Chapter 10: Intracranial Cerebrovascular Examination Flashcards by Billie Harney

cessation of oxygenated blood circulation to the brain

cerebral circulatory arrest

How well did you know this?

Not at all

Perfectly

endovascular mechanical thrombectomy used during ischemic stroke due to large vessel occlusion

cerebral thrombectomy

How well did you know this?

Not at all

Perfectly

a change in cerebral blood flow in response to a vasoactive stimulus

cerebrovascular reactivity

How well did you know this?

Not at all

Perfectly

A roughly circular anastamosis of arteries located at the base of the brain

circle of Willis

How well did you know this?

Not at all

Perfectly

A vessel that maintains blood flow via a secondary route for a stenotic or occluded vessel

collateral

How well did you know this?

Not at all

Perfectly

Microparticles circulating in the blood consisting of thrombi, platelet aggregates, or gas, which can be detected by Doppler ultrasound

emboli

How well did you know this?

Not at all

Perfectly

Middle cerebral artery mean velocity divided by the submandibular internal carotid artery mean velocity. This ratio is useful in differentiating increased volume flow from decreased diameter when high velocities are encountered in the MCA or intracranial ICA

Lindegaard ratio

How well did you know this?

Not at all

Perfectly

Expressed as the Gosling pulsatility index (peak systolic velocity minus end-diastolic velocity divided by the time-averaged peak velocity)

pulsatility

How well did you know this?

Not at all

Perfectly

Disorders of hemoglobin, the molecule in red blood cells that delivers oxygen to cells, which distorts RBCs into a sickle shape

sickle cell disease

How well did you know this?

Not at all

Perfectly

Ratio calculation used to determine vasospasm from hyperdynamic flow in the posterior circulation. The bilateral vertebral artery velocities taken at the atlas loop are added together and averaged. This averaged velocity is then divided into the highest basilar artery mean velocity.

Sviri ratio

How well did you know this?

Not at all

Perfectly

A noninvasive test that uses ultrasound to measure the velocity of blood flow through the intracranial cerebral vessels

transcranial Doppler (TCD)

How well did you know this?

Not at all

Perfectly

A noninvasive test of the intracranial cerebral blood vessels that uses ultrasound and provides both an image of the blood vessels and a graphical display of the velocities within the vessels

Transcranial Duplex Imaging (TCDI)

How well did you know this?

Not at all

Perfectly

A sudden constriction in a blood vessel causing a restriction in blood flow

vasospasm

How well did you know this?

Not at all

Perfectly

focal increase in velocity
poststenotic turbulence
use prestenotic/stenotic ratio

stenosis

How well did you know this?

Not at all

Perfectly

absent flow on color imaging and Doppler
High-resistance signal proximal to occlusion

occlusion

How well did you know this?

Not at all

Perfectly

MCA velocity >200 cm/s
Lindegaard ratio >6.0
can be present in more than one artery
temporal changes

severe vasospasm

How well did you know this?

Not at all

Perfectly

brief signal lasting <300 ms
M-mode high-power tracks sloping in flow direction
amplitude at least 3 dB above background
unidirectional signal
signal has snap, chirp, or moan soand

emboli

How well did you know this?

Not at all

Perfectly

absent, no flow signal

occluded with no residual flow

How well did you know this?

Not at all

Perfectly

low systolic, only velocity signal

no antegrade residual flow

How well did you know this?

Not at all

Perfectly

low velocity, damped systolic, and diastolic signal, with slow systolic acceleration, with a PI of <1.2

subtotal occlusion with sluggish antegrade flow

How well did you know this?

Not at all

Perfectly

High PI >1.2, systolic dominant signal with >30% higher than contralateral MCA

stenotic with recanalization

How well did you know this?

Not at all

Perfectly

velocity comparable to contralateral MCA with <30% difference and similar PI

Normal flow with total recanalization

How well did you know this?

Not at all

Perfectly

abnormal velocity criteria for sickle cell anemia

> 200 cm/s

How well did you know this?

Not at all

Perfectly

directly study the intracranial conducting arteries that lie at base of brain

TCD examinations

How well did you know this?

