Stroke Flashcards
What is a stroke?
a syndrome of rapid onset neurological deficit caused by focal cerebral, spinal or retinal infarction or haemorrhage
In which ethnicities is stroke more common? (2)
1) Asian
2) black African
What are the two major causes of stroke?
Ischaemic stroke (87%)
Haemorrhagic stroke (13%)
What is a ischaemic stroke?
Ischaemic strokes occur when the blood supply to an area of brain tissue is reduced, resulting in tissue hypoperfusion.
Give 6 ischaemic causes of stroke:
1) thrombosis
2) small vessel disease
3) cardio-embolic causes
4) hypoperfusion
5) carotid and vertebral artery dissection
6) venous stroke
How can an embolism cause an ischaemic stroke?
an embolus originating somewhere else in the body (e.g. the heart) causes obstruction of a cerebral vessel, resulting in hypoperfusion to the area of the brain the vessel supplies.
how can a thrombosis cause a stroke?
a blood clot forms locally within a cerebral vessel (e.g. due to atherosclerotic plaque rupture).
How does systemic hypoperfusion cause a stroke?
blood supply to the entire brain is reduced secondary to systemic hypotension (e.g. cardiac arrest).
how does cerebral venous sinus thrombosis cause a stroke?
blood clots form in the veins that drain the brain, resulting in venous congestion and tissue hypoxia.
Describe how small vessel disease can cause ischaemic stroke:
small penetrating arterial branches supply the deep brain parenchyma and can be affected by occlusive vasculopathy leading to small infarcts and gradual accumulation of diffuse ischaemic change in the deep white matter
What is lipohyalinosis?
A loss of normal arterial architecture and foam macrophage deposition in the arterial wall
Give 5 cardio-embolic causes of ischaemic strokes:
1) atrial fibrillation and arrhythmias
2) valve disease
3) infective vegetations
4) rheumatic and calcific changes
5) mural thrombosis
Describe how hypoperfusion can lead to ischaemic strokes:
severe hypotension can lead to infarction in watershed areas between vascular territories
What is an artery dissection?
where blood penetrates the subintimal vessel wall, forming a false lumen
Give two causes of carotid and vertebral artery dissection:
1) neck trauma e.g. whiplash
2) hyperextension e.g. osteopathic manipulation or hair washing in a salon
Describe how carotid and vertebral artery dissection can lead to ischaemic strokes:
blood penetrating the subintimal wall stimulates the release of thromboplastin release, leading to thrombosis and embolisation
What % of strokes are venous?
1%
What is the prognosis of the stroke?
Mortality – 20% in first 2 months, then roughly 10%/year
<40% of stroke (not TIA) patients make a full recovery
Drowsyness at presentation has a poor prognosis
Describe how a venous stroke comes about:
thrombosis can occur within intracranial venous sinuses such as the superior sagittal sinus
Which has a worse prognosis, ischaemic or haemorrhagic?
Haemorrhagic
what is a haemorrhagic stroke?
occurs secondary to rupture of a blood vessel or abnormal vascular structure within the brain
What is the difference between a intracerebral haemorrhage and subarachnoid haemorrhage?
Intracerebral haemorrhage involves bleeding within the brain secondary to a ruptured blood vessel. Intracerebral haemorrhages can be intraparenchymal (within the brain tissue) and/or intraventricular (within the ventricles) whereas subarachnoid haemorrhage is a type of stroke caused by bleeding outside of the brain tissue.
What are 6 causes of haemorrhagic strokes?
- Hypertension
- cerebral amyloid angiopathy
- Aneurysms
- Coagulopathies
- Anticoagulants and thrombolysis treatment
- arteriovenous malformation
how may hypertension lead to a stroke?
Damages arterial walls, and thus leads to increased risk of thrombus formation, and haemorrhage