0:00

Let's take a look at another case that has

0:03

some different anatomic variants and learn

0:06

to practice doing the Keros classification.

0:10

So once again, generally most

0:11

people start on the coronal images.

0:14

In this case, we have a more classic appearance

0:17

to bilateral concha, that aeration of the

0:20

middle turbinate, but it doesn't seem to

0:22

be narrowing the airway of the middle MEUs.

0:25

This is our ATE process, our ethmoidal bulla, and

0:29

we got nice, uh, nice anatomy here, nice and clear.

0:33

Paranasal sinuses.

0:35

I wanna point out the depth here

0:38

of the olfactory sulcus region.

0:42

So for this, I'm going to use my little

0:45

measuring device and cut across here and

0:48

then measure the distance from here to the.

0:53

Depth here, and as you can see, the length here is

0:56

eight millimeters, which would be a Keros classification.

1:00

Three for the depth of the

1:02

olfactory sulcus in this individual.

1:05

Another thing that I wanna point out on this

1:07

specific case is the appearance of the optic canal.

1:12

So here we have an area on the left optic canal.

1:18

Again, this is the anterior kink of process.

1:19

We're following the optic nerve from the orbit.

1:23

Through the optic canal, and you can see that

1:25

there is an area where the bone is very thin.

1:28

I would comment on this, particularly if it was

1:30

a patient going for endoscopic sinus surgery

1:33

directed towards the sphenoid sinus, and in

1:36

this case there's a little area of dehiscence.

1:40

The other anatomic variant that we want to mention

1:43

in, in this specific case is this air cell here,

1:47

which if we look on the sagittal reconstruction, is

1:51

an air cell, which is superior to the sphenoid

1:55

sinus, and this would be that OD cell, an ethmoid

1:59

air cell superior to the sphenoid sinus, which

2:01

as you can see, can have an approach to the cell.

2:05

This individual has an unusual variant in that

2:07

the posterior margin of the cell is aerated.

2:11

So this is our tuberculin cell and there is

2:15

aeration all the way back posteriorly here,

2:19

which you can sort of make out on the right side.

2:22

On the axial scan, so not on the left side, but

2:26

on the right side we have that aeration, which

2:28

goes all the way posterior to the cell region.

2:31

And again, if you were directing your surgery

2:33

towards this, you have to realize that going

2:36

through the posterior wall of this sphenoid sinus

2:39

air cell would lead you probably to the pons or the

2:43

basilar artery, which could be quite disastrous.

2:46

Another anatomic variant that we see in this

2:49

individual is the aeration of the OID processes.

2:54

So these are OID air cells, which communicate with

2:57

the sphenoid sinus that you can see is larger on the

3:00

right side than the left side, but present bilaterally.

3:05

Another of the many anatomic variants

3:07

that are important to understand.

3:10

So as I look at this sinonasal CT scan, first off, there

3:14

is no sinusitis, so we're good from that standpoint.

3:17

But I'm gonna be looking at my four locations.

3:20

I'm gonna be looking at the lamina papyracea

3:22

to see whether there are any dehiscence

3:24

here that may lead to orbital penetration.

3:27

I'm gonna be looking along the walls of the

3:29

optic nerve, and I've identified an area

3:31

of dehiscence in the left optic nerve wall.

3:34

Communicating with the sphenoid sinus that may

3:37

lead to potential injury to the optic nerve.

3:39

I'm gonna be looking along the wall of the sphenoid

3:42

sinus where the cavernous carotid artery resides, and

3:48

make sure that there are no areas of dehiscence here

3:51

where lateral penetration could injure the optic nerve.

3:55

And I'm gonna be looking at the wall of

3:57

the cribriform plate to make sure that

4:00

there are no areas of dehiscence where.

4:03

Potential intracranial frontal anterior

4:06

cranial fossa penetration could occur.

4:09

These are the four EUM danger zones.

4:13

Again, let me say them again.

4:15

The lamina papyracea of the orbit, the optic nerve

4:19

canal with the optic nerve at danger, the cavernous

4:24

carotid artery wall and the cribriform plate.

4:29

Those are the four areas where I will always look for

4:32

areas of dehiscence that potentially could lead to a

4:35

complication of functional endoscopic sinus surgery.