Not at all

Perfectly

Diameter of basal cerebral arteries range from ____

2-4 mm

formed by the intracranial circulation of ICA; first becomes accessible by TCD exam in cavernous portion

anterior circulation (circle of Willis)

Three segments of carotid siphon

parasellar, genu, supraclinoid

ICA divides into:

middle cerebral artery anterior cerebral artery

significant branches that arise from distal ICA

opthalmic artery (OA) posterior communicating arteries (pCoAs)

courses medially from ICA for a short distance before passing forward as A2 or postcommunicating segment

ACA

Where are the two ACAs connected?

connected above optic chiasm by the anterior communicating artery (ACoA)

continuation of extracranial vertebral arteries once they pass through foramen magnum, enter subarachnoid space, and course beneath brainstem

intracranial posterior circulation

usually arise from distal part of vertebral; supply brainstem and cerebellum

posterior inferior cerebellar arteries (PICAs)

created by the joining together of the two VAs and ends by terminating into right and left posterior cerebral arteries (PCAs); gives rise to two paired set of branches, the anterior inferior cerebellar and superior cerebellar arteries

Basilar artery

initial short segment arising from BA; before connection to the PCoA is called the P1 or precommunicating segment

PCAs

require insonation through foramen magnum

VAs and BAs

What kind of TCD instrument is optimable?

1-2 MHz pulsed-wave transducer and spectral

M-mode capabilities

PSV, EDV, TAP-V, Gosling pulsatility index (PI)

uses simultaneous signal acquisition from 33 sample gates, placed at 2 mm intervals

Power M-mode (PMD)

Optimal transducer for standard duplex TCDI exam

broadband phased array sector transducer; 1-5 MHz frequency range

traces outer edge of spectral waveform; provides real-time calculations of quantitative values

envelope line

located over temporal bone, superior to zygomatic arch, and anterior and slightly superior to tragus of ear conch

transtemporal approach

relies on transmission of ultrasound beam through thin orbital plate of frontal bone, optic canal, and superior orbital fissure

transorbital approach

natural opening in skull through which spinal cord passes; transducer placed 1 1/4 inches below base of skull; sound beam aimed toward nasion

foramen magnum approach

retromandibular ICA signal; transducer placed at angle of jaw with beam directed cephalad

submandibular approach

used to calculate BA/VA ratio; transducer placed 1.25 inches below mastoid process and behind sternocleidomastoid muscle

atlas loop approach

provides physiological information that complements anatomic imaging studies

standard transcranial Doppler exam

5 primary criteria used for ID of each vessel segment

1. approach 2. sample volume depth 3. direction of blood flow relative to ultrasound transducer 4. the spatial relationship of one artery to another 5. flow velocity

Flow velocity

MCA > ACA > PCA = BA = VA

arteries identified in the orbital approach

OA carotid siphon

waveform of OA

low velocity low diastolic flow

arteries identified in the temporal approach

MCA, ACA, terminal internal carotid artery (TICA), PCA

arteries identified in the foramen magnum approach

VAs and BAs

curves below brainstem and courses forward and superiorly; relatively long 33 +- 6mm

Basilar artery

Mechanical index is not to exceed ___ in an orbital approach

0.23

two hyperechoic lines shaped into a V in the orbital approach

lateral and medial rectus muscles

Branches of OA

central retinal artery and vein lacrimal artery long and short posterior ciliary arteries

waveform of OA

low velocity with high resistance

Where is the carotid siphon located?

below lateral and medial rectus muscles

transducer just superior and parallel to zygomatic arch

temporal approach

bright thin line produced by reflection from double layer of dura in interhemispheric fissure at midline

falx cerebri

echolucent butterfly or heart-shaped structure

midbrain

slightly above and parallel to lesser wing of sphenoid bone

middle cerebral artery

large median opening penetrating occipital bone

foramen magnum

How long is the BA?

