Cerebral Vasculature

Question 1

What are the perfusion demands of the brain and why is this significant?

Answer 1

10-20% of cardiac output
20% of body O2 consumption
66% of liver glucose
The brain is therefore very vulnerable if the blood supply is impaired

Question 2

What are the two main arteries that supply the brain?

Answer 2

Internal carotid artery
Vertebral artery

Question 3

Once the internal carotid artery enters the skull, what does it continue as?

Answer 3

Middle cerebral artery

Question 4

Outline the venous drainage of the brain

Answer 4

Cerebral veins -> drain into the venous sinuses in the dura mater -> drain into the internal jugular vein

Question 5

What are the different types of haemorrhage?

Answer 5

Extradural
Subdural
Subarachnoid
Intracerebral

Question 6

Label the dural venous sinuses

Answer 6

Question 7

What causes extradural haemorrhages and describe the nature of clinical effects?

Answer 7

Trauma - usually trauma to the side of the head e.g. pterion - directly beneath is middle meningeal artery – requires immediate treatment – build up of pressure compresses brain stem – shut down of cardio respiratory centres

Immediate clinical effects

Question 8

What causes subdural haemorrhages and describe the nature of clinical effects?

Answer 8

Trauma
Clinical effects may be delayed

Question 9

Why may the clinical effects of a subdural haemorrhage be delayed and what is the significance of this?

Answer 9

Rupture of a vein - lower pressure
Subdural so more space to fill
If a person has trauma to the head and is unconscious but wakes up feeling fine later, keep in hospital overnight as they may develop a subdural haematoma

Question 10

What is a cause of subarachnoid haemorrhages?

Answer 10

Ruptured aneurysms - weakening in vessel wall ( likely congenital)
Usually an incidental finding
Big risk of rupture if patient is hypertensive

Question 11

What can causes Intracerebral haemorrhages?

Answer 11

Spontaneous hypertensive cause

Question 12

Identify a suitable diagnosis based on the image below

Answer 12

Subdural haematoma

Question 13

Answer 13

Intracerebral haematoma

Question 14

Identify a suitable diagnosis based on the image below

Answer 14

Extradural haematoma

Question 15

Answer 15

Subarachnoid haemorrhage

Question 16

What is a stroke?

Answer 16

Cerebrovascular accident - rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration

Question 17

What are the two main causes of stroke?

Answer 17

Thrombo-embolic (85%)
Haemorrhage (15%)

Question 18

Define a transient ischaemic attack?

Answer 18

A rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours

Question 19

Define infarction

Answer 19

Degenerative changes which occur in tissue following occlusion of an artery

Question 20

What is cerebral ischaemia?

Answer 20

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

Question 21

What is thrombosis?

Answer 21

Formation of a blood clot (thrombus)

Question 22

Define embolism

Answer 22

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

Question 23

What are the risk factors for stroke?

Answer 23

Age
Hypertension
Cardiac disease
Smoking
Diabetes Mellitus

Question 24

Label this diagram of cerebral artery perfusion fields

Answer 24

Question 25

What are the symptoms of a stroke affecting the anterior cerebral artery?

Answer 25

Paralysis of contralateral structures (usually leg) Disturbance of intellect, executive function and judgement (abulia) Loss of appropriate social behaviour - aggression, hypersexuality

Question 26

What are the symptoms of a stroke affecting the middle cerebral artery?

Answer 26

Known as the “Classic stroke” Contralateral hemiplegia (usually arm) Contralateral hemisensory deficits Hemianopia Aphasia (L sided lesion) - e.g. Wernicke’s area - receptive aphasia

Question 27

What are the symptoms of a stroke affecting the posterior cerebral artery?

Answer 27

Visual deficits: - homonymous hemianopia (affects same side - e.g. two left or two right visual field defects) - visual agnosia

Question 28

What major risk factor for stroke is evident in this specimen?

Answer 28

The yellow discolouration in the walls of the vessels is a build-up of atheroma, fatty deposits that cause atherosclerosis or “hardening of the arteries” - can cause blockages

Question 29

Which cerebral artery has been occluded in this specimen?

Answer 29

Right middle cerebral artery