Ischaemic stroke Flashcards
Into what 2 groups can ischaemic strokes be further divided?
>24 hours = ischaemic stroke
<24 hours = transient ischaemic attacks
What is the definition of a transient ischaemic attack?
stroke in which the symptoms and signs last less than 24 hours
What proportion of all strokes are ischaemic strokes?
85%
What are 2 subtypes of ischaemic stroke based on the cause?
- Thrombotic: caused by thrombosis from large vessels e.g. carotid
- Embolic: usually blood clot but fat, air or clumps of bacteria may act as embolus
What is an important example of causes of embolic strokes?
AF is important cause of emboli forming in heart
What are 6 risk factors for cardiovascular disease?
- Age
- Hypertension
- Smoking
- Hyperlipidaemia
- Diabetes mellitus
- Atrial fibrillation
What are 5 general symptoms of stroke?
- Motor weakness
- Speech problems (dysphasia)
- Swallowing problems
- Visual field defects (homonymous hemianopia)
- Balance problems
What are 4 symptoms of cerebral hemisphere infarcts?
- Contralateral hemiplegia: initially flaccid then spastic
- Contralateral sensory loss
- Homonymous hemianopia
- Dysphasia
What is meant by lacunar infarcts?
small infarcts around the basal ganglia, internal capsule, thalamus and pons
What are 4 areas which may be the location of lacunar infarcts?
- Basal ganglia
- Internal capsule
- Thalamus
- Pons
What are 4 types of signs that lacunar infarcts may result in?
- Pure motor
- Pure sensory
- Mixed motor and sensory
- Ataxia
What is one of the formal types of classification system for strokes?
Oxford Stroke Classification (aka Bamford Classification) - classifies stroke based on initial symptoms
involves description of territory affected e.g. total anterior circulation infarcts (TACI)
What are 3 examples of types of stroke according to the Oxford Stroke Classification system, that considers initial symptoms?
- Unilateral hemiparesis and/or hemisensory loss of the face, arm and leg
- Homonymous hemianopia
- Higher cognitive dysfunction e.g. dysphasia
What are 4 types of stroke described by the territory affected?
- Total anterior circulation infarcts (TACI) - 15%
- Partial anterior circulation infarcts (PACI) - 25%
- Lacunar infarcts - 25%
- Posterior circulation infarcts (POCI) - 25%
Which 2 arteries are involved in total anterior circulation infarcts?
middle and anterior cerebral arteries
What are the criteria to diagnose a total anterior circulation infarct?
involve middle and anterior cerebral arteries
all 3 of the Oxford Stroke classification criteria are met:
- unilateral hemiparesis and/or hemisensory loss of the face, arm and leg AND
- homonymous hemianopia AND
- higher cognitive dysfunction e.g. dysphasia
What are the criteria to diagnose a partial anterior circulation infarct (PACI)?
involves smaller arteries of anterior circulation rather than middle/anterior cerebral, e.g. upper or lower division of middle cerebral artery. involves anterior OR middle cerebral artery
2 of Oxford Stroke criteria are present (hemiparesis/sensory loss, hemianopia, cognitive dysfunction) OR higher cerebral dysfunction alone
What are the criteria to diagnose a lacunar infarct (LACI)?
involves perforating arteries around the internal capsule, thalamus and basal ganglia
presents with 1 of the following:
- unilateral weakness (and/or sensory deficit) of face and arm, arm and leg or all three (pure motor stroke)
- pure sensory stroke
- sensorimotor stroke
- ataxic hemiparesis
What are 3 types of symptoms, 1 of which must be present to diagnose a lacunar infarct?
- Unilateral weakness (and/or sensory deficit) of face and arm, arm and leg or all three
- Pure sensory stroke
- Ataxic hemiparesis
What is the difference between hemiparesis and hemiplegia?
hemiparesis is weakness on half of body, hemiplegia is paralysis on half of body
What are the criteria to diagnose a posterior circulation infarct (POCI)? 6 aspects
involves vertebrobasilar arteries and presents with 1 of the following:
- cerebellar or brainstem syndromes
- conjugate eye movement disorder
- bilateral motor/sensory deficit
- ipsilateral cranial nerve palsy with contralateral motor/sensory deficit
- loss of consciousness
- cortical blindness/ isolated homonymous hemianopia
Which arteries are affected in a posterior circulation infarct (POCI)?
vertebrobasilar arteries
What are the 3 criteria, 1 of which the patient must present with, to diagnose posterior circulation infarct (POCI)?
