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Pathology > Cardiovascular disease & its effect on vision > Flashcards

Cardiovascular disease & its effect on vision Flashcards

1
Q

what is a transient ischaemic attack known as

A

a temporary disruption go blood supply (that results on no long term damage)

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2
Q

what can a transient ischaemic attack be the result from

A

an embolism (such as a circulating fragment of an atheromatous plaque) temporarily blocking a vessel, the function of the area supplied by the vessels in impaired

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3
Q

what happens when the embolism moves on in a transient ischaemic attack

A

function returns

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4
Q

name an example of a specific TSA associated with the eyes

A

amaurosis fugax (fleeting darkness/blindness)

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5
Q

what is amaurosis fugax

A

a painless unilateral loss of vision resulting from a transient retinal ischaemia caused by an embolism in the retinal vasculature

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6
Q

what is the loss in vision described as by a patient, of amaurosis fugax

A

vision goes dark, like a curtain descending or ascending on the eye for a short period of time, which then vision goes back to normal

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7
Q

what do the inner 5 layers of the retina receive oxygenated blood from

A

central retinal artery

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8
Q

what is the central retinal artery a branch off

A

ophthalmic artery

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9
Q

what does the ophthalmic artery arise from

A

carotid artery (a branch off the aorta)

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10
Q

what happens in the ophthalmic artery as a result of amaurosis fugax

A

a dislodge is stuck in the ophthalmic artery, patient goes blind as the retina becomes ischaemic & stops functioning, then the blood clot breaks up and resolves itself whereby patient can see again

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11
Q

what may form a transient occlusion of a retinal vessel

A

an atheromatous plaque in the carotid artery which may disintegrate

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12
Q

what may emboli of an atheromatous plaque in the carotid artery which may form a transient occlusion of a retinal vessel be made of

A

various materials such as:
cholesterol crystals
platelet aggregates
lipid

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13
Q

instead of an emboli (which is most common), what else can be the cause of transient ischaemic event

A

vasopastic events such as:
unusual narrowing of vessels (artery contracts itself)
or
haematological causes such as:
abnormalities in blood constituents e.g. sickle cell anaemia

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14
Q

why is the CNS particularly susceptible to infarction

A

it needs a continuous supply of oxygen & CNS tissue does not regenerate

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15
Q

what are cerebrovascular accidents CVAs most commonly know as, and what causes it

A

stroke

blood supply to vessels which supply the brain become blocked so it becomes non functional (infarct)

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16
Q

what are the two sources which supply the brain with oxygenated (arterial) blood

A
  • 2 internal carotid arteries

- 2 vertebral arteries

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17
Q

which part of the brain do the 2 internal carotid arteries supply

A

anterior

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18
Q

which areas do the 2 vertebral arteries supply

A

poster brain & spinal chord

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19
Q

what do the 2 vertebral arteries merge to form

A

basilar artery

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20
Q

what are the internal carotid & basilar arterial supplies united by

A

anterior & posterior communicating arteries at the circle of willis (found at the base of the brain)

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21
Q

why does the brain have two blood supplies

A

if one blood supply is impaired, the other can supply the brain

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22
Q

which three arteries arise fro the circle of willis

A

anterior cerebral artery
middle cerebral artery
posterior cerebral artery

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23
Q

what area of the brain does the anterior cerebral artery supply

A

front

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24
Q

what area of the brain does the middle cerebral artery supply

A

middle

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25
Q

what part of the brain does the posterior cerebral artery supply

A

back

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26
Q

what are the two types of stroke

A
  • hemorrhagic

- occlusive (ischaemic)

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27
Q

what is a hemorrhagic stroke caused by

A

a ruptured aneurysm or an AVM
(blood comes/leaks out & that area of the brain does not receive oxygen from the vessel & that part of the brain stays dead forever)

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28
Q

what % does a hemorrhagic stroke account for from all strokes

A

20%

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29
Q

what is an occlusive (ischaemic) stroke caused by

A

a thrombosis (blood clot) on an atheromatous plaque

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30
Q

how many % of strokes does an occlusive ischaemic stroke account for

A

80%

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31
Q

which type of stroke will be helped by medication

A

occlusive (ischaemic)

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32
Q

how does medication treat an occlusive (ischaemic) stroke

A

by unblocking the vessel

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33
Q

why is medication not suitable for hemorrhagic strokes

A

medication can make it worse (if for stopping clotting)

