0:01

This is the second portion of the orbital

0:04

scenario for emergency imaging.

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With regard to the orbital inflammation portion,

0:13

in general,

0:15

the studies are ordered with intravenous contrast

0:18

administered and generally these are

0:20

done as CT scans with contrast only.

0:26

So what we are going to be talking

0:27

about are the following entities.

0:30

They are preseptal or what we call periorbital cellulitis.

0:35

Post septal or the commonly called orbital cellulitis.

0:39

And then we have some of the complications thereof including

0:43

periostial abscess and spread outside the orbit,

0:47

possibly even into the intracranial compartment.

0:49

Our differential diagnosis for a red inflamed eye

0:54

includes what we refer to as pseudotumor.

0:57

But nowadays people use the term idiopathic orbital inflammation

1:01

or IOI or idiopathic orbital inflammatory syndrome

1:04

or IOIS or nonspecific orbital inflammation.

1:09

And there are variants to this.

1:10

There's even the IgG variety of orbital inflammation.

1:14

And the other differential in diagnosis include CC fistula,

1:17

which also can have an inflamed irritated edematous eye.

1:23

As you can tell by the naming,

1:25

there is preseptal and postseptal orbital cellulitis.

1:31

So we better understand the concept of the orbital septum.

1:34

The orbital septum is best demonstrated

1:37

on a sagittal diagram here.

1:40

And you can see that it is fibrous tissue

1:43

that attaches to the tarsus of the eye.

1:46

The muscles... musculature here,

1:49

and it is a relatively good barrier to inflammation

1:54

and it separates the preseptal space.

1:57

And when there is inflammation of the preseptal space,

2:00

we refer to it as periorbital cellulitis.

2:02

From the postseptal space,

2:04

which may be either extraconal, outside the muscle cone, or

2:09

intraconal, inside the muscle cone, or conal,

2:13

involving the muscles themselves.

2:16

So here, for example,

2:18

we have that anatomy with the orbital septum.

2:21

Here's the muscle attachment,

2:23

and here's the septum, and here's inflammation which

2:26

is superficial and therefore in the periorbital space.

2:30

You notice however in this diagram that we see inflammation

2:34

which is coming in the muscle cone.

2:37

This is our inferior rectus muscle and there's inflammation

2:40

that is posterior to deep to the orbital septum, and

2:46

this would be our orbital cellulitis example.

2:50

Periorbital cellulitis is manifested largely by the soft

2:54

tissues of the eyelids and maybe even coursing over the nose.

2:59

And you can see,

3:00

in this case, more on the right side than the left side,

3:02

this inflammatory process,

3:04

but it does not cross the orbital septum to enter

3:09

into the muscle cone or the extraconal space.

3:12

Again, some thickening here, but not crossing the orbital septum.

3:17

Contrast that with this case showing post

3:20

septal or orbital cellulitis. Again,

3:23

we usually use either of the term postseptal cellulitis

3:26

or preseptal cellulitis, or periorbital cellulitis,

3:29

and plane orbital cellulitis. In this case,

3:32

you have inflammation along the posterior aspect of

3:35

the globe extending into the retrobulbar space.

3:37

And this would be an example of

3:39

a patient with orbital cellulitis.

3:41

Here you can see the inflammation outside the muscle

3:45

cone. Here's the superior rectus muscle,

3:48

but in that extraconal fat within the orbit.

3:53

So it's encroached here

3:56

above the muscle,

3:58

but in the postseptal space.

4:02

And this would be our postseptal or orbital cellulitis.

4:06

Here another example, periorbital cellulitis with the inflammation

4:11

external to the, or superficial to the orbital septum.

4:15

Here we have the inflammation going and attaching

4:19

at the muscle. So this would be our orbital cellulitis.

4:22

Here again,

4:24

the orbital septum shows inflammation superficial to

4:28

it, and just this by itself would be periorbital cellulitis.

4:32

Except we have this whole collection over here in the

4:36

extraconal space extending from the paranasal sinuses

4:40

and this represents a periosteal abscess.

4:44

So again, crossing into the extraconal space,

4:49

but in the postseptal area.