- Cerebellar or brainstem syndromes
- Loss of consciousness
- Isolated homonymous hemianopia
What campaign exists to raise awareness of stroke symptoms?
FAST campaign:
- Face: has it fallen on one side, can they smile
- Arms: can they raise both arms and keep them there
- Speech: is speech slurred
- Time: time to call 999 if see any single one of these signs
What investigations are required in patients with suspected stroke?
emergency neuroimaging - to see if suitable for thrombolytic therapy to treat early ischaemic strokes
- non-contrast CT: must be done in first hour - checking for haemorrhagic stroke
- MRI
How long do transient ischaemic attacks typically last?
although by definition they are <24hr, vast majority <1 hour
What do NICE recommend for the immediate management of TIA?
give aspirin 300mg immediately, unless contraindicated e.g. bleeding disorder or taking anticoagulant (in which case, need immediate admission for imaging to exclude haemorrhage)
What are 2 situations that should make you discuss the need for admission or observation urgently with a stroke specialist for TIA?
- if patient has had >1 TIA (>1/week: crescendo TIA)
- patient has suspected cardioembolic source or severe carotid stenosis
What is the management if the patient has had a suspected TIA in the last 7 days?
arrange urgent assessment (witin 24 hours) by a specialist stroke physician
What is the management if a patient has had a suspected TIA which occurred more than a week previously?
refer for specialist assessment as soon as possible within 7 days
What are 4 vital signs to maintain within normal limits for ischaemic stroke management?
- blood glucose
- hydration
- oxygen saturation
- temperature
How should you approach the management of blood pressure when treating ischaemic stroke acutely?
should not be lowered in the acute phase unless there are complications e.g. hypertensive encephalopathy
What medication should be given immediately if ischaemic stroke is suspected AND haemorrhagic stroke has been excluded?
aspirin 300mg orally or rectally
(rectal if dysphagia)
What is the management of AF present alongside ischaemic stroke?
don’t start anticoagulants (DOAC/warfarin) until brain imaging has excluded haemorrhage, and usually not until 14 days have passed from the onset of an ischaemic stroke
What additional drug beyond antiplatelet therapy/thrombolysis should some patients who have had an ischaemic stroke be given?
statin
When are patients who have had ischaemic stroke offered a statin?
if cholesterol is >3.5 mmol/L
When is a statin often started following ischaemic stroke and why?
treatment often delayed until after at least 48 hours due to risk of haemorrhagic transformation
What are the 2 criteria which must be met for thrombolysis to be considered for acute ischaemic stroke?
- If it is administered within 4.5 hours of onset of stroke symptoms (unless part of clinical trial)
- Haemorrhage has been definitively excluded (i.e. imaging has been performed)
What are 11 absolute contraindications to thrombolysis following acute ischaemic stroke?
- Previous intracranial haemorrhage
- Seizure at onset of stroke
- Intracranial neoplasm
- Suspected subarachnoid haemorrhage
- Stroke or traumatic brain injury in preceding 3 months
- Lumbar puncture in preceding 7 days
- GI haemorrhage in preceding 3 weeks
- Active bleeding
- Pregnancy
- Oesophageal varices
- Uncontrolled hypertension >200/120 mmHg
What are 5 relative contraindications to thombolysis of acute ischaemic stroke?
- Concurrent anticoagulation (INR >1.7)
- Haemorrhagic diathesis
- Active diabetic haemorrhagic retinopathy
- Suspected intracardiac thrombus
- Major surgery / trauma in the preceding 2 weeks
Which drug is used for thrombolysis of acute ischaemic stroke?
IV alteplase (recombinant tissue plasminogen activator)
When is mechanical thrombectomy available to treat acute ischaemic stroke?
24 hours a day
What is required before decisions about thrombectomy are made?
they must take into account patient’s overall clinical status: pre-stroke functional status of less than 3 on the modified Rankin scale and more than 5 on the National Institutes of Health Stroke Scale (NIHSS)
After what time period following acute ischaemic stroke can thrombectomy be offered? What can it be given in combination with?
- as soon as possible and within 6 hours of symptom onset, together with IV thrombolysis (if within 4.5 hours)
- sometimes within 6-24 hours if meet certain criteria
What are 2 criteria for performing thrombectomy within 6 horus of ischaemic stroke symptom onset?
