Stroke Flashcards
Definition of stroke
Neurological deficit (loss of function) of sudden onset, lasting more than 24 hours, of vascular origin
What time defines a TIA?
< 24 hours
What does TIA stand for?
Transient ischaemic attack
Two types of causes of stroke
- Ischaemic stroke
2. Haemorrhagic stroke
What is the penumbra?
Area of tissue in the brain that can get some oxygen from other places and so is “asleep” - not dead
Causes of haemorrhage in stroke
Congenital weakness
HTN
Aneurysm
What do the symptoms of stroke correlate to?
Part of the brain affected
Main anatomical vessels of the brain
Anterior circulation
Posterior circulation
Circle of willis
What supplies the anterior part of the brain?
Two carotid arteries
What joins together to form the circle of willis?
Anterior and posterior circulations
Where is a clot most likely to go in the circle of willis?
Middle cerebral artery (MCA)
What does the carotid system supply?
Most of the hemispheres
Cortical deep white matter
What does the vertebra-basilar system supply?
Brainstem
Cerebellum
Occipital
What is found anterior to the central sulcus?
Motor cortex
What is found posterior to the central sulcus?
Sensory cortex
Function of motor cortex
Movement
Function of sensory cortex
Pain, heat and other sensations
Function of parietal lobe
Comprehension of language
Function of temporal lobe
Hearing
Intellectual and emotional functions
Function of occipital lobe
Primary visual area
Function of wernickes area
Speech comprehension
Function of cerebellum
Coordination
Function of brainstem
Breathing Swallowing Heartbeat Wakefullness centre Involuntary functions
Function of Brocas area
Speech
Function of frontal lobe
Smell
Judgement
Foresight
Voluntary movement
Definition of TIA
Warning stroke or mini stroke, with stroke like symptoms persisting less than 24 hours, that clears without residual ability
How many patients who have a TIA will have an acute stroke at some point?
1/3rd
Causes of stroke
Blockage of vessel with thrombus or clot
Disease of vessel wall e.g. atheroscleroma
Disturbance of normal properties of the blood e.g. leukaemia
Rupture of the vessel wall (haemorrhage)
What % of strokes are due to infarction?
85%
What % of strokes are due to haemorrhage?
15%
Causes of ischaemic stroke
Large artery atherosclerosis (e.g. carotid) Cardioembolic (e.g. AF) Small artery occlusion (lacunar) Undetermined/cryptogenic Rare causes - arterial dissection - venous sinus thrombosis
Causes of haemorrhagic stroke
Primary ICH
Secondary haemorrhage
- SAH
- AV malformation
How does a haemorrhagic stroke affect the brain?
Blood causes pressure effects and squashes the surrounding brain tissue
Where do most carotid stenosis occur?
Bifurcation
Commonest cause of cardioembolic stroke
AF
What does AF stand for?
Atrial fibrillation
What does a carotid dissection look like on angiogram?
Rat tail appearance
Risk factors for stroke
High BP AF Age Race FH
Which type of stroke is more prevalent in high income countries?
Ischaemic
Risk factors for haemorrhage after stroke
Infarct size Vessel occlusion DM BP Age Stroke severity Tissue changes Antiplatelets
What is the time frame for giving someone thrombolysis when admitted with stroke?
4.5 hours
What should not be used for treatment of patients in the acute phase for stroke?
Streptokinase
Examples of neurological deficits seen in stroke
Facial weakness
Limb weakness
Speech disturbances (dysphasia or dysarthria)
Hemianopia
Contraindications to thrombolysis
Minor neurological deficit or symptoms rapidly improving before the start of infusion
Symptoms of ischaemic attack began more than 4 hours prior to referral, or when time of symptom onset is unknown
Severe stroke
Seizure at onset of stroke
Symptoms suggestive of SAH, even if CT scan is normal
On warfarin or administration of heparin within the previous 48 hours and a thromboplastin time exceeding upper limit
Patients with history of prior stroke AND concomitant stroke
Prior stroke within last 3 months
Platelet count below 100,000/mm3
Systolic BP >185mmHg or diastolic >100mmHg or aggressive meds needed to reduce BP to these limits
BG < 3 or > 20
Known haemorrhagic diathesis , recent severe or dangerous bleeding, known ICH
age > 16 and < 80
Who needs a hemicraniectomy in stroke?
