0:00

This was a patient who presented with echolalia, that is,

0:04

feeling that they were hearing their own voice echoing in

0:08

their ear that became very disturbing to them,

0:11

and also with a mild sensory hearing loss.

0:16

This is a phenomenon that would direct us to the

0:19

semicircular canals. But let's take a quick look.

0:22

The external auditory canal looks normal from the cartilaginous,

0:24

as well as the bony portion.

0:27

Looking at our middle ear ossicles,

0:29

we got a nice demonstration of the head of the malleus,

0:32

short process of the incus,

0:33

the neck of the malleus and the long process of the incus,

0:36

a good incudostapedial joint with a stapes inserting

0:40

nicely on the oval window.

0:42

One of the phenomenon that I mentioned on one of the

0:45

previous cases was you should see really thin

0:49

bone or no bone at the oval window.

0:51

Sometimes that bone will be thickened and you

0:54

have oval window stenosis on a bony basis.

0:58

As we look at the cochlea,

1:01

we have a nice demonstration of the basal turn of

1:04

the cochlea with a spiral lamina within it,

1:06

a good-looking medialis, separating the middle and apical

1:11

turns of the cochlea and a nice wide open

1:15

cochlear aperture with, as you can see,

1:18

an opening in the bone for the cochlea and the cochlear

1:21

aperture and the cochlear nerve to pass through.

1:24

We have a good singular canal,

1:25

semicircular vestibule, and the semicircular canals,

1:31

lateral semicircular canal, posterior semicircular canal.

1:34

And as we go further superior,

1:37

we come to the superior semicircular canal,

1:40

and this is where we're going to be concerned about

1:42

the potential for dehiscence.

1:45

Now, this is in the axial plane,

1:47

which is not the best plane to look

1:49

for semicircular canal dehiscence.

1:51

We want to do that spiral analysis by putting an angle of...

1:57

an angle of curvature, perpendicular to the top of

2:02

the superior semicircular canal.

2:04

Fortunately, in this particular example,

2:06

we have a coronal view,

2:09

which very nicely demonstrates that

2:11

there is no bone overlying the superior semicircular canal

2:16

on the left side...

2:17

on the right side,

2:19

as well as the same phenomenon on the left side,

2:23

where you've lost that bony partition

2:26

overlying the superior semicircular canal.

2:30

The lateral semicircular canal and posterior

2:32

semicircular canals look fine.

2:34

You can see this also to an extent on the other

2:37

reconstructions that were performed.

2:39

But I think that the coronal reconstruction was pretty

2:43

much definitive in identifying the absence of bone,

2:46

in this case of superior semicircular

2:49

canal dehiscence, bilaterally.