischaemic stroke?
- carotid ultrasound
- CT/MRI angiography
- echocariogram
- serum glucose
- serum lipids
what is the mneumonic for chronic ischaemic stroke management?
HALTSS
what is the management of chronic ischaemic stroke?
H = hypertension -initiate antihypertensives 2 weeks post-stroke
A = antiplatelet therapy - clopidogrel 75mg OD
L = lipid-lowering therapy - atorvastatin 20-80mg OD
T = tobacco - smoking cessation
S = sugar - screened for diabetes
S = surgery - ipsilateral carotid artery stensosi requires carotid endarterectomy
what is an embolus?
anything that moves through the blood vessels until it reaches a vessel that is too small to let it pass
what is a thrombus?
blood clot that forms in a vein
what type of clot typically occurs in a large blood vessel occlusion?
embolus
as to have a clinical stroke event, occlusion has to be sudden and almost complete which is unlikely if it is a thrombotic occlusion
if a large artery occludes slowly with thrombosis, collaterals form and the acute occlusion goes unrecognised
where does large vessel infarcts typically occur?
cortex - produces cortical signs
what are cortical signs?
- left hemisphere (usually the dominant hemisphere)
- dysphasia
- agnosia
what conditions mimic strokes?
- migraine
- post seizure focal deficits
- hypoglycaemia
- acute presentations of subacute/chronic pathology like SOL
- demylination
- bell’s palsy
- non-organic states
what is amaurosis fugax?
form of stroke that affects the retinal/ophthalmic artery
what adverse side-effect do antipsychotics increase the risk of in elderly patients?
increased risk of stroke and VTE
what blood tests should be performed in patients >55 years who have no obvious cause of stroke?
- thrombophilia
- autoimmune screening
anterior cerebral artery stroke presentation
- contralateral hemiparesis and sensory loss
- lower extremities > upper
middle cerebral artery stroke presentation
- contralateral hemiparesis and sensory loss
- upper extremities > lower
- contralateral homonymous hemianopia
- aphasia
posterior cerebral artery stroke presentation
- contralateral homonymous hemianopia with macular sparing
- visual agnosia
