Cerebrovascular disease

Question 1

Cerebrovascular disease comes in two forms

Answer 1

• Localised interruption of blood or oxygen supply (Stroke)

- Generalised interruption of blood or oxygen supply

Question 2

Define a stroke?

Answer 2

A focal neurological deficit caused by disruption of supply oxygen and/or nutrient supply causing damage to brain tissue

Question 3

What could cause a stroke?

Answer 3

Vessel Wall:

• Aneurysm
• Atheroma
• Vasculitis
• Strangulation

Blood Constituents

• Thrombosis
• Bleeding due to anticoags or reduced platelet/clotting factors

Blood flow:

• Hypotension
• Hypertension -> Bursting

Question 4

So what are the 3 main causes of localised interrupted blood supply to the brain (Stroke)?

Answer 4

Ischaemic:

• Atheroma and thrombosis
• Thromboembolism (E.g. from Afib)

Haemorrhagic:
- Ruptured Aneurysm

Question 5

Whats the difference between a TIA & Stroke?

Answer 5

Both are ischaemia to a localised section of brain tissue

TIA:

• <24 hour symptoms
• Reversible Ischaemia
• Tissue still viable

Stroke:

• Symptoms last >24 hours
• Irreversible ischaemia
• Localised brain death (i.e. infarct)

Question 6

What happens to the brain tissue during a regional cerebral infarct?

Answer 6

The region is classically wedge shaped reflecting the in->out arterial supply.

The tissue becomes soft, yellowy discoloured and begins to disintegrate typically in a cystic appearance

There may be visible congested vessels and swelling around the area

Question 7

How does infarcted brain tissue appear histologically?

Answer 7

Visibly lost neurons

Foamy macrophages - Part of the repair process prior to gliosis (Scar tissue formation)

Question 8

Why are cerebral arteries so likely to have aneurysms?

Answer 8

They are very thin walled due to their lack of muscle.
This is so that there’s no way cerebral blood can be diminished .

This when coupled with hypertension leads to aneurysms which can burst

Question 9

How does a ruptured aneurysm cause localised interruption of blood flow?

Answer 9

The haemorrhage means blood doesnt get through and compresses the brain

Can also get distal ischaemia due to arterial spasm

Question 10

Where do cerebral aneurysms most often form?

Answer 10

• Microaneurysms in the Basal Ganglia

- Berry Aneurysms in the Circle of Willis

Question 11

What are the main causes of a generalised Interrupted blood supply or hypoxia?

Answer 11

• Low O2 in the blood (Hypoxic Hypoxia) e.g. CO poisoning or resp arrest
• Inadequate supply of blood e.g. Cardiac arrest, swollen brain or hypotension
• Rarely an inability to use the O2 such as cyanide posioning

Question 12

What are the main types of Generalised interrupted blood supply?

Answer 12

• Hypotension
• Cardiac Arrest
• Complex Case (Combines various types of ischaemia form multiple causes)

Question 13

What pattern of infarction could be caused during an Operation in which there is a prolonged period of hypotension?

Answer 13

Generalised interrupted blood flow

• -> poor Perfusion to the borders between arterial territories in the brain
• -> So you get a pattern of ischaemia and infarction at the interfaces between these area (watershed infarcts)

Question 14

IF someone goes into cardiac arrest and is resuscitated after several minutes, describe their pattern of ischaemia?

Answer 14

They go several minutes with no supply of blood (Generalised interruption)

Causes infarction all over the brain

They get Laminar (lined) cortical necrosis i.e. large areas of grey matter thin and necrose

Question 15

Lets say a women comes in with a known Coronary artery disease, bouts of pneumonia and suffers a cardiac arrest, describe her patterns of ischaemia?

Answer 15

This is known as a Complex Case, she has multiple different sources of ischaemia causing different patterns in her brain:

• Watershed infarcts from her time poorly ventilated due to pneumonia
• Regional infarcts related to localised loss of blood flow from atheromatous disease
• Laminar Cortical infarcts due to complete cessation of blood flow during cardiac arrest