Stroke Flashcards
Define a stroke
Represents a sudden interruption in the vascular supply of the brain
It is characterised by sudden onset of rapidly developing focal or global neurological disturbance, which lasts > 24 hours or leads to death
What is the other name for a stroke
cerebrovascular accident
Why does a loss of oxygen supply lead to irreversible damage in the brain
The neural tissue of the brain is completely dependent on aerobic metabolism (it cannot do anaerobic metabolism)
Hence a loss of oxygen supply lead to irreversible damage in the brain
There are two main types of strokes.
What are they
Ischaemic and Haemorrhagic
Why type of stroke is most common
a) Ischaemia
b) Haemorrhagic
Ischaemic Stroke (most common – 85%)
What happens in the brain for an Ischaemic stroke to occur
Occurs as a result of occlusion of the blood vessels that supply the brain parenchyma leading to infarction (tissue necrosis secondary to ischaemia)
What happens in the brain for an Haemorrhagic stroke to occur
The result of weakening of the cerebral vessels leading to cerebral rupture causing bleeding/haematoma formation within the brain parenchyma, ventricular system or subarachnoid space
What is the direct and indirect cause of he clinical deficits associated with haemorrhagic stroke
Clinical deficit is caused directly by neuronal injury
Indirectly by cerebral oedema (this peaks at day 5 following symptom onset)
Haemorrhagic stroke classification can be subdivided further.
Name these subdivision
Intracerebral haemorrhage (ICH) – most common
Subarachnoid haemorrhage (SAH)
What is the essential problem that causes an ischaemic stroke
‘Blockage’ in the blood vessel stops blood flow
What is the essential problem that causes a haemorrhagic stroke
Blood vessel ‘bursts’ leading to reduction in blood flow
What proportion of strokes are ischaemic
85%
What proportion of strokes are haemorrhagic
15%
Name some of the modifiable risk factors for stroke
- Cigarette smoking
- Obesity
- Hypercholesterolaemia (high serum cholesterol)
- Hypertension
- Combined contraceptive pill
- Sedentary lifestyle
Name some of the non-modifiable risk factors for stroke
- Cardiovascular disease comorbidities e.g, angina, myocardial infarction and peripheral vascular disease
- Age (>65 years old)
- Male gender
- Atrial fibrillation (5 x greater risk)
- Previous stroke or TIA
- Diabetes mellitus
- Hypercholesterolaemia
- Carotid artery disease
- Thrombophilia
- Sickle cell disease
- Vasculitis
Define the term “Transient Ischaemic Attack (TIA)”
It is transient neurological dysfunction secondary to ischaemia without infarction
How long will it take for most symptoms of the Transient Ischaemic Attack (TIA) to resolve?
Within 1 hr
Define the term “ischaemia”
Refers to the reduction/lack of blood flow to the tissue
Define the term “Infarction “
Refers to the cellular changes that can occur as a result of reduced/no perfusion to the tissue
Name the four key features of stroke
- Sudden weakness of limbs
- Sudden facial weakness
- Sudden onset dysphasia (speech disturbance)
- Sudden onset visual or sensory loss
Patients with what kind of stroke are more likely to present with global features such as headache and altered mental status.
haemorrhagic stroke
Name some of the clinical features associated with haemorrhagic stroke
- Headache
- Altered mental status
- Nausea & Vomiting
- Hypertension
- Seizures
- Decrease in the level of consciousness
Ischaemic Strokes are classified by what classification scale
Bamford/Oxford classification
Anterior cerebral artery supplies what lobes
Part of the frontal and parietal lobe.
What are the clinical features associated with an anterior cerebral artery ischaemic stroke
- Unilateral weakness and/or sensory deficit on the contralateral face, arms and/or legs
- Homonymous hemianopia: visual field loss on the same side of both eyes
- Higher cerebral dysfunction: dysphasia, visuospatial dysfunction e.g., neglect, agnosia
What are the clinical features associated with an middle cerebral artery ischaemic stroke
- Contralateral hemiparesis and sensory loss – upper extremity > lower
- Contralateral homonymous hemianopia (visual field loss on the same side of both eyes)
- Aphasia (inability to comprehend speech, occurs if it affects left/dominant hemisphere)
- Visuospatial problems
- Apraxia (inability to create speech, occurs if it affects the right/non-dominant hemisphere)
Middle cerebral artery supplies what lobes
Supplies a large proportion of the lateral surface of each brain hemisphere including the internal capsule and basal ganglia
Posterior cerebral artery supplies what lobes
Supplies the occipital lobe and inferior proportion of the temporal lobe as well as some deep structures (e.g. thalamus).
