Stroke & Vascular Disorders Flashcards
What are the clinical signs of a stroke?
- Sudden onset
- Focal neurological deficit
- Vascular origin
- Symptoms >24 hrs or leading to death
What are symptoms lasting
Transient Ischemic Attack (TIA).
What is another term for a stroke?
Cerebral apoplexy.
What is a stroke?
Sudden disease due to vascular lesion in the brain.
What are the 2 types of stroke?
- Infarction (85%)
- Haemorrhage (15%)
What is the pathophysiology for an acute ischemic stroke?
Initial reduction in cerebral blood flow»_space; ischaemia & cellular necrosis.
What is the average cerebral blood flow (CBF)?
800ml/min.
15% cardiac output
Why does blocking blood flow to the brain lead to relatively rapid cellular failure?
The brain cannot store energy.
-neurones require a constant supply of ATP
What happens to the amount of O2 extracted from the blood if flow is reduced?
Amount of O2 extracted increases.
What happens to blood vessels when paCO2 increases?
Vessels dilate with increased paCO2.
What is the sole substrate for cerebral metabolism?
Glucose.
How is glucose metabolised?
- Glycolytic sequence
- TCA/Krebs cycle
What is the glucose threshold for normal cerebral function?
> 20 ml/100g/min
What are the glucose thresholds for cerebral ischaemia (ml/100g/min)?
12-20»_space; electrical function impaired.
8-12»_space; release K+ and water movement.
> cell death.
What are the layers of ischaemia in a brain?
Core
» penumbra
» oligemia
» normal tissue
What are the 3 stages following an occlusion?
- Auto-regulation
- Impaired perfusion reserve
- Ischaemia
What happens during auto-regulation?
- Decreased cerebral perfusion pressure
- Increased vessel volume
What happens during impaired perfusion reserve?
- Decreased cerebral blood flow & perfusion pressure
- Increased O2 extraction
What happens during ischaemia?
Maximum O2 threshold crossed:
-decreased cerebral metabolic rate
At what stages following an occlusion do symptoms start?
Ischaemia.
What are the causes of an ischaemic stroke? (2)
- Thrombosis
- Embolism
Where are thromboses that cause ischaemic stroke?
- Large arteries (extra-cranial)
- Small arteries (intra-cranial)
Where do emboli that cause ischaemic stroke originate?
- HEART (cardiogenic embolism)
- PROXIMAL ARTERIES (artery to artery embolism)
What is the main mechanism for ischaemic stroke?
Large vessel atherosclerosis (40%).
What is the most common cause of cardiac embolism?
Atrial fibrillation.
What is warfarin used for?
2* prevention after TIA or minor stroke.
What does F.A.S.T. stand for (public posters)?
Face
Arms
Speech
Time
What is a ‘recombinant tissue plasminogen activator’ (rt-PA)?
IV thrombolysis agent used for acute stroke.
When is IV thrombolysis not always effective?
For clots in deep cerebral artery.
What type of occlusion accounts for 18-25% of all ischaemic stroke, but 60-70% of deaths/disability?
Proximal anterior circulation large vessel occlusion.
What are ‘stentrievers’?
Stents placed across occlusion in acute stroke. Most of clot attaches»_space; improve efficacy of IV.
What is the modified rankin scale?
Measure of disability after stroke.
- 0 (no symptoms)»_space; 6 (death)
What is a Transient Ischaemic Attack (TIA)?
Neurological deficit lasting
How long do most TIAs last?
> brain damage
What are the vascular risk factors? (3)
- Carotid/large artery disease
- Cerebral small vessel disease
- Cardiac embolism
-NB same as stroke
What proportion of strokes are preceded by TIAs?
20%
What are the main TIA mimics? (4)
- Seizures
- Syncope
- Hypoglycaemia
- Migraine
What are symptoms of TIA in anterior circulation? (4)
- Amarausis fugax
- Dysphasia
- Apraxia
- Inattention
What is amarausis fugax?
Temporary loss of vision in one eye.
What are symptoms of TIA in posterior circulation? (4)
- Ataxia
- Diplopia
- Vertigo
- Bilateral symptoms
What is ataxia?
Loss of control of movements.
What are symptoms of TIA in either posterior or anterior circulation?
- Visual field disturbance
- Hemiparesis
- Hemisensory loss
- Dysarthria
What is the ABCD2 score used to calculate?
