stroke Flashcards
def of stroke
rapid permanent neurological deficit from cerebrovascular insult
defined clinically as focal or global impairment of CNS function developing rapidly and lasting >24hr
subdivided by location (anterior circulation or posterior circ), or be path process ie infarction/haemorrhage
aetiology of stroke infarction
80%
thrombosis
- elderly - atherosclerosis in cerebral vessels affecting small vessels ->lacunar infarcts; less commonly large vessels eg middle cerebral art
- prothrombotic states eg dehydration or thrombophilia
- cerebral microangiopathy
emboli
- intimal flap of carotid dissection
- atheromatous plaques in carotid - atherothromboembolism
- from heart eg AF, endocarditis, MI
- rarely from venous circ - pass through R-L heart defet eg VSD
hypotension - If below the autoregulatory range maintaining cerebral blood flow, infarction results in the watershed zones between different cerebral artery territories
vasculitis
cocaine
haemorrhage stoke aetiology
10%
HTN
charcot-bouchard microaneurysm rupture
amyloid angiopathy
anteriovenous malformations
Less commonly, trauma, tumours, arteriovenous malformations, vasculitis.
anticoagulation
thrombolysis
sudden BP drop by >40mmHg - affect boundary zone between 2 vascular beds
carotid artery dissection - spontaneous/from neck trauma/fibromuscular dysplasia
vasculitis
SAH
venous sinus thrombosis
antiphospholipid syndrome
thrombophilia
fabry disease
CADASIL
pathology of stroke
ischemic brain becomes soft due to vasogenic oedema from breakdown of blood-brain barrier and prone to haemorrhagic transformation
can cause secondary damage to CNS
RF for stroke
htn
smoking
dm
heart disease - valvular, ischemic, AF
pvd
high PCV
carotid bruit
combined OCP
high lipids
high alcohol use
high clotting - high fibrinogen, low antithrombin 3
high homocysteine
syphilis
cardiac causes of stroke
non-valvular afib - risk of stroke of 4.5%/yr. Ischemic strokes in AF have a worse prognosis
CHADSVASc score - calculate risk of stroke in pts with AF. Anticoag if score 2 or more. Take bleeding risk into account - HAS-BLED score. Caution and regular review of oral anti-coag needed if HAS-BLED >3. Dont give stroke prevention if <65yrs and CHADSVASC is 0 in men or 2 in women
anti-coag from 2wks post stroke (or 7-10d if clinically and radiologically small) - DOAC or warfarin
cardiac sources of emboli
cardioversion
prosthetic valves
acute myocardial infarct with L vent wall motion abnormalities on echo
patent foramen ovale/septal defects
cardiac surgery
IE - give rise to septic emboli
epi stroke
common
annual incidence 2 in 1000
3rd most common cause of death in industrialised countries
70yrs
Young strokes (<50years merit extensive investigation).
Someone in the UK has a stroke every 3.5 minutes
sx of stroke
sudden onset - deterioration in seconds, worst at onset
Weakness, sensory, visual or cognitive impairment, impaired coordination, or consciousness.
Head or neck pain (in carotid or vertebral artery dissection).
Enquire time of onset (critical for emergency management if<4.5 h)
Enquire if history of atrial fibrillation, MI, valvular heart disease, carotid artery stenosis, recent neck trauma or pain.
signs of stroke
examine for underlying cause - AF, heart murmur, carotid bruit, fundoscopy
pointers to infarction - AF, carotid bruit, past TIA, IHD
Infarction:
- contralateral sensory loss/hemiplegia - initially flaccid (floppy limb, falls like a dead weight) -> becoming spastic (UMN)
- dysphasia
- homonymous hemianopia
- visio-spatial defect
anterior circulation stroke
anterior cerebral: lower limb weakness (motor cortex), confusion (frontal lobe)
middle cerebral: facial weakness, hemiparesis (motor cortex) hemisensory loss (somatosensory cortex), apraxia, hemineglect (parietal lobe), receptive or expressive dysphagia (language centres), quadrantanopia (superior or inferior optic radiations)
lacunar stroke
disease in the deep perforating arteries
internal capsule or pons - Pure sensory or motor deficit (or combination of both).
