Endoscopic Sinus Surgery with Navigation: Preoperative & Intraoperative Applications of Advanced Navigation

[Dr. Gopi Shah]:
Today we're going to talk about navigation. It's like the backbone, especially some of the advanced sinus and skull base surgery. Tell me first, when do you use navigation? Is it one of those where when you post a case, it's an automatic thing on your card, or when you're posting a case, you actually add, this is endoscopic sinus surgery with navigation. When do you use it?

[Dr. Raj Sindwani]:
Yes, that's a good point. Here, because I think the nature of my practice is more complex stuff, I don't have to check a box. They do have it in the room and the residents know to set it up pretty much with every single case. As a more broad question, when do we do, when does one use navigation? I would say it's whenever you're doing something complex enough, different enough, that you want to have a little bit more localization and orientation. That could take a lot of different forms, but usually when we're in the posterior ethmoids or sphenoid, most of us like to have navigation or doing final surgery.

Certainly, in this scenario of tumors, skull base orbit, when you know you're going to be up close to some pretty important landmarks, like the lamina or skull base, you want to have navigation then as well. We've done some complex maxillary sinus cases in the setting of trauma or tumors, where even for maxillary sinus surgery, you would want to have navigation. When you look at some of the position papers or even the academy's statement on navigation, it's purposely general and vague. The idea is really when you think it would help you to be more oriented, visualize better or localize better, you should use it.

[Dr. Gopi Shah]:
Yes. No, that's a great way to put it, because sometimes, you might be at a place where maybe the navigation system, it's maybe dated or it's not always available. When you are having to decide, how to post a case, where to post a case, you have to really think, "Am I going to use navigation?" If most of your practice is complex or you're using it routinely, it's going to be automatic. When it's not as common, sometimes it does have to be something that, okay, I need to think about and where am I going to do the case? Do you ever find situations where navigation hurts you? Is there ever a time?

[Dr. Raj Sindwani]:
Yes. I don't know about hurts you. It can frustrate you and delay you seemingly, because if it's off and you're using it to make a decision, am I in the right spot? Am I past the area that I want it to be in and so on. You want your clinical acumen and suspicions to trump anything a machine or a tool is telling you. Sometimes when you're trying to corroborate that, things can grind to a halt for a few minutes until you troubleshoot what the system is telling you versus what maybe you believe to be the truth as far as anatomy and landmark.

It can certainly be frustrating. I think that's why relying on some of the newer systems that really do help maintain accuracy and flag to your attention when things are awry can be very helpful.

[Dr. Gopi Shah]:
Yes. We're going to get to troubleshooting because I think that that's something that everybody has had to deal with at some point. Before we get there, so let's say a patient comes to your clinic. Let's say it's a new patient and it's some sort of sinus pathology. What on your history or physical exam on the image makes you say, "Okay, we're probably going to need to use navigation. This is how I'm going to use it." How do you start thinking about it upon evaluation?

[Dr. Raj Sindwani]:
Sure. It gets back to that idea of visualization. As I'm speaking to the patient, from a historical perspective, or even certainly by the time you get to look at their imaging, it has to do with the complexity of the problem. The disease process, and the complexity maybe of the surgery or the approach that you're going to be using. If the patient tells you, "I've had prior sinus surgery before, or I've had radiation before or trauma." Right away, before you even look at any imaging, that the anatomy is not going to be normal. It's not going to be straightforward. You might appreciate at one point or another during that surgery, once you get to it, having an extra tool to help you stay oriented.

