0:01

As I mentioned,

0:02

you may see on your request slip for temporal

0:05

bone imaging, Co m versus cholesteatoma.

0:08

The C-O-M referring to chronic otitis media,

0:11

and cholesteatoma referring to that ingrowth of

0:15

squamous epithelium that occurs

0:18

in the middle ear cavity.

0:19

That can lead to a lot of different complications,

0:23

which we'll see in just a moment.

0:26

The

0:28

typical explanation for the occurrence of a

0:32

cholesteatoma is that there is a defect that occurs in

0:36

the tympanic membrane, which allows that squamous

0:39

epithelium from the external auditory canal

0:41

to grow into the middle ear cavity.

0:43

And the portion of the tympanic membrane that

0:45

is usually affected is the pars flaccida.

0:50

The pars flaccida is the larger,

0:52

more superior portion of the tympanic membrane.

0:58

The inferior and posterior portion

1:00

is called the pars tensa.

1:03

It's said that 80% of cholesteatomas occur due

1:08

to the ingrowth through the pars flaccida.

1:12

From the pars flaccida ingrowth,

1:15

the cholesteatoma will show soft tissue

1:19

opacification in Prussak's space.

1:21

Remember that Prusac space is the space between.

1:24

the scutum and the middle ear ossicles.

1:28

And along the way, that scutum may.

1:30

be either blunted or eroded.

1:34

The complications of cholesteatoma include.

1:37

fistula to various structures.

1:39

You can have a fistula to the 7th cranial nerve.

1:42

you can have a fistula to the semicircular canals.

1:47

You can even have a fistula to.

1:49

the vascular structures.

1:51

So this is one of the dangerous complications.

1:56

obviously, of a cholesteatoma.

1:59

Cholesteatomas will also erode bone.

2:01

The most common sites of bony erosion are the tegmen.

2:05

tympani, that is the roof of the temporal bone.

2:08

the ossicular chain.

2:09

and typically we see the incus and malleus.

2:12

affected more commonly than the stapes.

2:15

It can affect the wall of the 7th cranial nerve.

2:19

particularly along its tympanic portion.

2:21

And as I mentioned, it may erode the scutum.

2:25

The 7th cranial nerve involvement is problematic.

2:29

because cholesteatomas can lead.

2:32

to facial nerve palsy.

2:34

and that is a complication that obviously.

2:38

is cosmetic as well as functional.

2:42

With regard to the muscles of facial expression,

2:46

cholesteatomas are seen otoscopically as a white pearl,

2:51

and this is not to be confused with the Black

2:53

Pearl of Pirates of the Caribbean.

2:57

So the white pearl is pearly white.

3:00

Of soft tissue that is seen deep

3:03

to the tympanic membrane.

3:05

This is going to be distinguished

3:08

from the red retro tympanic

3:13

lesion,

3:13

which are the vascular lesions and glomus tumors,

3:15

which we'll talk about in a moment.

3:19

There are two different theories about

3:21

the cholesteatoma's etiology.

3:24

One is the theory which says that chronic

3:27

eustachian tube dysfunction produces a vacuum

3:31

phenomenon within the middle ear, leading

3:33

to retraction pocket of the pars flaccida.

3:37

And then the lining of the epithelium of the tympanic

3:40

membrane or external canal grows through

3:43

and in this retraction pocket,

3:45

which extends to the

3:48

prussac space,

3:50

the epithelial invasion theory postulates ingrowth

3:53

of keratinized squamous epithelium due to

3:56

a perforation of the tympanic membrane.

3:58

So one postulate is that the problem is in the 80 00:04:02,324 --> 00:04:05,346 Middle ear and the vacuum phenomena and

4:05

the Eustachian tube dysfunction.

4:07

The other is a theory that occurs from external

4:12

auditory canal or tympanic membrane with

4:14

squamous ingrowth. In any case,

4:16

what we typically see is opacification of middle ear

4:19

structures, erosion of middle ear structures.

4:22

And then as you see here in the anterior epitympanic

4:25

space, you have loss of the bony confines.

4:27

And in this example,

4:30

we see that the cholesteatoma is fistulizing to

4:35

the lateral semicircular canal, anterior crux.

4:39

So this is an example of a perilymphatic fistula of

4:43

a cholesteatoma in the antiepitympanic

4:45

space to the semicircular canals.

4:51

Here is a diagrammatic example where we see the

4:57

ingrowing squamous epithelium initially on the

5:02

tympanic membrane and then infiltrating Prussak's

5:06

space. Remember, this is the malleus,

5:08

this would be the scutum, and this is Prussak's

5:10

space and the epitympanic space above.

5:12

So this would be sort of the ingrowth theory

5:16

of cholesteatoma development. Once it's here,

5:20

it may lead to erosion of these middle ear ossicles,

5:23

both the malleus and the incus.

5:25

As you can see,

5:25

the stapes is a little bit further away

5:27

and is less likely to be affected.

5:29

This is affecting the anterior superior portion of

5:33

the tympanic membrane, which is the pars flaccida.

5:36

This is the more posterior inferior portion

5:40

of the tympanic membrane, pars tensa.

5:43

So in this example on the CT scan,

5:46

we can see that the scutum has

5:48

been blunted and eroded.

5:52

There's soft tissue around the middle ear ossicles,

5:55

the incus, in this case.

5:58

And you see soft tissue

6:00

extending to the tegmen tympani here and eroding

6:03

the tegmen tympani. Not only that,

6:06

but the facial nerve canal,

6:07

which should be right here,

6:10

its undersurface has also been

6:12

eroded by this cholesteatoma.

6:15

Another example, scutum Prussak's space.

6:21

No middle ear ossicles were identified.

6:23

The facial nerve canal is possibly involved as well.

6:28

Another case, blunted scutum portions

6:31

of middle ear ossicles.

6:32

Here's incus with erosion of

6:35

the long process of incus.

6:37

We got a little bit of the articular process of the

6:39

long process of the incus with soft

6:41

tissue in the middle ear cavity.

6:47

One of the phenomena that cholesteatoma can do is

6:50

something called an automastoidectomy.

6:53

That is that it can erode the bone sufficiently in

6:57

the mastoid air cells as well

6:59

as the middle ear cavity.

7:00

That looks as if the patient has had post-surgical

7:05

mastoidectomy cavity with a canal wall down

7:09

mastoidectomy. This patient has not had any surgery.

7:12

It's the soft tissue cholesteatoma that's eroded all

7:15

of the ossicles as well as the middle

7:17

ear mastoid air cell septations.

7:20

And here you can see one about to do the same.

7:23

Again,

7:23

this is cholesteatoma eroding portions of the

7:26

mastoid and also no middle ear ossicles.

7:29

So the so-called auto mastoidectomy

7:32

of a cholesteatoma.