3-4 mm

because of high attenuation no signals will be obtained through temporal bone window; occurs uni or bilaterally

hyperostosis of temporal bone

primary diagnostic features of waveform

alteration in velocity deviations from laminar flow changes in pulsatility changes in direction of flow

can be calculated using equation (PSV-EDV)/TAP-V

resistance index

initial slope or time lapsed from systolic onset to PSV

systolic upstroke

calculated as MCA mean velocity divided by submandibular ICA mean velocity divided

Lindegaard ratio

used for determining vasospasm from hyperdynamic flow in posterior circulation; bilateral VI mean velocities taken at atlas loop added together and averaged, averaged velocity is then divided into highest BA mean velocity

Sviri ratio

presence of good LMCS in ischemic stroke

better outcomes reduced infarct size quicker recanalization

can extend into intracranial VAs and BAs; potentially impact flow through circle of Willis

subclavian steal

most common conditions that produce intrinsic narrowing of cerebral arteries

thromboembolic atherosclerotic disease

uncommon noninflammatory conditions that produce intrinsic narrowing of cerebral arteries

dissection fibromuscular dysplasia radiation induced vasculopathy Moyamoya disease

inflammatory and hematologic causes that produce intrinsic narrowing of cerebral arteries

temporal arteritis meningitis toxin-related vasculitis SCD

4 known risk factors that increase risk of large artery artherosclerotic stenosis

hyperlipidemia arterial hypertension cigarette smoking diabetes mellitus

Most common mechanism of posterior circulation stroke

embolism

most common cause of occlusion beyond circle of Willis

embolism

several types of cardiac disease lead to cerebral embolism

cardiac arrythmias ischemic heart disease valvular disease dilated cardiomyopathies atrial septal abnormalities intracardiac tumors

measures residual flow around clot, in general, larger amount of residual flow predicts success of thrombolysis

thrombolysis in brain ischemia

one of most significant causes of delayed cerebral ischemia

development of cerebral vasospasm during first 2 week period following initial bleed

transient, delayed narrowing involving cerebral arteries following SAH

cerebral vasospasm

When does onset of arterial contraction?

3-4 days following initial bleed, peak narrowing 6-8 days, resolution 2-3 weeks following SAH

goals of TCD in setting of SAH

detect elevated blood velocities that indicate cerebral vasospasm identify patients at risk for DCI

Most frequently monitored artery

MCA

referred to as high-intensity transient signals

microembolic signals

utilizes multiple sample gates to construct M-mode display simultaneously with a single gate spectogram

PMD

remnant of fetal circulation appearing as a slit-like tunnel between right and left atria of heart

PFO

allows for passage of blood from right to left cardiac chambers

RLS

Gold standard for identifying presence of RLS

TEE with agitated saline injections

During a successful valsalva maneuver, velocities ____ during abdominal muscle contraction and ______ when patient relaxes

increase decrease

genetic disorder that mostly occurs in African, Hispanic, Middle Eastern, and Asian Indian lineage

sickle cell disease

impacts red blood cells; causes development of sickle shape and become rigid, causing vascular injury

sickle cell disease

Elevated blood flow velocities in SCD related to:

severe anemia vessel stenosis vasodilation caused by tissue hypoxia

What is the range of the average diameter of basal cerbral arteries?

2-4 mm

It is estimated that 18% to 54% of individuals display variations at the level of the circle of Willis. Which of the following is NOT one of those variations? a. variation in number of arteries b. variation of caliber of vessels c. variation of the course of vessels d. variation of the origin of branches

Which statement about the anterior cerebral arteries is FALSE? a. Both arteries (right and left) are frequently identical b. The anterior communicating artery is located above the optic chiasm c. Both arteries communicate via the anterior communicating artery d. Both arteries first course medially to the internal carotid arteries

What is the term used when the posterior cerebral arteries depend on the internal carotid artery for blood flow (at least partly)?

fetal origin of the PCA

What is the optimal patient position for evaluation of the vertebral and basilar arteries through the foramen magnum?

lateral decubitus with head tilted inferiorly

Which of the following is a typical characteristic of a nonimaging transducer for transcranial Doppler? a. 1 to 2 MHz pulsed wave b. 1 to 2 MHz continuous wave c. >4 MHz pulsed wave d. >4 MHz continuous wave

What is the Doppler frequency range in standard duplex imaging system for transcranial imaging?

