stroke + TIA Flashcards
definition
sudden onset
focal neuro deficit
vascular lesion in origin
lasting >24hrs
epidemiology
1/1000 per yr [falling due to improvement in rx]
pathogenesis
85% due to ischemia causing INFARCTION
15% due to intracerebral HEMORRHAGE
types of stroke
There are two main types of strokes:
1. ischaemic: these can be further subdivided between into episodes which last:
- greater than 24 hours (termed an ischaemic stroke)
- episodes where symptoms and signs last less than 24 hours (transient ischaemic attacks, TIAs, sometimes termed ‘mini-strokes’ by patients)
2. haemorrhagic
s/s
Stroke is defined by the World Health Organization as a clinical syndrome consisting of ‘rapidly developing clinical signs of focal (at times global) disturbance of cerebral function, lasting more than 24 hours or leading to death with no apparent cause other than that of vascular origin’. In contrast, with a TIA the symptoms and signs resolve within 24 hours.
Features include:
- motor weakness
- speech problems (dysphasia)
- swallowing problems
- visual field defects (homonymous hemianopia)
- balance problems
Cerebral hemisphere infarcts may have the following symptoms:
- contralateral hemiplegia: initially flaccid then spastic
- contralateral sensory loss
- homonymous hemianopia
- dysphasia
Brainstem infarction
- may result in more severe symptoms including quadriplegia and lock-in-syndrome
Lacunar infarcts
- small infarcts around the basal ganglia, internal capsule, thalamus and pons
- this may result in pure motor, pure sensory, mixed motor and sensory signs or ataxia
how are strokes classified
One formal classification system that is sometimes used is the Oxford Stroke Classification (also known as the Bamford Classification), whichclassifies strokes based on the initial symptoms. A summary is as follows:
The following criteria should be assessed:
- unilateral hemiparesis and/or hemisensory loss of the face, arm & leg
- homonymous hemianopia
- higher cognitive dysfunction e.g. dysphasia
can you tell from the symptoms if the stroke is hemorrhagic or ischemic?
Whilst symptoms alone cannot be used to differentiate haemorrhagic from ischaemic strokes, patients who’ve suffered haemorrhages are more likely to have:
- decrease in the level of consciousness: seen in up to 50% of patients with a haemorrhagic stroke
- headache is also much more common in haemorrhagic stroke
- nausea and vomiting is also common
- seizures occur in up to 25% of patients
what is the public health campaign related to stroke
Over recent years there has been a public health campaign to raise awareness of stroke symptoms. The FAST campaign uses the following mnemonic:
- Face - ‘Has their face fallen on one side? Can they smile?’
- Arms - ‘Can they raise both arms and keep them there?’
- Speech - ‘Is their speech slurred?’
- Ttime - ‘Time to call 999 if you see any single one of these signs.’
Investigations
Patients with suspected stroke need to have emergency neuroimaging.
The main cause for urgency is to see whether a patient may be suitable for thrombolytic therapy to treat early ischaemic strokes.
The two types of neuroimaging used in this setting [within 1 hour] are:
- CT
- MRI
brain imaging should be performed immediately (ideally the next slot and definitely within 1 hour, whichever is sooner) for people with acute stroke if any of the following apply:
indications for thrombolysis or early anticoagulation treatment
- on anticoagulant treatment
- a known bleeding tendency
- a depressed level of consciousness (Glasgow Coma Score below 13)
- unexplained progressive or fluctuating symptoms
- papilloedema, neck stiffness or fever
- severe headache at onset of stroke symptoms
for all people with acute stroke without indications for immediate brain imaging, scanning should be performed as soon as possible (within a maximum of 24 hours after onset of symptoms)
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The objectives of identifying stroke risk factors are:
- to identify specific pathophysiological subtypes of cerebral infarction with different management and prognosis
- to ascertain specific risk factors and their possible prevention
Investigations that might contribute to these goals include:
- chest X-ray - cardiac enlargement in hypertension or valvular disease
- retinal examination - retinopathy in hypertension, embolic disease
- ECG - ventricular enlargement and/or arrhythmias in hypertensive/embolic disease; recent MI in embolic disease; conduction defect - embolic / output failure
- blood glucose - for hyperglycaemia in diabetes mellitus
- serum cholesterol and lipids - hyperlipidaemia in patients under 65 years
- ESR, auto-antibodies - for vasculitis, collagen vascular disease
- full blood count - for polycythaemia, thrombocytopenia
- urine analysis - polyarteritis, thrombocytopenia
- other haematological tests as indicated - e.g. neurosyphilis
- cervical spine X ray - for atlanto-axial subluxation
- note drug history - oral contraceptives, amphetamines, opiates
Further investigations as indicated:
- blood culture - if suspected infective endocarditis
- sickle cell screen, plasma electrophoresis, viscosity studies
Selected points relating to the management of acute stroke include:
- blood glucose, hydration, oxygen saturation and temperature should be maintained within normal limits
- blood pressure should not be lowered in the acute phase unless there are complications e.g. Hypertensive encephalopathy*
- aspirin 300mg orally or rectally should be given as soon as possible if a haemorrhagic stroke has been excluded
- with regards to atrial fibrillation, the RCP state: ‘anticoagulants should not be started until brain imaging has excluded haemorrhage, and usually not until 14 days have passed from the onset of an ischaemic stroke’
- if the cholesterol is > 3.5 mmol/l patients should be commenced on a statin. Many physicians will delay treatment until after at least 48 hours due to the risk of haemorrhagic transformation
Thrombolysis
- Thrombolysis should only be given if:
- it is administered within 4.5 hours of onset of stroke symptoms (unless as part of a clinical trial)
- haemorrhage has been definitively excluded (i.e. Imaging has been performed)
- Alteplase is currently recommended by NICE.
