Chapter 20

Question 1

what are capabilities for transcranial doppler TCD?

Answer 1

detect intracranial stenoses, occlusions, and assess collateral circulation
evaluate onset, severity and time course of vasoconstriction from subarachnoid hemorrhage
evaluate intracranial AVMs
assess patients with suspected brain death

Question 2

what are limitations for TCD?

Answer 2

recent eye surgery may eliminate transorbital approach
adequate penetration of temporal bone from hyperostosis
inaccurate vessel id with nonimaging techn

Question 3

what is patient positioning for TCDs?

Answer 3

patient supine and avoids speaking during exam

Question 4

what are the 3 acoustic windows for TCDs?

Answer 4

transtemporal, transorbital and transforaminal/suboccipital

Question 5

what frq pulsed doppler used?

Answer 5

2MHz

Question 6

what angle of insonation is assumed

Answer 6

zero

Question 7

what does accurate vessel id reguires?

Answer 7

• depth of sample volume
• velocity of the blood flow
• direction of the blood flow
• relationship of flow patterns to one another

Question 8

how is TCDs measured?

Answer 8

time average max velocity (TAMV) or mean velocity

Question 9

which vessels can you evaluate with the transtemporal approach?

Answer 9

MCA, ACA, PCA, terminal ICA

Question 10

with the transorbital approach what vessel do you identify?

Answer 10

ophthalmic artery and carotid siphon

Question 11

what approach would you use to evaluate the vertebral and basilar arteries?

Answer 11

transforaminal / suboccipital / transocciptal

Question 12

what is the depth used for a MCA?

Answer 12

30-60mm

Question 13

what is the depth used for terminal ICA?

Answer 13

55-65mm

Question 14

what is the depth for ACA

Answer 14

60-80mm

Question 15

what is the depth for PCA?

Answer 15

60-70mm

Question 16

what is the depth for ICA at siphon?

Answer 16

60-80mm

Question 17

what is the depth for ophthamlic?

Answer 17

40-60mm

Question 18

what is the depth for vertebral

Answer 18

60-90mm

Question 19

what is the depth for BA?

Answer 19

80-120mm

Question 20

what is the direction, velocity, and angle for MCA?

Answer 20

antegrade, 55cm/s, anterior and superior

Question 21

what is the direction, velocity, and angle for terminal ICA?

Answer 21

bi-directional, 55cm/s, anterior and superior

Question 22

what is the direction, velocity, and angle for ACA?

Answer 22

retrograde, 50 cms/s, anterior and superior

Question 23

what is the direction, velocity, and angle for PCA?

Answer 23

antegrade, 39cm/s, posterior

Question 24

what is the direction, velocity, and angle for ICA at siphon

Answer 24

paraseller-antegrade
supraclinoid-retrograde
genu-both directions

47cm/s
varies with angle

Question 25

what is the direction, velocity, and angle for ophth

Answer 25

antegrade, 21cm/, medial

Question 26

what is the direction, velocity, and angle for VA?

Answer 26

retrograde, 38cm/s, right and left of midline

Question 27

what is the direction, velocity, and angle for BA

Answer 27

retrograde, 41cm/s, midline

Question 28

what is flow chara based on?

Answer 28

``` direction velocity turbulance pulsatlity systolic upstroke ```

Question 29

what are the 3 collateral pathways?

Answer 29

cross over external to internal posterior to anterior

Question 30

what is the cross over collateral?

Answer 30

antegrade flow in ACA from cross-over collateraliztion | e.g flow from contralateral ACA via Acomm

Question 31

what is the external to internal collateral?

Answer 31

retrograde flow in ophthalmic artery

Question 32

what is the posterior to anterior collateral?

Answer 32

increased flow in PCA reversing direction of flow in the PCom artery

Question 33

what are factors that may alter intracranial blood flow?

Answer 33

age, sex, hematocrit, blood gases, metabolism

Question 34

where are occlusion most accurate?

Answer 34

most accurate in ICA or MCA

Question 35

which vessels do vasospasms happen?

Answer 35

most accurate in MCA

Question 36

what is the mean velocity for a vasospasm?

Answer 36

>120cm/s

Question 37

what is the velocity for a severe vasospasm?

Answer 37

>200cm/s

Question 38

what will happen with a AVM?

Answer 38

increased systolic and diastolic flow velocities very low pulsatility indices reduced flow in adjacent arteries

Question 39

T/F id of flow abnormalities may warrant change in surgical technique e.g carotid endarterectomy or coronary artery bypass grafting

Answer 39

true

Question 40

what is the technique for intraoperative monitoring?

Answer 40

headset utilized for continuous monitoring | not working in sterile field

Question 41

what is the interpretation for intraoperative monitoring?

Answer 41

significant decrease in MCA flow velocities during cross clamping of vessel may indicate need for shunting audible signal related to micro-emboli may alter surgical technq