Pathology of Cerebrovascular Disease: Ischaemia (Atheroma and thrombosis, thromoboembolism, Raptured aneurysm) and hypoxia generalised problems

Question 1

what three arteries supply blood to the cerebral cortex?

Answer 1

anterior, middle and posterior cerebral arteries

Question 2

do veins accompany arteries in the brain?

Answer 2

Veins do not accompany arteries

Large venous sinuses within dura

Question 3

which sinuses are responsible for venous drainage of the brain?

Answer 3

superior sagittal sinus

transverse vein

Question 4

what is ischaemia?

Answer 4

lack of blood flow

Question 5

what is hypoxia?

Answer 5

lack of oxygen

Question 6

what is the definition of stroke?

Answer 6

Focal neurological deficit (loss of function affecting a specific region of the central nervous system) due to disruption of blood supply

Question 7

what is the cause of stroke?

Answer 7

Interruption of supply of oxygen and nutrients, causing damage to brain tissue

Question 8

what can interruption of supply of oxygen be caused by?

Answer 8

Vessel wall
Blood flow (including blood pressure)
Blood constituents

Question 9

how can the vessel wall cause an interruption of supply in oxygen?

Answer 9

(abnormality of wall eg atheroma or vasculitis, outside pressure [eg strangulation, spinal cord compression, compression of veins])

Question 10

how can blood flow and pressure cause an interruption of supply in oxygen?

Answer 10

(eg decreased blood flow, increased blood pressure bursting vessels)

Question 11

how can blood constituents and pressure cause an interruption of supply in oxygen?

Answer 11

(Thrombosis of arteries and rarely veins. Bleeding due to anticoagulation, reduced platelets and clotting factors)

Question 12

what are the three main causes of localised interrupted blood supply?

Answer 12

Atheroma + thrombosis of artery causing ischaemia

Thromboembolism (for example, from left atrium) causing ischaemia

Ruptured aneurysm of a cerebral vessel causing haemorrhage

Question 13

how does atheroma and thrombosis affect an artery?

Answer 13

narrowing of artery

atheroma causes some narrowing

thrombosis results in severely narrowed artery

ussually occurs near bifurcation

Question 14

where is ischaemia found typically following internal carotid artery thrombosis?

Answer 14

typically get ischaemia in middle cerebral artery territory (but can affect elsewhere)

Question 15

what are transient symptoms of ischaemia defined as?

Answer 15

(<24 hours) – due to reversible ischaemia (transient ischaemic attack) = tissue still viable

Question 16

what are long standing symptoms of ischaemia defined as?

Answer 16

(>24 hours)– due to irreversible ischaemia causing localised brain death = infarct

Question 17

describe the pathogenesis of an ischaemic stroke?

Answer 17

Brain is very sensitive to oxygen ischaemia

A few minutes hypoxia or anoxia will cause brain ischaemia

Can lead to infarction. If infarction then damage to neurones is permanent. Neurones do not regenerate

Question 18

what is a localised area of brain death known as?

Answer 18

Regional cerebral infarct

Question 19

how are regional cerebral infarcts characterised?

Answer 19

Classically wedge-shape reflecting arterial perfusion territory

Soft and then becomes cystic

Question 20

how does an infarct present histologically?

Answer 20

Loss of neurones - causes clinical functional deficit

Microglia are brain macrophages that eat up dead tissue – repair process leading to gliosis

Gliosis is CNS equivalent of fibrosis

Question 21

why is the location of ischaemia very important?

Answer 21

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

Question 22

who are thrombosis of atrial appendages most common in?

Answer 22

people with arrhythmias such as atrial fibrillation

Question 23

how does a thromboembolism typically travel?

Answer 23

Heart with left atrial appendage thrombosis

Left atrium is connected directly to outflow of left side of heart

If thrombosis in left
atrial appendage breaks off it
will embolise to aorta and
possibly the carotid
(or any other) arteries

Right middle cerebral artery blocked by embolus - leads to ischaemia

Question 24

what causes an aneurysm to form?

Answer 24

Beyond carotids and vertebral arteries the cerebral arteries have thin walls.

Weakening of wall + hypertension causes aneurysm to form

Question 25

when is a vessel wall most liekly to rupture?

Answer 25

in severe hypertension

Question 26

what does a ruptured vessel wall cause?

Answer 26

haemorrhage and distal ischaemia Decreased blood flow distally to brain due to spasm of artery

Question 27

what are two common sites of ruptured vessels which cause haemorrhagic stroke?

Answer 27

Basal ganglia Circle of Willis

Question 28

what type of aneurysms form in hypertesnive patients in the basal ganglia?

Answer 28

microaneurysms form in hypertensive patients

Question 29

what type of aneurysms form in hypertesnive patients in the circle of willis?

Answer 29

Berry aneurysm forms in hypertensive patient

Question 30

which three factors cause generalised interupted blood supply/ hypoxia?

Answer 30

Low O2 in blood (hypoxia with intact circulation of blood) – eg. C02 poisoning, near drowning, respiratory arrest Inadequate supply of blood (flow of blood not occurring) – eg. cardiac arrest, hypotension, brain swelling (eg trauma) Rarely: Inability to use O2 – eg cyanide poisoning

Question 31

what causes Low O2 in blood (hypoxia with intact circulation of blood)?

Answer 31

C02 poisoning, near drowning, respiratory arrest

Question 32

what causes inadequate supply of blood (flow of blood not occurring)?

Answer 32

cardiac arrest, hypotension, brain swelling (eg trauma)

Question 33

what causes inability to use O2?

Answer 33

cyanide poisoning

Question 34

what are 3 examples of brain injury caused by generalised interrupted blood supply and/or hypoxia?

Answer 34

Hypotension Cardiac arrest Complex case

Question 35

Patient has coronary artery bypass with prolonged period of hypotension during operation – patient kept oxygenated by ventilation which part of their brain is better perfused?

Answer 35

Central part of arteries territories are perfused Watershed zones are poorly perfused So patient has prolonged period of poor perfusion pressure of brain, but blood is oxygenated Patient dies a few days after operation 🡪 autopsy - Zonal pattern of ischaemia and infarction at interface of territories

Question 36

what are Zones of infarction at interface of artery perfusion territores known as?

Answer 36

Watershed’ infarcts (Pure hypotension with oxygenated blood)

Question 37

what are watershed infarcts?

Answer 37

Pure hypotension with oxygenated blood

Question 38

60 year old male suffers myocardial infarct. Doing well then, Cardiac arrest followed several minutes later by resuscitation - what happens during those minutes?

Answer 38

no circulation to brain and no oxygen in blood – all of brain deprived of blood flow and O2

Question 39

60 year old male suffers myocardial infarct. Doing well then, Cardiac arrest followed several minutes later by resuscitation - patient dies what will autopsy show?

Answer 39

Large areas of grey matter necrosis

Question 40

60 year old male suffers myocardial infarct. Doing well then, Cardiac arrest followed several minutes later by resuscitation - id patient had lived longer what would have happened to grey matter?

Answer 40

laminar cortical necrosis

Question 41

what is complete loss of perfusion and oxygen?

Answer 41

cortical necrosis (infarction)

Question 42

75 year old woman with known coronary artery disease Suffers bout of pneumonia Periods of poor oxygenation but adequate circulation (due to pneumonia) Then suffers cardiac arrest – period of no perfusion and no oxygen Successful resuscitation then further arrest then dies at autopsy what various types of infarcts may be seen?

Answer 42

watershed infarcts laminar corticsl necrosis (infarction) regional infarcts related to poor flow through cerebral vessels narrowed by atheroma?