Those are the things that I'm listening for. By the time it gets to the navigation, the imaging, then of course you are looking to see how abnormal the anatomy is. How extensive the disease process is as well. Again, we're lucky because in sinus surgery, the more routine sinus surgery, we have fixed bony landmarks. When we are done, the sphenoid face is there, the skull base is there, and the lamina is there. Everything else can come out depending on what the indications are for surgery. As long as those main boundaries are in mind, that's where we start thinking of how navigation can be helpful.
Now in the setting of tumors, whether that's sinonasal tumors or certainly intracranial tumors, as you know we use navigation not just for the bony landmarks that I mentioned, but also for the soft tissue that we'll also be manipulating during surgery. It's not uncommon, and actually in our practice, quite routine to get CT imaging, high resolution, less than one millimeter. Also MRI scans with a skull base protocol to be able to superimpose those images that we'll use together for the approach, the resection, and also sometimes to help with some of our reconstructive options as well.

[Dr. Gopi Shah]:
Are there certain cases where, I guess, in the case of where a patient might have a tumor, when you are like, "Okay, let me go ahead and get an MRI because I'm going to need MRI image guidance as well as CT image guidance." I imagine the skull base, pituitary cases, but if you could expand on that a little bit more.

[Dr. Raj Sindwani]:
Yes, so anytime you're going intracranial or doing any CNS pathology, whether that's pituitary, meningiomas, and so on, as your viewership knows, CT shows us bony landmarks and MRI is better for soft tissue. When we're actually operating on soft tissues, it's helpful. That includes sinonasal tumors as well, because you'll want to be able to know the detailed anatomy of the tumor, not just the bony box, i.e. the sinuses that the tumor is sitting in, or that you'll have to traverse to get into the tumor. Other kinds of softer calls might be if you're worried about an orbital dehiscence. Sometimes it's easy to plan out the lamina and you can see it as a straight line.

Once in a while, you'll notice some gaps in it. Now, if it's next to an aerated sinus, like the ethmoid is aerated, you may be very clear and obvious that there's a dehiscence of that lamina and some orbital contents pooching into the ethmoid. Sometimes, in the setting of disease, you can't tell that so well, between volume averaging of the thin bones already and so on. That's one indication where I think it's very wise to get an MRI.

If you are suspicious that there's been an orbital injury in the past and you have some orbital contents that might be in your field. Of course, CSF leaks with soft tissue in the area of the bony defect, you'll want to get an MRI as well. Not just to characterize the extent of meningoencephalocele that might be present. We also use MRI, as you know to look for stigmata of IIH, for example. The disease process also dictates what imaging we get.

[Dr. Gopi Shah]:
Do you use any navigation for in-office sinus work in your practice?

[Dr. Raj Sindwani]:
Yes. We are just doing more and more in-office surgery. As you know all of us are dabbling in it. Especially if you can get the same goals met, rather than being in the high-price environment of an operating room, it makes a lot of sense from every dimension. The insurance companies, the surgeon has an easier time scheduling it. Of course, it's the best for the patient because you don't have to worry about the risk of general anesthesia. Or really the inconvenience of having to go to the operating room. I think this idea of wanting to know where you are and being accurate makes sense, whether you're in the OR, in an ASC, or in the clinic.

You would think that maybe in the clinic setting, there may even be an argument to be made that you want to be more localized because the patients are awake. They could move. They could only tolerate so much, so to speak. You want to be efficient in getting in, accomplishing the goals, and coming out. I think the same rationale should hold true regardless of where you're doing the surgery. You need to know where you are, know where your landmarks are, and know where your "no-fly zones are." That should hold true in the clinic environment as well.

[Dr. Gopi Shah]:
You also have some of the same navigated instruments as well, if you need a microdebrider, potentially, depending on what your plans are as well.

[Dr. Raj Sindwani]:
Exactly. Whether you're doing a balloon procedure, you're usually doing more minimally invasive things in the clinic because it's an awake patient. Exactly, from the balloons to your other instruments, including curettes and microdebriders, you can track them all the same way. I think that's a nice way to get facile with using the systems as well. Do some of it using a patient that's under general anesthesia, then you get facile with it. You almost crave it when you're in the clinic as well so that you can do the same, at least, level of surgery, if you will, from a completeness standpoint, even though the patient may be awake.