0:01

This was another patient who had pulsatile tinnitus.

0:05

And upon otoscopy,

0:09

they saw a fleshy pulsatile mass in the

0:14

right middle ear cavity. So again,

0:16

our differential diagnosis included something

0:18

like this aberrant heterotopic,

0:22

minor salivary gland tissue,

0:24

or it could be neoplasm that usually

0:26

wouldn't be pulsatile.

0:28

But one of the other things to consider would be

0:31

something that would be coming from above.

0:34

So here on this axial CISS image,

0:37

we see that the patient has mastoid fluid,

0:40

middle ear fluid,

0:42

and we come upon this soft tissue mass,

0:45

which almost looks like it's

0:46

right at the aditus ad antrum.

0:48

So this is that little hourglass figure of the

0:52

aditus ad antrum going from the middle ear cavity

0:56

into the mastoid air cells.

0:58

So we go to look at the post-gadolinium on the scan

1:02

and we see that this abnormality is

1:05

not showing contrast enhancement.

1:07

So most of the time that minor salivary gland tissue

1:10

could usually enhances and tumors usually would

1:13

enhance. It's not going to be a glomus tumor.

1:15

It's not enhancing quite enough.

1:18

And as you look at the superiormost

1:20

aspect of the lesion,

1:21

we start to see what looks like a communication with

1:25

the temporal lobe and the middle cranial fossa.

1:28

So naturally,

1:29

what we want to do is to look at coronal images.

1:32

And this patient had a CISS image that had coronal

1:37

reconstructions. Here is the abnormality.

1:40

If I magnify,

1:42

we see that in point of fact the temporal lobe has

1:45

herniated into the middle ear cavity through

1:49

a dehiscence in the tegmen tympani.

1:51

So this darker signal intensity is the tegmen

1:53

tympani. This is a portion of the temporal lobe.

1:55

You see a little bit of traction of tissue down

1:58

into the defect at the tegmen tympani.

2:02

And here is our lateral semicircular canal,

2:05

or superior semicircular canal or vestibule.

2:07

So this is in the middle ear cavity and it

2:10

represents an encephalocele with brain tissue

2:15

herniating into the middle ear cavity. That

2:18

would appear to be flesh-colored.

2:21

And it may pulsate because of the CSF pulsations of

2:25

the brain being transmitted into this tissue down

2:29

below. So this is, again, a congenital abnormality,

2:33

an encephalocele going through the tegmen tympani.

2:36

Can you have non-congenital encephaloceles?

2:39

For sure. For example,

2:41

cholesteatomas can erode the tegmen tympani.

2:44

And once they do that with chronic pressure,

2:46

one can see temporal lobe herniations from where the

2:50

cholesteatoma has eroded the tegmen tympani.

2:52

You might also see this post-op.

2:54

So after a mastoidectomy,

2:57

if the tegmen has been removed as part of the

3:00

cholesteatoma removal process,

3:02

you can have herniation of tissue through there.

3:05

Finally, we are seeing increasing numbers of patients

3:08

who have temporal lobe encephaloceles or

3:12

meningoencephaloceles associated with idiopathic

3:15

intracranial hypertension or what was previously

3:18

called pseudotumor cerebri.

3:20

These may occur at the Meckel's cave region, where you

3:24

may have encephaloceles that may even be bilateral,

3:28

or you may have them at the tegmen tympani,

3:31

or you can even have them in the perinasal sinuses.

3:34

Again, these are some of the developmental

3:37

or non-congenital causes of an encephalocele.