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Let's take a moment to review the vascular displacements

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that occur with paragangliomas and schwannomas.

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Remember that the carotid body tumor will splay the

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internal carotid artery posteriorly and the

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external carotid artery anteriorly

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as it sits in the carotid bifurcation.

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The vagus schwannoma will displace the internal carotid

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artery anteromedially and the internal

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jugular vein posterolaterally,

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identifying this as arising from the vagus nerve between

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the internal carotid artery and the jugular vein.

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Another of the schwannomas that we run into in the

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carotid sheath is the sympathetic

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nervous system plexus schwannoma.

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This occurs in the posteriormost portion

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of the carotid sheath. Therefore,

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it is more likely to displace the carotid

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artery and the jugular vein anteriorly.

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So both of them are going to be displaced anteriorly,

1:02

identifying a sympathetic nervous system plexus

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schwannoma. If we had a schwannoma of the ANSA cervicalis,

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this is those nerve tissue that helps innervate C1

1:14

through C3 segmental levels of the cervical spine

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that sits in the anteriormost portion of the carotid

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sheath and therefore would displace both carotid

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artery and jugular vein posteriorly.

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When we have a pharyngeal mucosal

1:30

system squamous cell carcinoma,

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it's more likely to grow and encase the blood vessels,

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which is relatively rare in the paragangliomas,

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save for the Shamblin type three carotid body tumor.

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Here is an example of an infrahyoid vagal schwannoma.

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So in the infrahyoid compartment,

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you see that the internal carotid artery

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is being displaced medially.

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The jugular vein is not so much

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displaced posterolaterally.

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It is being displaced and splayed away

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from the common carotid artery,

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but it's not as much posterior laterally displaced.

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So this differential diagnosis would include

2:15

a sympathetic nervous system schwannoma.

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Here you can see that although this is

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a contrast-enhanced examination,

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this schwannoma and this vagus schwannoma

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do not show very much enhancement,

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which is not unusual on a CT scan of these tumors.

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So neck schwannomas tend to not enhance as avidly as,

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for example, an acoustic or a vagus schwannoma.

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This one displacing the carotid artery,

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anteromedially the jugular vein laterally without as much

2:51

a posterior component. Contrast that with this lesion.

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So here we see the carotid artery.

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This is probably the common carotid artery and the.

3:00

Jugular vein,

3:01

both of which are being displaced anteriorly

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by this enhancing soft tissue mass.

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This would be good for a sympathetic

3:08

nervous system schwannoma.

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Differential diagnosis is a schwannoma coming off

3:13

of one of the cervical spine nerve rootlets,

3:16

which also would be in the lateral neck and behind both

3:20

the carotid artery and the jugular vein and displacing

3:24

the carotid sheath structures anteriorly.

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Another example of a sympathetic

3:30

nervous system schwannoma.

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We see that the vasculature is being displaced

3:36

anteriorly by this low-density mass.

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Here you see the low-density mass and you see the

3:43

jugular vein and portions of the carotid system being

3:46

displaced anteriorly by the mass carotid

3:50

sheath posteriorly located.

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Sympathetic nervous system schwannoma.