- Contraindications to thrombolysis attached as picture
Acute management: ABC
1. Airways/Breathing: protect – prevent hypoxia and aspiration
2. Circulation:
o Pulse (AF)
o BP: Rx severe HTN can → ↓ cerebral perfusion
- Disability/don’t forget glucose:
o Blood glucose: hypoglycaemia N.B. aim: 4-11mmol/L – Rx sliding scale
-
Imaging:
o Urgent CT/MRI: thrombolysis
Diffusion-weighted MRI is most sensitive for acute infarct
CT will exclude primary haemorrhage -
Thrombolysis: onset <4.5h (onset of symptoms)
o Alteplase (rh-tPA) IV 0.9mg/kg
o → ↓ death and dependency (OR 0.64)
o CT 24h post-thrombolysis to look for haemorrhage - Nil by mouth: choking risk – IVI hydration
-
Antiplatelet agents: Aspirin 300mg (+PPI) – once haemorrhagic stroke ruled out.
o Clopidogrel if aspirin CI
2ry prevention
Recommendations from NICE include:
- clopidogrel is now recommended by NICE ahead of combination use of aspirin plus modified release (MR) dipyridamole in people who have had an ischaemic stroke
- aspirin plus MR dipyridamole is now recommended after an ischaemic stroke only if clopidogrel is contraindicated or not tolerated, but treatment is no longer limited to 2 years’ duration
- MR dipyridamole alone is recommended after an ischaemic stroke only if aspirin or clopidogrel are contraindicated or not tolerated, again with no limit on duration of treatment
With regards to carotid artery endarterectomy:
- recommend if patient has suffered stroke or TIA in the carotid territory and are not severely disabled
- should only be considered if carotid stenosis > 70% according ECST** criteria or > 50% according to NASCET*** criteria
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Primary Prevention (pre-stoke)
Control RFs: HTN, ↑ lipids (statin ↓ risk 17%), DM, smoking, cardiac disease
Exercise: ↑ HDL, ↑glucose tolerance
Folate supplements: ↓ plasma homocysteine
Smoking cessation
life-long anticoagulation: consider in AF (use CHADS2)
Secondary Prevention (prevent stroke)
Risk factor control as above
o Start anti-hypertensives and statin
Antiplatelet therapy: Aspirin / clopi 300mg for 2wks after stroke then either
o Clopidogrel 75mg OD (preferred option)
o Aspirin 75mg OD + dipyridamole MR 200mg BD
Anticoagulation: Warfarin instead of aspirin/clopidogrel if
o Cardioembolic stroke or chronic AF
o Start from 2wks post-stroke (INR 2.5-3.5)
o Don’t use aspirin and warfarin together.
Carotid endarterectomy if good recovery + ipsilat stenosis ≥70%
Management
Ischaemic strokes
Urgent neuroimaging classifies the stroke as either ischaemic or haemorrhagic.
If the stroke is ischaemic, and certain criteria are met, the patient should be offered thrombolysis.
Example criteria include:
- patients present with 4.5 hours of onset of stroke symptoms
- the patient has not had a previous intracranial haemorrhage, uncontrolled hypertension, pregnant etc
Once haemorrhagic stroke has been excluded patients should be given aspirin 300mg as soon as possible and antiplatelet therapy should be continued.
Transient ischaemic attacks
Remember with TIAs the, by definition, symptoms last less than 24 hours although in the vast majority of cases the duration is much shorter, typically 1 hour or so. For this reason most patients symptoms will have resolved before they see a doctor.
The ABCD2 prognostic score has previously been used to risk stratify patients who present with a suspected TIA. However, data from studies have suggested it performs poorly and it is therefore no longer recommended by NICE Clinical Knowledge Summaries. Instead, NICE recommend:
Immediate antithrombotic therapy:
give aspirin 300 mg immediately, unless contraindicated e.g. the patient has a bleeding disorder or is taking an anticoagulant (needs immediate admission for imaging to exclude a haemorrhage)
If the patient has had more than 1 TIA (‘crescendo TIA’) or has a suspected cardioembolic source or severe carotid stenosis:
- discuss the need for admission or observation urgently with a stroke specialist
If the patient has had a suspected TIA in the last 7 days:
- arrange urgent assessment (within 24 hours) by a specialist stroke physician
If the patient has had a suspected TIA which occurred more than a week previously:
- refer for specialist assessment as soon as possible within 7 days
management: Haemorrhagic strokes
If imaging confirms a haemorrhagic stroke neurosurgical consultation should be considered for advice on further management.
The vast majority of patients however are not suitable for surgical intervention.
Management is therefore supportive as per haemorrhagic stroke.
- Anticoagulants (e.g. warfarin) and antithrombotic medications (e.g. clopidogrel) should be stopped to minimise further bleeding.
- If a patient is anticoagulated this should be reversed as quickly as possible.
- Trials have shown improved outcomes in patients who have their blood pressure lowered acutely and this is now part of many protocols for haemorrhagic strokes.
stroke by anatomy: Anterior cerebral artery
Contralateral hemiparesis and sensory loss, lower extremity > upper
stroke: assessment [ROSIER SCORE]
The FAST screening tool (Face/Arms/Speech/Time) is widely known by the general public following a publicity campaign. It has a positive predictive value of 78%.
A variant of FAST called the ROSIER score is useful for medical professionals. It is validated tool recommended by the Royal College of Physicians.
ROSIER score
Exclude hypoglycaemia first, then assess the following:
ABCD2 Score
Predicts stroke risk following TIA
