Cerebrovascular Disease

Question 1

what is the blood supply to the brainstem and the cerebellum?

Answer 1

vertebral and basilar arteries

Question 2

in the brain do veins accompany the arteries?

Answer 2

no they are in large venous sinuses within the dura

Question 3

define stroke

Answer 3

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

Question 4

what are the causes of stroke?

Answer 4

interruption of supply of:
> oxygen
> nutrients
causing brain damage

Question 5

what causes interruption to the supply of oxygen to the brain?

Answer 5

changes in:
> vessel wall
> blood flow (increased or decreased pressure)
> blood constituents

Question 6

what changes in the vessel wall can cause interruption in oxygen supply?

Answer 6

> atheroma
vasculitis
outside pressure- spinal cord, strangulation

Question 7

give some examples of changes in the constituents of the blood that leads to altered oxygen supply to the brain

Answer 7

> thrombosis of arteries and (rarely) veins

> bleeding due to anticoagulation, reduced platelets and clotting factors

Question 8

name the three main causes of localised interrupted blood supply

Answer 8

> atheroma and thrombosis (causing ischaemia)
thromboembolism (causing ischaemia)
ruptured aneurysm (haemorrhage)

Question 9

describe the pathology of atheroma and thrombosis

Answer 9

> often at a bifurcation of an artery
atheroma causes narrowing
thrombosis (on top of the atheroma), made from platelets and fibrin, resulting in severely narrowed artery

Question 10

define ischaemia

Answer 10

a relative or absolute lack of blood supply in a tissue or organ

Question 11

is tissue still viable in a transient ischaemic attack?

Answer 11

yes as it is reversible

Question 12

what can longstanding symptoms due irreversible ischaemia lead to?

Answer 12

infarct, localised brain death

Question 13

describe the pathogenesis of ischaemic stroke

Answer 13

> brain is sensitive to ischaemia, a few minutes of hypoxia/anoxia will cause ischaemia
this can lead to infarction where the damage to neurones is permanent as they do not regenerate

Question 14

describe a regional cerebral infarct

Answer 14

> localised area of brain death
classically wedged shaped reflecting arterial perfusion territory
soft then becomes cystic
eventually there is a loss of brain tissue
swelling of surrounding brain tissue

Question 15

describe the histology of an infarct

Answer 15

> loss of neurons (causing clinical functional deficit)

> foamy macrophages (repair process leading to gliosis-fibrosis)

Question 16

why is the location of ischaemia very important?

Answer 16

> small area of brain affected in the periphery would cause less impairment than a similar sized area in another part of the brain

Question 17

why does thromboembolism lead to stroke?

Answer 17

when the thrombus embolises to the cerebral blood supply oxygen content to tissues is lowered

Question 18

why do cerebral arteries have thin walls?

Answer 18

they have less muscle so that there is no constriction with large amounts of angiotensin ensuring that the cerebral blood flow is not disturbed

Question 19

what can cause aneurysms to form?

Answer 19

> weakening of walls

> hypertension

Question 20

what is the affect on brain distal to the haemorrhage of an artery?

Answer 20

decreased blood flow due to spasm of the artery = ischaemia

Question 21

name two common sites of ruptured vessels In the brain

Answer 21

> basal ganglia (microaneurysms)

> circle of willis (berry aneurysms)

Question 22

name three things that can lead to generalised interrupted blood supply or hypoxia

Answer 22

> low O2 in blood- hypoxia will intact circulation
inadequate blood supply - blood flow not occurring
inability to use o2 (cyanide poisoning)

Question 23

what can cause hypoxia with intact circulation of blood?

Answer 23

> CO poisoning
near drowning
respiratory arrest

Question 24

what can cause in adequate supply of blood to the brain?

Answer 24

> cardiac arrest with immediate ressus
hypotension
brain swelling (trauma)

Question 25

what are watershed infarcts?

Answer 25

zones of infarction at interface of artery perfusion territories

Question 26

what can lead to watershed infarcts?

Answer 26

pure hypotension with oxygenated blood

Question 27

what leads to cortical necrosis?

Answer 27

when there is no circulation to the brain and no oxygen in the blood so all the brain is derived of blood flow and o2 (cardiac arrest)

Question 28

what is cortical necrosis?

Answer 28

large areas of grey matter thinning and necrosis

Question 29

what is laminar necrosis?

Answer 29

lines of necrosis and thinning

Question 30

a patient with coronary artery disease and pneumonia suffers a heart attack. what infarcts would you expect to see?

Answer 30

> watershed infarcts (periods of hypoxia due to pneumonia)
laminar cortical necrosis (due to total lack of oxygenation)
regional infarcts (cerebral vessels narrowed by atheroma)