Risk of TIA leading to a stroke.
What are the 5 factors of an ABCD2 score?
- Age
- BP
- Clinical features
- Duration symptoms
- Diabetes
What are the risks of stroke for different ABCD2 scores?
5 = high risk
What is the risk of stroke with ‘recurrent “crescendo” TIAs’?
High risk regardless of ABCD2 score.
What are the most effective 2* preventions for TIAs? (5)
- Warfarin
- Diet
- Exercise
- Stop smoking
- Aspirin
Polypill combines many medications to possibly reduce stroke risk. What drugs does it contain? (4)
- Statin
- Aspirin
- Antihypertensives
- Folic acid
What is a 2* vascular prevention of stroke?
Carotid endarterectomy.
-for carotid territory TIA
What are the risks of a carotid endarterectomy?
Stroke/death
Nerve palsy
What is the intervention for an occluded carotid artery?
No intervention - technically impossible.
What is the 3rd most common cause of death in the UK?
Stroke.
What weaknesses do strokes cause?
- Contralateral weakness of LIMBS
- Weakness of OROPHARYNGEAL muscles (» dysarthria & incoordination of swallowing)
Where is Broca’s area located?
Infero-lateral frontal lobe.
What does damage to Broca’s area cause?
Stilted speech/expressive dysphasia.
- difficulty finding words
- reading & writing relatively intact
Where is Wernicke’s area located?
Left posterior superior temporal lobe.
What does damage to Wernicke’s area cause?
Fluent flow of speech, but neologisms (made up words) & mistake words (e.g. yes/no).
-Reading & writing impaired
What happens to BP after a stroke?
Rises acutely, then may settle within days.
When is anti-hypertensive treatment recommended after acute stroke? (4)
- Intracerebral haemorrhage wuth systolic BP > 200
- Hypertensive encephalopathy
- Aortic dissection
- Eclampsia
How is swallowing assessed?
- Give teaspoon of water
- Give 2 more
- Give 50 ml water
- No drooling»_space; SAFE.
- Drooling/coughing at any point»_space; UNSAFE»_space; NG tube
What are possible complications associated with strokes?
- ASPIRATION PNEUMONIA (NG tube not completely protective)
- DVT
- PRESSURE ULCERS
- SHOULDER SUBLAXATION (muscle weakness/neglect)
- PAIN
- INCONTINENCE
Why do strokes cause pain?
Damage to sensory cortex»_space; contralateral disturbance.
What are the 2 types of pain phenomena caused by strokes?
- Positive phenomena (paraesthesia, burning pain)
- Negative phenomena (decreased sensation)
How is pain due to stroke treated?
Pregabalin & Gabapentin.
-paracetamol/NSAIDs don’t work
How should DVT be treated?
- Consider low molecular weight heparin.
- Warfarin for 6 months.
How may patients compensate for weakness on affected side?
Increased use of unaffected side.
-neglect affected side
What happens physiologically in the first few days after stroke?
Natural recovery.
- Resolution of oedema
- Reperfusion of ischaemic penumbra
What happens physiologically in the weeks/months following a stroke?
Neuronal plasticity & cortical remodelling.
- dendrite sprouting
- synaptic remodelling.
Where is input from the right half of the visual field processed?
In the left hemisphere.
When does neglect occur and what senses does it affect?
Right parietal lobe stroke.
-visual & somatosensory
What is neglect due to?
Failure to attend to left side.
What is agnosias?
Inability to interpret senses & recognise things.
What is prosopoagnosia?
Type of agnosia.
|»_space; inability to recognise faces
What is dyspraxia?
Loss of ability to conceptualise/plan a sequence of motor actions.
- loss of cortical pathways
- e.g. difficulty walking
What are possible anatomical lesions leading to dyspraxia? (2)
- Left inferior parietal lobe
- Supplementary motor area
What are the symptoms of spastic hemiparetic gait?
- Stiff legged
- Short, slow steps
- Risk of falls
What may cause a painful hand after a stroke?
Spasticity - hypereexcitability of stretch reflex.
What are symptoms of hand spasticity?
- Loss of function
- Unable to maintain hygiene
- Pain
How is hand spasticity managed?
- Physiotherapy
- Drugs (botulinum toxin, baclofen)
