Blood Supply to the Brain and the Clinical Relevance

Question 1

how long duration of anoxia to the brain causes unconsciousness

Answer 1

20 seconds

Question 2

how long duration of anoxia causes permanent unconsciousness and neurone death

Answer 2

5 mins

Question 3

normotensive cerebral bloodflow

Answer 3

~50ml/100g brain per min

Question 4

how does CO2 and O2 content in blood affect bloodflow to brain

Answer 4

incr CO2 or decr O2 increases bloodflow

Question 5

what does autoregulation of cerebral bloodflow ensure

Answer 5

enough bloodflow to brain over wide range of BP and sO2

Question 6

what mean arterial pressures can sufficient cerebral bloodflow be regulated over

Answer 6

60-160 mmHg

Question 7

why is venous return from the brain more reliant on gravity than other bodyparts

Answer 7

no valves, muscles, or elasticity to help return

Question 8

2 arteries supplying total cerebral bloodflow

Answer 8

carotid arteries
vertebral arteries

Question 9

are the anterior and posterior communicating arteries usually open or closed

Answer 9

closed

Question 10

does each vertebral artery supply 1 or 2 hemispheres

Answer 10

1 unless artery blockage opens communicating arteries

Question 11

which cerebral artery has the largest territory

Answer 11

middle cerebral artery

Question 12

3 arteries supplying the cerebral cortex

Answer 12

posterior cerebral artery
middle cerebral artery
anterior cerebral artery

Question 13

what creates watershed regions in brain bloodsupply

Answer 13

anastomoses between arteries

Question 14

posterior cerebral circulation main 3 branches

Answer 14

vertebral arteries
basilar artery
posterior cerebral artery

Question 15

what does PICA branch from and supply

Answer 15

branches from vertebral artery
supplies dorsal medulla of brainstem

Question 16

what does the basilar artery supply

Answer 16

pons
cerebellum

Question 17

what does the posterior cerebral artery supply

Answer 17

inferior ad medial aspects of temporal and occipital cortex
thalamus
posterior internal capsule
midbrain

Question 18

arteries supplying the midbrain

Answer 18

posterior cerebral artery
superior cerebellar artery
posterior communicating artery
interpeduncular rami of posterior cerebral artery

Question 19

arteries supplying the pons

Answer 19

basilar artery - long circumferential, short circumferential, and paramedian branches

Question 20

arteries supplying the medulla

Answer 20

posterior inferior cerebellar artery
anterior inferior cerebellar artery
anterior spinal artery

Question 21

which veins cross the subarachnoid space

Answer 21

superficial cerebral veins (become bridging veins)

Question 22

which veins pierce the dura and enter the dural venous sinuses

Answer 22

bridging veins

Question 23

which way do arachnoid granulations allow CSF to flow between dural sinuses and the subarachnoid space

Answer 23

into sinuses
prevent blood backflow into subarachnoid space

Question 24

which dural sinus controls 80% of venous return from the brain

Answer 24

superior sagittal sinus

Question 25

which 3 sinuses converge and the confluence of sinuses

Answer 25

superior sagittal sinus, straight sinus, and occipital sinus

Question 26

dural venous sinuses

Answer 26

superior sagittal sinus inferior sagittal sinus straight sinus signmoid sinus occipital sinus transverse sinus comfluence of sinuses

Question 27

is right or left dominance more common in cerebral venous drainage

Answer 27

right

Question 28

what can cause spontaneous cerebral haemorrhage

Answer 28

arterio venous malformation aneurism

Question 29

causes of haemorrhagic stroke

Answer 29

hypertension aneurism elderly trauma alcoholism arteriovenous malformation

Question 30

how does age and alcoholism increase haemorrhagic stroke risk

Answer 30

brain atrophy and neurone loss -> bridging veins sink -> higher tension on bridging veins -> increased risk of breakage