thalamus - loss of consciousness, hemisensory deficit
basal ganglia - hemichorea, hemiballismus, parkinsonism
posterior circulation stroke
posterior cerebral - hemianopia
anterior inferior cerebellar artery - vertigo, ipsilateral ataxia, ipsilateral deafness or tinnitus, ipsilateral facial weakness
posterior inferior cerebellar artery (lateral medullary syndrome of Wallenberg) - vertigo, ipsilateral ataxia, ipsilateral Horner’s syndrome, ipsilateral hemifacial sensory loss, dysarthria and contralateral spinothalamic sensory loss
basilar artery - combination of cranial nerve pathology and impaired consciousness = emergency
vascular dementia
urinary incontinence
gait apraxia (‘marche a petits pas’, shuffling small step gait with upright posture and often normal or excessive arm swing)
5 syndromes:
- ataxic hemiparesis
- pure motor
- pure sensory
- sensorimotor
- dysarthria/clumsy hand
cognition/consciousness intact except for in thalamic strokes
MULTIPLE lacunar infarcts
brainstem infarct
25%
varied
quadriplegia
gaze and vision disturbances
locked in syndrome
signs of haemorrhage
pointers to bleed - meningism, severe headache, coma
intracerebral:
- headache
- meningism
- focal neurological signs
- nausea and vomiting
- signs of raised ICP
- seizures
- coma
ix for stroke
blood
ECG - arrhythmias that pre-dispose to embolism
echo
carotid doppler US - exclude carotid artery disease
CT head
MRI brain
CT cerebral angio
retinopathy, nephropathy, cardiomegaly - signs of HTN
CXR - enlarged LA
check for hypoglycaemia, hyperglycaemia, dyslipidaemia, hyperhomocysteinaemia
vasculitis - high ESR, ANCA, VDRL to look for active, untreated syphilis
prothrombotic states - thrombophilia, antiphospholipid syndrome
hyperviscosity - polycythaemia, sickle cell disease
thrombocytopenia and other bleeding disorders
genetic tests - CADASIL, Fabry disease
echo stroke
identifies cardiac thrombus, valvular endocarditis or other sources of embolism, valvular lesions in rheumatic heart disease
consider bubble contrast study for R to L shunt eg VSD
hyperkinetic segment of cardiac muscle post MI
(Transoesophageal is more sensitive than transthoracic)
CT head stroke
rapid detection of haemorrhages
often normal, especially in lacunar infarcts, or very early in stroke ie <6hr
MRI brain stroke
rarely available acutely
higher sensitivity for infarction
diffuse weighted imaging (DWI) - differentiate between recent strokes (<2wks) and old strokes
ct cerebral angio stroke
detect artery dissection or intracranial stenosis
alternatively MRA with T1 fat saturation can be useful
hyperacute stroke mx
protect airway - avoid hypoxia/aspiration
<4.5hr from onset and haemorrhage excluded on CT head, IV thrombolysis considered with alteplase - CT 24hr after to identify bleeds
NO aspirin in 1st 24hr
Follow local protocols due to very strict inclusion and exclusion criteria (NINDS andECASS3 trials, IST3 trial for thrombolysis<6 h is ongoing).
CI to thrombolysis - major infarct or haemorrhage, mild/non-disabling deficit, recent surgery/trauma/artery or vein puncture at uncompressable site, previous CNS bleed, AVM/aneurysm, severe liver disease, varices or portal HTN, seizure at presentation, blood glucose <3 or >22, stroke/serious head injury in last 3mo, GI or urinary tract haemorrhage in last 21 days, known clotting disorder, anticoag or INR>1.7, platelets <100x10(9), history of intracranial neoplasm
acute ischemic stroke mx
aspirin 300mg/clopidogrel to prevent thrombosis once haemorrhage excluded on CT head
heparin considered in certain subgroups where risk of emboli recurrence or stroke progression eg carotid dissection, recurrent cardiac emboli, critical carotid artery stenosis
formal swallow assessment vital - NG tube might be necessary
close nursing and GCS monitoring
thromboprophylaxis (but no evidence of net benefit from graded compression stockings in CLOTS trial).
Hemicraniectomy may be indicated for mass effect from infarcted tissue in the first 48 h
maintain homeostasis - keep blood glucose between 4-11mmol/L, BP if HTN emergency (eg encephalopathy/aortic dissection) or thrombolysis considered (aim <110/85) - only in these cases because treating v high may impair cerebral perfusion
intracerebral haemorrhage Mx
control HTN and seizures
IV mannitol and hyperventilation helps lower ICP
Evacuation of haematoma or ventricular drainage may be required.
stroke secondary prevention
300mg aspirin (2wk) and slow release dipyridamole, or aspirin then clopidogrel
warfarin anticoagulation if AF
stop smoking
control HTN and hyperlipidaemia
treatment of carotid artery disease
surgical mx stroke
controversial in asymptomatic disease
Carotid endarterectomy (removal of plaque) within 2 weeks of stroke or TIA reduces risk of further stroke in ECST and NASCET trials, although carries a significant peri-operative risk.
considered in:
- symptomatic stenosis of 70–99% (ECST criteria),
- symptomatic stenosis of 50–99% (NASCET criteria) or
- crescendo TIAs not responding to medical treatment.
endovascular carotid artery angioplasty with stenting if unfit for surgery - this has higher peri-procedure stroke and mortality rates
thrombectomy - intra-arterial mechanical thrombectomy = additional benefit if large artery occlusion in proximal anterior circulation
complications of stroke
cerebral oedema - high ICP and local compression
immobility
infections eg pneumonia, UTI, from pressure sores
CVS events - arrhythmias, MI, cardiac failure
death
px of stroke
stroke - 10% mortality in 1st mo
up to 50% who survive remain dependent
1 in 4 die in a year
10% have recurrence in 1yr
poorer for haemorrhage than infarction
overall 60000/yr
drowsiness = poor prognosis
