Pathology of cerebrovascular disease

Question 1

Which 3 arteries supply the cortex

Answer 1

anterior cerebral artery
middle cerebral artery
posterior cerebral artery

Question 2

Venous drainage of the brain

Answer 2

large venous sinuses within dura

superior sagittal sinus - largest drains into transverse sinus

Question 3

What does the transverse sinus drain into?

Answer 3

transverse sinus becomes the sigmoid sinus before draining into the internal jugular vein

Question 4

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

Cause of stroke

Answer 5

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

many reasons/ways that O2 supply can be interrupted

Question 6

Interruption of supply of oxygen caused by changes in what?

Answer 6

Virchow’s triad:

Vessel wall

Blood flow (including blood pressure)

Blood constituents

Question 7

Give examples of abnormalities in vessel walls

Answer 7

atheroma
vasculitis
outside pressure [eg strangulation, spinal cord compression, compression of veins]

Question 8

Give examples of causes of changes in blood flow and pressure

Answer 8

decreased blood flow, increased blood pressure bursting vessels

Question 9

Give examples of causes of abnormalities in blood constituents

Answer 9

thrombosis of arteries and rarely veins

Bleeding due to anticoagulation

reduced platelets and clotting factors

Question 10

In practice, what are the 3 main causes of localised interrupted blood supply to the brain causing strokes

Answer 10

Atheroma + thrombosis of artery causing ischaemia

Thromboembolism (for example, from left atrium) causing ischaemia

Ruptured aneurysm of a cerebral vessel causing haemorrhage

Question 11

How does Atheroma + thrombosis of artery cause a stroke

Answer 11

Narrowing of artery causes ischaemia (usually in middle cerebral artery but can affect elsewhere) results in reduced blood flow - reduced O2

often occurs at bifurcation of arteries ie carotid arteries and the point where the two vertebral arteries join to form the basilar artery

Question 12

What is a thrombus made up of

Answer 12

platelets and fibrin

Question 13

Define ischaemia

Answer 13

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

Question 14

What characterises a transient ischaemic attack

Answer 14

Transient symptoms (<24 hours)

due to reversible ischaemia = tissue still viable

Question 15

What characterises an infarction stroke

Answer 15

Longstanding symptoms (>24 hours) – due to irreversible ischaemia causing localised brain death = infarct

Question 16

Pathogenesis of ischaemic stroke

Answer 16

Brain is very sensitive to oxygen ischaemia

A few minutes hypoxia or anoxia will cause brain ischaemia which can lead to infarction.

If infarction then damage to neurones is permanent. Neurones DO NOT regenerate

Question 17

What do localised areas of brain death (regional cerebral infarct) appear like?

Answer 17

starts off soft and then becomes cystic

classically wedge-shape reflecting the arterial perfusion territory (ie the area around the artery perfusing the area)

Question 18

Describe the local effect of a regional cerebral infarct

Answer 18

tissue disintegration

congested vessels at outside of arterial territory

Yellow discolouration at edge of infarcted area - loss of nuclei and infiltration of macrophages

Swelling of surrounding brain tissue outside wedge-shaped territory

Question 19

What would the histology of a brain infarct look like? (2)

Answer 19

Loss of neurones - causes clinical functional deficit

Foamy macrophages –repair process leading to gliosis

Question 20

What is Gliosis?

Answer 20

Gliosis is CNS equivalent of fibrosis

hypertrophy or proliferation of glial cells due to damage to CNS

Question 21

What is it about the ischaemia that is important in determining the damage caused in the brain

Answer 21

the location of the ischaemia

A small affected area of one part of brain may not cause too much impairment but similar size elsewhere may be devastating

Question 22

Thromboembolism

Answer 22

Thrombus in left atrial appendage breaks off and embolises to the aorta and possibly the carotid arteries or cerebral arteries

the right middle cerebral artery in the circle of willis can become blocked

causes an ischaemic stroke

Question 23

What is thrombosis of atrial appendages common in?

Answer 23

People with arrhythmias such as AF

Question 24

How can aneurysms form in the cerebral arteries?

Answer 24

they have thin walls

weakening of the wall and hypertension causes aneurysm to form

the wall can then rupture, especially if severe hypertension

Decreased blood flow
distally to brain due to
spasm of artery

a ruptured vessel wall causes haemorrhage and distal ischaemia

Question 25

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

Answer 25

Basal ganglia – micro-aneurysms

Circle of Willis – Berry aneurysm forms - looks like a berry on a narrow stem - most common type of brain aneurysm

Question 26

What makes up the basal ganglia?

Answer 26

old fashioned term - should be basal nuclei (in CNS)

Subcortical nuclei.(collection of neuronal cell bodies – grey matter) deep within each cerebral hemisphere

Made up of the caudate nucleus, putamen and globus pallidus

Question 27

2 ways you might get generalised interrupted blood supply or hypoxia

Answer 27

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 eg cyanide poisoning

Question 28

Examples of ways you might have low O2 level in blood (3)

Answer 28

C02 poisoning
near drowning
respiratory arrest

Question 29

When might you have inadequate supply of blood (3)

Answer 29

cardiac arrest

hypotension

brain swelling (eg trauma)

Question 30

3 examples of brain injury caused by generalised interrupted blood supply and/or hypoxia

Answer 30

hypotension

cardiac arrest

complex case

Question 31

What are watershed areas of the brain?

Answer 31

regions of the brain that simultaneously receive blood supply from two separate groups of arteries.
Ie borders between anterior, middle and posterior cerebral

If there is a blockage or interruption of blood flow of one of the blood vessels, it can be problematic

Question 32

Watershed stroke

Answer 32

Zones of infarction at edge of artery perfusion territories are called ‘Watershed’ infarcts as they are poorly perfused

(ie between the tissues supplied by the anterior, posterior and middle cerebral arteries - further away from artery = reduced perfusion)

pure hypotension with oxygenated blood - watershed infarcts

Question 33

what is laminar necrosis of brain tissue?

Answer 33

laminar = lines of necrosis and thinning of grey matter

Question 34

What does complete loss of perfusion and O2 cause?

Answer 34

cortical necrosis (infarction)

Question 35

Is white or grey matter injured more by ischaemia?

Answer 35

It is well known that ischemic stroke can cause grey matter injury but white matter is exquisitely vulnerable to ischemia and is often injured more severely than gray matter

Question 36

What is another term for the cerebral cortex

Answer 36

The grey matter at outer edge of cerebral hemispheres

Question 37

During hypotension what has better perfusion

Answer 37

central part near artery

Question 38

If damaged, which cerebral artery is most likely to affect the legs?

Answer 38

Anterior cerebral artery

Question 39

If damaged, which cerebral artery is most likely to affect the face/arms?

Answer 39

Middle cerebral artery

Question 40

If damaged, which cerebral artery is most likely to cause visual problems?

Answer 40

Posterior cerebral artery