8 Stroke Flashcards
Define stroke
The sudden loss of blood circulation to an area of the brain, resulting in a corresponding loss of neurological function
(can be focal deficit - arm/leg, can lead to coma and/or death)
Describe stroke,
it’s incidence etc.
Stroke like presentations can be relatively acute onset, with neurological symptoms (weakness, numbness)
- Increasing incidence with age, peak incidence 80-84 years of age
- Common - more than 100,000 strokes in the UK each year (4th leading cause of death in the UK)
> leading cause of disability in the UK (2/3 of survivors leave with disability)
- More common in men than women
- Stroke can be survived
- Subarachnoid haemorrhage can be considered as a type of stroke
Give the 2 types of strokes
- Ischaemic stroke (85%): decreased arterial blood flow or venous outflow from a tissue (lack of O2)
> if cells die from this = infarction - Haemorrhagic: from a burst blood vessel
Give the pathophysiology of stroke (Ischaemic stroke)
Ischaemic stroke is the most common cause of stroke (85%). This is caused by:
- Platelet thrombosis that develops over a disrupted atherosclerotic plaque; commonly involves arteries:
> Middle cerebral artery
> Internal carotid artery near bifurcation (where plaque often is)
> And the basilar artery - OR embolism of clot from another source e.g. heart (cardioembolic stroke) - from AF
Describe the gross and microscopic findings in Stroke
- Stoke develops at the periphery of the cortex (happens furthest from the nutrient artery)
- Reperfusion often does not occur, so the area of infarct remain pale - pale infact (blocked part is end artery)
- Swelling of the brain occurs (a hallmark of cellular damage):
> Loss of demarcation between grey + white matter
> Breakdown of myelin - Gliosis = reaction to injury
> Astrocytes proliferate at the margins of the infarct
> Microglial cells (macrophages) remove lipid debris - Cystic area (spaces) develops 10 days - 3 weeks after due to liquefactive necrosis
> Brain - does this (soft)
Cystic change - old infarct in the territory of R middle cerebral artery
Give some risk factors of stroke
- Most thromboembolic strokes are associated with atherosclerosis, and therefore have the same risk factors as other atherosclerotic conditions (e.g. Angina, myocardial infarction - plaque rupture)
> Smoking, obesity, hypolipidemia, hypertension, etc. - Hypercoagulable states are also a risk factor + any other part of Virchow’s Triad (stasis, vessel wall injury, and hypercoagulation) - anything that increases clot formation
- Risk factors for embolic strokes relate to the heart primarily, e.g. atrial or ventricular thrombus (chances increased by AF - shaking of blood), vegetations (infection) and atrial myxomas (tumour, that is affecting the flow of blood in the heart; vessel turbulence = cause blood clotting)
> Blood clot in the calf (stasis of heart) - forms a deep vein thrombosis = PE
Give details about emboli that may be involved in strokes
Most often originate from the left-hand side of heart:
- Mural thrombi in the left ventricle after a MI
- Aortic and/or mitral valve vegetation + L atrium in AF
Shower emboli refer to emboli blocking numerous small vessels.
Normal people (without patent foramen ovale) - clot from calves travel to lungs
- People with patent foramen ovale - clot can slip from R to L side of the heart - then to the brain
> results in STROKE (hear for patent foramen ovale)
List some modifiable risk factors for stroke
- High BP
- High blood cholesterol
- Diabetes (type 2)
- Being overweight
- Smoking
- Alcohol consumption
- Drug use
- No physical exercise
List some non-modifiable risk factors for stroke
- Age
- Ethnicity
- Gender
- Family history of heart disease
- History of heart disease
- PFO (patent foramen ovale) - hole in heart
- Diabetes (type 1)
- Atrial Fibrillation
Describe the role + significance in the development of stroke
AF contributes to under 20% of all strokes in the UK.
