Transcranial Doppler ch.23

Question 1

What vessels does the transtemporal window for a TCD evaluate?

Answer 1

MCA, ACA, Terminal ICA, PCA

Question 2

What vessels does the suboccipital/ transforamenal window for a TCD evaluate?

Answer 2

VA, BA

Question 3

What vessels does the transorbital window for a TCD evaluate?

Answer 3

ICA and ophthalmic

carotid siphon

Question 4

vessel: MCA

window, depth, direction, velocity, and angle

Answer 4

transtemporal, 30-60 mm, antegrade, 55 +/- 12, anterior and superior

Question 5

vessel: terminal ICA

window, depth, direction, velocity, angle

Answer 5

transtemporal, 55-65 mm, bidirectional, 55 +/- 12, anterior and superior

Question 6

vessel: ACA

window, depth, direction, velocity, angle

Answer 6

transtemporal, 60-80mm, retrograde, 50 +/- 11, anterior and superior

Question 7

vessel: PCA

window, depth, direction, velocity, angle

Answer 7

transtemporal, 60-70mm, antegrade, 39 +/- 10, posterior

Question 8

vessel: ICA

window, depth, direction, velocity, angle

Answer 8

transorbital, 60-80mm, parasellar: antegrade supraclinoid: retrograde genu: both, 47 +/- 14, varies

Question 9

vessel: ophthalmic

window, depth, direction, velocity, angle

Answer 9

transorbital, 40-60mm, antegrade, 21 +/- 5, medial

Question 10

vessel: VA

window, depth, direction, velocity, angle

Answer 10

transforamenal/ suboccipital, 60-90mm, retrograde, 38 +/- 10, right and left of midline

Question 11

vessel: BA

window, depth, direction, velocity, angle

Answer 11

transformenal/ suboccipital, 80-120mm, retrograde, 41 +/- 10, midline

Question 12

crossover collateralization

Answer 12

antegrade flow in the ipsilateral anterior cerebral artery, flow comes from the contralateral ACA via the AcomA
ipsilateral MCA flow diminishes with contralateral compression of the CCA and respond positively to contralateral oscillation maneuvers of the CCA

Question 13

external to internal collateralization

Answer 13

retrograde flow in the ipsilateral OA, flow comes from the ECA branches, flow reduction, obliteration, or reversal of flow occurs in the OA with compression of the ipsilateral ECA branches

Question 14

posterior to anterior collateralization

Answer 14

when flow velocities in the ipsilateral PCA exceed those in the ipsilateral MCA >125%
increased flow velocities in the PCA may occur with compression of the ipsilateral CCA confirms the patency of the PcomA

Question 15

General considerations for TCD

Answer 15

accessibility of the ultrasonic windows within the skull that can be penetrated with the ultrasonic beam are often limited
arteries at the base of the skull vary greatly in size, course, development, and site of access
the power measured behind the skull is rarely >35% of the transmitted power, the bone of the skull absorbs the major portion of the power

Question 16

To achieve acceptable signal to noise ratio systems utilize dopplers with

Answer 16

lower bandwidth

larger and less defined sample volume

Question 17

TCD systems use….

Answer 17

2MHz pulsed-wave doppler

Question 18

TCCS systems use

Answer 18

transcranial color-coded duplex sonography

1.8-3.6 MHz phased array sector transducer

Question 19

instrument requirements

Answer 19

transmitting powers between 10 and 100mW/cm2
adjustable doppler gate width
PRF up to 20kHz
focusing of the ultrasound beam at a depth of 40-60mm
online display of: TAMV and peak systolic velocity

Question 20

what is the submandibular approach useful for?

Answer 20

ICA dissection
chronic ICA occlusion
velocities for calculating the Lindegaard ratio

Question 21

Hyperemia

Answer 21

globally elevated mean velocities, intra- and extracranially

Lindegaard ratio <3 TAMV of MCA/ TAMV of ICA

Question 22

vasospasm and stenosis due to atherosclerosis

Answer 22

focal velocity elevation

distal turbulence

Question 23

patients with SAH and suspected vasospasm

Answer 23

initial baseline study should demonstrate relatively normal mean velocities
vasospasm due to SAH generally occur by the 5th day
most often there will be a gradual increase in mean velocity measurements, with changes noted over time

Question 24

treatment of vasospasm

Answer 24

percutaneous transluminal angioplasty

pharmacologic infusion- generally papaverine (vasodilator)

Question 25

HITS aka MES

Answer 25

high intensity transient signals aka microembolic signals

Question 26

HITS or MES commonly occur during what?

Answer 26

operative procedures: CEA or cardiopulmonary bypass

Question 27

HITS aka MES criteria

Answer 27

short in duration, <300ms increased intensity, at least 3dB above background signal unidirectional within doppler spectrum sound chirp or snap

Question 28

Why and how do you do a vasomotor reactivity testing?

Answer 28

to identify patients at higher risk of stroke | testing is done using various stimuli, such as increasing or decreasing CO2 and monitoring the response.

Question 29

Normal vasomotor reactivity test

Answer 29

increased carbon dioxide: decrease in blood pH, vasodilatation of resistance vessels of the brain, increase in cerebral blood flow decreased carbon dioxide; increase in blood pH, vasoconstriction of resistance vessels of the brain, decrease in cerebral blood flow

Question 30

vasomotor reactivity test abnormal

Answer 30

occlusive disease of extracranial internal carotid arteries and intracranial cerebral arteries- maximal dilatation of the resistance vessels of the brain, autoregulation functions of the distal vessels are diminished, carbon dioxide testing.

Question 31

Abnormal MCA velocity waveform

Answer 31

decreased amplitude and pulsatility, increased acceleration time due to proximal occlusive disease moyamoya disease

Question 32

Most common cause of subarachnoid hemorrhage

Answer 32

ruptured cerebrovascular aneurysm: occurs in approx. 28,000 people in north america annually with the mortality rate exceeding 50%

Question 33

other causes of SAH

Answer 33

trauma, tumor, AVM, spontaneous bleed

Question 34

What can result from a SAH?

Answer 34

possible vasospasm (delayed, sustained contraction of the cerebral arteries)

Question 35

vasospasm vs. hyperemia, lindegaard ratio | normal ?

Answer 35

mean velocity: 30-80 cm/s

Question 36

vasospasm vs. hyperemia, | degree of vasospasm: hyperemia

Answer 36

< 3.0

Question 37

vasospasm vs. hyperemia, | degree of vasospasm: moderate

Answer 37

3-6

Question 38

vasospasm vs. hyperemia | degree of vasospasm: severe

Answer 38

> 6

Question 39

triple H therapy

Answer 39

hemodilution, hypertension, hypervolemia