0:00

I've mentioned some of the danger zones for the

0:04

preoperative evaluation of a patient who is undergoing

0:08

functional endoscopic sinus surgery, and emphasize

0:11

those four locations, those being the lamina

0:14

papyracea, the optic nerve canal, the carotid artery

0:18

in the cavernous sinus, and the cribriform plate.

0:22

However,

0:23

it is also important to understand

0:26

that sometimes the complications can

0:27

occur after endoscopic sinus surgery.

0:31

So how do we interpret the CT scan

0:34

in the postoperative setting of

0:37

functional endoscopic sinus surgery?

0:39

Well, I usually just go through the normal

0:43

anatomy and identify what is no

0:46

longer present. Again, in the 2020s,

0:50

most of the time the endoscopic sinus

0:52

surgeon is going to be removing the uncinate

0:55

process and doing a medial antrostomy,

0:58

and opening along the medial wall of the

1:01

maxillary sinus, and potentially

1:04

doing a partial ethmoidectomy.

1:06

That is what is typically performed

1:08

nowadays, and it's sort of a minimalistic

1:11

approach to the endoscopic sinus surgery.

1:14

However, what you see is missing

1:16

is what should be described in the

1:18

report.

1:19

Then I'm going to be looking at whether

1:21

there's any soft tissue inflammation,

1:24

residual inflammatory or granulation tissue,

1:28

and whether there are operative defects,

1:30

again, particularly in those four

1:32

areas that I'm most concerned about,

1:34

that might be problematic if they

1:36

go back in for repeat surgery.

1:40

Those four areas as described previously.

1:43

Sometimes they will be obliterating a sinus,

1:47

and you have to describe what's in the sinus.

1:50

This is particularly true when they do

1:51

a frontal sinus osteoplastic surgery,

1:54

where they have obliterated the sinus.

1:57

Frequently you're seeing these defects in

2:02

patients who have surgery via a sinus approach

2:06

to the base of the skull.

2:09

In fact, I would say nowadays the most common

2:12

post-op case that I see is the patient who

2:15

has had a pituitary adenoma resection via a

2:19

transseptal approach or transsphenoidal approach.

2:22

And I'm describing the anatomy, not because of the

2:24

sinus inflammation, but because of the approach

2:27

for the surgical removal of a skull base mass.

2:31

So you wanna describe four W's: what's removed,

2:34

what's left, what's above, and what's down below.

2:38

And those include the normal structures

2:40

or potentially herniating structures.

2:43

So let's look at this case, which

2:44

I believe we saw previously.

2:46

Here we have a patient who has had the uncinate

2:50

process removed, the middle turbinate has been

2:53

removed, the ethmoidal bulla has been removed.

2:57

And in point of fact, it looks

2:58

like they've done an extensive

3:01

ethmoid sinus resection.

3:04

What's concerning is that we have this little blob

3:07

hanging down here from the skull base, and it looks

3:10

like there may be a defect in the cribriform plate.

3:15

So is this residual sinus inflammation?

3:18

Is this granulation tissue?

3:21

Is it a portion of the intracranial

3:23

contents with a meningocele?

3:27

Is it a portion of the intracranial contents

3:30

with brain tissue, an encephalocele or a meningo-

3:33

encephalocele? A lot of times, since we don't know,

3:35

we just call 'em generically cephaloceles, but this

3:39

is an important structure that we want to describe.

3:42

We note also that there seems to

3:45

be an area of dehiscence along the

3:47

lamina papyracea, the medial orbital wall.

3:50

Where is that bone?

3:52

It's no longer there.

3:53

This is a potential complication, as I

3:55

mentioned, of removal of the middle turbinate.

3:58

When you pull on that middle turbinate, you can pull

4:03

the basal lamella and injure the lamina papyracea,

4:07

that thin paper wall. You can pull on it and pull

4:11

down at the cribriform plate and lead to a dehiscence.

4:15

The cribriform plate, which can lead to

4:17

an encephalocele or meningoencephalocele, and

4:20

that in fact could lead to CSF leakage.

4:25

There are a number of potential complications

4:27

after functional endoscopic sinus surgery.

4:28

I mentioned CSF leakage where you have a

4:31

small defect in the cribriform plate or

4:34

anywhere along the paranasal sinuses that has

4:36

a communication with the cerebrospinal fluid.

4:39

You can have herniation of brain tissue or

4:44

just meninges.

4:45

In these cephaloceles, you can have inflammation,

4:49

which now has a communication between the

4:51

intracranial contents and the sinus and nasal cavity,

4:54

leading to meningitis, encephalitis, et cetera.

4:58

And you can injure a blood vessel such as the

5:02

carotid artery or small branches in the skull

5:05

base that can lead to subarachnoid hemorrhage.

5:09

Here's another example.

5:11

Again, these images you see

5:12

are relatively early CT scans.

5:15

They look like old CT scans because these

5:17

date to the 1990s. Nowadays, it's very

5:20

rare to see endoscopic sinus surgery

5:22

where they're removing as much as this.

5:25

In this case, what you see that has been

5:26

removed is the uncinate process on both sides.

5:29

You see that the middle turbinate

5:31

has been removed on both sides.

5:33

You see a gross

5:34

ethmoidectomy bilaterally, and we also see

5:38

that area of dehiscence in the right cribriform

5:41

plate where there could potentially be CSF

5:44

leakage or spread of inflammation intracranially.

5:48

So this is unusual nowadays to see, but you may

5:53

see that from patients who have had previous

5:55

surgery. Here again, another area where I

5:57

would be worried about an area of dehiscence

6:00

in the lamina papyracea of this patient.

6:03

This patient had intrathecal iodinated

6:07

contrast inserted via a lumbar approach, and

6:10

then run intracranially in order to identify

6:14

whether or not the patient had a CSF leak.

6:17

In point of fact, the endoscopic surgeon knew

6:19

that there was a CSF leak because he had seen

6:22

the fluid and tested it for transferrin, which

6:25

is a compound which is pretty typically seen in CSF

6:29

and should not be seen in the sinonasal cavity.

6:33

We have the contrast dye in the interhemispheric

6:36

fissure here and along the skull base in the sella.

6:40

But what you also see is contrast dye, which

6:42

is accumulating here at the cribriform plate,

6:46

where there appears to be a dehiscence.

6:47

And this is a patient who has a concha. This is

6:52

the middle turbinate opposed to the nasal septum.

6:54

There's a little bit of contrast even

6:56

accumulating within the concha, recognizing that

7:00

there has been a leak from the intracranial

7:02

contents into the sinonasal cavity.