Pathology of Cerebrovascular Disease

Question 1

Explain the blood supply to different parts of the cortex?

Answer 1

Question 2

Do veins accompany arteries in the brain?

Answer 2

No they do not

Question 3

What drains the dura mater?

Answer 3

Large venous sinuses

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 a 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

Vaugly, what is the cause of stroke?

Answer 7

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

Question 8

What can an interruption in oxygen to the brain be caused by changes in?

Answer 8

Vessel wall

Blood flow (including blood pressure)

Blood contituents

Question 9

What changes in the vessel wall can cause an interruption of blood supply to the brain?

Answer 9

Atheroma or vasculitis

Outside pressure (strangulation)

Spinal cord compression

Compression of veins

Question 10

What changes to blood flow can cause an interruption of oxygen delivery to the brain?

Answer 10

Decreased blood flow

Increased blood pressure bursting vessels

Question 11

What changes to blood constituents can cause interruption to delivery of oxygen to the brain?

Answer 11

Thrombosis of arteries and rarely veins

Bleeding due to anticoagulation

Reduced platelets and clotting factors

Question 12

In practice, what are the 3 main causes of localised interruptions of blood supply?

Answer 12

Atheroma and thrombosis of artery causing ischaemia

Thromboembolism (for example from left atrium) causing ischaemia

Ruptured aneurysm of cerebral vessel causing haemorrhage

Question 13

What are the 2 kinds of ischaemia?

Answer 13

Transient symptoms

Longstanding symptoms

Question 14

What are transient symptoms ischaemia?

Answer 14

Less than 24 hours

Due to reversible ischaemia (transient ischamia attack)

Tissue still viable

Question 15

What are long standing sympotoms ischaemia?

Answer 15

More than 24 hours

Due to irreversible ischaemia

Causes localised brain death (infarct)

Question 16

Explain the pathogenesis of ischaemic stroke?

Answer 16

Brian is very sensitive to oxygen ischaemia

Few minutes of hypoxia or anoxia will cause brain ischaemia

Can lead to infarction, it it does then damage to neurons is permanent as neurons do not regenerate

Classically wedge shaped reflecting arterial perfusion territory

Question 17

How long is required to cause brain ischaemia?

Answer 17

Few minutes of hypoxia

Question 18

What is a local area of brain death called?

Answer 18

Regional cerebral infarct

Question 19

What is seen in histology of ischaemic stroke?

Answer 19

Loss of neurons (causes clinical functional deficit)

Foamy macrophages (repair process leading to gliosis)

Gliosis is CNS equilvalent of fibrosis

Question 20

Why is the location of ischaemia important?

Answer 20

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 21

What artery in the brain is often blocked due to an atheroma or maybe thromboembolism from the internal carotid artery?

Answer 21

Middle cerebral artery

Question 22

What is the pathogenesis of a ruptured aneurysm causing ischaemic stroke?

Answer 22

1) Beyond carotids and vertebral arteries the cerebral arteries have thin walls
2) Weakening of wall and hypertension causes aneurysm to form
3) Wall can then rupture, especially if severe hypertension
4) Decreased blood flow distally to brain due to spasm of artery (haemorrhage)

Question 23

What are 2 common sites of ruptured vessels causing haemorrhage stroke?

Answer 23

Basal ganglia (microaneurysm forms in hypertensive patients)

Circle of Willis (berry eneurysm forms in hypertensive patients)

Question 24

Vaugly, what can cause strokes as well as local problems?

Answer 24

General problems

Question 25

What are some examples of general problems that can cause stroke?

Answer 25

Low oxygen in blood

Inadequate supply of blood

Inability to use oxygen

Question 26

What are examples of low oxygen in blood causing stroke?

Answer 26

Carbon dioxide poisoning

Near drowning

Respiratory arrest

Question 27

What does low oxygen in blood causing stroke mean?

Answer 27

Hypoxia with intact circulation of blood

Question 28

What does inadequate supply of blood causing stroke mean?

Answer 28

Flow of blood not occuring

Blood may be oxygenated or not

Question 29

What are examples of things that cause inadequate supply of blood causing stroke?

Answer 29

Cardiac arrest

Hypotension

Brain swelling (such as trauma)

Question 30

What is an example of inability to use oxygen?

Answer 30

Cyanide poisoning

This is rare

Question 31

How does hypotension lead to stroke?

Answer 31

Central parts of arteries territory is better perfused

Leads to watershed zones that are poorly perfused, which are zonal patterns of ischaemia and infarction at interface of territories

Question 32

How does cardiac arrest cause stroke?

Answer 32

Causes complete loss of perfusion and oxygen for a few minutes

Leads to laminar cortical necrosis (infarction)

Question 33

What are the different patterns of infarction?

Answer 33

Watershed infarcts

Laminar cortical necrosis

Regional infarcts