Cerebral vasculature

Question 1

What are the perfusion demands of the brain?

Answer 1

10-20% of cardiac output
20% of O2 consumption
66% of liver glucose

this makes it very vulnerable if blood supply is impaired

Question 2

What are the arteries that supply the brain with blood?

Answer 2

Internal carotid artery

Vertebral artery

Question 3

What do the vertebral arteries fuse to become?

Answer 3

Basilar artery.

Question 4

What does the basilar artery divide to become?

Answer 4

Posterior cerebral artery

Question 5

What is the main branch of the internal carotid artery?

Answer 5

Middle cerebral artery

Question 6

What is the second branch of the internal carotid artery?

Answer 6

Anterior cerebral artery

Question 7

Which arteries complete the circle of Willis?

Answer 7

Anterior & Posterior communicating artery

Question 8

What is the advantage of the circle of Willis?

Answer 8

If you have a blockage in one of the internal carotids, you have a chance of compensatory flow from the other side. But this is often quite weak.

Question 9

How does blood leave the brain?

Answer 9

Cerebral veins drain into venous sinuses in the dura mater, which drain into the Internal jugular vein

Question 10

What are the types of intracranial haemorrhage ?

Answer 10

Extradural - trauma, immediate clinical effects due to high arterial pressure.
Subdural - trauma, can have delayed clinical effects due to lower venous pressure.
Subarachnoid - ruptured aneurysms
Intracerebral - Spontaneous hypertensive

Question 11

What is a stroke?

Answer 11

Rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hrs of duration

Question 12

What causes strokes?

Answer 12

Thromboembolic - 85%

Haemorrhage - 15%

Question 13

What is a Transient Ischaemic attack TIA?

Answer 13

Rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours.

Question 14

Define Infarction

Answer 14

Degenerative changes which occur in tissue following occlusion of an artery

Question 15

Define Cerebral Ischaemia

Answer 15

Lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly.

Question 16

Define Thrombus

Answer 16

Formation of a blood clot

Question 17

Define Embolism

Answer 17

Plugging of a small vessel by material carried from a larger vessel, e.g. thrombi from the heart or atherosclerotic debris from the internal carotid

Question 18

Why are strokes a public health issue?

Answer 18

3rd commonest cause of death
100,000 deaths in the UK per annum
50% of survivors are permanently disabled
70% show an obvious neurological deficit
FAST campaign

Question 19

What are the risk factors for stroke?

Answer 19

Age
Hypertension
Cardiac disease
Smoking
Diabetes Mellitus

Question 20

What are the 3 cerebral arteries?

Answer 20

Anterior, Middle, Posterior cerebral artery

Question 21

Which cerebral artery has the largest perfusion field?

Answer 21

Middle cerebral artery

Question 22

What are Anterior cerebral artery symptoms?

Answer 22

Paralysis of contralateral structures - leg>arm, face
Disturbance of intellect, executive judgement & function - abulia
Loss of appropriate social behaviour

Question 23

What are the Middle cerebral artery symptoms?

Answer 23

Classic stroke
Contralateral hemiplegia - arm>leg
Contralateral hemisensory deficits
Hemianopia
Aphasia

Question 24

What are Posterior cerebral artery symptoms?

Answer 24

Visual defects - homonymous hemianopia, visual agnosia