0:01

This is a little twist on the incomplete

0:04

partition type two story. In this case,

0:07

looking for our congenital sensory neuro hearing

0:09

loss, we again look at the external auditory canal,

0:13

which is normal in appearance.

0:15

We look at the middle ear ossicles and make

0:18

sure they have a normal configuration.

0:20

We've got great-looking

0:22

stapes here at the A window

0:27

and we come to the inner ear structures and we're

0:30

going to start with our vestibular aqueduct

0:33

and see that it is markedly dilated.

0:35

So this is quite large on the right,

0:38

quite large on the left.

0:39

We next look at the appearance of the cochlea and we

0:44

notice that on the right-hand side, we really don't have

0:47

any good meioses, and there is poor development of

0:54

the middle and apical turns.

0:56

On the left-hand side, we have a little bit more of

0:59

a bony architecture of the cochlea on the left,

1:03

but even so, we really don't have good development

1:06

of the middle and apical turns of the cochlea.

1:09

What the little twist in this case is that as we

1:12

look at the vestibule, we say this is

1:15

a very funny-looking vestibule.

1:17

What we see is an enlarged vestibule, and we also

1:22

see this dilated anterior rim of

1:25

the lateral semicircular canal.

1:28

So it should have a uniform caliber,

1:33

both the posterior portion and the anterior portion.

1:35

And what we have is this quite dilated limb.

1:39

And on the left-hand side, it has a more normal

1:43

appearance, a little bit dilated approximately,

1:46

but you can see that this is the normal symmetrical

1:50

limb width of the semicircular canals.

1:55

So in this case, we have this fat-widened anterior

1:59

limb of the lateral semicircular canal

2:02

associated with a bulbous vestibule,

2:06

in this case of incomplete partition type two.

2:09

You notice also that when we compare the anterior

2:12

limb of the superior semicircular canal,

2:16

it too is two to three times larger than the

2:20

posterior limb, and that is also

2:23

identified on the left side.

2:26

So this patient has both incomplete

2:29

partition type two,

2:30

but also additional anomalies associated

2:33

with the semicircular canals.