Pathology of cerebrovascular disease Flashcards
what are the different parts of the brain
frontal lobe parietal lobe occipital lobe temporal lobe cerebellum brain stem spinal cord
what parts of the cerebrum does the anterior cerebral artery supply
medial and superior (excluding occipital
what parts of the cerebrum does the middle cerebral artery supply
lateral
what parts of the cerebrum does the posterior cerebral artery supply
inferior and occipital
what do the arteries in the cerebrum join to form
circle of willis
what are the large venous sinuses within the dura
superior sagittal inferior sagittal transverse sinus straight sinus sigmoid sinus jugular vein
what is the WHO definition of stroke
Focal neurological deficit (loss of function affecting a specific region of the central nervous system) due to disruption of blood supply
what can cause stroke
interruption of supply of oxygen and nutrients, causing damage to brain tissue
can be changes in:
- vessel wall
- blood flow (including pressure)
- blood constituents
give examples of changes to the vessel walls that can cause stroke
abnormality of wall eg atheroma or vasculitis,
outside pressure eg strangulation, spinal cord compression, compression of veins
give examples of changes to the blood flow and pressure that can cause stroke
decreased blood flow, increased blood pressure bursting vessels
give examples of changes to the blood constituents that can cause stroke
thrombosis of arteries (rarely veins)
bleeding due to anticoagulation, reduced platelets and clotting factors
what are the three main causes of LOCALISED interrupted blood supply
- Atheroma + thrombosis of artery causing ischaemia
- Thromboembolism (for example, from left atrium) causing ischaemia
- Ruptured aneurysm of a cerebral vessel causing haemorrhage
where can atheroma + thrombosis usually occur
bifurcation of the internal carotid arteries
causes internal carotid artery thrombosis
what area does internal carotid artery thrombosis usually affect
ischaemia usually in the MCA territory
but can be elsewhere
what is ischaemia
a relative or absolute lack of blood supply in a tissue or organ
what do transient (<24hr) ischaemic symptoms indicate
TIA
- reversible ischaemia
= tissue still viable
what do longstanding (>24hr) ischaemic symptoms indicate
Infarct
- irreversibel ischaemia
= localised brain death
summarise the pathogenesis of stroke
hypoxia/anoxia
= ischaemia
prolonged ischaemia
= infarction
= permanent damage - neurons do not regenerate
what is a localised area of brain known as
regional cerebral infarct
classically wedge shaped - reflects arterial perfusion territory
soft then becomes cystic then loss of brain tissue
what is gliosis and what causes it
CNS equivalent to fibrosis
macrophages in the repair process
why is the location of ischaemia more important than size
Small affected area of one part of brain may not cause too much impairment
Similar size of affected area in another part of brain may be devastating
briefly summarise the pathophysiology of thromboembolism
thrombosis
- embolism breaks off
- embolises to vessel
- blocks blood supply
- causes ischaemic stroke
give an example of a common site of thromboembolism
left atrial appendage thrombosis
- LA connected directly to outflow of left side of hear
- thrombosis breaks off and embolises to the aorta and possibly carotid arteries
- embolus blocks right middle cerebral artery
what causes an aneurysm to form
weakening of thin cerebral artery walls and hypertension