2-3 MHz

What is the initial target vessel to be explored through the transtemporal acoustic window?

MCA

What do the Lindegaard and the BA/VA ratios help categorize?

vasospasm

What does the relation MCA >ACA >PCA =BA = VA?

relative flow velocities

Which of the following is NOT a criterion used for the identification of vessels or vessel segments in the intracranial circulation? a. the direction of flow in relation to the transducer b. the diameter of the vessel c. the sample volume depth d. the vessel flow velocity

Which imaging technique creates a display that demonstrates flow intensity and dissection in bands of color at multiple depths, creating a "road map" to follow signals from vessels?

power M-mode

Which of the following is NOT a primary diagnostic feature of the Doppler signals for evaluation of intracranial vessels? a. changes in vessel diameters from established criteria b. changes in velocity from esetablished criteria c. changes in flow pulsatility from established standards d. changes in flow direction from established standards

Which of the following would cause anterior to posterior collateralization? A. MCA occlusion B. ACA stenosis C. Mid basilar artery occlusion D. Proximal vertebral artery stenosis

Which characteristic is not part of the five primary criteria used to identify intracranial arterial segment? A. Flow direction B. Pulsatility index C. Sample volume depth D. Window/approach used

A limited transcranial Doppler or transcranial duplex imaging exam could be ordered for all of the following except: A. Evaluate for sickle cell anemia B. Monitor microembolism during endarterectomy C. Follow up for vasospasm D. Evaluate single vessel patency

Which statement regarding the use (and advantages) of audio signals during TCD and TCDI is false? A. Nuances in signal can be heard before they can be seen on the Doppler spectrum B. High-velocity signals could be missed by turbulent flow on the Doppler spectrum C. Audio signals can help in redirecting the sonographer in the acquisition of Doppler spectrum D. TCDI does not have audio capability

Which of the following is the atlas loop approach used for? A. Visualizing the internal carotid siphon B. Visualizing the distal vertebral arteries C. Obtaining data to characterize basilar artery vasospasm D. Alternative window to the forsaken magnum approach

To ensure patient safety when using the transorbital approach, which technical setting should you always address? A. Decrease the acoustic intensity B. Increase the color Doppler scale C. Decrease the velocity scale D. Increase the Dopple gain

At a depth of approximately 65 mm from the trans temporal window, with a Doppler sample gate of 5 to 10 mm, you should obtain two Doppler spectra (one on each side of the baseline). What do these Doppler spectra correspond to?

MCA/ACA

When is evidence of vasospasm usually seen following subarachnoid hemorrhaging?

3-4 days after the bleed started

A 68 year old male patient presents to the vascular lab for TCD evaluation. During the exam, mean velocities in the MCA reach 140 cm/s proximal my, with turbulence and damped, delayed spectral waveforms noted distally. What do these findings suggest?

>70% MCA stenosis

What is a remnant of the fetal circulation that appears as a slit-like tunnel between the right and left atria of the heart?

Patent foreman ovale

What is the most likely mechanism of cryogenic stroke in patients with a PFO and right-to-left cardiac shunt?

Paradoximal embolism

When performing TCD on a patient with sickle cell disease, velocities in the MCA are considered abnormal when they reach which value?

>200 cm/s

On average, the center of the circle of Willis is approximately the size of a ______.

Thumbnail

The anterior intracranial arterial circulation is formed as a continuation of the _____.

ICA

The parasellar, genu, and supraclinoid segments are part of the _____.

Siphon

The anterior inferior cerebellar and superior cerebellar arteries are branches of the _____.

Basilar

From the trans orbital window, the carotid siphon is identified at a depth of _____ mm.

60-75

The best acoustic window to insinuate the vertebral and basilar arteries is through the ______.

Foramen of magnum

The vessel identified through the trans temporal window at a depth of 65 mm with posterior and inferior rotation on the transducer is the _____.

PCA

Independently of the technique used (TCD or TCDI), the documentation of data obtained on intracranial arteries is based on ____.