- Acute ischaemic stroke AND
- Confirmed occlusion of proximal anterior circulation demonstration by CT angiography (CTA) or magnetic resonance angiography (MRA)
What are 2 criteria that must be met for thrombectomy to be offered to those last known to be well between 6 and 24 hours prior to ischaemic stroke symptoms?
- Confirmed occlusion of proximal anterior circulation demonstrated by CTA or MRA AND
- if there is potential to salvage brain tissue, as shown by imaging such as CT perfusion or diffusion-weighted MRI sequences showing limited infarct core volume
What does the extension to within 6-24 hours of symptom onset for thrombectomy include?
wake-up strokes
What are 2 criteria that must be met to consider thrombectomy (together with intravenous thrombolysis i.e. altenplase if within 4.5 hrs) for people known to be well up to 24hr previously?
- Acute ischaemic stroke and confirmed occlusion of the proximal posterior circulation (i.e. basilar or posterior cerebral artery) demonstrated by CTA or MRA AND
- There is potential to salvage brain tissue, as shwon by imaging such as CT perfusion or diffusion-weighted MRI sequences showing limited infarct core volume
What are first, second and third line secondary prevention following ischaemic stroke?
- First line: clopidogrel
- Second line: aspirin + modified release dipyridamole if clopidogrel contraindicated/not tolerated
- Third line: MR dipyridamole alone
When is carotid artery endarterectomy recommended as management of ischaemic stroke?
- if patient has suffered stroke or TIA in the carotid territory and are not severely disabled
What criteria of carotid stenosis must be met to consider carotid artery endarterectomy?
- only if carotid stenosis >70% according to ECST criteria or >50% according to NASCET criteria
- ECST = European Carotid Surgery Trialists’ Collaborative Group
- NASCET = North American Symptomatic Carotid Endarterectomy Trial
How do thrombolytic drugs work?
activate plasminogen to form plasmin
plasmin degrades fibrin and helps break up thrombi
What proportion of patients who cannot swallow post-stroke will recover within 2-4 weeks?
80%
Why is it important to manage fluids in the immediate post-stroke period?
hypovolaemia can worsen the ischaemic penumbra, as well as increase risk of other complications such as infection, deep vein thrombosis, constipation and delirium
What is meant by the ischaemic penumbra?
the cerebral area surrounding the ischaemic event there there is ischaemia without necrosis. this area is amenable to recovery with thrombolysis
What are 3 risks of over-hydration in the fluid management of patients post-stroke?
- Cerebral oedema
- Cardiac failure
- Hyponatraemia
What is the recommendation for managing hydration in post-stroke patients?
- oral hydration preferable if can swallow safely
- IV hydration otherwise may be necessary - isotonic saline WITHOUT dextrose is agent of choice
- consider electrolyte disturbances and/or cardiovascular status
What are 3 reasons why glycaemic control post-stroke is very important?
- May be nil by mouth due to concerns regarding swallowing safety
- May be diabetic
- Post stroke, patients with hyperglycaemia have increased mortality independent from age and severity of stroke
What blood sugar level is recommended to be maintained in patients acutely post-stroke?
4-11mmol/L
What is the managment of glycaemic control in diabetic patients post-stroke?
- provide intensive management for diabetics post acute stroke
- optimise insulin treatment using IV insulin and glucose infusions
- hypoglycaemia also needs to be managed appropriately
Why is it important to prevent hypoglycaemia following stroke?
can cause neuronal injury as well as mimic-stroke-related neurological deficits
What are the 5 situations when anti-hypertensive medications sohuld be used post-ischaemic stroke?
hypertensive emergency with one or more of the following concomitant issues:
- hypertensive encephalopathy
- hypertensive nephropathy
- hypertensive cardiac failure/ myocardial infarction
- aortic dissection
- pre-eclampsia/eclampsia
Why is it important not to lower blood pressure too much following stroke?
it can potentially compromise collateral blood flow to the affected region, and can possibly hasten the time to complete, irreversible tissue infarction
If blood-pressure lowering treatment is indicated following acute stroke, what is the recommended management? 3 options
cautious lowering of BP by 15% in first 24 hours after stroke onset
IV labetalol, nicardipine and clevidipine as first line agents
By how much is it recommended to lower BP following acute stroke, if treatment is indicated?
cautious lowering of BP by 15% in first 24 hours after stroke onset
If stroke patients are candidates for thrombolytic therapy how does the management of blood pressure change?