AF makes you 5x more likely to have a stroke
- Px who have known AF -
take anticoagulants to prevent clots from forming (brain)
- If px had it before + it’s gone, it tends to return sometimes
Atrial fibrillation is notable, as the progenitor of embolic strokes due to thrombus formation in the left atrium from the stasis of blood
- AF is irregular, (without a fixed, repetitive rhythm - some normal parts of PCG, but no defined P waves - wavering baseline is the fibrillation of the atria
Describe a lacunar stroke
Lacunar strokes are small ischaemic stroke to the deep white matter of the brain
- Cystic areas of microinfarction < 1cm in diameter
Caused by:
- hyaline arteriosclerosis - thickening of the small vessels (high pressure)
- Secondary to either Hypertension (most common)
- Or diabetes mellitus (worse if occurring with Hypertension
Describe haemorrhagic stroke
Anything that increases chances of bleeding INCREASES the risk of haemorrhagic stroke
They are most often caused by stress placed on vessels by hypertension
- Branches of lenticulostriate vessels develop Charcot-Bouchard microaneurysms
- Rupture of the aneurysm (widening of blood vessels - balloon - intrinsic weakness in wall + increase in pressure) produces intracerebral haemorrhage [hematoma]
Intracerebral hematoma pushes brain tissue aside
List some common sites of haemorrhages
- Basal ganglia (35-50% occur in the putamen)
- Thalamus (10% of cases)
- Pons and cerebral hemispheres (10% of cases)
Describe strokes under the surface of the brain
- These small arteries are sensitive to changes in pressure + can pop
Describe the signs and symptoms of stroke
[FAST]
F ace - ask the person to smile - drooping on one side of the face
A rms - ask the person to lift both arms, does one arm drift downwards
S peech - ask the person to repeat a simple sentence - is speech slurred
T ime - time to call 999 (the faster, the better)
Describe some symptoms of stroke
Movement and sensation
- Contralateral (opposite side of the lesion to side of the body), hemiparesis/hemiplegia and sensory loss in limbs, trunk, or face
Speech
- expressive aphasia (if Broca’s area [motor speech problem] is involved in the dominant hemisphere); or receptive aphasia if Wernicke’s area is affected
Vision
- Visual field defects [25-50% of visual field is absent]
Personality
- frontal lobes affected (executive function is affected - decision making)
> Px can have psychiatric changes
Describe how a diagnosis of stroke would be made
Patient with acute onset of a neurological syndrome with persisting symptoms + signs (i.e. suspected stroke)
- needs urgent diagnostic assessment to differentiate between acute stroke and other causes needing their own specific treatment
Describe some investigations that can be done when testing for stroke
- CT scan without contrast - best for diagnosis, will distinguish haemorrhage (no clot-busting therapy - bleed to death) from non-haemorrhagic stroke
- MRI (clot/no clot - if you can’t see on CT) is also utilised in equivocal (ambiguous cases) - useful for identification of posterior fossa defects, but only after CT
> more sensitive to infarcts, but more expensive and longer (not 1st line)
Describe different prevention strategies for stroke
Stroke treatment acutely
- Depends on what type of stroke and elapsed time to arrival at the hospital
Thromboembolic stroke - thrombolytic therapy (CLOT BUSTING)
- utilising depends on the time between initial symptoms and presentation to hospital - (faster the better) - WITHIN 4.5 HOURS
Intra-arterial clot extraction - can also be done in patients whose thrombolysis is contraindicated in
Thrombolytics are contraindicated in haemorrhagic strokes (cause to bleed)
- In some circumstances, intracerebral haemorrhages can be surgically evacuated
Define and describe TIAs (Transient ischaemic attack) - a mini-stroke
Definition: a transient episode of neurological dysfunction caused by focal brain/spinal cord or retinal ischaemia without infarction,
(symptoms of stroke < 24hrs) = TIA
Most atherosclerotic strokes are preceded by TIAs
Describe treatment for a TIA
Anti-platelet therapy as soon as intracranial haemorrhage is ruled out
- Aspirin, clopidogrel
- Possible endarterectomy
- Treat risk factors and offer lifestyle advice
- The intention here is to prevent future strokes
Describe treatment for chronic stroke
Chronic treatment in stroke
- Antiplatelet treatment (aspirin, clopidogrel) - lifelong
- Warfarin (or Factor Xa inhibitor like Apixaban) for embolic type strokes caused by AF
- Treat risk factors for stroke
> e.g. Hypertension, diabetes, carotid stenosis
> Education for e.g. smoking
Describe some common Stroke mimics
H: Hypoglycaemia (and hyperglycaemia)
E: Epilepsy
M: Multiple sclerosis (and hemiplegic migraine)
I: Intracranial tumours (or infections, such as
meningitis, encephalitis, and abscesses)
