0:01

We're in the neoplastic category of carotid space

0:05

lesions and we looked at the benign tumors of

0:08

which paragangliomas are the most common.

0:11

And within the paragangliomas,

0:13

The carotid body tumor is the most common of

0:16

the paragangliomas in the carotid space.

0:19

The carotid body itself is a small organ that

0:23

is located in the adventitia of the carotid bifurcation.

0:27

And it is the tissue that controls heart rate,

0:33

blood pressure and respiratory rate.

0:36

The normal carotid body measures about 2 to 6 mm in size.

0:41

But the size of the carotid body does

0:43

get larger at higher altitudes.

0:46

So if you're like me living in Evergreen, Colorado,

0:48

with an altitude of about 8200ft,

0:51

you do see larger normal carotid bodies

0:55

in individuals in my neighborhood.

0:57

This is thought to be stimulated by hypoxia.

1:00

And in point of fact.

1:02

When I measure my O2 saturation.

1:04

I'm usually at about 94% at that altitude.

1:08

Carotid body tumors occur in older individuals.

1:13

50 to 70 years of age.

1:15

And they are more common in women than in men.

1:18

These represent the most common of the

1:20

paragangliomas of the head and neck, 50% to 60%.

1:24

The next most common will be your glomus tumors.

1:28

And the third most common,

1:29

representing about five to 10%,

1:31

are the glomus jugulare tumors.

1:34

There is a familial form that leads to bilateral and

1:37

multiple paragangliomas, and when that occurs,

1:41

they will be present in about 32%.

1:44

The right side is more commonly involved than

1:47

the left side with carotid body tumors.

1:50

And as I mentioned,

1:51

usually these patients present with a neck mass,

1:54

if they present at all.

1:55

Some of them are asymptomatic.

1:56

They just feel a fullness in the neck.

1:58

It's not as if they're seeing changes in their heart

2:01

rate or their blood pressure or the respiratory

2:03

rate. That is really not the symptoms that we see.

2:06

What we see is a patient who has a neck mass which

2:10

might be somewhat painful. There is a staging,

2:13

if you will,

2:14

for carotid body tumors, and this relates to the

2:17

ease at which they are able to be removed.

2:21

So group one are tumors that are minimally attached

2:24

to the vessels and therefore easily resectable, less

2:28

than 180 degrees of circumferential involvement.

2:31

So normally you have that carotid tumor sitting

2:33

right at the carotid bifurcation.

2:35

It may circumferentially involve either the

2:38

external or the internal carotid artery.

2:40

We're most concerned with the internal carotid

2:43

artery because that cannot be sacrificed.

2:45

Group two are those that partially surround the

2:48

vessel and are more adherent to the adventitia of

2:51

the vessel. These are difficult to dissect,

2:55

but they can be completely removed from

2:57

the carotid artery. And these are

3:00

ones that generally have circumferential

3:02

involvement of between 180 to 270 degrees.

3:07

The final grouping are the ones that are most

3:09

difficult to remove from the carotid arteries.

3:13

These are adherent to the entire circumference

3:16

of the carotid bifurcation,

3:17

or at least nearly the entire circumference.

3:20

Surgical dissection is impossible.

3:23

It often requires sacrifice of the internal

3:26

carotid artery with vessel replacement.

3:28

And usually they will do something analogous to

3:31

a temporary balloon occlusion test to see how

3:35

symptomatic the patient would be if that internal

3:38

carotid artery had to be sacrificed.

3:41

So greater than 270 degrees involvement is a key to

3:46

determining whether this is a tumor that will be

3:49

able to be removed from the carotid artery.

3:53

This 270 degrees of involvement reflects back on a

3:57

paper I wrote back early in my career about the

4:02

malignancies that involve the carotid sheath.

4:05

And again, it's the same criterion.

4:08

And that is that if a malignancy involves greater

4:11

than 270 degrees of the circumference of the

4:15

internal carotid artery, it is unlikely

4:18

to be salvageable. In other words,

4:20

that carotid artery is going to have to go out

4:22

in the surgical specimen with the tumor.