TAP

All the arteries examined during a TCD or TCDI examination supply the brain except the ______.

Opthamalic arteries

When the transducer is placed 1.25 in below the mastoid process and posterior to the steenocleidomastoid muscle, the technique is called the ______.

Atlas loop

The Gosling index expresses the _______ of the Doppler signal.

Pulsatility

The MCA mean velocity divided by the submandibular ICA mean velocity represents the calculation for the ______ ratio.

Lindegaard

Ipsilateral increased velocities observed in the ACA and PCA with a significant stenosis or occlusion of the MCA is a result of ______ collateralization.

Leptomeningeal

Evaluation of the MCA from a temporal window with a more posterior location will require aiming the transducer _____.

The most common mechanism of posterior circulation stroke, usually of cardiac origin, is ___.

Embolism

Pediatric patients with _______ are recommended to have annual TCD screening to help prevent stroke.

Sickle cell anemia

For acute thrombosis, the _____ scale is used to classify changes that can occur rapidly with recanalization and reocclusion in acute stroke.

TIBI

Mean flow velocities in the MCA of >200 cm/s, a rapid daily rise in flow velocities and a hemispheric ratio of >6.0 predicts the presence of significant ______.

Vasospasm

A TCD signal that contains a very short or brief, high amplitude, unidirectional “snaps”, “chirps”, or “moans” indicates _______.

Microembolic signals

Which of the following is not a segment of the carotid siphon? A. Auricular B. Parasellar C. Supraclinoid D. Genu

Terminal branches of the internal carotid artery include:

The middle cerebral and anterior cerebral arteries

No imaging TCD equipment typically uses:

A 1-2 MHz pulsed wave transducer

Which type of duplex ultrasound transducer is used for TCDI examination?

A phased array with Doppler frequencies of 2-3 MHz

During a TCD examination, which of the following arteries do not normally display high flow during diastole? A. MCA B. PCA C. BA D. OA

Which of the following is not an acoustic window used during a TCD or TCDI exams. A. Suboccipital B. Transparietal C. Transorbital D. Submandibular

Which one of the following is not a subdivision of the temporal window? A. Inferior B. Anterior C. Frontal D. Posterior

Which statement below best describes the proper orientation for the foramen magnum approach? A. The transducer is placed 2-3 inches below the base of the skull and the sound beam is aimed toward the nasion B. The transducer is placed 2-3 inches below the base of the skull and the sound beam is aimed toward the parietal bone C. The transducer is placed 1.25 inches below the base of the skull and the sound beam is aimed toward the parietal bone D. The transducer is placed 1.25 inches below the base of the skull and the sound beam is aimed toward the nasion

During a TCD exam, primary criteria used for vessel identification include all of the following except: A. Direction of flow relative to the transducer B. Acceleration time C. Mean flow velocity D. Sample volume depth

Which statement correctly describes the ACoA and PCoA? A. The ACoA is rarely identified, but the PCOA is normally seen inferior and posterior to the MCA B. The ACoA and PCoA are virtually never identified during a TCD or TCDI exam C. The PCoA is rarely identified, but the ACoA is normally easily seen connected to the right and left anterior cerebral arteries D. The ACoA and PCoA are usually only identified when serving as collaterals

Using a trans temporal window, what initial depth should be used to obtain Doppler signals from the MCA?

50 mm

When performing a TCDI exam using the transoribital approach, the structure can be seen casting an acoustic shadow.

The optic nerve

The Lindegaard ratio is calculated by:

Dividing the MCA mean velocity by the submandibular ICA mean velocity

This calculated hemodynamic parameter is used to determine vasospasm from hyper dynamic flow in the posterior circulation.

