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Characterizing Carotid Encasement

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Let's gild the lily, as we say,

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and look at a few more cases of carotid encasement

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to make sure that we understand the concepts.

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On the top left, we have a case of nasopharyngeal

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carcinoma. This tumor is outlined as you see here,

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coming from the nasopharynx.

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When we look at the internal carotid artery,

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we see that there is less than 180 degrees of

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involvement of the wall of the left internal carotid

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artery. Therefore, were this to be operated on,

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this tumor should be able to be peeled off

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of the internal carotid artery.

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Now,

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nasopharyngeal carcinoma is not a surgical tumor.

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Nasopharyngeal carcinoma is treated with

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radiation therapy and chemotherapy.

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And in this case, it's irrelevant because they're not

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going to go in for the internal carotid artery.

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Remember, however,

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that radiation therapy can lead to vascular

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inflammation and weakness in the wall of the

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internal carotid artery and could lead

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to potential carotid blowout.

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How about this case in the bottom right,

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this is an oropharyngeal cancer from

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the palatine tonsil. However,

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It has grown posteriorly and laterally to involve.

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the carotid chief structures.

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Here's our normal internal carotid artery.

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Here's our normal internal jugular vein.

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Here is our carotid artery.

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Here, once again,

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we see that the tumor comes to the wall of the

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carotid artery but is involving less

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than 270 degrees of involvement.

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This tumor would be operated on, and it should be able

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to be peeled off of the internal carotid artery

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without causing it to have to be sacrificed.

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This is the 270-degree rule that was established

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in the article back in the 1980s.

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Contrast that with this case.

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So this is a very large tumor that has infiltrated

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not just the deep lobe of the parotid gland,

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but also the soft tissues laterally

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in the right side of the neck.

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If we look at the internal carotid artery in this

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case, despite the very large size of the lesion,

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the internal carotid artery wall is not involved

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greater than 270 degrees. And therefore,

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this very large tumor would be able to be peeled

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off of the internal carotid artery.

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How about this case? Here we have another case.

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This was actually involving the soft palate

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and growing into the posterior pharynx.

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But in this case,

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it seems as if the carotid artery is

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circumferentially involved. You might argue, well,

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how much is the normal width of the carotid wall?

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The carotid wall should be indistinguishable.

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Therefore, this small amount of tissue

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that is around the posterior lateral wall of the

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internal carotid artery can be presumed to be tumor.

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And therefore,

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this is 360 degrees of involvement of

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the carotid artery. And therefore,

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in this squamous cell carcinoma,

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this carotid artery cannot be salvaged.

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This is a primary tumor.

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This is nodal disease. Here, once again,

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we have the carotid artery with tissue which is

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encircling the carotid artery. Not 360 degrees,

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but very close to 360 degrees.

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I put it from here all the way around.

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You can see the nodal disease here,

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nearly 360 degrees.

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But greater than 270 degrees, this carotid

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artery would not be able to be salvaged.

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So again, treatment effect.

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Either they say this is nonsurgical disease,

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nonresectable disease, and treat

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with chemo and radiation,

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or they put up a balloon and occlude

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the internal carotid artery,

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see whether the patient is able to tolerate it

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without neurological symptoms and take the carotid

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artery at the time that they do the

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nodal dissection. In this case,

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the patient was treated with chemo radiation.

Report

Description

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Neuroradiology

Neuro

Neoplastic

MRI

Head and Neck

CT

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