0:00

Our next case is a parotid mass

0:03

with perineural spread of disease.

0:05

Um, as hopefully most of you know, uh,

0:08

per capita, adenocystic carcinoma is the tumor with

0:11

the highest rate of perineural spread of disease.

0:14

Although in, um, in brute numbers, it is

0:18

squamous cell carcinoma just because it is so

0:20

much more common than adenocystic carcinoma.

0:23

And, uh, these are the, uh, key images.

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So now I'm going to, uh, go to the case.

0:30

All right, so this is a person that

0:32

presented with a parotid space mass.

0:35

Um, this is a flare, uh, sequence and

0:38

you can see that there's significant

0:40

enlargement of the entire, uh, gland.

0:42

Remember that to differentiate between the

0:44

superficial and the deep lobe of the parotid,

0:47

you need to use the retromandibular vein.

0:50

This is important because the cranial nerve

0:53

VII runs in the deep space of the parotid lobe.

0:56

And when the surgeon is operating, they need to

0:59

know, um, if they're going to have to go into

1:02

the deep space of the parotid gland as they're

1:05

at risk, of course, of injuring the nerve.

1:08

As you can see, there's significant

1:10

restricted diffusion along the entire

1:13

parotid gland, which is very abnormal.

1:17

70 percent of parotid mass lesions tend to

1:21

be benign pleomorphic adenomas, and they don't

1:25

show this significant increased restriction.

1:29

Again, accompanied by low ADC values,

1:32

which is compatible not with T2 shine

1:34

through but with actual true restriction.

1:37

We can see that there's a lot of

1:38

vascularity in this lesion.

1:42

And then there's cord-like enlargement

1:44

of the auriculotemporal nerve here, right?

1:47

So this is the normal parotid gland,

1:50

which tends to be fatty, somewhat bright,

1:53

both on T1 and T2 weighted sequences.

1:56

But you can see that there's this kind

1:58

of cord-like lesion along the course

2:01

of the auriculotemporal nerve.

2:03

Which is clearly abnormal.

2:06

Then, as we move on to our enhanced images,

2:12

we can see the same kind of appearance, right?

2:15

So we have a significantly enlarged parotid

2:19

gland, both the superficial and the deep lobe.

2:22

Again, you have to find that

2:24

retromandibular vein to separate both.

2:26

And you can see this cord-like thickening

2:29

and abnormality of the auriculotemporal

2:32

nerve, which, of course,

2:35

is suggestive of auriculotemporal nerve

2:37

invasion and perineural spread of disease.

2:42

In fact, this patient, when they went

2:47

to pathology after resection,

2:50

it was confirmed by pathological evaluation

2:53

that they did have perineural spread of

2:55

disease and that the tumor was, in fact,

2:58

an adenocystic carcinoma, which was

3:02

suspected based on the perineural appearance.

3:06

So, for the audience question, things to

3:08

think about, um, as I do the presentation,

3:12

um, the auriculotemporal nerve is in

3:14

which perineural, uh, spread highway, uh,

3:17

cranial nerve, uh, six to seven, five to six.

3:21

7, 8 to 7.

3:24

I don't know.

3:26

So this is critical in the evaluation of

3:30

perineural spread of disease, especially if you're

3:33

dealing with superficial lesions to the parotid.

3:35

So it doesn't only have to be a parotid mass.

3:37

It can be, um, like, uh, skin squamous

3:41

cell carcinoma, melanoma, or metastatic

3:45

disease from, um, different, um, metastatic

3:49

tumors that might affect the face.

3:51

Because we have two different large

3:53

nerves that live in that area.

3:56

So cranial nerve 5 and cranial nerve 7.

3:58

And you can see that there are areas where

4:01

they interact with each other, right?

4:02

Where they mix with each other.

4:05

The most common one being this auriculotemporal

4:07

nerve, which is a branch of Which is a branch

4:11

of V5, but then it has a connecting branch

4:14

to the chorda tympani, which is a branch of

4:16

V7, uh, with the chorda tympani living within

4:20

the, um, the deep space of the parotid gland.

4:24

And this is that, uh, highway that we see here,

4:27

uh, when we see it affected in this patient.

4:32

So, uh, this is another case from the literature.

4:35

Um, this is the, uh, mandibular ramus, right?

4:40

And the mandibular condyle, the, uh,

4:44

auriculotemporal nerve runs in a C shape

4:46

behind, uh, this area and connects to V3, right?

4:51

This is the foramen ovale.

4:53

This is foramen ovale here on the right, on

4:56

the left side, which is abnormally enlarged

4:58

and enhancing, normal on the right side.

5:01

And you can see that there's this cord-

5:03

like thickening and enhancement compared

5:06

to the normal contralateral side.

