0:00

This was a patient who had chronic right-sided,

0:03

right-sided hearing problems as well as vertigo.

0:07

I'm showing you the T2 CISS image on the right-hand

0:12

side of the screen and the post-gadolinium enhanced

0:15

scan on the left-hand side of the screen.

0:18

Let's look at the CISS image initially.

0:20

So what we see on the CISS image is a nice

0:23

demonstration of the cranial nerves.

0:26

Good look at the brainstem.

0:28

This is actually a nice also demonstration of the

0:32

6th cranial nerve here going into Dorello's canal.

0:36

And here we come to the IAC with the cranial nerves

0:39

looking pretty good, and no mass is identified.

0:42

So normally, we would still perform post-gadolinium

0:46

enhanced scan to make sure that there was not an

0:48

additional lesion in the internal auditory canal,

0:51

even though you see these cranial nerves quite nicely.

0:54

In retrospect,

0:55

we might look at the signal intensity of the cochlea,

1:00

vestibule, and semicircular canals and compare

1:03

the right side to the left side.

1:05

This was only apparent to me in retrospect.

1:09

So this is brighter in signal intensity in the cochlea

1:13

on the left versus the right.

1:15

And also, it looks a little bit dirty on the right side

1:20

and much clean on the left side.

1:24

However, this all becomes much clearer on

1:26

the post-gadolinium enhanced scan.

1:27

So here we have the post-gadolinium enhanced scan,

1:30

and normally, the cochlea does not enhance. And normally,

1:32

the vestibule does not enhance.

1:34

And normally, the semicircular canals do not enhance.

1:36

But as I said previously,

1:38

the 7th cranial nerve may enhance.

1:40

In this case,

1:41

we see on this slice that base...

1:45

the middle and apical turns of the cochlea

1:49

are showing contrast enhancement,

1:51

the vestibule is showing contrast enhancement,

1:53

and the lateral semicircular canal is showing

1:56

contrast enhancement.

1:57

That's abnormal and it correlates with the lower

2:01

signal intensity and replacement of the normal

2:04

periolymph and endolymph by inflamed tissues

2:07

on the right side. So, as I mentioned,

2:10

when we see a unilateral process showing labyrinthitis,

2:13

we're more likely to suggest that it's a complication

2:17

of otomastoiditis, middle ear infection, as opposed

2:21

to a primary viral or autoimmune labyrinthitis.

2:26

In this case,

2:27

the middle ear cavity actually looked fine and the

2:29

patient did not have a history of any inflammation in

2:34

the middle ear, and thus this was eventually

2:38

diagnosed as a viral labyrinthitis.