ensure BP is stabilised and maintained at or below 180/105 for at least 24 hours after treatment
What must all patients presenting with acute stroke be screened for prior to oral intake (fluids, food, medications) and why?
safe swallowing function: dysphagia common after stroke, so this is to reduce risk of aspiration
What should be done if there are any concerns regarding swallowing following stroke?
specialist assessment of swallowing, preferably within 24 hours of admission, no greater than 72 hours after
Within what time frame should specialist assessment of swallowing be performed if there are any concerns about swallowing post-stroke?
within 24 hours of admission, no greater than 72 hours after
What should be done prior to specialist assessment of swallowing if there are concerns?
patient should remain nil by mouth to prevent complications
What are 3 things that must be done for patients deemed unsafe for oral intake due to swallowing problems following stroke?
- Should receive nasogastric tube feeding, ideally within 24 hours of admission, unless have had thrombolytic therapy
- If NG tube not tolerated, should be considered for nasal bridle tube/gastrostomy instead
- Medications need to be assessed as to whether suitable for NG feeding, or if conversion to subcut/IV required
What are 3 reasons why nutritional support may be required for patients at risk of malnutrition post-stroke?
- Dysphagia
- Poor oral health
- Reduced ability to self-feed due to waekness or paralysis
Why are disability scales used for patients who have had a stroke?
can measure functional decline post event and subsequent improvement after medical intervention
How is disability often measured?
in terms of functional status (basic activities of daily living)
Who may patients be referred to due to disability and when?
following medical stabilisation after a stroke, may require transfer to a rehabilitation team for ongoing treatment depending on their level of disability
What is most commonly used to measure disability as an outcome measure for stroke?
Barthel index (BI)
What does the Barthel index consist of to measure disability following stroke?
- 10 tasks, scored according to amount of time or assistance required by patient for each given task
- tasks include: feeding, moving from wheelchair to bed, personal toileting, getting on/off toilet, bathig, walking on level surface, ascending/descending stairs, dressing, controlling bowels and controlling bladder
- total score from 0 to 100 (0=completely dependent, 100=completely independent)
How can AF cause ischaemic strokes?
stasis of blood flow in left atrium predisposes to thrombus formation in the left atrium, and subsequent embolisation to the brain
What are 3 examples of rare causes of ischaemic stroke?
- Vasculitis
- Arterial dissection
- Haematological causes (prothrombotic states)
What are 5 weaker risk factors for ischaemic stroke?
- Hypercholesterolaemia
- Obesity
- Poor diet
- Oestrogen-containing therapy
- Migraine
Which blood vessels are involved in a total anterior circulation infarction (TACI)?
anterior AND middle cerebral arteries on the affected side
Which blood vessels are involve in a partial anterior circulation infarct (PACI)?
anterior OR middle cerebral artery on affected side
What are 3 things that should NOT be present in a lacunar infarct (LACI)?
- Visual field defect
- Higher cerebral dysfunction
- Brainstem dysfunction
What are 3 regions which may be involved in a POCI (posterior circulation stroke), that are supplied by the vertebrobasilar arteries and associated branches?
- Cerebellum
- Brainstem
- Occipital lobe
What are the 4 different posterior stroke syndromes to be aware of?
- Basilar artery occlusion → locked in syndrome/ loss of consciousness, sudden death
- Anterior inferior cerebellar artery → lateral pontine syndrome
- Wallenberg’s sydrome → lateral medullary syndrome
- Weber’s syndrome → medial midbrain syndrome
What is locked-in syndrome?
quadriparesis with preserved consciousness and ocular movements
What are 3 things which basilar artery occlusion (form of posterior stroke syndrome) may result in?
- Locked-in syndrome
- Loss of consciousness
- Sudden death
What syndrome does anterior inferior cerebellar artery result in (form of posterior circulation infarction)?
Lateral pontine syndrome
What does lateral pontine syndrome consist of?
similar lateral medullary syndrome (ipsilateral Horner’s syndrome, ipsilateral loss of pain and temperature sensation on face, contralateral loss of pain and temperature sensation over contralateral body) PLUS involvement of pontine cranial nerve nuclei
What is another name for Wallenberg’s syndrome?
Lateral medullary syndrome
What are the features of Wallenberg’s syndrome (lateral medullary syndrome)?
- Horner’s syndrome
- Ipsilateral loss of pain and temperature sensation on the face
- Contralateral loss of pain and temperature sensation over the contralateral body.
