Cerebral vasculature

Question 1

Why is the brain very vulnerable if the blood supply is impaired?

Answer 1

it uses
10-20% cardiac output
20% of body O2 consumption
66% of the liver glucose

Relied very heavily on blood supply

Question 2

How does blood get to the brain?

Answer 2

The common carotid from the brachiocelphalic artery.
It divides into external for the face and internal carotid to cranial cavity

Vertebral artery comes from subclavian, goes posteriorly up behind the verterbrae into cranial cvity

Question 3

What us special about the circle of willis?

Answer 3

anastomatic circuit vessels are joined

Question 4

Describe the venous drainage of the brain?

Answer 4

Cerebral veins –> venous sinuses in the dura mater –> internal jugular

Question 5

Why is having anastomised circle of willis useful e.g. in carotid blockage?

Answer 5

If one branch is blocked and leads to a carotid atherlocarotid build up the posterior circulation and the other branch can continue circulation to the other side of the brain

• however posterior communicating arteries are very thin

Question 6

Describe the dural venous sunuses?

Answer 6

Look at slide 8, many sinuses shown in the midsaggital section. Brain removed

Question 7

What is an intracranial haemorrhage?

Answer 7

Bleed in the cranial cavity

Question 8

What are the four types of haemorrhage?

Answer 8

Extradural
Subdural
Subarachnoid
Intracerebral

Question 9

What causes extradural haemorrhage and what clinical effects are there?

Answer 9

• Trauma
• Immediate clinical effects :
  Arterial, high pressured

Question 10

What causes Subdural haemorrhage and what clinical effects are there?

Answer 10

• Trauma
• Can be delayed clinical effects :
  Venous, lower pressure

Question 11

What causes Subarachnoid haemorrhage and what clinical effects are there?

Answer 11

Ruptured aneurysms, usually in circle of willis

• generally congenital aneurysms -weaknesses in blood vessels. In hypertensive px it can burst and bleed

Question 12

What causes Inrtacerebral haemorrhage and what clinical effects are there?

Answer 12

usually seen in chronic raised hypertensive

Question 13

What is a stroke?

Answer 13

Cerebrovascular accident - CVA

Definition: “rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration”

Thrombo-embolic (85%) or haemorrhage (15%)

Question 14

What is a transient ischaemic attack? TIA

Answer 14

• rapidly developing
• focus disturbance of brain function
• from presumed vascular origin
• resolves within 24 hours

: need to keep an eye out for future strokes

Question 15

What is an infarction?

Answer 15

Degenerative chances which occur in tissue following occlusion of an artery

*ischaemia can cause infarction

Question 16

What is a Cerebral Ischaemia?

Answer 16

Lack of sufficient blood supply to nervous tissue

–> permanent damage if not restored quick

Question 17

What is a thromboembolic stroke?

Answer 17

thrombosis: formation of a blood clot

Embolism : plugging of a smaller vessel by something carried in a larger vessel

Question 18

Give an example of material that can cause embolism?

Answer 18

• Thrombi from heart
• Atherosclerotic debri from internal carotid
• Air e.g. from iv injection air bubble

Question 19

Why are strokes a major public health issue?

Answer 19

3rd commonest cause of death
100,000 deaths annually uk

50% survivors are permanently disabled

70% show obvious neurological deficit

Question 20

What are the risk factors for stroke?

Answer 20

• age
• hypertension
• cardiac disease
• smoking
• diabetes mellitus

Question 21

If anterior cerebral artery is affected (slide 26/27) what symptoms are seen?

Answer 21

• paralysis of contralateral structures , leg>arm, face
• Disturbance of intellect, executive function and judgement
• Loss of appropriate social behaviour

Question 22

If Middle cerebral artery is affected what are the symptoms?

Answer 22

‘Classic stroke features’

• Contralateral hemiplagia : arm/leg
• contralateral hemisensory deficits
• Hemianopia
• Aphasia ( L sided lesion )

Question 23

If posterior cerebral artery is affected, what are the symptoms?

Answer 23

Visual deficits:

• Homonymous hemianopia
• Visual agnosia