lecture 18 - stroke Flashcards
What are the general risk factors for all types pf stroke?
hypertension, hyperlipidaemia, increasing age, smoking, alcohol abuse, physical inactivity, obesity, stress, diabetes
What is a transient ischaemic attack?
An acute attack of temporary focal neurological dysfunction caused by a vascular event without infarction.
What are the key types of stroke?
Ischaemic (80%), haemorrhagic (20%)
What are the 2 key sub-types of haemorrhagic stroke?
Hypertensive intracerebral bleeding, subarachnoid haemorrhage
How does a haemorrhagic stroke cause neuronal injury?
There is a rapid increase in pressure resultiung in swelling and raised ICP and a reduction in perfusion. Blood triggers vasospasm which causes further ischaemia.
What are the focal features of a haemorrhagic stroke?
These are specific to the damaged area, and may include weakness, sensory loss, visual field defects, etc. Will often be unilateral
What are non-localised features of a haemorrhagic stroke?
Signs of raised ICP: headache, nausea, vomiting, confusion, coma
What are the 2 key subtypes of ischaemic strokes?
Global cerebral ischaemia, focal ischaemia
What are the 2 types of focal ischemic stroke?
Emobilic, Thrombotic
What is the pathophysiology of hypertensive cerebrovascular disease and stroke?
hypertension causes hyaline arteriosclerosis in deep penetrating arteries of the basal ganglia, hemispheric white matter and brain stem. It also causes atherosclerosis in cerebral arteries. When large vessels rupture it causes intraparenchymal haemorrhage and when small penetrating vessels rupture it results in slit haemorrhages/lacunar infarts
Where in the brain does hypertensive intracerebral haemorrhage usually occur?
Centrally - basal ganglia, thalamus, pons
What is the most common cause of a subarachnoid haemorrhage?
Rupture of a berry aneurysm in the Circle OF Willis
What is the penumbra in a stroke?
An area lying around an ischaemic region of tissue that has potentially reversible damage if circulation is restored
What type of infarct is associated with an emoblic stroke?
Haemorrhagic
What are common causes of an embolic stroke?
emboli formed from MI, AF, valvular heart disease, thrombosis of atherosclerotic plaques, DVT passing through PFO
What is the gross appearance of an embolic stroke?
Area of haemorrhagic ischaemia with multiple petechial haemorrhages and an area of redness
Why does an embolic stroke cause a haemorrhagic infarct?
The ischaemic area is reperfused through collateral circulation or fibrinolyisis occurs and blood leaks through necrotic vessels.
What type of infarct is associated with a thrombotic stroke?
Non-haemorrhagic
What causes a thrombotic stroke?
Atherosclerotic plaques in medium sized arteries in the brain rupture caused thrombosis.
What is the gross appearance of a thrombotic stroke?
Pale, bland infarct, followed 48 hours later by blurring of the grey-white matter interface and eventually liquefactive necrosis
What are the effects of anterior cerebral artery occlusion?
Contralateral hemiplegia and sensory loss, greatest in the lower limb
What are the effects of middle cerebral artery occlusion?
contralateral hemplegia, greeates in the upper limb and face. Contralateral sensory loss, greatest in the upper limb. Severe aphasia (if stroke is in the dominant hemisphere)
What are the effects of posterior cerebral artery occlusion?
Contralateral homonymous hemianopia (loss of vision on half of each eye that is on the opposite side to the lesion)
What is lateral medullary syndrome?
Occlusion of the posterior inferior cerebellar artery (PICA), resulting in cerebellar and brain stem signs.
What is the relationship between INR and stroke?
Low INR increases risk of ischaemic stroke, while INR increases risk of haemorrhagic stroke
What investigations are indicated in a patient with TIAs?
Dopplers of carotid arteries to check for plaque, lipid profile, blood pressure, ECG
What pharmacological therapies are used in patients with TIAs to prevent stroke?
Antiplatelet therapy (clopidogrel, low dose aspirin), anticoagulants (warfarin, dabigatran), antihypertensives, antidyslipidaemics, antiarrhythmics
What are some of the general signs and symptoms of stroke?
Motor weakness, sensory deficits, vision/hearing impairment, swallowing dysfunction, dysphasia, ataxia
What are the 3 principles of AF management?
- Rate control
- Thromboembolism prevention
- Rhythm control
What is the purpose of the CHADS-VASc score?
Approximates the risk of ischaemic strokes in patients with atrial fibrillation. Out of 9, with anticoagulation indicated for a score >2
What diagnostic tests can be used to diagnose iscahemic stroke?
CT (usually only changes after 48 hours), perfusion scan
What are the non-pharmacological interventions used in stroke treatment?
Carotid stenting, endarterectomy (plaque removal from cartoids)
What drug is used to acutely treat ischaemic stroke?
IV alteplase
What is the mechanism of action of alteplase in stroke management?
Alteplase is a tissue plasminogen activator that breaks down blood clots by catalysing the conversion of plasminogen to plasmin which cleaves fibrin.
What are the general principles of acute treatment in ischaemic stroke?
score stroke severity, establish last known well time, blood tests, exclude hypoglycaemia, neurological examination, head CT to exclude haemorrhage, IV alteplase
What are the principles of acute management of a haemorrhagic stroke?
score stroke severity, establish last known well time, general medical care, blood tests, exclude hypoglycaemia, neurological examination, CT/MRI, surgical evacuation/aneurysm repair, antihypertensives, anticonvulsants
What drug can be used to reduce intracranial pressure and oedema following a haemorrhagic stroke?
Mannitol (an osmotic diuretic)
What action is taken if a patient is on anticoagulants and has a haemorrhagic stroke?
Emergency anticoagulant reversal
How do you acutely reverse heparin?
Protamine sulphate
How do you acutely reverse warfarin?
Fresh frozen plasma, prothromin concentrates, vitamin K (but takes hours to work)
What is non-fluent aphasia?
Damage to Broca’s area, resulting in the inability to produce language
What is fluent aphasia?
Damage to Wernicke’s area resulting in the inability to interpret language
