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When I'm looking for a vascular injury

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in the head and neck, or for that matter, atherosclerotic stenosis in the head neck,

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I usually focus on a single vessel at a time as I scroll up and down.

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So, generally looking at both carotid

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arteries, generally looking at both vertebral arteries.

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Let's start with looking at the left carotid arteries.

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So we're going to go all the way down and identify the origin here at the aortic

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arch and follow the left common carotid artery up.

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These are thin-section images.

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So you see it's a little bit noisy.

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Here we are following the left common carotid artery to the carotid bifurcation.

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So here we've got the carotid bifurcation on the left side.

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Normally expect the internal carotid artery

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to come off posterolaterally and the external carotid artery to come off anteriorly.

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Here's bifurcating blood vessels. That must be external carotid artery.

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Let's focus on the internal carotid artery.

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So as we come up and watch the internal

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Carotid artery on the left side, we see that it gets kind of widened out

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here and misshaping and it has a small flap that is occurring within its lumen.

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Here we can see that flap going across

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the lateral aspect of the blood vessel before it enters the petrous portion.

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So this is what we're looking for, for a carotid dissection.

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And the little ballooning "L" part could represent right here a pseudoaneurysm

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of the internal carotid artery secondary to that dissection.

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So we're not finished yet.

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This is sort of like Occam's razor or satisfaction-of-search.

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Let's look at the contralateral internal carotid artery and common carotid artery.

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So here we have the origin of the right common carotid artery, and we're going

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to follow the right common carotid artery superiorly.

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It's a little bit tortuous.

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And here we get to the carotid bifurcation.

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External carotid artery anterior.

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Posterior carotid artery.

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Internal carotid artery posterolaterally.

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Let's follow the right internal carotid artery.

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It's coming medially.

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Gets a little fat here.

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What happened there? It went from this wide lumen to a much wider lumen right here.

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And then we have a plane through

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the internal carotid artery on the right side.

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And here is that flap in the internal carotid artery, identifying

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yet another, and bilateral, carotid dissection.

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Now this could be on a traumatic basis.

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The other thing that could be happening is

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the patient might have a disease entity that predisposes to a dissection.

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That includes Marfan syndrome, Loeys-Dietz syndrome,

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fibromuscular dysplasia, some of the collagen vascular diseases.

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Let me see whether we have a good coronal

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reconstruction here that might help better define the pathology.

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If we see areas of widening and narrowing within the internal carotid artery or

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the vertebral arteries, we might suggest the possibility of FMD.

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Here you can see the dissected vessel with the pseudoaneurysm

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and the dissection more distally of the internal carotid artery on the right side.

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Here is our left side with a little bit of an outpouching right here.

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And the dissection is seen right over here.

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This is in the upper cervical region.

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Let's just look at it on the sagittal plane.

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So here we have the carotid bifurcation, the internal carotid artery.

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We followed it up. Here's

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the outpouching on the left side

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of the pseudoaneurysm, with the dissecting plane here and here.

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As we cross over to the right side,

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we have the internal carotid artery coming off posteriorly.

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We go anterior. Again,

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a little bulbous portion right here, where it gets wider

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and the plane of the dissection is

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actually better seen on the axial and coronal.

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Of course, we would next look

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at the vertebral arteries and see whether they had any dissection.

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In this particular case, the vertebra arteries were intact.