0:00

This patient also had painful right ear.

0:05

Looking at the CT scan bone windows

0:08

on the axial plane,

0:09

we see the relatively dramatic thickening

0:12

of the wall of the external ear canal,

0:15

both anteriorly and posteriorly.

0:18

On the external bony portion.

0:22

We have the tympanic membrane here, which is okay,

0:25

and nothing in the middle ear cavity

0:26

and the middle ear ossicles.

0:29

What was identified, however,

0:31

was some irregularity along the anterior wall with

0:35

little divots and dots of bone erosion that was

0:41

evident on this external canal anterior wall,

0:45

which should have a nice smooth margination.

0:48

Once you start seeing bony erosion of the external

0:52

canal with associated external otitis,

0:55

you want to start worrying about potential spread

0:58

to the bony region of the skull base.

1:02

So this indeed was a patient who had diabetes and

1:07

had a Pseudomonas external auditory canal infection.

1:12

You may be presented only with a temporal bone

1:16

CT for the evaluation of these patients,

1:19

which does not allow you to see the full skull base,

1:22

and that's what occurred in this particular example.

1:25

Here we have the soft tissue window from the CT scan

1:31

for external otitis externa. And as you can see,

1:34

the field of view was cut off to not demonstrate

1:37

the skull base. However,

1:40

you note that the patient did receive contrast.

1:42

So this is our transverse sinus and sigmoid

1:45

sinus coming to the jugular foramen and

1:48

the jugular vein. So on this example,

1:52

the only thing that really helped us was windowing

1:56

for soft tissue and demonstrating that within the

1:58

parapharyngeal space fat there was edema that

2:02

was not present on the left side.

2:05

We also noted that the shape of the jugular vein at

2:09

the skull base was slightly irregular and

2:12

there was soft tissue posterior to it.

2:15

So this is spread of otitis externa

2:19

around the carotid sheath structures.

2:21

So here's our internal carotid artery in jugular

2:24

vein and from there to the parapharyngeal space,

2:28

all indicative of otitis externa

2:31

of the skull base. In this case,

2:33

we did not see anything on the CT scan at the skull

2:37

base to identify osteomyelitis. However,

2:41

this is an indication for skull-based MRI scanning,

2:46

because as I showed in the PowerPoint,

2:48

the MRI scan may be much more sensitive to the

2:51

edema in the bone marrow than a CT scan in.