0:01

In the last case, we saw a patient who had multiple,

0:03

multiple fractures of various types.

0:06

Let's look at this patient who effectively got punched

0:09

in the eye. Which eye are we got to look for?

0:11

Well,

0:12

if it's a right-handed person who is punching,

0:14

it's going to be the left eye.

0:16

So here we go on the axial scans. Again,

0:19

Focus on the thin section images.

0:22

If your institution is only giving you you the

0:26

reconstructed five millimeter

0:27

or three millimeter sections,

0:29

I would recommend that you request to have the

0:32

raw data thin sections for all the trauma cases.

0:36

This is useful for identifying subdural

0:39

hematomas in the brain,

0:40

but also for relatively subtle fractures.

0:43

So we at Johns Hopkins always get the

0:46

full data set, including the thinnest,

0:50

most raw data of the sections,

0:52

and those are usually at 0.5 to 0.75 mm.

0:56

So looking at this patient, we come to the

1:00

marker for the floor of the orbit, which is the

1:02

infraorbital foramen on the right side,

1:05

and on the affected left side,

1:07

we see that there are some bone fragments

1:10

that are along the wall of the infraorbital foramen.

1:13

We see that there is an air fluid level of

1:16

material that is hyperdense lying in the

1:19

maxillary antrum. Again, suggestive of trauma.

1:22

As we come further anteriorly,

1:23

we see some air in the soft tissues as well as

1:26

air along the floor. And coming further superiorly,

1:32

we can see that there is a comminuted fracture of the

1:35

lamina papyracea with marked displacement here

1:38

more posteriorly and a bone fragment that is

1:42

displaced. And we can measure the distance here.

1:45

This appears to be indenting

1:47

the medial rectus muscle.

1:50

The lateral orbital wall looks fine.

1:52

The superior orbit looks fine, even though

1:54

there is some fluid in the frontal sinus.

1:57

And again, we look at wherever we're seeing

2:00

the little droplets of air,

2:01

we can see that there is usually a fracture nearby,

2:03

right?

2:04

And the absence of any air on the unaffected side.

2:08

Let's look quickly at the soft tissues to make

2:10

sure that there's no soft tissue ocular injury.

2:15

Okay, so there's the hyperdense blood collection layering

2:19

in the maxillary antrum. Here's our globe.

2:22

And the lens looks pristine.

2:25

The interior chamber looks good.

2:27

That bright margin of the cornea and

2:31

sclera overlying the globe looks fine.

2:34

Retrobulbar space looks fine.

2:37

So the soft tissues look good other than the

2:39

presence of orbital emphysema. As I mentioned,

2:42

the coronal reconstructions and the

2:44

sagittal reconstructions are useful for

2:47

identifying fractures of the orbit.

2:49

They're great for identifying the depression

2:51

of the orbital fracture.

2:54

They're great for identifying the medial

2:57

orbital wall fracture fragment.

3:00

And we can see that air.

3:02

Now, I want to point out a few subtle things

3:05

about the coronal image here.

3:08

So the subtle things I want to point out here are

3:11

what's going on with the extraocular muscles?

3:14

So for that,

3:15

we want to look at the soft tissue windows.

3:17

And as we can see here,

3:20

there is mal orientation of

3:22

the medial rectus muscle.

3:24

There is fat herniating at the corner here between

3:29

the orbital floor and the medial orbital wall.

3:32

Both of these could be an indicator for entrapment.

3:36

When the muscle goes through the fracture

3:39

fragment or the fat goes through the fracture

3:42

fragment, with tugging of the muscle, there's a good

3:45

chance that the patient has entrapment.

3:47

Again, this is a clinical evaluation but we do have

3:50

our imaging findings that are suggestive that

3:53

the patient will likely have entrapment.

3:56

You notice that in this case the

3:58

superior-inferior dimension

4:00

of the inferior rectus muscle and its shape is

4:03

different than the normal inferior rectus muscle.

4:06

So this kind of edema of the inferior rectus muscle

4:09

might also be an indicator that that muscle might

4:12

be in part entrapped or just traumatized.

4:16

On the coronal scan,

4:17

I want to point out another finding and that

4:20

is that just previously on the previous case

4:24

I mentioned to you the importance of not

4:27

mistaking the entry of the anterior ethmoidal artery

4:32

from a fracture. Notice on the left side, however,

4:37

that the wall of the entry of the anterior ethmoidal artery

4:41

has been fractured and it's mal oriented.

4:45

This is important because injury to the

4:47

anterior ethmoidal artery can lead to a large

4:51

expanding hematoma in the orbit.

4:56

And a large expanding hematoma in the orbit,

4:58

the risk is that the upper

5:00

nerve could be compressed and lead

5:02

to ischemic optic neuropathy.

5:04

So the importance of mentioning that the

5:07

anterior ethmoidal artery wall is involved is that

5:11

they will be more careful at observing the patient

5:14

to making sure that there isn't increasing proptosis

5:17

or increasing pressure in the eye that might suggest

5:20

that the optic nerve might become at risk.

5:24

And this is, again, seen not as well

5:27

but you want to compare where that fracture is

5:31

with the contralateral side to make sure

5:34

that the superior oblique muscle,

5:36

which is the one that's closest

5:37

to that entry site,

5:39

is not much larger on the affected side

5:42

than the unaffected side. Finally,

5:44

I want to again emphasize that when

5:47

I'm looking at orbital trauma cases,

5:49

I do spend sometime on the sagittal scan because,

5:54

as you can see here,

5:56

the floor fracture is very nicely demonstrated

6:00

on the sagittal scan,

6:01

and you can actually measure the degree of

6:03

the superior-inferior depression, as well as

6:07

sometimes see the muscle entrapped

6:09

in the fracture fragment.

6:11

One of the things that we do mention about when

6:13

we have orbital floor fractures is, is there

6:15

involvement of the infraorbital nerve?

6:18

This doesn't really affect how

6:19

they treat the fracture,

6:21

but it will explain hypoesthesia in the V2

6:26

distribution. So what do I mean by hypoesthesia?

6:29

So you have this absence of sensation and numbness

6:32

that can occur in the second division of the

6:35

fifth cranial nerve, the maxillary nerve,

6:38

as it is affected by the infraorbital

6:40

foramen fracture.

6:42

And this can also be demonstrated

6:44

on the sagittal reconstruction,

6:46

where we see a portion of the infraorbital foramen

6:48

in here. The contralateral side,

6:51

nice, smooth, intact orbital floor.

6:54

This is the normal infraorbital nerve

6:57

coming out at the floor of

6:59

the right orbit as compared to the left orbit.

7:03

So here's our normal nerve looking just fine.

7:07

So important features to consider when one is

7:11

dealing with orbital floor and

7:13

medial orbital wall fractures.