Pathology of Cerebrovascular Disease

Question 1

How does the vasculature of the brain differ from other parts of the body?

Answer 1

Vein do not accompany arteries

Question 2

How are the veins arranged in the brain?

Answer 2

There are large venous sinuses within the dura

Question 3

Give examples of the venous sinuses found within the brain.

Answer 3

• Superior sagittal sinus
• Inferior sagittal sinus
• Transverse sinus
• Sigmoid sinus
• Straight sinus

Question 4

What is the WHO definition of stroke?

Answer 4

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

Question 5

What causes a stroke??

Answer 5

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

Question 6

Interruption of supply of oxygen caused by changes in…

Answer 6

• Vessel wall
• Blood flow (including blood pressure)
• Blood constituents

Question 7

What can cause changes in the vessel wall?

Answer 7

Abnormality of wall

• Atheroma
• Vasculitis

Outside pressure

• Strangulation
• Spinal cord compression
• Compression of veins

Question 8

What can cause changes in blood flow?

Answer 8

• Decreased blood flow

- Increased blood pressure bursting vessels

Question 9

What can cause changes in blood constituents?

Answer 9

• Thrombosis of arteries and rarely veins

- Bleeding due to anticoagulation, reduced platelets anc clotting factors

Question 10

What are the 3 main causes of localised interrupted blood supply?

Answer 10

• Atheroma and thrombosis of artery causing ischaemia
• Thromboembolism (for examples from the left atrium) causing ischaemia
• Ruptured aneurysm of cerebral vessel causing haemorrhage

Question 11

Where is a common place for atheroma and thrombosis?

Answer 11

Carotid artery bifurcation

Question 12

What is a thrombosis formed from?

Answer 12

Platelets and fibrin

Question 13

What does atheroma and thrombosis of a vessel lead to?

Answer 13

Severe narrowing of the vessel

Question 14

Where does ischaemia typically occur with internal carotid artery thrombosis?

Answer 14

Middle cerebral artery territory

Question 15

Ischaemia

Answer 15

Relative of absolute lack of blood supply In a tissue or organ

Question 16

What is the outcome of ischaemia causing transient symptoms?

Answer 16

• Last <24 hours
• Due to reversible ischaemia (TIA)
• Tissue still available

Question 17

What is the outcome of ischaemia causing longstanding symptoms?

Answer 17

• Last >24 hours
• Due to irreversible ischaemic causing localised brain death
• Infarction

Question 18

What is the brain very sensitive to?

Answer 18

Oxygen ischaemia

Question 19

What will a few minutes of hypoxia or anoxia cause?

Answer 19

Brain ischaemia which can lead to infarction

Question 20

Why is the damage permanent of infarction occurs?

Answer 20

The damage to the neurones is permanent. Neurons do not regenerate

Question 21

How does localised area of brain death appear?

Answer 21

-There will be regional cerebral infarct-Classically wedge shaped reflecting arterial perfusion territory-Soft and then becomes cystic

Question 22

What does the histology of infarct look like?

Answer 22

• Loss of neurones which cause clinical functional deficit
• Foamy macrophages: repair process leading to gliosis
• Gliosis is CNS equivalent of fibrosis

Question 23

Why is the location of ischaemia very important?

Answer 23

• 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 24

Who is thromboembolism of atrial appendage common in?

Answer 24

People with arrhythmias such as AF

Question 25

How does thromboembolism occur from the left atrium?

Answer 25

- Heart with left atrial appendage thrombosis - Left atrium is connected directly to outflow of left side of the heart - If thrombosis in left atrial appendage breaks off it will embolise to aorta and possibly the carotid (or any other) arteries

Question 26

How can vessel walls rupture to cause a stroke?

Answer 26

- Beyond carotids and vertebral arteries the cerebral arteries have thin wall. - Weakening of wall and hypertension causes aneurysm to form - Wall can then rupture, especially if severe hypertension - Decreased blood flow distally to brain due to spasm of artery

Question 27

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

Answer 27

- Basal ganglia: microaneursyms form in hypertensive patients - Circle of Willis: Berry aneurysm forms in hypertensive patient

Question 28

What are the causes of generalised interrupted blood supply or hypoxia?

Answer 28

- Low O2 in blood (hypoxia with intact circulation of blood) - Inadequate supply of blood (flow of blood not occurring) (blood may be oxygenated or not) - Rarely: Inability to use O2 such as cyanide poisoning

Question 29

What can cause low O2 levels in the blood?

Answer 29

- CO poisoning - Near drowning - Respiratory arrest

Question 30

What can cause inadequate supply of blood?

Answer 30

- Cardiac arrest with immediate resuscitation - Hypotension - Brain swelling (trauma)

Question 31

Describe the what would happen if someone experience a prolonged period of hypotension but was kept well oxygenated?

Answer 31

- There is prolonged period of poor perfusion but blood is oxygenated - Central part of arteries territories are perfused OK - Watershed zones are poorly perfused - Zonal pattern of ischaemia and infarction at interface of territories

Question 32

What are watershed zones?

Answer 32

Zones at interface of artery perfusion territories

Question 33

What does pure hypotension with oxygenated blood lead to?

Answer 33

Watershed infarcts

Question 34

What may found on autopsy of someone with a period of no oxygenation and no circulation to the brain?

Answer 34

- Large areas of grey matter thinning and necrosis | - Laminar appearance

Question 35

What does complete loss of perfusion and oxygen lead to?

Answer 35

Cortical necrosis

Question 36

What will a complex case lead to?

Answer 36

Complex pattern