What are the clinical features associated with a posterior cerebral artery ischaemic stroke
- Contralateral homonymous hemianopia with macular sparing
- Memory deficits
- Several visual defects – lack of depth, hallucinations
Broca’s area is responsible for ____ speech
a) Fluent
b) The understanding of
a) Fluent
Wernicke’s area is responsible for ____ speech
a) Fluent
b) The understanding of
Wernicke’s area is responsible for the understanding of speech
A lesion in the Broca’s area results in _____
a) Expressive dysphasia
b) Receptive dysphasia
A lesion in the Broca’s area results in a) Expressive dysphasia
A lesion in the Wernicke’s area results in _____
a) Expressive dysphasia
b) Receptive dysphasia
A lesion in the Wernicke’s area results in b) Receptive dysphasia
What is the name of the tool used in the community to recognise stroke
FAST tool
What is the name of the tool used in the hospital to recognise stroke
ROSIER
ROSIER tool to recognise stroke is based on what factors?
Clinical scoring tool based on clinical features and duration
Stroke is likely if the patient scores what on the ROSIER tool
> 0
What is the gold standard investigation for stroke
Non-contrast CT head scan
Why is neuroimaging needed urgently if there is a suspection of stroke
Urgent imaging as patient may be suitable for thrombolytic therapy to treat early ischaemic strokes
If CT scan is contraindicated for whatever reason what is the next best neuroimaging modality for stroke
MRI scan of head
What are the key CT features of an ischaemic stroke
May appear normal in the first few hours of the stroke - areas of low density in the grey and white matter will develop over time
What are the key CT features of a haemorrhagic stroke
Areas of hyperdense material (blood) surrounded by low density (oedema)
What is the first line management for a patient with a stroke
ABCDE assessment - making sure they are haemodynamically stable
At what GCS does a patient need intubated to protect their airways
GCS < 8
What is the management of a haemorrhagic stroke
Management depends on the extent of bleeding and the suitability for neurosurgical interventions
Potentially neurosurgical input (particularly for larger bleeds)
Most small bleeds, there is no requirement for neurosurgical intervention.
Managing underlying risk factors (see secondary prevention of stroke)
What are the potential neurosurgical interventions for managing a large haemorrhagic bleed
Includes use of decompressive hemicraniectomy in those meeting specific clinical criteria or suboccipital craniotomy for posterior fossa bleeds
What is the initial management of an ischaemic stroke
Loading dose aspirin (300mg) and consider:
<4.5 hrs from symptom onset: thrombolysis
< 24 hrs from symptom onset: thrombectomy
What drug is used in Thrombolysis of ischaemic stroke
Alteplase
What is Alteplase
Alteplase is a tissue plasminogen activator that rapidly breaks down clots and can reverse the effects of a stroke
Name three contraindictors against thrombolysis use in ischaemic stroke
Neurosurgery last 3 months
Active internal bleeding (hence done only after CT has excluded haemorrhagic stroke)
Onset of Symptoms > 4.5 hrs
What is the thrombolysis window for ischaemic stroke
Onset of symptoms < 4.5 hrs
Limited benefit beyond this time with increased bleeding risk
Name a post thrombolysis complication
Intracranial or systemic haemorrhage
What is involved in thrombectomy
Involves mechanical removal of the clot causing the ischaemic stroke in specialist centres by the interventional neuroradiology team
What is the timeframe in which thrombectomy can be used in the management of patients with ischaemic stroke
Not used after 24 hours from the onset of symptoms
Name some of the secondary preventions for strokes
- Clopidogrel 75mg once daily (alternatively dipyridamole 200mg twice daily)
- Atorvastatin 80mg should be started but not immediately
- Carotid endarterectomy or stenting in patients with carotid artery disease
- Treat modifiable risk factors such as hypertension and diabetes
Following a stroke, patients who drive a car or motorcycle should be advised to stop driving for how long?
One month
Name the 5 parts of managing a patient with a stroke
Part 1: Stablising the patient (ABCDE assessment)
Part 2: Imaging with non contrast CT head scan
Part 3: Intervention
Haemorrhagic stroke - consider neurosurgical intervention
Ischaemic stroke - loading dose aspirin (300mg) and:
<4.5 hrs from symptom onset: thrombolysis
< 24 hrs from symptom onset: thrombectomy
Part 4: Secondary prevention
Part 5: Stroke rehabiliation