5:09

Remember again that this auriculotemporal

5:11

nerve then will connect to the chorda tympani

5:14

branch of cranial nerve seven, living in

5:17

the deep lobe of the parotid, causing that

5:19

cranial nerve five to cranial nerve seven,

5:23

uh, perineural highway, uh, spread of disease.

5:28

This is another example from the literature.

5:31

This is the same finding but

5:33

on the other side, right?

5:35

So this is the pharyngobasilar fascia,

5:39

which is around the nasopharynx and

5:41

lateral to that is where we find our

5:44

cranial nerve V3 foramen ovale.

5:46

So this is a normal foramen

5:48

ovale, not enlarged, not enhancing.

5:50

This is an abnormal foramen ovale, very enlarged

5:53

and enhancing with associated cord-like

5:57

thickening and enhancement of the auriculotemporal

6:01

nerve, again, very concerning for perineural

6:04

spread of disease, and putting the patient

6:07

at risk of the cranial nerve 5, right,

6:09

to cranial nerve 7, uh, perineural spread of

6:12

disease highway, uh, connecting to the chorda

6:15

tympani in the deep lobe of the parotid gland.

6:20

Now there are multiple, uh, cranial nerve 5

6:23

to 7 highways, um, so I'll just mention them.

6:28

A couple of the more, uh,

6:29

um, um, more prominent ones.

6:33

So hopefully everybody knows that the, uh,

6:36

greater superficial petrosal nerve arises

6:38

from the geniculate ganglion, um, which is

6:42

the ganglion of cranial nerve, uh, seven.

6:45

And via that lingual nerve, we can have

6:48

a, um, greater superficial petrosal nerve,

6:52

uh, uh, highway, uh, that connects

6:55

with the, uh, cranial nerve five.

6:58

Here again, we have an abnormally enlarged foramen

7:00

ovale, which carries again cranial nerve five,

7:04

abnormal enhancement of the cavernous sinus with

7:07

a retrograde, um, extension through the greater

7:10

petrosal nerve, uh, into the geniculate ganglion.

7:16

Um, this is another one, uh, with the, uh,

7:19

pterygopalatine ganglion connection at V2, um, with

7:24

connection to V7 through the greater superficial

7:27

petrosal nerve via the, uh, um, the Vidian nerve.

7:31

Hopefully everybody recognizes this structure

7:33

as the pterygopalatine fossa, usually

7:36

containing fat and some vessels, some nerves.128 00:06:20,195 --> 00:06:23,254 Now there are multiple, uh, cranial nerve 5

6:23

to 7 highways, um, so I'll just mention them.

6:28

A couple of the more, uh,

6:29

um, um, more prominent ones.

6:33

So hopefully everybody knows that the, uh,

6:36

greater superficial petrosal nerve arises

6:38

from the geniculate ganglion, um, which is

6:42

the ganglion of cranial nerve, uh, seven.

6:45

And via that lingual nerve, we can have

6:48

a, um, greater superficial petrosal nerve,

6:52

uh, uh, highway, uh, that connects

6:55

with the, uh, cranial nerve five.

6:58

Here again, we have an abnormally enlarged foramen

7:00

ovale, which carries again cranial nerve five,

7:04

abnormal enhancement of the cavernous sinus with

7:07

a retrograde, um, extension through the greater

7:10

petrosal nerve, uh, into the geniculate ganglion.

7:16

Um, this is another one, uh, with the, uh,

7:19

pterygopalatine ganglion connection at V2, um, with

7:24

connection to V7 through the greater superficial

7:27

petrosal nerve via the, uh, um, the Vidian nerve.

7:31

Hopefully everybody recognizes this structure

7:33

as the pterygopalatine fossa, usually

7:36

containing fat and some vessels, some nerves.

7:39

But here you can see it's abnormally

7:41

enlarged, abnormally thickened, noting

7:45

that, of course, in the pterygopalatine

7:46

fossa, we have the branches of V2.

7:49

Then we have retrograde flow through the

7:51

foramen rotundum, which is the, uh, foramen,

7:55

uh, that carries, uh, cranial nerve, uh, five

7:59

V2 branches back into the, um, cavernous sinus.

8:03

And we see retrograde extension again

8:06

through that greater superficial

8:08

petrosal nerve into our geniculate ganglion

8:12

with abnormal enhancement of both the

8:14

tympanic and the labyrinthine section

8:18

of the, uh, facial nerve, uh, cranial nerve seven.

8:21

Uh, again, demonstrating another

8:23

cranial nerve five, cranial nerve seven

8:25

highway, this time through V2 branches.

8:30

All right.

8:31

So we'll do the audience response now.

8:36

Okay.

8:36

Awesome.

8:37

I am so pleased to see this.

8:39

Yes.

8:39

Um, definitely the auriculotemporal nerve is

8:42

the, uh, cranial nerve five to seven highway.

8:45

Uh, the most important one, although as

8:47

I mentioned, there's quite a few of them.