Stroke & TIA Flashcards
What is stroke?
Sudden onset of neurological deficit caused by focal cerebral, spinal or retinal infarction or haemorrhage.
Who does stroke affect?
3rd most common cause of death + leading cause of adult disability
Higher in Asians and black African
Stroke risk increases with age
What are the 2 broad categories of strokes?
Ischaemic stroke / infarction (85%) => thrombotic => large-artery stenosis => small-vessel diseases => cardio-emboli => hypoperfusion
Haemorrhagic (10%)
=> Intracerebral haemorrhage
=> Subarachnoid haemorrhage
Other (5%)
=> arterial dissection
=> venous sinus thrombosis
=> vasculitis
What is the pathology underlying ischaemic stroke?
Arterial disease & artherosclerosis => main pathological processes causing stroke
What are the causes of stroke?
- Small vessel occlusion or thrombosis
=> thrombosis at the site of ruptured mural plaque leads to embolism or occlusion. - Cardiac emboli
=> atrial fibrillation (x5 higher risk)
=> infective endocarditis ; rheumatic & degenerative calcific valve changes
=> congenital valve disorders
=> left ventricular mural thrombus
=> severe hypoperfusion due to MI = infarction in watershed areas especially if there is severe stenosis of proximal carotid vessel
- Atherothromboembolism from carotid
- CNS bleed due to hypertension, trauma, aneurysm rupture, anticoagulation, thrombolysis
What is the most common cause of stroke?
Atrial fibrillation => thrombosis in a dilated left atrium => emboli = the most common cause of stroke
What are other causes of stroke?
Other causes:
Consider in younger patients:
=> sudden BP drop >40mmHg
=> carotid artery dissection (spontaneous or from neck trauma)
=> Vasculitis
=> Subarachnoid haemorrhage
=> venous sinus thrombus
=> Anti-phospholipid syndrome
=> Thrombophilia
What are the modifiable risk factors for stroke?
Smoking
Diabetes
Hypertension
Dyslipidaemia
Obesity
Alcohol
What are the non-modifiable risk factors of stroke?
Age
Men under 65 and Women over 65 years more likely to have stroke (due to loss of E2)
South asian and Afro-carribean
Heart disease (valvular, ischaemic, AF)
Peripheral vascular disease
Carotid bruit
Pregnancy
Combined oral contraceptive pill
Increased clotting i.e. high plasma fibrinogen, low antithrombin III
Polycythaemia vera
Family history
Which main arteries make up the circle of willis to supply the anterior cerebral circulation and the posterior cerebral circulation?
Anterior cerebral circulation => two internal carotid arteries
Posterior cerebral circulation => vertebrobasilar arteries
Cerebral infarction
Vessel occlusion => brain ischaemia => neuronal failure => infarction + cell death
The ‘CORE’ is the centre of the stroke - the ischaemic area where hypoxia leads to neuronal damage.
=> Fall in ATM results in release of glutamate => opens calcium channel, releasing free radicals => inflammation, necrosis and apoptotic cell death
The ischemic ‘PENUMBRA’ surrounds the ischemic region which is not functioning but is structurally intact.
=> timely revascularisation can help regain function in this area
Where does anterior circulation infarcts take place?
What are the associated symptoms?
Infarcts in territory of: => internal carotid => middle cerebral (MCA) => anterior cerebral (ACA) => ophthalmic arteries
Complete MCA infarct = devastating stroke
=> contralateral hemiplegia
=> facial weakness
=> contralateral sensory loss
=> aphagia / dysphagia
=> hemianopia
=> neglect syndrome / visua-spatial defect
=> initially flaccid limbs (floppy limbs like dead weight) then becomes spastic
Internal carotid strokes = similar picture as MCA strokes
What is lacunar infarction?
Lacunes = small infarcts
Hypertension is the major risk factor
Lacunar infarcts often symptomless.
What is lacunar infarction?
What area is affect?
What are the symptoms?
Lacunes = small infarcts in basal ganglia, internal capsule, thalamus and pons
Hypertension is the major risk factor
Lacunar infarcts often symptomless or: => Ataxia hemiparesis => Pure motor => Pure sensory => Sensorimotor => Dysarthia/clumsy hand
*cognition/consciousness intact
What are the symptoms of a brainstem infarct?
Brainstem infarct is posterior circulation stroke.
Quadriplesia
Disturbance of gaze & vision
Locked in syndrome (aware but unable to respond)
*symptoms depended on assoc. with cranial nuclei.
Purpose of investigation in stroke is to confirm clinical diagnosis and differentiate between ischaemic or haemorrhage stroke.
What is the immediate urgent investigation of stroke presenting <1h?
What further investigations are carried out within 24h?
- CT brain => demonstrate haemorrhage immediately but cerebral infarct not detected in acute phases
=> Repeat CT at 24h for all patients
- insert cannulas before scan + take bloods
2. Blood count and glucose (+ clotting study if on anti-coagulation)
Further investigation:
=> Routine blood test (FBC, ESR, glucose, clotting studies, lipids)
=> ECG for AF
=> Carotid doppler studies in patients with anterior circulation stroke fit for surgery
What additional tests may be carried out to find out underlying cause of the stroke?
- Chest Xray => cardiac source of emboli
2. Carotid doppler ultrasound ± CT/MRI angiography => carotid artery stenosis
What are the differential diagnosis for stroke?
Head injury
Hypo/hyperglycaemia
Subdural haemorrhage
Intracranial tumours
Hemiplegic migraine
Post-ictal (Todd’s palsy)
CNS lymphoma
Wernicke’s encephalopathy
Hepatic encephalopathy
Encephalitis
Toxoplasmosis
Cerebral abscess
Mycotic aneurysm