TCD

Cavernous ICA aka

carotid siphon

3 parts of the carotid siphon:

parasellar segment

genu

supraclinoid

ICA branches

opthalamic and posterior communicating artery

Anterior circulation:

carotid siphon and middle cerebral artery

Posterior circulation:

Vertebrals, basilar, and posterior cerebral arteries

what transducer is used

1-2 MHz pulsed wave

• Sample volume should be _______, resulting in spectral broadening in all waveforms.

large

TAP-V or ______ _________ are typically measured and reported

mean velocities

All vessels except OA have _______ resistance with _______diastolic flow

low resistance with high diastolic flow

Four TCD approaches:

transtemporal

transorbital

transoccipital

submandibular

Transtemporal approach is superior to the ______ _____

zygomatic arch

Transoccipital aka

foramen magnum approach

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

submandibular approach

Atlas loop approach used to evaluate the

extracranial vertebral artery

Criteria used to identify vessels:

approach

sample volume depth

direction of flow

spatial relationship

flow velocity

Transorbital approach evaluates:

ophthalmic artery and carotid siphon

Ophthalmic artery depth

40-60 mm

Ophthalmic artery direction

towards

Carotid siphon depth

55-80 mm

Carotid siphon direction

away, bidirectional, towards

Temporal approach arteries seen:

MCA, ACA, TICA, PCA

ICA bifurcation is identified at a depth of

55 to 65 mm

MCA depth

30-60 mm

MCA direction

towards

MCA/ACA depth

55-65 mm

MCA/ACA direction

bidirectional

ACA depth

60-80 mm

ACA direction

Away

PCA depth

60-70 mm

PCA direction

towards

ICA terminal depth

55-65 mm

ICA terminal direction

towards

Foramen magnum approach identifies which vessels

vertebral and basilar

Vertebral depth

60-90 mm

Vertebral direction

away

Basilar depth

80-120 mm

Basilar direction

away

OA waveform characteristics

low velocity with high resistance

_________ in geriatric patients

hyperostosis

External carotid to internal carotid through reversed _________ artery

opthalamic

Crossover collateral through the ACA

retrograde flow in ACA

Posterior to anterior collateral through the

posterior communicating artery

TCD is useful for detection of >__% intracranial stenoses and occlusions.

>50%

Most common cause of intracranial stenosis

atherosclerosis

Conditions that produce stenosis include:

atherosclerosis

dissections

FMD

radiation induced vasculopathy

moyamoya disease

inflammatory vasculopathies

_____________ disease is a disease in which certain arteries in the brain are constricted. Blood flow is blocked by constriction and blood clots

moyamoya

____________ was the most common cause of occlusion beyond the circle of Willis.

embolism

_________ preferred treatment method and TCD plays important role in determining effectiveness.

thrombolysis

TIBI

thrombolysis in brain ischemia

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

vasospasm

Vasospasm usually begins within _________ to ________ days after SAH, peaks around 6 to 8 days, and resolves within 2 to 4 weeks.

3 to 4

TCD used to detect _______ blood velocities indicative of vasospasm and to identify patients at risk of delayed ischemic neurologic deficits (DINDs)

elevated

What vessel is most commonly monitored in vasospasm?

MCA

Interpretation of vasospasm is complicated by:

intracranial pressure

blood pressure

hematocrit

collateral flow

arterial co2

autoregulation

response to therapuetic interventions

Normal mean velocity/ratio for vasospam

<85 cm/s and <3

Hyperemia velocity/ratio

85-120 cm/s and <3

Mild spams velocity/ratio

85-120 cm/s and >3

Moderate spasm velocity/ratio

120-200 cm/s and 3-6

Severe vasospasm velocity/ratio

>200 cm/s and >6

TCD can be used to monitor for emboli during these procedures:

carotid endart

carotid stenting

cardiopulmonary bypass

neurological procedures

Microembolic signals have a unique Doppler signature called

HITS

TCD can be used to detect the presence of _________ ______ ________-

patent foramen ovale

Sickle cell patients are prone to stroke involving _____ and _______

MCA and ACA