Cerebral Vasculature

Question 1

perfusion demands of 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
it is therefore very vulnerable if the blood supply is impaired

Question 2

blood supply to the brain

Answer 2

brachiocephalic trunk -> common carotid and subcalvian arteries
common carotid -> internal carotid and (external carotid)
subclavian -> vertebral artery and (others)

common carotid, internal carotid, vertebral arteries

Question 3

arteries of the brain

Answer 3

circle of willis

Question 4

venous drainage of the brain

Answer 4

blood in great cerebral vein -> dural venous sinuses -> superior sagittal sinous -> drains to back of head into occipital area -> confluence of sinuses -> drains laterally into transverse then sigmoid sinus -> internal jugular vein

Question 5

intracranial haemorrhage

Answer 5

bleeding within the cranial cavity

important to know where exactly bleed is to manage symptoms and inform treatment

Question 6

types of haemorrhage

Answer 6

• extradural
• subdural
• subarachnoid
• intracerebral

Question 7

extradural haemorrhage

Answer 7

trauma
immediate clinical effects
arterial, so high pressure
acute emergency, can cause dura to peel away from skull due to pressure
commonly seen in pterion fractures, as middle meningeal artery runs behind

Question 8

subdural haemorrhage

Answer 8

trauma
delayed clinical effects
venous, so lower pressure
can take hours or days to develop

Question 9

subarachnoid haemorrhage

Answer 9

ruptured aneurysms (weaknesses in vessel walls that are generally congenital)
causes increased intercranial pressure
most relevant at base of skull in circle of willis

Question 10

intracerebral haemorrhage

Answer 10

spontaneous hypertensive
usually close to the origin of the middle cerebral artery
chronic hypertension can cause these bleeds

Question 11

stroke

Answer 11

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

85% thrombo-embolic
15% haemorrhagic

Question 12

transient ischaemic attack

Answer 12

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

Question 13

infarction

Answer 13

degenerative changes which occur in tissue following occlusion of an artery

Question 14

cerebral ischaemia

Answer 14

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

Question 15

thrombosis

Answer 15

formation of a blood clot (thrombus)

Question 16

embolism

Answer 16

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 (can also be blocked by air)

Question 17

public health statistics for stroke

Answer 17

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

Question 18

risk factors for stroke

Answer 18

age
hypertension (haemorrhage risk)
cardiac disease (blood clot risk)
smoking (general effects on vasculature)
diabetes mellitus (general effects on vasculature)

Question 19

anterior cerebral artery perfusion field

Answer 19

midline portions of the frontal lobes

superior medial parietal lobes

Question 20

middle cerebral artery perfusion field

Answer 20

lateral portion of the frontal lobe
lateral surface of the temporal and parietal lobes (including the primary motor and sensory areas of the face, throat, hand and arm)
areas for speech (in the dominant hemisphere)
most subcortical deep structures

Question 21

posterior cerebral artery perfusion field

Answer 21

occipital lobe
inferior part of the temporal lobe
various deep structures (including the thalamus and the posterior limb of the internal capsule)

Question 22

ACA stroke symptoms

Answer 22

paralysis/hemiplegia of contralateral structures (leg > arm, face)
disturbance of intellect, executive function and judgement (abulia)
loss of appropriate social behaviour

Question 23

MCA stroke symptoms

Answer 23

“classic stroke”
paralysis/hemiplegia of contralateral structures (arm > leg)
contralateral hemisensory deficits
hemianopia
aphasia/inability to comprehend or formulate language (only if brocas area affected, usually in left sided lesions)

Question 24

PCA stroke symptoms

Answer 24

visual deficits:
homonymous hemianopia
viisual agnosia (unable to identify objects)
prosopagnosia (unable to recognise faces)