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CNIH > Vertebral arteries- collateral flow > Flashcards

Vertebral arteries- collateral flow Flashcards

1
Q

Vertebral basilar system provides how much cerebral blood flow?

A

20-30%

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2
Q

In the case of Vertebral occlusion near its origin flow is shunted to where? (2)

A

thyrocervical and costocervical trunks

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3
Q

What occurs in a vertebral artery occlusion?

A
  • flow is shunted to the thyrocervical and costocervical trunks
  • Compensatory enlargement of the opposite Vertebral artery occurs
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4
Q

Where do the vertebral arteries arise?

A

Subclavian arteries

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5
Q

how do the vertebral arteries course?

- where on cervical spine?

A
  • cephalad within the vertebral foramen on the transverse processes of the cervical spine C6-C2
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6
Q

How do the vertebral arteries enter the skull?

A

Through the foramen megnum

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7
Q

How to the vertebral arteries run intracranially?

A

anterior to the brain stem to form the Basilar A.

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8
Q

What is a normal variant of the vertebral arteries?

- what % of patients?

A

left vertebral artery may arise directly from the aortic arch- seen in 6% of patients

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9
Q

The basilar artery connects to the circle of willis via?

A

PCAA

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10
Q

Symptoms and signs of posterior circulation ischemia-vertobrobasilar territory

A

Dizziness / vertigo
Drop attacks/loss of consciousness
Difficulty ambulating/loss of balance
Ataxia(loss of full control of body movements)
Inability to maintain erect posture/muscular coordination
Upper extremity hypotonia/bilateral parasthesia
Blindness/blurred vision/diplopia/hemianopia/bilateral visual defects
Nystagmus(rapid involuntary movements of the eye)
Poorly reactive pupils
Difficulty focusing and reading
Memory loss
Somnolence(sleepiness or drowsiness)

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11
Q

Normal blood flow pattern- vertebrals?

  • resistance
  • simular to
  • velocity range
A
  • low-resistant
  • simular to ICA
  • velocity range from 20-60cm/s
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12
Q

What is images more frquently the right or left vertebral artery?

A

Right vertebral is imaged 80% of time

Left vertebral is imaged 60% of time

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13
Q

What part of the vertebral arteries is least likely to be diseased?

A

Mid portion is seen with least difficulty-least likely level diseased

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14
Q

What vertebral artery is larger? (LT OR RT)

A

Left

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15
Q

What % of vertebral arteries are hypoplastic?

A

7-10%

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16
Q

what should the vertebral flow direction be?

A

Antegrade (towards head)

17
Q

Spectral tracing must be displayed in correct directional orientation to rule out?

A

suspected Subclavian Steal Syndrome=SSS

18
Q

Vertebral flow-normal?

  • flow pattern?
  • windows?
  • velocities?
A
  • Normal flow pattern: Low resistant
  • Window not always present
  • Velocities 40-60 cm/s
19
Q

Vertebral arteries taking on a high resistant flow pattern and no diastolic component implies?

A
  • Distal VA stenosis or occlusion
  • Hypoplastic VA

S/S: dizziness and unsteady walking

20
Q

Collateral pathway if there is a LT SCA origin occlusion or high grade stenosis?

A

Flow is reversed in the ipsilateral vertebral artery

Subclavian steal syndrome

21
Q

SSS is and results from?

A
  • A short low resistant path (along the subclavian artery) becomes a high resistant path (due to narrowing)
  • hemodynamically significant stenosis or occlusion in proximal subclavian arteries can result in the vertebral acting as a collateral pathway
22
Q

SSS blood flows?

A
  • Blood flows around the narrowing via the arteries that supply the brain (left and right vertebral artery, left and right internal carotid artery)
  • The blood flow from the brain to the upper limb in SSS is considered to be stolen as it is blood flow the brain must do without
23
Q

Compensatory flow may be seen in the vertebral artery in the presence of?

A

ipsilateral carotid occlusive disease

24
Q

Increased peak velocities in the vertebrals show their ability to?

A

maintain flow via circle of Willis to cerebrum

25
Q

High-grade stenosis in SCA-SSS?

  • side
  • PSV
  • Signal
  • artifact
  • BP
  • distal flow
  • reversed flow
A
  • More common on the left side
  • High PSV >500cm/s
  • Loss of normal triphasic signal
  • Color aliasing
  • Decreased ipsilateral Brachial Artery systolic BP- 40mmhg difference between arms
  • Damped flow distally (monophasic)
  • Reversed flow ipsilateral VA
26
Q

When the VA has not completely reversed, exercising the arm will do what?

A

completely reverse the signal below the baseline

CNIH (69 decks)

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