Acute Stroke Flashcards
What is stroke also known as?
Cerebrovascular event
What is a stroke?
A clinical syndrome caused by disruption to the blood supply of the brain
What is a stroke characterised by?
Rapidly developing signs of focal or global disturbance of cerebral functions, lasting for more than 24 hours or leading to death
What is a transient ischaemic attack?
A similar presentation that resolves within 24 hours
What are the 2 types of stroke?
- Ischaemic
- Haemorrhagic
Can ischaemic and haemorrhagic strokes be distinguished clinically?
Not reliably, but there are pointers
What clinical signs point towards a haemorrhagic stroke?
- Meningism
- Severe headache
- Coma within hours
What clinical signs point towards an ischaemic stroke?
- Carotid bruit
- Atrial fibrillation
- Past TIA
What happens in ischaemic stroke?
There is loss of blood supply to part of the brain
After how long does brain tissue cease to function when deprived of oxygen?
60-90 seconds
After how long does brain tissue suffer irreversible injury when deprived of oxygen?
After approx 3 hours
How might atherosclerosis be involved in stroke?
It can disrupt blood supply by narrowing the lumen of blood vessels, leading to a reduction in blood flow
By what methods can atherosclerosis cause the formation of blood clots?
- Due to the reduction in blood flow
- May release showers of small emboli through the disintegration of atherosclerotic plaques
What is an embolic infarction?
When the emboli formed elsewhere in the circulatory system
Where do the emboli typically form in embolic infarction?
- Heart
- Carotid arteries
What can cause embolic infarction originating from the heart?
AF
What happens in an embolic infarction?
The clots enter the cerebral circulation, then lodge in and block brain blood vessels
What are haemorrhagic stroke classified on the basis of?
Their underlying pathologies
Give 5 causes of haemorrhagic strokes
- Hypertensive haemorrhage
- Ruptured aneurysm
- Ruptured AV fistula
- Transformation of prior ischaemic infarction
- Drug-induced bleeding
How do haemorrhagic strokes result in tissue injury?
- Causing compression of tissue from an expanding haematoma(s)
- Blood released by brain haemorrhage appears to have direct toxic effects on brain tissue and vasculature
What might result from compression of brain tissue from a haematoma in haemorrhagic stroke?
It may lead to loss of blood supply to affected tissue, with resulting infarction
What are the causes of stroke in a younger patient?
- Vasculitis
- Thrombophilia
- Subarachnoid haemorrhage
- Venous sinus thrombosis
- Carotid artery dissection
What are the causes of stroke in older patients?
- Thrombosis in situ
- Atherothromboembolism
- Heart emboli
- CNS bleed
- Sudden BP drop
- Vasculitis
- Venous sinus thrombosis
What might cause heart emboli leading to stroke?
- Atrial fibrillation
- Infective endocarditis
- Myocardial infarction
What might cause a CNS bleed leading to stroke?
- Hypertension
- Head injury
- Aneurysm rupture
What sudden BP drop may lead to stroke?
More than 40mmHg
Give an example of a type of vasculitis that can lead to stroke
Giant cell arteritis
What are the risk factors for stroke?
- Hypertension
- Smoking
- Diabetes mellitus
- Heart disease
- Peripheral arterial disease
- Post-TIA
- Polycythaemia vera
- Carotid artery occlusion or carotid bruit
- COCP
- Hyperlipidaemia
- Excess alcohol
- Clotting disorders
What kinds of heart disease increase the risk of stroke?
- Valvular
- Ischaemic
- Atrial fibrillation
What can cause a CNS bleed leading to a stroke?
- Hypertension
- Head injury
- Aneurysm rupture
What sort of vasculitis can lead to a stroke?
Giant cell arteritis
What two ways do strokes typically present?
- Sudden onset
- Step-wise progression of symptoms over hours
What tool can be used to assess sudden onset symptoms that resemble stroke?
FAST
What are the steps of FAST tool for stroke symptom assessment?
- Face (weakness or asymmetry)
- Arm (weakness)
- Speech (difficulty)
- Time to call 999
What do the symptoms of stroke depend on?
The area of the brain that is affected
What affects the severity and quantity of symptoms of stroke?
How extensive the affected area of brain is
What are some possible symptoms of cerebral hemisphere infarct?
- Contralateral hemiplegia
- Contralateral sensory loss
- Homonymous hemianopia
- Dysphasia
How does the contralateral hemiplegia in a cerebral hemisphere stroke progress?
Flaccid initially then becomes spastic
What are some possible symptoms of a stroke involving posterior circulation ischaemia?
- Motor deficits in any combination of arms and legs up to quadriplegia
- ‘Crossed’ syndromes
- Sensory deficits
- Homonymous hemianopia
- Ataxia, imbalance, unsteadiness or disequilibrium
- Vertigo
- Diplopia
- Dysphagia
- Dysarthria
- Locked in syndrome
What motor deficits can occur in a posterior circulation ischaemia?
- Weakness
- Clumsiness
- Paralysis
What is meant by ‘crossed’ syndromes?
Ipsilateral cranial nerve dysfunction and contralateral long motor or sensory tract dysfunction
What sensory deficits can occur as a result of posterior circulation ischaemia?
Numbness including loss of sensation or parasthesia in any combination of the extremities
What causes a locked in syndrome?
Complete infarction of the pons
What are the features of a locked in syndrome?
- Quadriparesis
- Loss of speech
- Preserved awareness and cognition
- Sometimes preserved eye movements
What are lacunar infarcts?
Small infarcts around the basal ganglia, internal capsule, thalamus and pons
What can lacunar infarcts cause?
- Pure motor
- Pure sensory
- Mixed signs
- Ataxia
What is left intact by a lacunar infarct?
Cognition/consciousness
What is an important symptom that affects a large proportion of stroke patients?
Dysphagia
How is a diagnosis of stroke made?
Clinically with imaging to assist
What modes of imaging can be helpful in assessing a patient who has had a stroke?
- CT scan
- MRI scan
What group of stroke patients is a CT scan recommended in?
Those in the acute phase of the stroke
Which type of stroke is a CT scan very sensitive in diagnosing?
Haemorrhagic stroke in acute stage
How does the appearance of a CT scan progress in a patient with an ischaemic stroke?
Often normal at first but improved accuracy after 6 hours
What is an MRI better than a CT scan at assessing in stroke patients?
The site and extent of ischaemic damage
What proportion of stroke patients is an MRI contra-indicated in?
1/3
What can contra-indicate an MRI scan in a stroke patient?
- Too ill
- Confusion
- Pacemaker
- Other metal
Why may additional studies be needed once a stroke has been diagnosed?
To assess the underlying cause of the acute event
What helps to indicate which test may be useful in identifying underlying cause of a stroke?
- Age
- Comorbidities
- Presentation