Question 31

effect of MCA stroke in left hemisphere

Answer 31

global aphasia sensorimotor loss on contralateral face, upper limb, and trunk

Question 32

effect of MCA stroke in right hemisphere

Answer 32

neglect syndrome

Question 33

neglect syndrome

Answer 33

contralateral hemispatial neglect - ignore 1/2 of everything

Question 34

why does neglect syndrome generally improve over time

Answer 34

other parts of brain take over from damaged part

Question 35

effects of ACA stoke

Answer 35

contralateral sensorimotor loss below waist urinary incontinence personality defects - unemotional then impulsive split brain syndrome

Question 36

why does ACA stroke cause split brain syndrome

Answer 36

ACA supplies corpus callosum

Question 37

TIA

Answer 37

transient episode of neurological dysfunction caused by focal brain, spinal cord, or retina ischaemia without acute infarction

Question 38

what is a TIA a warning sign of

Answer 38

heart attack stroke

Question 39

anterior circulation TIA symptoms

Answer 39

motor weakness hemi sensory loss dysarthria transient monocular blindness - blocked opthalmic artery

Question 40

posterior circulation TIA symtoms

Answer 40

vertigo diplopia ataxia amnesia

Question 41

do TIA symptoms always return to normal within 24 hours

Answer 41

no - multiple TIAs could cumulate in permanent damage

Question 42

where does blood collect in an epidural, subdural, and subarachnoid haematoma

Answer 42

epidural - between skull and dura mater subdural - between dura mater and arachnoid mater subarachnoid - between arachnoid mater and pia mater

Question 43

where is extra axial bleeding

Answer 43

outside brain tissue - epidural, subdural, and subarachnoid

Question 44

which type of extra axial bleed is most common

Answer 44

subarachnoid

Question 45

rupture of which veins causes subdural haematoma

Answer 45

bridging veins

Question 46

causes of extra axial bleeds

Answer 46

trauma aging ruptured aneurysm ruptured arteriovenous malformation

Question 47

how may a traumatic epi/extradural haematoma present

Answer 47

lucid period immediately after trauma then unconsciousness

Question 48

which blood vessels commonly cause epi/extradural haematoma

Answer 48

middle meningeal artery anterior ethmoidal artery large venous sinuses

Question 49

do epi/extradural haematomas cross suture lines

Answer 49

no - dura more tightly attached at sutures

Question 50

epi/extradural haematoma symptoms

Answer 50

contralateral weakness of extremities contralateral visual field loss CN3 compression

Question 51

how do epi/extradural haematomas cause symptoms

Answer 51

blood collection compresses intracranial structures

Question 52

3 types of subdural haematoma

Answer 52

acute subacute chronic

Question 53

what source of subdural haematoma has the slowest onset

Answer 53

venous bleeds - can take days to weeks

Question 54

subdural haematoma symptoms

Answer 54

irritability seizures headache numbness disorientation

Question 55

do subdural haematomas cross suture lines

Answer 55

yes

Question 56

subarachnoid haemorrhage symtoms

Answer 56

thunderclap headache vomiting confusion lowered/fluctuating consciousness

Question 57

extra/epidural, subdural, and subarachnoid haematoma appearance on CT

Answer 57

extra/epidural - biconvex hyperdense subdural - crescent hyperdense subarachnoid - white diffuse signal over sulci

Question 58

which type of extraaxial bleed can cause blood or bilirubin to be present in lumbar puncture

Answer 58

subarachnoid

Question 59

xanthochromia

Answer 59

presence of bilirubin in the cerebrospinal fluid

Question 60

2 types of cerebral aneurysm

Answer 60

saccular fusiform

Question 61

what type of extra axial bleed is caused by aneurysm rupture

Answer 61

subarachnoid

Question 62

where do brain aneurysms tend to form

Answer 62

junction points

Question 63

is a berry aneurysm a type of saccular or fusiform anaurysm

Answer 63

saccular

Question 64

how can a saccular aneurysm be prevented from rupturing

Answer 64

stent vessel clip aneurysm fill with coil

Question 65

risks from brain arteriovenous malformations

Answer 65

damage to surrounding tissue leakage weak spots in vascular system

Question 66

how can arteriovenous malformations be treated

Answer 66

radiotherapy surgical resection embolisation