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34
Q

what is a result of both hemorrhagic and occlusive (ischaemic) strokes

A

brain tissue at one part of the brain to die

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35
Q

how does a CVA effect vision

A

by effecting one of the 30 visual areas of the brain (different parts of brain deal with different aspects of vision)

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36
Q

what does the early part of the visual pathway consist of

A

projections from the retina, along the optic pathway, via the LGN to v1 (area 17 or striate cortex)
can have a stroke at any of these areas

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37
Q

which part of the brain is the striate cortex located

A

occipital lobe/back of the brain

38
Q

what supplies the occipital lobe/back of brain

A

posterior cerebral artery

39
Q

what can a blockage of the PCA e.g. from a thrombosis result in

A

death of cells in v1 and patient will become blind in that hemifield (bilateral hemianopia) BUT with macular sparing

40
Q

what is the reason for macular sparing of a patient who has had a blockage of their PCA which resulted in the death of v1 cells

A

the posterior part of the occipital cortex, which subserves macular vision, also receives blood supply from the MCA (so lose most vision in that field due to blocked PCA, except macula)

41
Q

what type of attribute do v1 cells do for an image

A

basic attributes

42
Q

what does stroke to a particular area of extra striate cortex cause

A

a particular attribute of vision loss i.e. specific agnosias

43
Q

what does a lesion to area v4 result in

A

achromatopsia (form vision normal etc)

not due to loss of visual pigment, things actually look black & white

44
Q

what can a lesion to area v5 result in

A

disturbed motion detection - akinotopsia (won’t see cars moving or pouring of tea will look like frozen glacier)

45
Q

what can a lesion/damage to the temporal lobe by a stroke result in

A

inability to distinguish faces, even familiar ones - prosopagnosia

46
Q

what can also impair visual function, apart from a hemorrhagic or occlusive stroke

A

an aneurysm

47
Q

where do 80-90% of aneurysms occur

A

in the circle of willis

48
Q

where do aneurysms most often form and why

A

where vessels branch, as they are the weakest here

49
Q

what happens to the BV from an aneurysm

A

BV bulges out and presses on things

50
Q

what can an aneurysm of the internal carotid artery compress

A

the lateral aspect of the chiasm

51
Q

what does the lateral aspect of the chiasm house

A

uncrossed temporal fibres from the ipsilateral eye

52
Q

what will a lesion to the uncrossed temporal fibres from the ipsilateral eye (from internal carotid aneurysm) result in

A

disruption of the temporal retina of the ipsilateral eye, causing nasal field loss (ipsilateral nasal hemianopia)

53
Q

as well as an aneurysm compressing the visual pathway, what can it also affect which can affect vision

A

compressing a cranial nerve

54
Q

what other type of aneurysm of the carotid is there, as oppose to one causing damage to the chiasm

A

damage to the wall of the cavernous sinus (where the carotid also lies near)

55
Q

how many % do intracavernous carotid aneurysms account for of all intracranial aneurysms

A

2-3% rare

56
Q

what are the unique set of symptoms of an intracavernous carotid aneurysm based on

A

arrangement of cranial nerves and symptoms are largely ocular

57
Q

what does the carotid artery lie within

A

the walls of the cavernous sinus

58
Q

what system is the cavernous sinus a part of

A

venous drainage system of the brain

59
Q

which wall of the cavernous sinus does the internal carotid lie within

A

medial wall of cavernous sinus

60
Q

of which arteries is the blood pressure highest

A

in the major arteries nearest the heart

61
Q

why is venous pressure much lower than arterial

A

they are far from the pump of the heart and due to elasticity nature of veins

62
Q

when can an aneurysm within the artery wall compress the sinus

A

as the pressure in the internal carotid artery exceeds that of the cavernous sinus

63
Q

what will a compression of the cavernous effect

A

the cranial nerves that lire within the walls of the sinus, which will impact several ocular structures

64
Q

what can damage to the oculomotor CN 3 cause

A

damage to fibres which go to:

