Ischaemic stroke Flashcards
List some DDx for a presentation of:
- 70yo woman
- inability to speak
- R sided weakness (arms>legs)
- R sided facial droop
- prev transient visual loss L eye (6/12 ago)
PDx. Ischaemic stroke of MCA (aphasia suggests Broca/frontal lobe, amaurosis fugax suggests carotid a stenosis and thromboembolism) DDx. CVA: - ischaemic stroke (post limb of internal capsule) - haemorrhage (intracerebral, epidural, subdural, subarachnoid) - watershed infarct (secondary to global ischaemia) - TIA Space occupying lesion: - tumour (primary, met) - abscess Metabolic - hyponatraemia - hypoglycaemia Infective - meningitis - encephalitis Other neuro: - MS - seizure disorder
Explain her prev episode of transient L eye vision loss?
Amaurosis fugax: transient, painless monocular vision loss -> due to TIA
Most commonly ischaemia (thromboembolism or hypoperfusion)
1) thromboembolism (most common): ipsilateral carotid a stenosis -> emboli -> reduced blood flow to retinal, opthalmic and ciliary arteries -> retinal hypoxia
2) hypoperfusion: ipsilateral carotid a stenosis -> 90-100% occlusion -> retinal and/or choroidal hypoperfusion -> recurrent episodes (assoc w reduced ocular perfusion pressure/ postural change)
What could her incomprehensible speech be due to?
Possibly multifactorial:
1) Broca’s expressive dysphagia- inferior frontal gyrus of dominant frontal lobe (superior MCA division) -> difficulty forming words (sparse output, non-fluency), comprehension relatively sparred
2) Wernicke’s receptive dysphagia- posterior superior temporal gyrus -> fluent aphasia, impaired comprehension, pt unaware
3) Conduction dysphagia- during recovery from Wernicke’s and deep parietal white matter -> impaired repetition, comprehension sparred
4) Dysarthria- motor articulatory disorder due to facial motor cortex dysfunction, vagus nerve (recurrent laryngeal verve), oropharynx muscular disorder
What are some risk factors for ischaemic stroke?
Non-modifiable: age >55yo, male, FMHx CVA, AF, hypercoagulable
Modifiable: hyperlipidaemia, HTN, obesity, T2DM, smoking
What signs of risk factors do you look for on exam?
- Vascular disease: carotid (bruit, pulses), peripheries (cool, pulses)
- Cardiac disease: surg, AAA, prosthetic valve, murmur, AF
- HTN
- Diabetes (retinopathy, ulcers)
- Hypercholesterolaemia (xanthalesmas, corneal arcus)
- Smoking (nicotine staining)
What are some CT findings for an ischaemic stroke?
Non-contrast brain CT:
- hypodense lesion (L temporal lobe here)
- cerebral oedema -> compression of ventricle and sulci effacement
- dense artery signs (thrombus or embous in artery)
- blurring of grey-white matter junction (oedema)
Describe the pathogenesis of ischaemic stroke?
Intracerebral or extracerebral causes:
1) Intracerebral: HTN causes diffusion of protein into vessel -> hyaline arteriosclerosis -> smaller lumen -> occlusion
2) Extracerebral:
- mural thrombus: mural thrombus forms over desynchronised contracting heart wall -> haemostasis -> clot formation (Virchow’s triad) -> embolise to common carotid -> ICA -> MCA -> liquefactive necrosis
- systemic hypoperfusion: shock -> generalised ischaemia -> watershed infarcts
3) other: vasculitis, arterial dissection
-> blockage -> deprivation of glucose and O2 to cerebral tissue -> inflammatory cascade -> liquefactive necrosis
Describe the MCA distribution?
MCA: motor and sensory cortices of upper limb and face, Wernicke’s area (temporal) and Broca’s area (frontal)
Superior division:
- primary motor cortex (precentral gyrus) -> movement of arms and face
- primary somatosensory cortex (postcentral gyrus) -> sensation of arms and face
- association cortex (parietal lobe) -> visuospacial disturbance and neglect (hemineglect if non-dominant side)
- Broca’s area -> expressive dysphagia
Inferior divison:
- optic radiation -> contralateral homonymous hemianopia
- Wernicke’s area -> receptive dysphagia
- Putamen and globus pallidus (lenticulostriate a)
List some complications of a stroke?
Short term:
- haemorrhagic transformation (esp larger infarcts, anticoag)
- DVT
- PE
- Seizure (esp ACA affecting pons and thalamus)
- Brain oedema -> raised ICP -> herniation and hydrocephalus (4th ventricle compression)
Long term:
- neuro deficits: immobility, poor speech, poor swallowing, QOL
- depression (QOL)
- aspiration pneumonia (stroke dysphagia)
- recurrent stroke
List some causes of death in the first 2 weeks?
- tonsilar herniation -> cardioresp failure
- another stroke in basilar a -> cardioresp failure
- septic shock: aspiration pneumonia (dysphagia), UTI (catheter), staph bacteraemia (cannula), pressure sore
- PE (DVT)
List some organisms causing aspirational pneumonia?
- bacteroides
- prevotella
- fusobacterium
- peptostreptococcus
