Stroke Flashcards
Stroke
Syndrome of rapid onset neurological defect caused by a reduction in the blood supply due to cerebral infarction or haemorrhage
Ischaemic stroke
Occlusion of an intracranial or neck vessel leading to ischaemia and subsequent infarction of brain tissue
Haemorrhagic stroke
Bleeding into or around the brain classically due to a burst aneurism
Which stroke type is more common
Ischaemic
4 mechanisms of ischaemic stroke
Thrombosis
Embolism
Systemic hypoperfusion - Watershed stroke
Venous sinus thrombosis
Do thrombi or emboli more commonly cause stroke
Thrombi
How does atherosclerosis form
Endothelial damage -> lipoproteins and monocytes adhere to vessel wall + enter intima -> monocytes differentiate to macrophages -> macrophages engulf lipoproteins becoming foam cells -> cholesterol and foam cells accumulate forming fatty streak -> foam cells release pro inflammatory cytokines -> smooth muscle proliferation + CT deposition -> fibrous cover and necrotic cord form
Foam cell
Macrophages that have engulfed cholesterol
What is the first step in atheroma formation
Endothelial damage
How do foam cells cause smooth muscle cell proliferation
Release pro inflammatory cytokines
Why can atheroma form a necrotic core
Lack of capillaries
How can atheroma cause thrombosis
Plaque ruptures removing the endothelium and exposing fibrous cap, which causes clotting
2 types of Haemorrhagic stroke
Intracerebral
Subarachnoid
Most important stroke risk factor
Hypertension
Main symptom of subarachnoid haemorrhage
Thunderclap headache
What investigation can identify >95% Haemorrhagic stroke
CT Scan
What investigation is ordered if Haemorrhagic stroke suspected but CT clear
Lumbar puncture
What causes a watershed stroke
Systemic hypoperfusion
Stroke symptoms
Face asymmetry
Slurred speech
Difficulty raising both arms
Headache
Confusion
Aphasia
Dizziness
Loss of balance
Visual disturbance
4 categories in bamford stroke classification
Total anterior circulation stroke
Partial anterior circulation stroke
Lacunae syndrome
Posterior circulation syndrome
What is lacunae syndrome
Small strokes in deep area of brain
Stroke risk factors
Age
Hypertension
Diabetes
Atrial fibrillation
Hyperlipidaemia
Smoking
Obstructive sleep apnea
How are strokes prevented
Treat risk factors
What can cause cerebral necrosis
Mechanical compression
Cerebral oedema
Excitotoxicity
How does cerebral oedema form
Decr ATP -> Na pump function limited -> incr Na conc in neurones -> water enters
How can cerebral oedema lead to death
Skull limits expansion so cerebral veins compressed and intracerebral pressure increased
Coning
Cerebella herniation of tonsils through foramen magnum
What causes coning
Incr intracranial pressure
How does brain coning cause death
Compression of lower brainstem and upper cervical spinal cord
What triggers excitotoxicity
Ischaemia
What is excitotoxicity
Incr glutamate in synapses -> NMDA receptors activated -> Ca2+ influx -> incr intracellular Ca -> cell death
How does incr Ca2+ conc in cell cause apoptosis and necrotic cell death
Free radical release
Protease activation
Nitric oxide formation
Penumbra
Potentially salvageable brain tissue
What is the target for acute stroke therapy
Penumbra - may be able to save cells
What is the dead area of brain tissue after a stroke called
Ischaemic core
Why is non contrast CT used for in suspected strokes
Rule out/in haemorrhage
What imaging may be used in stroke diagnosis
CT
MRI
Carotid ultrasound
Why may carotid ultrasound be used in stroke investigation
Check for atherosclerosis
Acute stroke therapies
Thrombolysis
Mechanical thrombectomy
Thrombolysis
Intravenous fibrinolytic therapy using altepase to break down clot
When can Thrombolysis be used
Within 4.5 hrs of stroke onset
Haemorrhage clearly excluded by imaging
Thrombolysis contraindications
intracranial haemorrhage history
Stroke in last 3 months
Major surgery or sig trauma in last 3 months
Mechanical thrombectomy
Endovascular removal of a thrombus from a large artery
When can mechanical thrombectomy be used
Confirmed ischaemic stroke in large artery
TIA
Sudden loss of function with complete recovery
Anterior circulation TIA signs and symptoms
Unilateral weakness
Aphasia
Amaurosis fugax
Hemisensory loss
Hemianopic visual loss
Posterior circulation TIA signs and symptoms
Diplopia
Vertigo
Vomiting
Choking
Dysarthria
Ataxia
Hemisensory loss
Bilateral visual loss
Acute TIA management
Aspirin
TIA clinic with 24hrs