The sviri ratio

Evidence of crossover collateral flow through the ACA can be found in the following except: A. Retrograde flow in the A2 ACA segment Ipsilateral to the extracranial carotid stenosis B. High velocities detected at midline in the small anterior communicating artery C. Increas flow velocities in the contralateral ACA D. Retrograde flow in the ACA, A1 segment Ipsilateral to the extracranial carotid stenosis

All of the following can be a cause of intracranial stenosis or occlusion except: A. Meningitis B. Temporal arteritis C. Sickle cell disease D. Buerger disease

Which of the following statements best describes changes following subarachnoid hemorrhage? A. Vasospasm occurs within 24 hours following the initial bleed, peaks within 3-4 days, and resolves within 1 week B. Vasospasm occurs approximately 7-10 days following initial bleed, peaks within 48 hours after onset of vasospasm, and resolves within the following week C. Vasospasm beings 3-4 days following the initial bleed, peaks at 6-8 days, and resolves in 2-4 weeks D. Vasospasm can occur at any time during the first 2 weeks following the initial bleed and resolves by week three

Microembolic signals have which of the following characteristics? A. They should last less than 100 ms and have a signal at least 10 db kabobs background signals B. They should last longer than 500 ms and have a signal at least 10 Db above background noise C. They should last less than 300 ms and have a signal at least 3 dB above background signals D. They should last longer than 300 ms and have a signal at least 3 dB above background signals

The use of TCD to detect patent foramen ovale involves the use of:

Agitated saline and the detection of Microembolic signals

Which statement best describes the utilization of TCD with theombolytic agents? A. Ultrasound energy is used to activate thrombolytic agents B. Ultrasound energy is used to burst microbubbles and release the thrombolytic agents C. Ultrasound is strictly used to monitor blood velocities before and after administration of thrombolytic agents D. Ultrasound energy can slightly move fibrin strands to allow for more contact with thrombolytic agents

3 segments of carotid siphon

Parasellar Genu Supraclinoid

Internal carotid artery branches

Ophthalmic artery Posterior communicating artery

Anterior circulation

Cavernous internal carotid artery Middle cerebral artery Anterior cerebral artery Anterior communicating artery

Posterior circulation

Middle cerebral artery Anterior cerebral artery Anterior communicating artery Vertebral arteries Basilar artery Posterior cerebral arteries

What position should a patient be positioned for evaluation of posterior circulation?

LLD

Dedicated nonimaging TCD instrument

1-2 MHz pulled wave transducer

Dedicated duplex ultrasound system instrument

Broadband phased array 2-3 MHz Doppler frequency 4 MHz imaging frequencies

All vessels in a TCD study except _____, have low resistance with relatively high diastolic flow.

For common acoustic windows used to assess cerebral vasculature

Transtemporal Transorbital Transoccipital Submandibular

Located over the temporal bone, superior to zygomatic arch

Transtemporal

Transtemporal subdivided into

Posterior Middle Anterior Frontal

Ultrasound is transmitted through the thin orbital plane of frontal bone

Transorbital approach

Transducer is placed at base of skull and aimed toward nasion

Foramen magnum approach

Transducer is placed at the angle of the jaw and beam is directed cephalad

Submandibular approach

Transducer is placed below the mastoid process, behind the sternocleidomastoid muscle

Atlas loop approach

Allows interrogation of the very distal extracranial ICA

Submandibular approach

Used to evaluate extracranial vertebral artery

Atlas loop approach

Five primary criteria used to identify vessels

Approach Sample volume depth Direction of blood flow relative to ultrasound transducer Spatial relationship of one artery to another Flow velocity

Arteries identified orbital approach

OA Carotid siphon

Arteries identified temporal approach

MCA ACA TICA PCA

Arteries identified foramen magnum approach

Vertebral arteries Basilar arteries

Waveform opthalmis artety

Low velocity high resistance

Anatomic variations in circle of Willis

Differences in origin, size, course of vessel

Most common cause of intracranial stenosis

Atherosclerosis

_____ was the most common cause of occlusion beyond the circle of Willis

Embolism

The transient and delayed narrowing of basal cerebral arteries following subarachnoid hemorrhage

Vasospasm

Usually begins within 3-4 days after SAH, peaks around 6-8 days, and resolves within 2-4 weeks.

Vasospasm

Most commonly monitored artery with vasospasm

MCA

Short systolic spike followed by either a small retrograde deflection in diastole or no flow in diastole

Cerebral circulatory arrest

_____ patients are prone to stroke involving MCA and ACA

Sickle cell