What is another name for Weber’s syndrome?
Medial midbrain syndrome
What blood vessels are involved in the cause of medial midbrain syndrome (Weber’s syndrome)?
paramedial branches of upper basilar and proximal posterior cerebral arteries
What are the features of Weber’s syndrome (medial midbrain syndrome)?
ipsilateral oculomotor nerve palsy and contralteral hemiparesis
In posterior circulation strokes, up to what time post-stroke can mechanical thrombectomy be performed?
up to 12 hours after onset
For how long should patients take aspirin following an ischaemic stroke, and at what dose?
300mg orally once daily for 2 weeks
If hyper-acute treatments are offered for ischaemic stroke, when is aspirin treatment usually started?
24h after treatment following a repeat CT head that excludes any new haemorrhagic stroke
What are 4 post-acute investigations which may be performed following ischaemic stroke to help identify cause/ risk factors?
- Carotid ultrasound - to identify stenosis
- CT/MR angiography - identify intracranial and extracranial stenosis
- Echocardiogram - if cardio-embolic source suspected
- In young patients, vasculitis screen or thrombophilia screen may be necessary
What is the mnemonic to help you remember the key steps in secondary stroke prevention?
HALTSS
- H: hypertension
- A: antiplatelet therapy
- L: lipid-lowering therapy
- T: tobacco. smoking cessation support
- S: sugar, screen for diabetes and manage
- S: surgery - carotid endarterectomy
What is the long-term antiplatelet therapy and dose that is recommended first line for patients post-ischaemic stroke?
clopidogrel 75mg od
What is the recommended long-term anticoagulation therapy for patients with ischaemic stroke secondary to AF?
warfarin or a DOAC (rivaroxaban or apixiban)
What is the target INR for warfarin when being used as anti-platelet therapy following stroke caused by AF?
2-3
When is warfarin/DOAC initiated post-stroke for patients whose stroke was caused by an embolism due to AF?
initiated 2 weeks post-stroke
When are patients typically offered carotid endarterectomy?
if ipsilateral carotid artery stenosis more than 50%
What are 4 important things in the MDT approach to rehabilitation for patients post-stroke?
- Physiotherapy
- Occupational therapy
- Speech and language therapy
- Neurorehabilitation
What are 4 regions supplied by the posterior brain circulation?
- Occipital lobes
- Cerebellum
- Brainstem
- Thalamus
What are 4 areas suppled by the anterior circulation?
- Frontal lobe
- Parietal lobes
- Temporal lobes
- Eyes (amaurosis)
What is the posterior circulation vascular system?
two vertebral arteries join to form basilar artery, which bifurcates to two posterior cerebral arteries
What does the anterior circulation of the brain consist of?
internal carotid arteries, middle cerebral arteries, anterior cerebral arteries
Which 2 regions may be involved in pure motor hemiparesis due to lacunar infarction?
- Internal capsule or
- Pons
Which 3 regions may be involved in a lacunar infarction causing a hemisensorimotor pattern?
- Internal capsule
- Pons
- Corona radiata
Which 2 regions may be involved in a lacunar infarction causing an ataxic hemiparesis pattern?
- Internal capsule
- Pons
What region may be involved in a lacunar infaction causing a pure hemisensory pattern?
thalamus
What drug should be offered alongside aspirin and when?
PPI: previous dyspepsia
What type of surgery may sometimes be performed for acute ischaemic stroke?
decompressive hemicraniectomy
If performed, within what time frame must decompressive hemicraniectomy take place?
within 48h of symptom onset
What are 3 criteria for a decompressive hemicraniectomy to be performed following acute ischaemic stroke?
- Clinical deficits that suggest infarction in territory of MCA, with score above 15 on NIHSS
- Decreased level of consciousness, with score of 1 or more on item 1a of NIHSS
- Signs on CT of infarct of at least 50% of MCA territory
- with or without additional infarction in territory of anterior or posterior cerebral artery on same side Or
- with infarct volume >145ml as shown on diffusion weighted MRI scan
What is the NIHSS?
National Institudes of Health Stroke Scale - quantifies stroke severity based on weighted evaluation findings
What does decompressive craniectomy involve?
part of skull removed to allow swelling brain room to expand without being squeezed
ischaemic tissue shifts through the surgical defect rather than to naffected regions of brain, thus avoiding secondary damage due to increased ICP
