Blood Supply To The Central Nervous System

Question 1

Demands of the brain

Answer 1

Brain makes up 2% of body weight but uses:

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

Question 2

Blood supply to the brain

Answer 2

Two sources:
     - internal carotid arteries
     -vertebral arteries
Circle of Willis
Cerebral arteries

Slide 5 [pic]

Question 3

Arteries of brain

Answer 3

Slide 6-8 [pic]

Vertebral artery come together to form basilar artery (just in front of the pons).
Basilar artery splits into posterior cerebral arteries
Middle cerebral artery has many branches:
- anterior cerebral artery
- internal carotid artery

Question 4

Venous drainage of the brain

Answer 4

Cerebral veins
Venous sinuses
Dura mater
Internal jugular vein

Slide 9 [pic]

Question 5

Which of the following arteries of the circle of Willis is unpaired?

1. Anterior cerebral
2. Anterior communicating
3. Middle cerebral
4. Posterior cerebral
5. Posterior communicating

Answer 5

Anterior communicating

Question 6

Stroke

Answer 6

Cerebrovascular accident (CVA)
Rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration
Infarction (85%) or haemorrhage (15%)

Question 7

Transient Ischaemic Attack (TIA)

Answer 7

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

Question 8

Infarction

Answer 8

Degenerative changes which occur in tissue following occlusion of an artery

Question 9

Cerebral ischaemia

Answer 9

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

Question 10

Causes of occlusions

Answer 10

Thrombosis
- formation fo a blood clot (thrombus)
Embolism
- plugging of small vessel by material carried from larger vessel, e.g. thrombi from the heart or atherosclerotic debris from the internal carotid

Question 11

Epidemiology of stroke

Answer 11

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

Question 12

Risk factor for stroke

Answer 12

Age
Hypertension
Cardiac disease
Smoking
Diabetes mellitus

Question 13

Middle cerebral artery

Answer 13

Supplies lateral part of brain

Slide 21-22 [pic]

Question 14

Anterior cerebral artery

Answer 14

Supplies along the midline (parasaggital)

Slide 21-22 [pic]

Question 15

Posterior cerebral artery

Answer 15

Inferior part of temporal lobe
Most of occipital lobe

Slide 22-23 [pic]

Question 16

Probelm with anterior cerebral artery diffusion area

Answer 16

Paralysis of contralateral leg> arm, face
Disturbance of intellect, executive function and judgement (abulia)
Loss of appropriate social behaviour

Question 17

Probelm with middle cerebral artery

Answer 17

“Classic stroke”
Contralateral hemiplegia: arm>leg
Contralateral hemisensory deficits
Hemianopia
Aphasia (L sided lesion)

Question 18

Probelms with posterior cerebral artery

Answer 18

Visual deficits

- homonymous hemianopia
 - visual agnosia

Question 19

Lacunar infarcts

Answer 19

Lacune is a small cavity
Appear in deep structures as a result of small vessel occlusion
Deficit is dependent on anatomical location
Hypertension

Question 20

Haemorrhagic stroke

Answer 20

Extradural - trauma, immediate effects
Subdural - trauma, delayed effects
Subarachnoid - ruptured aneurysms
Intracerebral - spontaneous hypertensive