Patients up to age 60, who suffer acute MCA territory ischaemic stroke complicated by massive cerebral oedema
When should a hemicraniectomy be given?
Within 48 hours of stroke onset
Why do stroke units improve morbidity and mortality?
Mobilise early
Swallowing, positioning focus
Early therapy
Concentrating of expertise
What % of stroke patients get swallowing problems?
50%
What is the Neumonic used by the public to remember stroke symptom recognition?
FAST
Secondary prevention of stroke
Clopidogrel or aspirin 75mg plus dipyridamole MR 200mg bd
Statin
BP drugs (even if in normal range)
Carotid endarterectomy
Presentation of stroke
Dead numbness Loss of vision Loss of speech (fluid or comprehensive) Loss of power Loss of sensation Loss of coordination
What may the neurological exam of a stroke show?
Clumsy or weak limb Loss of sensation Dysarthria/dysphagia Neglect/visuospatial problems Loss of vision in one eye Hemianopia Gaze palsy Ataxia/vertigo/incoordination/nystagmus
If there is a left optic nerve compression, what visual field defect would be present?
Unilateral field loss
If there is chiasmal compression from a pituitary tumour, what visual field defect would be present?
Bitemporal hemianopia
If there is a left cerebrovascular event, what visual field defect will be present?
Homonymous hemianopia
What parts of the brain can a stroke be localised to?
Left or right
Carotid territory or vertebrobasilar territory
Cerebral hemispheres or brainstem
Cortex or deep white matter
Subtypes of stroke
TACS
PACS
LACS
POCS
What does TACS stand for?
Total anterior circulation stroke
What does PACS stand for?
Partial anterior circulation stroke
What does LACs stand for?
Lacunar stroke
What does POCS stand for?
Posterior circulation stroke
What % of strokes are TACS?
20%
Presentation of TACS
Weakness
Sensory deficit
Homonymous hemianopia
Higher cerebral dysfunction (e.g. dysphagia, dyspraxia)
What are TACS usually due to?
Occlusion of
- proximal MCA or
- ICA
What % of strokes are PACS?
35%
Presentation of PACS
2/3 of TACS criteria OR
Restricted motor/sensory deficit e.g. one limb, face and hand or cerebral dysfunction alone
What is usually affected in PACS?
More restricted cortical infarcts - occlusion of branches of MCA
Presentation of LACS
Since motor fibres travel together and sensory fibres travel together can be either PURE SENSORY or PURE MOTOR
PURE MOTOR is commonest; complete or incomplete weakness of one side, involving 2 or 3 body areas (face/arm/leg)
Ataxic hemiparesis
What is ataxic hemiparesis?
Hemiparesis and ipsilateral cerebellar ataxia
What causes ataxic hemiparesis in LACS?
Small infarcts in basal ganglia or pons
Intrinsic disease of single basal perforating artery
What % of strokes are POCS?
25%
What areas can POCS affect?
Brainstem
Cerebellum
Occipital lobe
Presentation of POCS
Variable, frequently complex Bilateral motor / sensory deficit Disordered conjugate eye movement Isolated homonymous hemianopia Ipsilateral CN palsy with contralateral sensory / motor deficit Coma Disordered breathing Tinnitus Vertigo Horner's
Which type of stroke has the highest mortality?
TACS
Which type of stroke has the highest recurrence rate at 1 year?
POCS
Investigations for stroke
FBC Lipids ECG CT MRI Carotid doppler ECHO
What should patients with AF post stroke be started on?
Anticoagulation with warfarin or another anticoagulant
What to do with haemorrhagic stroke if on warfarin?
Stop warfarin
Give IV Vit K
Prothrombin complex concentrate
Management of a patient with AF who has a stroke/TIA
Warfarin or a direct thrombin or factor Xa inhibitor
What should be started in a patient with a TIA in the absence of AF?
Clopidogrel
When should a patient with acute stroke (not haemorrhagic) have their anticoagulation started? Why?
2 weeks after the event
Due to the risk of hae morrhagic transformation
What anti-platelet medication should a patient be put on following a stroke?
Aspirin 300mg daily for 2 weeks THEN
Clopidogrel 75mg daily lifelong
What does the ABCD2 score look at?
Predicts stroke risk following TIA