1b Cerebral Vasculature

Question 1

What percentage of the bodies oxygen consumption does the brain use?

Answer 1

20% - therefore the brain is very vulnerable if the blood supply is impaired

Question 2

Describe the blood supply to the brain?

Answer 2

The common carotid artery is a branch of the brachiocephalic trunk - this splits into the internal and external carotid artery

Question 3

What is the point where the cerebral veins converge?

Answer 3

Point of confluence

Question 4

What are the four types of haemorrhages?

Answer 4

1. Extradural
2. Subdural
3. Subarachnoid
4. Intracerebral

Question 5

What is the most common cause of an extradural haematoma?

Answer 5

Trauma = blow to the pterion - rupture the middle meningeal artery

Question 6

Why is an extradural haematoma a surgical emergency?

Answer 6

arterial bleed, therefore high pressure and loss of blood is fast

Question 7

Why can the clinical effects of a subdural haematoma be delayed?

Answer 7

venous bleed therefore lower pressure so less of a clinical emergency

Question 8

What will patients with a sub arachnoid bleed experience?

Answer 8

Thunderclap headache

Question 9

What causes subarachnoid bleeds?

Answer 9

ruptured aneurysms

Question 10

What causes an intracerebral bleed?

Answer 10

Spontaneous hypertensivity

Question 11

What is a stroke?

Answer 11

A rapidly developing focal disturbance of brain function of presumed vascular origin and greater than 24 hours in duration

Question 12

What are the two main types of strokes?

Answer 12

Thrombo-embolic or haemorrhage

Question 13

What is a TIA?

Answer 13

Transient Ischaemic Attack - rapidly reveloping focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours

Question 14

What is an infarction?

Answer 14

Degenerative changes which occur in the tissue following an occlusion of an artery

Question 15

What is cerebral ischaemia

Answer 15

Lack of sufficient blood supply to the nervous tissues resulting in permanent damage if blood flow is not restored properly

Question 16

What is thrombosis?

Answer 16

formation of a blood clot

Question 17

What is an embolism?

Answer 17

plugging of a small vessel by material carried from a larger vessel eg thrombi from the heart or atherosclerotic debris from the internal carotid

Question 18

What are some key signs of a stroke?

Answer 18

Loss of symmetry
slurred speech
drooping of face and mouth - one side

Question 19

What are the risk factors for stroke?

Answer 19

Diabetes mellitus
smoking
Age
Hypertension
Cardiac Disease

Question 20

Draw a diagram showing the cerebral artery perfusion fields?

Answer 20

Question 21

What symptoms would be experienced by patients if they have an anterior cerebral artery blockage?

Answer 21

Paralysis of contralateral structures with a tendancy for lower limbs over arm

FRONTAL LOBE FUNCTIONS:
Disturbance of intellect, executive function and judgment (Abulia)

Loss of appropriate social behaviour

Question 22

What symptoms would be experienced by patients if they have an middle cerebral artery blockage?

Answer 22

“Classic stroke”
Contralateral hemiplagia (upper limbs)
Contralateral hemisensory deficits
Hemaniopia
Aphasia (L Sided lesion)

Question 23

Why is hemiplagia common in middle cerebral artery conditions?

Answer 23

the middle cerebral artery supplies all pathways to the spinal cord, therefore there is likely to be subcortical damage

Question 24

What type of aphasia will damage to Broca’s area produce?

Answer 24

Expressive Aphasia - they can understand but not reply

Question 25

What type of aphasia will damage to Wernicke’s area produce?

Answer 25

Receptive Aphasia - cannot understand but can speak

Question 26

What does damage to the posterior cerebral artery result in?

Answer 26

Visual defects - homonymous hemaniopia and visual agnosia

Question 27

What is agnosia?

Answer 27

Inability to recognise faces

Question 28

What is a major risk factor for stroke?

Answer 28

Atherosclerosis - yellow discolouration in the walls of the vessel represent atherosclerosis or hardening of the arteries

Question 29

Draw the circle of willis

Answer 29

Question 30

What is the benefit of the circle of willis?

Answer 30

Compensatory flow - if one of the arteries is lacking - the others can compensate

Question 31

What is the treatment for Subdural Haematoma?

Answer 31

Burr Holes - remove skull flap and then remove blood

Question 32

How can you distinguish a SDH from other bleeds?

Answer 32

Delayed presentation = as SDH is a venous bleed therefore lower presure and hence slower presentation

Question 33

Why do you have a persistent headache in SDH?

Answer 33

Due to sheering of the delicate bridging veins in the subdural space

Question 34

What pathologies are seen on a scan of a SDH?

Answer 34

the bleed
compressed ventricles on the side of the bleed
Other ventricle large as filled with alot of CSF to compensate

Question 35

What are the signs of an intra-cerebellar bleed?

Answer 35

Drowsy, slurred speech, wobbly eye movements, ataxia, broad based gait

Question 36

Which type of bleed is due to hypertension usually?

Answer 36

Intra-parenchymal/cerebral bleed

Question 37

What is the treatment for Intra-parenchymal bleeds?

Answer 37

Manage hypertension - usually difficult to remove surgically as it is inside the brain

Question 38

Which cerebral artery has the largest perfusion field?

Answer 38

Middle cerebral artery

Question 39

Stroke of which artery results in a disturbance of intellect, executive function and judgement?

Answer 39

Anterior cerebral artery

Question 40

What causes a venous haemorrhage?

Answer 40

Shearing of bridging veins

Question 41

What is the presentation of a subdural haemorrhage?

Answer 41

Gradually worsening headache - due to pressure building up

Drowsiness / loss of consciousness due to pressure on the brainstem

Question 42

If a lemon shaped bleed is on a CT, which type of bleed is this?

Answer 42

Extradural bleed