blood supply to the central nervous system

Question 1

outline needs of blood supply to the brain.

Answer 1

brain = 2% body weight

• 10-20% cardiac output
• 20% O2 consumption
• 66% liver glucose.

Question 2

List sources of blood supply to brain.

Answer 2

Internal carotid arteries.

Vertebral arteries.

Circle of Willis

Cerebral arteries.

Question 3

Label arteries of brain (inferior view=

Answer 3

Question 4

Name components of venous drainage of brain.

Answer 4

Cerebral veins

Venous sinuses (formed from dura mater)

Dura Mater

Internal jugular vein

Question 5

Label diagram showing dura mater sinuses

Answer 5

Question 6

Define stroke.

Answer 6

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

Question 7

What proportion of strokes are infarctions.

Answer 7

85% (15% haemorrhage)

Question 8

Define TIA.

Answer 8

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

Question 9

Define infarction.

Answer 9

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

Question 10

Define cerebral ischaemia.

Answer 10

—Lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly (relating both to O2 and lack of nutrients)

Question 11

Name two cuases of occlusions.

Answer 11

Thrombosis

• formation of a blood clot (thrombus)

Embolism

-plugging of small vessel by material from larger vessel (e.g. thrombus from dislodged athersclerotic plaque)

Question 12

Epidemiology of stroke.

Frequency, percetnage of survivors disabled, percentage survivors showing obvious neurological deficit.

Answer 12

3rd commonst cause of death

100,000 deaths UK/year

50%

70%

Question 13

Name 5 main risk factors for stroke.

Answer 13

Age

Hypertension

Cardiac disease

Smoking

Diabetes Mellitus.

Question 14

Understand areas of brain supplied by key arteries. Label diagram.

Answer 14

Question 15

Cross sectional view of areas of brain perfused by key arteries. Label diagram.

Answer 15

Question 16

Give 3 characteristics of stroke affecting anterior cerebral artery

Answer 16

—Paralysis of contralateral leg > arm, face

—Disturbance of intellect, executive function and judgement (abulia)

—Loss of appropriate social behaviour

Question 17

Give 4 characteristics of stroke affecting the middle cerebral arteries.

Answer 17

—Contralateral hemiplegia: arm > leg

—Contralateral hemisensory deficits

—Hemianopia

—Aphasia (L sided lesion) (speech)

Question 18

Give characteristics of stroke affecting the posterior cerebral artery.

Answer 18

Visual deficits:

• homonymou hemianopia
• visual agnosia.

Question 19

What is a risk factor for lacunar infarcts?

Answer 19

hypertension

Question 20

What is a lacune

Answer 20

a small cavity

Question 21

Where are Lacunes found?

Answer 21

In deep structures. A result of small vessel occlusion.

Deficit dependent on anatomical location.

Question 22

List and outline 3 types of haemorrhagic stroke.

Answer 22

Extradural - trauma, immediate effects.

Subdural - trauma, delayed effects.

Subaracnoid - ruptured, aneurysms.

Intracerebral - spontaneous hypertensive.