Pathology of Cerebrovascular Disease

Question 1

What is a stroke?

Answer 1

Neurological deficit cause by disruption of blood flow to the brain

Question 2

Main causes of stroke?

Answer 2

• Atheroma + Thrombosis of arteries causing ischaemia
• Thromboembolism: causes ischaemia
• Ruptured aneurysm of a cerebral vessel causing haemmorrhage

Question 3

Where will thrombosis in the internal carotid artery typically tend to affect?

Answer 3

The middle cerebral artery (MCA) territory of the brain

lateral aspect of brain
(language and movement deficits)

Question 4

How does the reversibility of brain tissue ischaemia influence the outcome of the neurological deficit?

Answer 4

• Reversible ischaemia (TIA): causes transient symptoms, last for <24hrs
• Irreversible ischaemia: causes brain tissue death (infarction), longstanding symptoms

Question 5

Why are cerebral infarcts usually wedge shaped?

Answer 5

• Wedge shaped because it reflects the arterial profusion territory

Question 6

How does a cerebral infarct progress after death?

Answer 6

• Foamy macrophages get rid of the dead brain tissue
• Gliosis occurs (glial cell proliferation - CNS equivalent of fibrosis)
• Ends up with just loss of brain tissue, yellow colouration at edge of infarcted area

Question 7

Is location of the infarction important?

Answer 7

Yes

Small lesion in one part of the brain may cause few symptoms. Similarly sized lesion in another part of the brain may be severely debilitating

Question 8

How do the walls of arteries change as you get deeper into brain supply?

Answer 8

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

Question 9

What causes brain aneurysms to form?

Answer 9

Weakening of the artery walls + hypertension

Question 10

What are the two common sites of haemorrhagic stroke?

Answer 10

• Basal ganglia

- Circle of Willis

Question 11

What are the main causes of generalized interruption of blood supply causing brain hypoxia?

Answer 11

• Low O2 in blood (CO2 poisoning, drowning etc.)

- Inadequate supply of blood flow (cardiac arrest, HF)

Question 12

How can hypotension (even with oxygenated blood) cause brain hypoxia related issues?

Answer 12

• Since BP is low, the central areas supplied by the cerebral arteries remain perfused
• Areas on the outskirts, “watershed areas” (at the edges of different arteries perfusion) are not perfused due to too low of BP.
• These areas can sustain damage

Question 13

Where in the brain does complete loss of perfusion (eg. MI) affect first?

Answer 13

Affects the cortex

• Cortical necrosis can occur in patients who undergo a period of cardiac arrest

Question 14

What are the “watershed” areas of the brain?

Answer 14

Areas between the areas at the centre of perfusion by the cerebral arteries

On the outskirts of the areas of the brain supplied by the cerebral arteries

Question 15

Cardiac arrest causes what type of necrosis in the brain?

Hypoperfusion causes?

Answer 15

• CA: Cortical necrosis
• Hypoperfusion: Watershed infarction

Can have complicated cases that involve both