  • ciliary muscle - effects/impairs accommodation
  • iris sphincter - impairs pupil constriction
  • levator palpebrae - impaires eyelid to open/raise causing ptosis
  • 4 EOMS - MR, SR, IR, IO - impaires eye movements
65
Q

what can damage to the trochlear CN 4 cause

A

loss of innervation of superior oblique EOM

66
Q

what can damage to the ophthalmic division of the trigeminal CN 5 cause

A

loss of sensation of anterior eye e.g. cornea

67
Q

what can damage to the abducens CN 6 cause

A

loss of innervation of lateral rectus EOM

68
Q

list the CNs which disrupt eye movements

A
  • oculomotor 3rd
  • trochlear 4th
  • abducens 6th
69
Q

why are pupil anomalies complex

A

as both parasympathetic fibres in the 3rd CN and sympathetic fibres from the SCG are associated with the cavernous sinus, so both may be affected, therefore the pupil may be sluggish and smaller than usual/not normal

70
Q

what is a fistula

A

any connection between two structures which shouldn’t be connected

71
Q

what can there be a fistula of, as a direct result of ruptured aneurysms

A

cavernous venous sinus & carotid artery

72
Q

what type of people are connections/fistula of the cavernous sinus and carotid artery in

A

middle ages females or caused by head trauma (75%)

73
Q

what does the cavernous sinus do

A

takes deoxygenated blood from the eye

74
Q

due to higher pressure in the arterial system, what will fistula od the cavernous sinus and carotid artery result in

A

the sudden onset of many of the symptoms associated with a carotid artery aneurysm such as ophthalmegia (paralysis of intra and extra ocular muscles)

75
Q

as the cavernous sinus receives venous blood from the eye, what can happen in a case of an accident such as whiplash & which mainly occurs in women

A

ocular vessels become engorged i.e. blood goes in the opposite direction in the vein

76
Q

what things can severe engorgement result in

A
  • chemosis
    or
  • exophthalmus/pulsatile proptosis
77
Q

what is chemosis (as a result of severe engorgement)

A

bulba conjunctiva full of blood, cornea is fine

78
Q

what is exophthalmus/pulsatile proptosis, (as a result of severe engorgement)

A

as the heart pumps, the eye pushes out

79
Q

what can an aneurysm of the posterior communicating artery in the circle of willis present

A
  • a sudden onset of full 3 CN palsy - ptosis, abnormal eye position, dilated and fixed pupil
    &
  • a severe unilateral frontal headache
80
Q

what is cranial arteritis

A

inflammation of the medium to large arteries coming off the aorta, (most notably those associated with the carotid system)

81
Q

what actions should be taken is cranial arteritis is detected

A

ocular emergency, immediate referral

82
Q

what part of the BV/artery gets inflamed in cranial arteritis

A

lots of inflammatory cells within the tunica interna of artery leading to its fragmentation & among these are giant multinucleate cells & one of those inflammatory cells is a huge macrophage

83
Q

what leads to the occlusion of the vessels as a result of cranial arteritis

A

lots of inflammatory cells within the tunica interna of artery leading to its fragmentation & among these are giant multinucleate cells & one of those inflammatory cells is a huge macrophage, & the proliferation of cells within the tunica interna

84
Q

what are the major symptoms of a cranial arteritis

A

headache & tenderness of the scalp

85
Q

why is headaches & tenderness of the scalp symptoms of cranial arteritis

A

due to involvement of the superficial temporal arteries and pain of the jaw when eating

86
Q

how can cranial arteritis also result in severe visual defects

A

as the ophthalmic artery (which arises from the internal carotid) is also affected & as this artery supplies to most of the eye, its disruption can result in a large number of ocular symptoms

87
Q

which branch of the ophthalmic artery is particularly effected in cranial arteritis

A

posterior ciliary arteries (which form a circle around the ONH)

88
Q

what do the posterior ciliary arteries supply

A

the circle of Zinn-Haller

89
Q

what do the circle of Zinn-Haller supply

A

nutrients to the ONH

90
Q

what does the disruption of the ciliary arteries cause

A

anterior ischaemic optic neuropathy (neuropathy of the anterior part of the optic nerve) can cause blindness in that eye

91
Q

which other artery which supplies the retina can also be effected by cranial arteritis

A

central retinal artery

92
Q

which artery is thought to be associated with the sudden blindness that results from cranial arteritis

A

disruption to the posterior ciliary arteries affecting the ONH (circle of Zinn-Haller)

Pathology (20 decks)

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