Stroke Flashcards
What is a stroke?
a syndrome of rapid onset neurological deficit caused by focal cerebral, spinal or retinal infarction or haemorrhage
In which ethnicities is stroke more common? (2)
1) Asian
2) black African
What are the two major causes of stroke?
Ischaemic stroke (87%)
Haemorrhagic stroke (13%)
What is a ischaemic stroke?
Ischaemic strokes occur when the blood supply to an area of brain tissue is reduced, resulting in tissue hypoperfusion.
Give 6 ischaemic causes of stroke:
1) thrombosis
2) small vessel disease
3) cardio-embolic causes
4) hypoperfusion
5) carotid and vertebral artery dissection
6) venous stroke
How can an embolism cause an ischaemic stroke?
an embolus originating somewhere else in the body (e.g. the heart) causes obstruction of a cerebral vessel, resulting in hypoperfusion to the area of the brain the vessel supplies.
how can a thrombosis cause a stroke?
a blood clot forms locally within a cerebral vessel (e.g. due to atherosclerotic plaque rupture).
How does systemic hypoperfusion cause a stroke?
blood supply to the entire brain is reduced secondary to systemic hypotension (e.g. cardiac arrest).
how does cerebral venous sinus thrombosis cause a stroke?
blood clots form in the veins that drain the brain, resulting in venous congestion and tissue hypoxia.
Describe how small vessel disease can cause ischaemic stroke:
small penetrating arterial branches supply the deep brain parenchyma and can be affected by occlusive vasculopathy leading to small infarcts and gradual accumulation of diffuse ischaemic change in the deep white matter
What is lipohyalinosis?
A loss of normal arterial architecture and foam macrophage deposition in the arterial wall
Give 5 cardio-embolic causes of ischaemic strokes:
1) atrial fibrillation and arrhythmias
2) valve disease
3) infective vegetations
4) rheumatic and calcific changes
5) mural thrombosis
Describe how hypoperfusion can lead to ischaemic strokes:
severe hypotension can lead to infarction in watershed areas between vascular territories
What is an artery dissection?
where blood penetrates the subintimal vessel wall, forming a false lumen
Give two causes of carotid and vertebral artery dissection:
1) neck trauma e.g. whiplash
2) hyperextension e.g. osteopathic manipulation or hair washing in a salon
Describe how carotid and vertebral artery dissection can lead to ischaemic strokes:
blood penetrating the subintimal wall stimulates the release of thromboplastin release, leading to thrombosis and embolisation
What % of strokes are venous?
1%
What is the prognosis of the stroke?
Mortality – 20% in first 2 months, then roughly 10%/year
<40% of stroke (not TIA) patients make a full recovery
Drowsyness at presentation has a poor prognosis
Describe how a venous stroke comes about:
thrombosis can occur within intracranial venous sinuses such as the superior sagittal sinus
Which has a worse prognosis, ischaemic or haemorrhagic?
Haemorrhagic
what is a haemorrhagic stroke?
occurs secondary to rupture of a blood vessel or abnormal vascular structure within the brain
What is the difference between a intracerebral haemorrhage and subarachnoid haemorrhage?
Intracerebral haemorrhage involves bleeding within the brain secondary to a ruptured blood vessel. Intracerebral haemorrhages can be intraparenchymal (within the brain tissue) and/or intraventricular (within the ventricles) whereas subarachnoid haemorrhage is a type of stroke caused by bleeding outside of the brain tissue.
What are 6 causes of haemorrhagic strokes?
- Hypertension
- cerebral amyloid angiopathy
- Aneurysms
- Coagulopathies
- Anticoagulants and thrombolysis treatment
- arteriovenous malformation
how may hypertension lead to a stroke?
Damages arterial walls, and thus leads to increased risk of thrombus formation, and haemorrhage
Describe how cerebral amyloid angiopathy can cause haemorrhagic strokes:
deposition of amyloid-beta in the walls of small and medium arteries increases the risk of haemorrhage
Give two groups of patients who are at increased risk of cerebral amyloid angiopathy:
1) Alzheimer’s patients
2) those with apolipoprotein E genotypes
Give 8 general risk factors for stroke:
1) hypertension
2) obesity
3) smoking
4) atrial fibrillation
5) alcohol
6) diabetes
7) low exercise
8) high cholesterol
What is CADASIL?
cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (genetic disorder than causes strokes)
Caused by a defective NOTCH3 gene
How can smoking increase the risk of a stroke?
Increases BP, as well as direct effects on arterial walls. Stopping reduces risk by 50% in the first year, and is indistinguishable from non-smoker after 5 years.
How does AF increase the risk of a stroke?
Increases the chances of thrombus formation in the heart
What is the Bamford stroke classification?
divides the different types of stroke into TACS, PACS, POCS and LACS, depending on the clinical features.
What is a TACS stroke?
