2.4 Cerebral Vasculature

Question 1

What % of cardiac output does the brain require?

Answer 1

10-20%

Question 2

What % of body O2 consumption does the brain require?

Answer 2

20%

Question 3

Why is the brain so vasularised?

Answer 3

high metabolic demands

Question 4

What % of liver glucose does the brain require?

Answer 4

66%

Question 5

Where does the basilar artery sit?

Answer 5

the base of the pons

Question 6

How does venous blood drain from the brain?

Answer 6

cerebral veins
venous sinuses into the dura mater
internal jugular vein
heart

Question 7

How would blood drain from the superior sagittal sinus?

Answer 7

into the confluence of sinuses 
into the transverse sinus
into the sigmoid sinus
through the jugular foramen
then becomes the internal jugular vein

Question 8

Where are the venous sinuses?

Answer 8

lie in-between the two layers of the dura mater
outer periosteal layer of dura mater
inner meningeal layer of dura mater

Question 9

Is there space in between the dura and the skull?

Answer 9

no

Question 10

What are the 3 layers of the meninges?

Answer 10

skull
dura (split into two layers)
arachnoid
pia
brain

Question 11

What are the 4 types of haemorrhage?

Answer 11

extradural
subdural
subarachnoid
intracerebral

Question 12

Where is the most likely place of an extradural haemorrhage?

Answer 12

the pterion

where the frontal, parietal, temporal, and sphenoid bones join

Question 13

What is an extradural haemorrhage?

Answer 13

arterial bleed (bleeding from arterial supply to dura)
high pressure so forces blood inbetween dura and skull
leads to very high intercranial pressure --> immediate clinical effects

Question 14

What is an extra-dural haemorrhage caused by?

Answer 14

trauma

Question 15

What is an subdural haemorrhage caused by?

Answer 15

trauma

Question 16

What is an subarachnoid haemorrhage caused by?

Answer 16

ruptured aneurysms

aneurysms often congenital

Question 17

What is an intracerebral haemorrhage caused by?

Answer 17

spontaneous hypertensive

often those with chronic hypertension

Question 18

Where is a subdural haemorrhage?

Answer 18

bleeding in between the dura and arachnoid

Question 19

What is the presentation of a subdural haemorrhage?

Answer 19

loss of consciousness then wake up
delayed onset symptoms slowly getting worse
venous, lower pressure

Question 20

What is a stroke?

Answer 20

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

Question 21

What are the two types of stroke?

Answer 21

thrombo-embolic (85%) (blockages)

haemorrhage (15%)

Question 22

What is a transient- ischaemic attach (TIA)?

Answer 22

rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours
(>24 hr = stroke, <24 = TIA)

Question 23

What is an infarction?

Answer 23

degenerative changes which occur in tissue following occlusion of an artery

Question 24

What is cerebral ischaemia?

Answer 24

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

Question 25

Why should you investigate a TIA?

Answer 25

warning sign for stroke further down the line

Question 26

What is thrombosis?

Answer 26

formation of a blood clot (thrombus)

Question 27

What is an embolism?

Answer 27

plugging of small vessel by material carried from larger vessel e.g. thrombi from the heart or athesclerotic debris from the internal carotid, air

Question 28

Why is stroke a major public health issue?

Answer 28

50% survivors permanently disabled 70% show obvious neurological deficit 3rd commonest death FAST (face, arms, speech, time)

Question 29

What are the risk factors for stroke? (5)

Answer 29

age hypertension cardiac disease (leads to forming of clots) smoking diabetes mellitus --> many are risk factors due to effects on vasculature

Question 30

What are the 3 main cerebral arteries?

Answer 30

anterior cerebral artery middle cerebral artery posterior cerebral artery

Question 31

Which artery has the biggest perfusion field?

Answer 31

middle cerebral artery

Question 32

What is the perfusion field of the anterior cerebral artery?

Answer 32

midline structures all the way until the parietal occipital fissure

Question 33

What is the perfusion field of the middle cerebral artery?

Answer 33

temporal fossa area (covering part of the temporal, parietal and frontal) part of brain

Question 34

What is the perfusion field of the posterior cerebral artery?

Answer 34

occipital lobe and inferior part of temporal lobe

Question 35

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

Answer 35

paralysis of contralateral (opposite structure) (leg> more than arm, face) (motor cortex) disturbances of intellect, executive function and judgement = abulia (frontal lobe) loss of appropriate social behavior (frontal lobe)

Question 36

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

Answer 36

classic stroke paralysis of contralateral structures (hemiplegia): usually arm not leg, could be whole side of body as deep motor structures contralateral hemisensory defects (sensory cortex) hemianopia loss of one half of visual field. aphasia if left sided lesion

Question 37

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

Answer 37

``` Mostly visual field defects homonymous hemianopia (cannot see left half of field in both eyes for example) visual agnosia (cannot visually process) ```