0:01

We've already discussed some of the benign neoplasms

0:04

of the middle ear, and they have

0:06

included the paragangliomas.

0:08

And we saw examples of glomus tympanicum and glomus

0:11

jugulotympanicum, generally presenting on the one

0:15

hand over the cochlear promontory, or with regard to

0:18

glomus jugulotympanicum growing from the jugular

0:22

foramen upward and outward into the middle ear

0:26

cavity to cause a soft tissue mass in the middle

0:29

ear. Those are the retrotympanic red masses.

0:34

We also discussed hemangiomas of either

0:38

de novo in the middle ear cavity or associated

0:40

with the facial nerve.

0:41

These may be called ossifying facial nerve

0:44

hemangiomas because they really are in the wall of

0:47

the facial nerve canal, and we usually think of them

0:50

more as venous vascular malformation

0:53

rather than a true neoplasm.

0:55

Remember that hemangiomas really refers to

0:57

lesions that occur in children,

1:00

often having a growth phase followed

1:04

by an involutional phase,

1:05

whereas the thing that stays on into adulthood

1:08

is really a venous vascular malformation.

1:11

So let's move to the next category of the nine

1:14

neoplasms of the middle ear, and those are

1:16

the schwannomas or neurogenic tumors.

1:20

These two are not retrotympanic vascular masses nor

1:25

retrotympanic white masses, I-E-R cholesteatomas,

1:28

but they're flesh-colored

1:30

like the minor salivary gland rests

1:33

and like what

1:33

we will find out the adenomas down below.

1:36

So most of the schwannomas that we think of with

1:40

regard to the temporal bone are usually in the

1:42

internal auditory canal are vestibular schwannomas.

1:46

However,

1:46

you can have ones that affect the inner ear,

1:48

the so-called labyrinthine ones,

1:50

or those that affect the facial nerve

1:53

which are your facial nerve schwannomas,

1:56

which can affect the tympanic portion

1:58

and present as a middle ear mass.

2:00

The adenomas are neuroendocrine tumors.

2:03

They are very rare.

2:05

Middle ear adenomas will show

2:07

avid contrast enhancement.

2:10

Here we have a patient who has a mass which is seen

2:15

as enlargement of the geniculate ganglion and the

2:20

proximal portion of the tympanic portion of the

2:22

facial nerve. So here we are at the first genu.

2:24

We're catching a little bit of the labyrinthine

2:27

portion of the facial nerve, and here

2:30

it is on the coronal scan.

2:32

This lesion did not have that same kind of salt and

2:35

pepper reticulated appearance that

2:38

the facial nerve hemangioma has.

2:41

And here we can see a characteristic one that

2:44

has that matrix of kind of calcification

2:47

bone trabeculation, etc.

2:49

which is more typical of a facial nerve hemangioma

2:53

or venous vascular malformation.

2:54

This one was a facial nerve schwannoma

2:57

affecting geniculate ganglion and the

3:00

tympanic and proximal portions of the labyrinthine

3:04

portion of the facial nerve.

3:06

Just a quick comment about facial nerve enhancement.

3:09

The tympanic and mastoid portions of the facial

3:14

nerve will normally show contrast enhancement.

3:17

And in this classic, classic article from 1992,

3:20

probably before some of you were in medical school,

3:24

you can... Gabarski,

3:26

Steven Gabarski from University of Michigan looked

3:28

at the facial nerve and saw that the right-left

3:32

discrepancy in enhancement between the tympanic

3:37

or mastoid portion was stereotypical.

3:40

It was 69% have a asymmetry from right to left of this

3:44

facial nerve portions of the geniculate ganglion,

3:47

the tympanic portion and the mastoid segment.

3:49

The portion that should not enhance is the

3:52

intracanalicular portion in the internal auditory canal

3:56

and the labyrinthine portion. The preganglionic

3:59

portion of the facial nerve should not enhance.

4:01

When those enhance, we think of Bell's palsy

4:05

for example,

4:06

or we may be thinking of schwannomas or your

4:11

hemangiomas, your venous vascular malformations.

4:15

So here, for example,

4:16

is a patient who we can see at intermittent portions

4:19

of the descending portion of the mastoid portion of

4:23

the facial nerve. It shows contrast enhancement.

4:26

Some portions of the tympanic portion of the facial

4:29

nerve will enhance. This is all normal.

4:31

What should not enhance is the intracanalicular

4:34

portion or the labyrinthine portion.

4:37

The geniculate ganglion will show normal

4:40

contrast enhancement. So again,

4:43

normally, we see, you can see enhancement

4:46

in the geniculate ganglion,

4:47

the tympanic portion of the facial nerve, and

4:49

the mastoid portion of the facial nerve.

4:51

You should not see enhancement of the

4:54

portion in the internal auditory canal,

4:56

the intracanalicular portion,

4:57

nor the labyrinthine portion in the fallopian

5:01

canal prior to the geniculate ganglion.