0:01

Congenital middle ear anomalies are uncommon.

0:05

They usually are associated with external

0:07

auditory canal atresia.

0:09

As you recall from the external auditory canal talk,

0:12

we often see ossicular anomalies and ossicular

0:16

mass of fused malleus and incus in the setting

0:20

of an external auditory canal atresia.

0:22

External auditory canal atresia is associated with the first brachial

0:26

apparatus, whereas the incus long process and stapes

0:30

are associated with the second brachial apparatus.

0:33

It's pretty uncommon to have an isolated

0:35

second brachial apparatus abnormality.

0:38

The other thing that can occur in a congenital

0:40

form is the congenital cholesteatoma.

0:43

I shudder to use the term cholesteatoma

0:46

in this setting.

0:47

I usually use the term epidermoid in the setting of a

0:50

congenital cholesteatoma to separate it from the

0:53

acquired retraction pocket cholesteatoma.

0:57

But for the time being, they do look alike.

1:00

They are both white lesions, and they

1:03

both have restricted diffusion.

1:05

There are different locations where they may occur

1:08

including along the cochlear promontory,

1:10

just as with a glomus tympanicum or along the fusion

1:17

of the mastoid bone, so-called Körner's septum.

1:24

congenital anomaly, and that is salivary gland

1:27

rests within the middle ear cavity.

1:29

This is heterotopic minor salivary gland

1:32

tissue, which is flesh-colored,

1:34

which can occur in the middle ear as well.

1:36

With regard to the external auditory canal atresias

1:39

and stenosis, as you can see,

1:41

middle ear ossicular anomalies occur in about 50%.

1:44

And remember that we always watch for where the

1:46

location is of the facial nerve, so that way when the

1:49

surgeon is operating to correct the external auditory canal

1:54

atresia, it doesn't interfere with the facial nerve.

1:57

So as I mentioned,

1:58

the second branchial apparatus is the one that is

2:00

associated with the stapes and the incus in the

2:05

endodermal portion, as opposed to the

2:09

ectodermal and mesodermal tissues.

2:12

Here is our patient who has external auditory

2:15

canal atresia with an ossicular mass.

2:18

There's just a sort of fused portion

2:21

of the malleus and incus.

2:22

Usually, it can be attached to the lateral wall as

2:26

you see here on the coronal image where the

2:29

malleus is fused to the lateral wall.

2:31

And again,

2:33

no separation between the malleus and incus.

2:36

And really anomalous looking, you can see that the

2:39

patient also had microtia with calcification

2:42

in this distorted ear.

2:44

Here's another small ear microtia on the left hand

2:49

side. So, as demonstrated in this beautiful diagram,

2:53

the first pharyngeal arch accounts for the

2:57

malleus and the short process of the

3:00

incus,

3:00

whereas the second pharyngeal arch is thought to be the

3:03

source of the long process of the incus

3:06

and the stapes. Now,

3:08

where the stapes inserts at the oval window or the

3:13

so-called otic capsule that is derived from the

3:15

otocyst and otic placode rather than

3:18

from the second branchial apparatus.

3:21

So here is a case that was given

3:23

to me by Suresh Mukherji,

3:25

and what it shows is the neck of the malleus,

3:29

the long process of the incus,

3:31

and a monopodial stapes. We've got one crus of the stapes

3:36

but not the other crus of the stapes.

3:38

And this is a potential second pharyngeal

3:41

arch anomaly. Here is another case.

3:44

Here we have a patient who has

3:47

the neck of the malleus,

3:48

and we're actually seeing a portion of the tensor

3:52

tympani muscle. But where's that second dot,

3:55

the more posterior dot?

3:57

That's the long process of the incus

3:59

which in this case was congenitally absent.

4:01

Again, a case given to me by Suresh Mukherji.

4:04

I'm not sure whether he just photoshopped it

4:06

out or whether it really wasn't there,

4:08

but it accounts for the absence of the long process

4:11

of the incus in a second branchial apparatus anomaly.

4:15

Here was a retrotympanic white mass.

4:18

So when we have the retrotympanic white mass,

4:20

we always worry about an acquired cholesteatoma.

4:23

However, at otoscopy, the surgeons,

4:27

the otolaryngologists will see there

4:30

is retraction of the tympanic membrane,

4:32

maybe a defect in the tympanic membrane.

4:35

There's a history of potentially chronic

4:37

otitis media. In this case,

4:39

there was no history of chronic otitis media.

4:41

The patient presented purely as a finding on

4:45

pediatric otoscopy, and it was a retrotympanic white mass.

4:49

And this is an epidermoid,

4:52

a congenital cholesteatoma white mass seen along the

4:57

cochlear promontory. Here's the cochlear promontory,

4:59

just anterior to it in this situation. Here's

5:03

something called a malleus bar.

5:05

So sometimes the bony portion of the malleus will

5:09

fuse either anteriorly or laterally, associated

5:14

with a conductive hearing loss,

5:16

because the malleus no longer is able to move

5:19

in the appropriate method to transmit sound.

5:22

So when you have this fusion of the bone,

5:26

the ossicle to the epitympanic cavity

5:29

or the tympanic cavity,

5:30

we would call this a malleus bar when

5:32

it's associated with the malleus.

5:35

Sometimes you'll see calcifications leading from the

5:38

middle ear ossicles to the lateral or anterior

5:41

walls. Those may be ligamentous calcifications.

5:45

You see the ligaments here and here and here.

5:47

These ligaments may be calcified when

5:50

you have labyrinthitis ossificans.

5:52

That's a disease that usually primarily

5:55

affecting the inner ear structures.