Extracranial Cerebrovascular Flashcards
What’s the typical pressure of the arterial system?
80-100mmHg
How much blood does the ICA get from the CCA?
70-80%
ICA brings blood to what portions of the brain?
Anterior and middle
What brings blood to the posterior portion of the brain?
Vertebrals (join together to become the basilar a)
8 branches of the ECA:
Superior thyroid Asc pharyngeal Lingual Facial Occipital Posterior auricular Maxillary Superficial temporal
Seven angry ladies fighting over PMS
Vertebrals come off which vessel?
Subclavian
What are TIA’s most often caused by?
An embolic event where a clot or other debris (plaque) gets lodged in the cerebral vessels causing a temporary interruption of blood flow
Common origins are *Heart and carotids
Does a RIND or TIA last longer?
RIND >24hrs– but the symptoms also completely resolve
Plaque is composed of lipids known as
Fatty streaks
Ulcerative plaque
Complete loss of the vascular endothelium. Considered unstable and a risk of emboli
What conditions cause the heart to be the most common origin of an emboli?
Atrial fib, LV dysfunction and paradoxical emboli
On sonographic evaluation of the carotids, you see a hypoechoic structure by the bulb. It is hypervascular. What is it? What would be the patients symptoms?
Carotid bulb tumor – vascular because it receives it’s blood supply from the ECA.
Difficulty swallowing and a large pulsatile mass
What’s the difference between atherosclerosis and FMD?
Athero affects prox segments of the arteries, FMD affects the middle & dst segments
FMD affects young women and the renal and carotid arteries
FMD is best seen by what modality? What does it appear as
Angiography – string of beads
What is neointimal hyperplasia caused by?
Surgical intervention – can result in a hemodynamically significant stenosis or occlusion and is the main reason for restenosis within the first 2yrs
What causes a dissection
Trauma
An aneurysm is a focal dilation of an artery that is ____% greater than the diameter of it’s normal segment
50
Where is the stenosis if the left vertebral has a reversal of flow?
Lt SCA
Where is the most common location for a Subclavian Steal? Why?
Lt due to the origin off the aortic arch
What drop in pressure do we see with subclavian steal?
15-20mmHg in the ipsilateral arm
Symptoms of SSS?
Often asymtpomatic – however can see symptoms of verterobasilar insufficiency and may worsen w arm exercise
What is the most important risk factor for stroke ?
Hypertension
Hemiparesis
Weakness/paralysis
Hemiparesthesia
Numbness, tingling, or loss of feeling
What typically causes amaurosis fugax?
Often from an emboli in the opthalamic artery from the ipsilateral ICA
What is hemianopia? What typically causes it?
Blindness in 1/2 of one or both eyes, typically caused by an occlusion of the MCA
If someone has a symptom of anterior circulation issues, which vessels would be of concern?
ICA, MCA and ACA
If someone has a symptom of posterior circulation issues, which vessels would be of concern?
VA, basilars, and PCA… if these are affected they will cause symptoms that will affect the body as a whole. Nonlateralizing
Ataxia
A group of disorders that affect coordination, balance and speech
What is another somewhat reliable way to screen for a carotid stenosis, other than duplex imaging?
Listening for a carotid bruit
Where is the most common place for an occlusion to occur? During carotid US
ICA
While scanning the carotid bulb, you notice there is some heterogenous plaque with anechoic areas within. What is the concern?
This most often represents an intraplaque hemorrhage. When this is seen, it’s important to identify that the surface is intact and if it has a smooth or irregular surface. Irregular surfaces indicate that plaque has ruptured or ulceration, and is considered unstable
What is latent steal:
When a subclavian steal hasn’t manifested fully and there is alternating flow directions in systole and diastole
Majority of carotid artery disease occurs within _____ of the ICA
2cm (this means usually the pre stenotic zone is in the CCA)
If you see a loss of diastolic flow in the ipsilateral ICA, where would the stenosis be?
Intracranial ICA or MCA
If you see that both left and right CCA’s have a diminished waveform, where is the source of problem?
Heart
What can help confirm the presence of a Lt ICA occlusion?
Loss of diastolic flow in the Rt CCA
The ECA has a velocity of 134cm/s, and a ratio of 3. What grade of stenosis?
N/A. The grading system cannot be used on vessels other than the ICA
A patient gets a CEA and within two years it is restenosed. What is the issue?
Would not be plaque, likely would be neointimal hyperplasia
What would one expect to see in a patient with a stent?
Increased velocities
What’s the first branch off the ICA?
Opthalamic (happens intracranially)
The first branch of the thoracic aortic arch?
Innominate
Which of the following lesions is most likely to cause a subclavian steal syndrome?
(A) Innominate artery stenosis
(B) Left proximal subclavian artery stenosis
(C) Left distal subclavian artery stenosis
(D) Both A and B
D– Both an innominate artery and proximal left subclavian artery stenosis are likely to cause a subclavian steal syndrome because they would be proximal to the origin of the vertebral arteries. A stenosis in the distal left subclavian artery would be past the origin of the vertebral artery thus not resulting in a steal.
A 75-year-old man is scheduled for a carotid duplex and presents with symptoms of complete loss of mobility in the left arm. In which vessel would you most likely find disease?
(A) Left internal carotid artery
(B) Left common carotid artery
(C) Right internal carotid artery
(D) Right vertebral artery
C– Complete loss of mobility on one side of the body is a lateralizing symptom that is associated with ICA disease
The pressure gradient across a stenotic segment as it increases from a 50% narrowing to a 90% narrowing
(A) Decreases
(B) Does not change
(C) Is unaffected
(D) Increases
(D) A pressure gradient refers to the difference between two pressures, in this case, the pressure proximal and distal to the stenosis. As a stenosis increases from a 50% narrowing to a 90% narrowing the distal pressure will decrease even more resulting in an increased difference between pressures.
All of the following are lateralizing symptoms caused by a disturbance of blood flow to the contralateral hemisphere EXCEPT
(A) Hemiparalysis
(B) Amaurosis fugax
(C) Hemiparesthesia
(D) Aphasia
Amaurosis fugax is the only lateralizing symptom not caused by disturbance to blood flow on the contralateral side of the body. It is caused by emboli traveling through the ipsilateral ICA to the ophthalmic artery resulting in a temporary loss of vision.
