Microsurgical Resection of an Intracranial Dural Arteriovenous Fistula

CHAPTER 1

Hello my name is Marcus Czabanka. Today we are going to operate an arteriovenous fistula in a 74 year old patient. Here you can see the images over there. Here you can see the feeding of this fistula over here by the external carotid artery. And the reason why we operate on this patient is because the patient was embolized before in 2002, and they couldn't really achieve a complete occlusion, and now it has really grown since then. So, the indication now is  to microsurgically – microsurgically resect the fistula.

For this purpose we going to do five steps. The first step obviously will be the craniotomy and the approach. The second step will be wide opening of the dura to see as much space as possible. Third step then will be an intraoperative in angiography to visualize the fistula. And then the fourth step, we’re going to coagulate and cut the fistula, which is then followed by the fifth step, which is the closing of the operative field.

CHAPTER 2

Okay, so. We have two – that's a 74 year old patient with a AV fistula. It was embolized already before but it recurred. And you can see the two major fistula points on the – on the CT angel that we navigated. One is up here, and the other one should be down here.

So, we’re going to make our approach right here, then make a rather big one left-sided osteoplastic craniotomy. And then we go look for the fistula, and then we are going to close it. That's our - that's our idea. Yeah, and we’re going to start now.

Okay, that's our surgical setup.  So we do the skin incision, okay. Use a very simple straight cut.

Okay, that's our approach. I'm going to use the navigation now to show where we’re going to do our burr holes and where we’re going to plan to do the craniotomy. Okay, you can see – you can see on the left - on the lower row, the left image. You can see the two fistula points, so actually we’re going to do our craniotomy a little larger than that, so we have more space. So, we’re going to do one burr hole here. Nice.

Okay. Some of them – pointer. Okay here, and the other one. Yeah okay, the other one there.

So I'm - I’m about to save this bone to put it back into the burr holes when we close. Okay. It's always gets a mess over the sinus, especially if the patients are older.

Okay now we lift the flap after we did the craniotomy. So we put something on the sinus to cover it. I see. Okay. It’s interesting.

So that’s something I didn’t expect - all these adhesions. So, I'm going to switch now to the microscope. So I didn't expect these adhesions in this way, so I prefer to change to the microscope - has better control and better visualization.

CHAPTER 3

Okay. Okay, now we have some control over the bleeding, so we continue with our opening of the dura.

So now we've done the approach. Now it would be nice to really identify the fistul – the fistula. Here.

There - there they were - these were the fistulas already right there. We changed them when we opened the dura. That's one way of doing it. There you go. See this? They were not in the midline, but they were over here.

I expected the fistula to be more in the midline, but the fistula was actually so far lateral, that I did cut the fistula when I opened the dura. Here we can see some remnants of the fistula. So we’re going to check them. Clamp here.

So we are going to check the flow in these - in these vessels with ICG angiography. Okay, since I really cannot 100% identify the two major fistula points - there we go. So for this vascular intra - for this intraoperative vascular diagnostic, we use fluorescence, and then we’re going to check whether here's the artery supply. We’ve already changed the microscope to the fluorescent filter. And I'm also going to use the navigation to check if that might be the point - that should be too deep. Perfect. Let’s see – yeah that’s draining, that’s a draining vein.

Just to show you where we are - we are right here on the posterior right. Okay let's go back. Ah, there we go. Here we might also have a candidate - and here. Oh, here.

Okay, cut this vein. Then I cut. Then I cut this vein. K. Okay, so I think that’s it.

See that’s the big vein - it’s draining over there. Nice. But here, we cut it already. There you go, so it's not draining anymore. Good. Okay that's - so we have cut all the connections in this area between the - the dura and the - and the brain, and we have shown with the ICG that the big draining vein is not perfused anymore. So surgery should be finished now. We’re just going to close. And that's it.

CHAPTER 4

When we opened the dura, they were localized more laterally than I expected them to be. I thought they would be more in the midline, but that's how it is, that's also the reason why - why we - why we open the dura over a larger area, because we never can 100% predict where the fistula point really is. But that was interesting - see all the vessels - when I opened the dura, all the vessels that were I think the major feeding vessels. But I expected them to be here, but they were over here. Because - this you cannot always – you cannot always say 100% on the angel where the fistula exactly is, so that's the reason why you have to do big openings - or bigger openings - for these kind of surgeries.

Okay now we close it. That’s okay. So now we start - that's the closure. So we put in the bone flap. And now we do the subcutaneous - subcutaneous suturing. The end.

CHAPTER 5

The end result of the surgery was good. So we did see in the intraoperative angiography that the big draining vein was not filling anymore, and we were able to cut it. Surgery had one surprise. I think the major surprise was that when we open the dura, we had already encountered the two fistula points, and we already cut the fistula points by opening the dura. We found other connections between the dura and the brain, and we were able to to cut them out either, so I think the chances are very good that the fistula will be treated now and cured for that patient.