0:01

What do we mean when we refer to orbital

0:03

blow out fractures? Generally,

0:06

this is a situation where there has been acute

0:10

increase in the pressure in the orbit by either

0:15

something hitting the globe or the orbital

0:18

structures via the baseball in this case,

0:21

or a fist, whatever it may be.

0:23

And with that increasing pressure,

0:25

something has to give.

0:27

And usually it's the orbital floor or the

0:29

medial orbital wall, which are the most vulnerable.

0:33

The orbital floor potentially because of the

0:36

presence of the infraorbital foramen,

0:39

which is a weakness in the orbital

0:41

floor, and the medial orbital wall,

0:44

because as we talk about it,

0:45

the lamina papyracea refers to papyracea,

0:50

which means paper thin. Papyracea

0:52

paper, paper thin medial orbital wall.

0:55

So it's not unusual to see a fracture of the orbital

0:59

floor when you're hitting the eye or the medial

1:03

orbital wall, lamina papyracea.

1:04

You notice in both of these examples, the

1:07

inferior rectus muscle is crossing the plane

1:11

of the fracture along with orbital fat.

1:14

And here, you can make out the medial rectus muscle

1:19

crossing the plane of the fracture

1:21

along with orbital fat.

1:23

These are going to be the risk factors that we as

1:25

normal radiologists will evaluate

1:28

as likely causing entrapment.

1:32

So when you have an orbital floor fracture,

1:34

assess that inferior rectus muscle for its

1:37

shape and position to assess the fascial

1:39

sling of the globe if round,

1:41

if rounded and inferior located and / or the

1:44

fat, that's more likely to be an indicator

1:48

of entrapment. In children,

1:50

you can have these little flaps that occur or trap

1:52

door fractures that also may entrap the muscles.

1:56

With regard to the medial orbit,

1:58

again, high rate of diplopia,

2:00

usually either because of edema of the medial rectus

2:04

muscle or because of entrapment of the

2:06

medial rectus muscle. Both of them,

2:09

because there is an orbital tissue which is

2:14

exiting the orbit and going into the paranasal

2:16

sinuses may lead to enophthalmos, the eye

2:20

actually sinking in compared to the

2:22

contralateral eye from the involvement. I mentioned

2:27

in the case discussion about the importance of

2:30

mentioning whether or not the

2:32

orbital rim is involved. Now,

2:35

the orbital rim is the very anteriormost

2:38

portion of the orbital floor.

2:41

And you see that both on the axial scan as well as

2:44

the anterior most image of the coronal imaging.

2:48

And these lead to what are called impure fracture.

2:51

These impure fractures involve

2:53

orbital rim, often need need emergent realignment

2:56

of the floor because of the attachments

3:00

of the muscle and leading to decreased extraocular

3:03

motility. If the lateral wall is involved,

3:06

and I've only shown you one case

3:07

where the lateral wall is involved,

3:09

you have to think about the potential

3:11

for a trimalleolar or a tripod fracture,

3:14

and we'll refer to these as ZMC

3:17

fractures in just a moment.

3:18

So look elsewhere for the attachment

3:21

of the zygoma to the frontal bone,

3:23

the maxillary bone and the sphenoid

3:25

bone. Roof fractures,

3:27

I showed an example of lots of potential

3:30

intracranial complications because of the potential

3:33

communication with the subarachnoid space

3:36

leading to potentially meningitis.

3:38

If you have infection from that fracture,

3:41

it may also lead to an extra axial

3:43

collection of purulent material,

3:46

usually manifesting as an epidural abscess.

3:50

As I mentioned,

3:51

coronal reconstructions are key. If you don't get

3:53

them routinely from your technologists

3:56

or from the scanner,

3:57

make your own from the thin-section axial scans,

4:01

so that way you have the greatest resolution

4:04

for detecting these fractures.

4:06

Beware retrobulbar hematoma

4:08

and the orbital apex fractures,

4:10

because they can lead to encroachment on the optic

4:14

nerve, leading to an ischemic optic neuropathy,

4:17

leading to blindness due to the optic nerve being

4:20

injured. And finally, another pearl, as I said,

4:23

was look for any little droplets of air.

4:26

Wherever you see a droplet of air,

4:28

try to explain it with an adjacent fracture.

4:31

So here are just to make the points,

4:34

orbital floor fracture with orbital

4:37

emphysema on the right side.

4:40

Here we have lamina papyracea fracture

4:42

with little droplets of air nearby.

4:45

Here we have air fluid levels indicative of

4:48

potential hemorrhage from orbital floor fractures.

4:52

Here we see fracture involving the infraorbital

4:55

foramen, but as importantly,

4:56

this is the anterior orbital rim.

5:00

So this is an impure fracture involving the

5:04

orbital rim. And finally, as I mentioned,

5:07

the presence of air fluid levels that will indicate

5:11

whether or not there is a fracture.

5:13

So in this case,

5:13

looking at the infraorbital foramen and a fracture

5:16

that went right through the infraorbital foramen,

5:18

and compare that to the normal side.