Stroke Flashcards
What is it a stroke?
A neurological deficit ( loss of function) of sudden onset and lasting more than 24 hours. It is of vascular origin.
Describe the circulation in the head
Carotid aa. supplies anterior circulation
Vertebro-basilar supplies posterior circulation
How can haemorrhage cause a stroke?
Blood builds up in the white matter and compresses brain tissue
If a stroke is small but affects deep white fibres what will the result be?
Can cause major deficit as the fibres are packed close together
What are the causes of a stroke?
Occlusion due to thrombus or clot Disease of vessel wall Disturbance of normal blood due to infection (increases WBC) Rupture of vessel wall - haemorrhage Carotid stenosis Cardioembolic
What can a carotid stenosis cause a stoke?
Bifircation of a vessel is a common place for atheroma to develop due to turbulent blood flow
If it partially occludes vessel, perfusion can still occur and leads to formation of a thrombus which can detach and occlude another vessel (embolism)
How does a cardioembolic stroke occur?
AF dislodges clots in LA and the thrombus travels to brain and occludes vessel
What are the symptoms of a stroke?
Loss of: Power Sensation Speech (dysphasia) Vision Coordination
What are the two types of strokes?
haemorrhagic or ischaemic
What investigations should be carried out for stroke?
Blood: FBC, lipids ECG CT - identify haemorrhage (shows blood) MRI - shows area of infarct Carotid doppler Echo
What are the treatment options?
Thrombolysis
Hemicraniotomy
Carotid endarectomy for carotid stenosis
What is the use of hemicraniotomy
For <60yrs who suffer an acute MCA territory ischaemic stroke complicated by massive cerebral oedema
Surgical decompression by hemi offered within 48hr
How does a stroke occur?
Damage to part of the brain due to blockage of vessels by thrombus or embolus, or haemorrhage due rupture of vessels
Tissue then does not receive adequate O2 nutrition -> necrosis
What is a transient ischaemic attack?
A neurological deficit of sudden onset and vascular origin that last less than 24hours
What is aphasia/dysphasia?
Language disorder marked by deficiency in the generation of speech
What can be found in the history of a stroke?
Time of onset Witnesses Headache Vomiting Neck stiffness Photophobia (suggest haemorrhage) Loss of consciousness Fit Incontinence
What are the findings on clinical examination?
Motor (clumsy or weak limbs) Sensory (loss of feeling) Speech (dysarthria/dysphasia) Neglect/visuospatial problems Vision: loss in one eye, or hemianopia Gaze palsy
Ataxia
Vertigo
Incoordination
Nystagmus
What is Nystagmus?
A condition in which the eyes make repetitive and uncontrolled movements - sign of stroke
Dysarthia vs aphasia
Dysarthia - weakened muchness around mouth
Dysphasia - problem finding words.
What are three circulations in the brain?
Anterior circulation
Posterior circulation
Circle of Willis
What is the frontal lobe responsible for?
Judgement, foresight and voluntary movement
What is the parietal lobe responsible for?
Comprehension of language
What is the occipital lobe responsible for?
Vision
What is the function of the brain stem?
Swallowing, breathing, heartbeat
What does the carotid artery supply?
Most of the hemispheres and critical deep white matter
What does the vertebra basilar system supply?
the brain stem, cerebellum and occipital lobes
What is the function of the cerebellum?
Coordination
What is the function of the motor cortex?
Movement
What is the function of the Broca’s area?
Speech
What is the function of the temporal lobe?
Intellectual and emotional functions
What is a lacunar stroke?
An ischemic stroke when the small arteries deep within the brain becomes blocked
How can a carotid dissection cause a stroke?
Separation of the layers on the vessel wall, allowing blood to enter and compress truth artery channels resulting in a total artery occlusion and form a thrombus
What can you tell from the symptoms about the stroke?
Which side of brain is affected If in the brainstem If cortex is involved If lesion is in the deep white matter What blood vessel in involved
Where has the occlusion occurred in a cortical stroke?
Cortex
Why is it important to localise the stroke?
Confirms stroke diagnosis
All better selection of imaging
Gives an indication of cause
Gives indication of prognosis
How can vision suggests the location of lesion?
Type of visual eye defect gives indication
What are the 4 subtypes of strokes?
Total anterior circulation stroke
Partial anterior circulation stroke
Lacunar stroke
Posterior circulation stroke
What are the three visual field defects?
Unilateral field loss Bitemporal hemianopia (tunnel vision) Homonymous haemianopia (can't see on one side)
Describe effect of a total anterior circulation stroke
Weakness, sensory deficit
Homonymous hemianopia
Higher cerebral dysfunction (dysphasia, dyspraxia)
Usually due to occlusion of proximal middle cerebral artery or internal carotid artery
Describe the effect of a partial anterior circulation stroke
2/3 of TACS criteria or restricted motor/sensory deficit
Occlusion of branches of middle cerebral artery
What are the different types of lacunar strokes?
Pure motor
Pure sensory
Sensorimotor
Ataxic hemiparesis - in basal ganglia or pons
Often silent - undiagnosed
What is the presentation of a posterior circulation stroke?
Affect brainstem, cerebellar or occipital lobes, may include: Bilateral sensory/motor deficit Homonymous hemianopia Cranial nerve palsy Coma Disordered breathing Tinnitus Vertigo Horner's
What is important to remember about the symptoms of a stroke?
Symptoms come on rapidly
Symptoms depend on which part of the brain is affected
What are modifiable risk factors of stroke?
Atrial fibrillation
High blood pressure
What are non-modifiable risk factors for stroke?
Age
Race
FH
CT vs MRI
CT: quick and shows blood
MRI: 30 mins and shows ischaemia better
What is the purpose of carrying out a carotid doppler?
Looks at vessels
Why can an echo be useful?
Looking for clots in the heart
Why can an ECG be useful?
Detecting irregularities in heart rhythm — such as atrial fibrillation — that can lead to the forming of blood clots that can later get flow to the brain
What is the importance of stroke units?
Better prognosis of patient: Mobilise ASAP Concentrate of simple tasks i.e. swallowing Early therapy Expertise
What is the aim of thrombolysis?
To restore perfusion before cell death occurs
What are the risks of haemorrhage occurring after thrombolysis?
Depends on: Infarct size Vessel occlusion Diabetes BP Age Stroke severity Tissue changes If already on anti platelets
What is an invasive method to enable reperfusion?
Clot retrieval
What are the contradictions to thrombolysis?
Age - licenced for <80yrs
What is a hemicraniectomy?
The surgical removal of half of the cranium to enable brain surgery
What fraction of people who have a TIA will go on to have an acute stroke?
1/3
How can people who have TIAs reduce risk of recurrent stroke?
Early treatment for prevention
What drugs are given for secondary prevention of a stroke?
Aspirin 75mg
or
Clopidogrel 75mg
Statin
BP drugs, even if BP in normal range
