0:01

As I mentioned,

0:02

neoplasms account for a very small percentage of the

0:05

pathology of the inner ear and of the neoplasms.

0:09

Malignant neoplasms account for an even smaller

0:13

representation of the pathology.

0:16

The malignant neoplasms of the inner ear usually

0:19

arise in the petrous apex and then grow from

0:23

there into the inner ear structure.

0:25

This is a patient who has a lesion of the petrous

0:30

apex that is growing into the inner ear structures.

0:33

You can see them on the contralateral side.

0:35

This lesion has internal calcifications from matrix

0:39

and this represents a chondrosarcoma.

0:42

Chondrosarcomas can occur in the petrous apex and

0:45

they may occur along the suture lines in the

0:50

temporal bone and from there infiltrate the inner

0:53

ear structure and present with

0:55

sensorineural hearing loss.

0:57

The other consideration would be metastatic

1:01

disease to the petrous bone.

1:03

That would account for the additional other cases

1:06

of malignancies affecting the inner ear.

1:09

I want to remind you also of the potential

1:13

for trauma to the inner ear structures.

1:16

Remember that we now classify temporal bone

1:19

fractures not as longitudinal or vertical fractures

1:24

or transverse or horizontal fractures,

1:26

but otic capsule sparing fractures or

1:30

otic capsule violating fractures.

1:33

The otic capsule violating fractures are a relatively

1:36

small minority of the fractures,

1:38

but these are the ones that will cross the cochlea

1:41

or the vestibule and therefore have a higher

1:44

rate of sensorineural hearing loss.

1:47

Otic capsule violating fractures usually occur

1:51

secondary to a blow from the occiput and they may be

1:54

associated with 7th nerve paralysis as they

1:57

cross the plane of the 7th cranial nerve.

2:00

Finally, they may also lead to CSF leakage,

2:03

particularly if they affect the petrous apex.

2:07

So with otic capsule violating fractures,

2:12

we usually have sensorineural hearing loss,

2:14

not conductive hearing loss.

2:17

We have CSF leakage secondary to tegmen tympani

2:21

injury or petrous apex injury where you have fluid

2:25

which can leak into the petrous apex air cells.

2:28

Hemorrhage may occur into the inner ear structures

2:31

when you have an otic capsule violating fracture and

2:34

that can lead at the endpoint to labyrinthitis

2:37

ossificans. Finally,

2:39

we have to consider vascular injury because

2:42

if the petrous apex is involved,

2:45

you may injure the petrous internal carotid artery.

2:48

The petrous internal carotid artery vascular injury may

2:51

be manifest as a dissection or at worst,

2:55

a pseudoaneurysm of the petrous internal carotid

2:58

artery which might stimulate, for example,

3:00

a cholesterol granuloma.

3:02

Both the dissection as well as the pseudoaneurysm

3:05

can lead to emboli in the internal carotid artery

3:08

system and therefore strokes that

3:11

can occur intracranially.

3:13

Here is on your left a fracture which

3:16

is outlined by the arrows.

3:18

We see that the fracture extends from the jugular

3:21

vein across the cochlea and even into the expected

3:26

location of the geniculate ganglion of the

3:29

facial nerve. Here is our jugular vein,

3:32

here is the fracture line,

3:33

here is the cochlea with the fracture line going

3:37

through the basal turn of the cochlea.

3:39

And the fracture line continues here

3:41

across the 7th cranial nerve.

3:43

So this patient likely has sensorineural hearing

3:48

loss secondary to the injury to the cochlea and

3:50

may have a facial nerve paralysis as well,

3:53

and then may also have a hemolabyrinth from the blood

3:58

products occurring in the cochlea which can

4:02

ultimately lead to labyrinthitis ossificans.

4:05

Here you see the fracture line which is crossing the

4:09

petrous apex and which may injure the

4:13

petrous internal carotid artery.

4:16

So I'd like to thank you for your attention

4:18

in this talk on the inner ear.

4:21

As the final chapter of the temporal bone,

4:24

we dealt with the external auditory canal,

4:27

we dealt with the middle ear cavity and now we've

4:29

completed our triad of the temporal bone

4:33

with the analysis of the inner ear.

4:35

As you can see,

4:36

this portion of the anatomy is quite a challenge,

4:39

but when you master it, it is very rewarding.

4:43

It's very interesting because you have

4:44

different categories of disease,

4:46

while in the inner ear we have mostly congenital and

4:49

inflammatory lesions with less likely neoplasm and

4:53

the rare otic capsule-violating traumatic lesion.

4:56

Elsewhere in the temporal bone you have lots of

4:59

vascular lesions such as those paragangliomas we

5:02

talked about in the middle ear and the vascular

5:05

abnormalities of the aberrant internal carotid

5:07

artery and jugular bulb descent and diverticula

5:11

in the middle ear cavity.

5:12

And it really is an exciting area to master.

5:16

So I hope you agree that this has been a tour de force

5:19

of the temporal bone with the final

5:21

chapter being the inner ear.

5:23

I hope you enjoyed going over this anatomy

5:26

and pathology as much as I have.

5:28

Thank you very much for your attention.