1b Cerebral Vasculature Flashcards

1
Q

What percentage of the bodies oxygen consumption does the brain use?

A

20% - therefore the brain is very vulnerable if the blood supply is impaired

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2
Q

Describe the blood supply to the brain?

A

The common carotid artery is a branch of the brachiocephalic trunk - this splits into the internal and external carotid artery
the subclavian artery (second branch of brachiocephalic trunk) branches into vertebral artery

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3
Q

What is the point where the cerebral veins converge?

A

Point of confluence

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4
Q

What are the four types of haemorrhages?

A
  1. Extradural
  2. Subdural
  3. Subarachnoid
  4. Intracerebral
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5
Q

What is the most common cause of an extradural haematoma?

A

Trauma = blow to the pterion - rupture the middle meningeal artery

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6
Q

Why is an extradural haematoma a surgical emergency?

A

arterial bleed, therefore high pressure and loss of blood is fast

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7
Q

Why can the clinical effects of a subdural haematoma be delayed?

A

venous bleed therefore lower pressure so less of a clinical emergency

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8
Q

What will patients with a sub arachnoid bleed experience?

A

Thunderstorm headache

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9
Q

What causes subarachnoid bleeds?

A

ruptured aneurysms

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10
Q

What causes an intracerebral bleed?

A

Spontaneous hypertension

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11
Q

What is a stroke?

A

A rapidly developing focal disturbance of brain function of presumed vascular origin and greater than 24 hours in duration

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12
Q

What are the two main types of strokes?

A

Thrombo-embolic or haemorrhage

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13
Q

What is a TIA?

A

Transient Ischaemic Attack - rapidly reveloping focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours

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14
Q

What is an infarction?

A

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

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15
Q

What is cerebral ischaemia

A

Lack of sufficient blood supply to the nervous tissues resulting in permanent damage if blood flow is not restored properly

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16
Q

What is thrombosis?

A

formation of a blood clot

17
Q

What is an embolism?

A

plugging of a small vessel by material carried from a larger vessel eg thrombi from the heart or atherosclerotic debris from the internal carotid

18
Q

What are some key signs of a stroke?

A

Loss of symmetry
slurred speech
drooping of face and mouth - one side

19
Q

What are the risk factors for stroke? (5)

A

Diabetes mellitus
smoking
Age
Hypertension
Cardiac Disease

20
Q

Draw a diagram showing the cerebral artery perfusion fields?

A
21
Q

What symptoms would be experienced by patients if they have an anterior cerebral artery blockage?

A

Paralysis of contralateral structures with a tendancy for lower limbs over arm

Disturbance of intellect, executive function and judgment (Abulia)

Loss of appropriate social behaviour

22
Q

What symptoms would be experienced by patients if they have an middle cerebral artery blockage?

A

“Classic stroke”
Contralateral hemiplagia (upper limbs)
Contralateral hemisensory deficits
Hemaniopia
Aphasia (L Sided lesion)(brocks area)

23
Q

Why is hemiplagia common in middle cerebral artery conditions?

A

the middle cerebral artery supplies all pathways to the spinal cord, therefore there is likely to be subcortical damage

24
Q

What type of aphasia ill damage to Broca’s area produce?

A

Expressive Aphasia - they can understand but not reply

25
Q

What type of aphasia will damage to Wernicke’s area produce?

A

Receptive Aphasia - cannot understand but can speak

26
Q

What does damage to the posterior cerebral artery result in?

A

Visual defects - homonymous hemaniopia and visual agnosia

27
Q

What is agnosia?

A

Inability to recognise faces

28
Q

What is a major risk factor for stroke?

A

Atherosclerosis - yellow discolouration in the walls of the vessel represent atherosclerosis or hardening of the arteries

29
Q

Draw the circle of willis

A
30
Q

What is the benefit of the circle of willis?

A

Compensatory flow - if one of the arteries is lacking - the others can compensate

31
Q

What is the treatment for Subdural Haematoma?

A

Burr Holes - remove skull flap and then remove blood

32
Q

What are the signs of an intra-cerebellar bleed?

A

Drowsy, slurred speech, wobbly eye movements, ataxia, broad based gait

33
Q

Which type of bleed is due to hypertension usually?

A

Intra-parenchymal bleed

34
Q

What is the treatment for Intra-parenchymal bleeds?

A

Manage hypertension - usually difficult to remove surgically as it is inside the brain

35
Q

Which cerebral artery has the largest perfusion field?

A

Middle cerebral artery

36
Q

Stroke of which artery results in a disturbance of intellect, executive function and judgement?

A

Anterior cerebral artery

37
Q

What causes a venous haemorrhage?

A

Shearing of bridging veins

38
Q

What is the presentation of a subdural haemorrhage?

A

Gradually worsening headache - due to pressure building up

Drowsiness / loss of consciousness due to pressure on the brainstem

39
Q

If a lemon shaped bleed is on a CT, which type of bleed is this?

A

Extradural bleed