A total anterior circulation stroke
- caused by an infarct in the middle and anterior cerebral arteries
How does a TACS present?
- Unilateral weakness and/or sensory deficit of the face arm and legs
- Homoymous hermianopia (loss of half the visual fields in both eyes)
- Higher cerebral function (dysphasia, visuospatial disorder)
What is a PACS?
A partial anterior circulation stroke and causes 2 of the TACS symptoms or just higher cerebral dysfunction alone
What is POCS?
posterior circulation syndrome - an infarct affecting posterior circulation
What symptoms does POCS cause?
- Cranial nerve palsy with a contralateral motor or sensory deficit
- Bilateral motor/sensory deficit
- Conjugate eye movement disorder
- Symptoms of cerebellar dysfunction such as vertigo, nystagmus or ataxia
- Isolated homonymous hermianopia
What is LACS?
A lacunar stroke
What can a LACS cause?
pure motor, sensory, sensorimotor, or cause ataxic hemiparesis alone
What is the BEFAST acronym?
Balance: sudden loss in balance?
Eyes: loss of vision or double vision?
Face: is there a facial droop?
Arms: can the person lift both arms above their head?
Speech: is the speech slurred, or are they using inappropriate words?
Time: time to call an ambulance
How does an infarction show up on a CT and MRI?
A wedge shape
Haemorrhage – blood appears bright white (dense) on CT – but the longer it has been present, the darker it becomes. After 1-2 weeks it may be indistinguishable from brain tissue.
What is management of ischaemic strokes?
Aspirin – 300mg/day for 2 weeks, then 75mg day
Be wary asthma and GI bleeds
If aspirin hypersensitive, give clopidogrel
Dipyridamole – should also be given if ischaemia confirmed by CT / MRI.
The use of warfarin should be considered once the cause is known (i.e. if AF, or if definite thrombosis). Treatment range s usually an INR of 2-3.
Carotid endartectomy – is also considered in many patients. Those with carotid obstruction of >60% are generally considered.
How is a haemorrhagic stroke managed?
Treatment is essentially supportive. If anticoagulants and antiplatlets have been given, then the effect can be reversed with vitamin K, fresh frozen plasma (FFP) and platelet transfusions.
Hypertension should only be treated if systolic is >185 mm Hg
If the haemorrhage causes a mass of >3cm diameter, then surgery can be lifesaving.
The occlusion of which vessels are considered anterior circulation infarcts? (4)
1) internal carotid
2) anterior cerebral artery
3) middle cerebral artery
4) ophthalmic artery
Give 6 clinical features associated with anterior circulation infarct ischaemic strokes:
- Contralateral hemiplegia
- Facial weakness
- Hemisensory loss
- eye deviation towards the affected side
- aphasia
- Hemianopia
Hemi/tetraparesis following a stroke indicates a lesion in which brainstem region?
corticospinal tract
Sensory loss following a stroke indicates a lesion in which brainstem region?
medial lemniscus and spinothalamic tracts
Diplopia following a stroke indicates a lesion in which brainstem region?
oculomotor system
Facial numbness following a stroke indicates a lesion in which brainstem region?
CNVII nerve nuclei
Nystagmus and vertigo following a stroke indicates a lesion in which brainstem region?
vestibular connections
Dysphagia and dysarthria following a stroke indicates a lesion in which brainstem region?
CNIX and CNX nerve nuceli
Ataxia, vomiting and hiccups following a stroke indicates a lesion in which brainstem region?
cerebellar peduncles
Horner’s syndrome following a stroke indicates a lesion to which neurological region?
sympathetic fibres
Coma and altered consciousness following a stroke indicates a lesion to which brainstem region?
reticular formation
Are basilar artery infarcts typically caused thrombosis or embolisms?
thrombosis
Are posterior cerebral infarcts typically caused by thrombosis or embolisms?
embolisms
What presentation is associated with basilar artery infarcts?
locked-in syndrome
What 2 presentation are associated with posterior cerebral infarcts?
- Homonymous hemianopia
- Anton’s syndrome (cortical blindness)
Give 5 presentations associated with watershed circulation brain infarcts:
1) complex patterns of visual loss
2) memory loss
3) intellectual impairment
4) motor deficits
5) vegetative state
What investigations should be carried out within 24 hours of presentation for a suspected stroke (3)?
1) ECG
2) carotid doppler ultrasound
3) routine blood test
Give the 5 steps of management for an ischaemic stroke:
1) give oxygen and confirm airway patency
2) brain CT
3) if ischaemic, commence thrombolysis therapy
4) admit to multidisciplinary stroke unit
5) rehabilitation
Give two forms of thrombolysis therapy:
1) endovascular therapy (stenting)
2) alteplase therapy
Give 3 drugs used in thromboembolism prophylaxis following an ischaemic stroke:
1) aspirin
2) warfarin
3) DOACs
