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Endolymphatic Sac Decompression

Calhoun D. Cunningham III, MD, C. Scott Brown, MD
Duke University Medical Center



So this patient is a 69 year old male with intractable left-sided Meniere's disease. He has failed multiple medical regimens, including diuretic therapy, low sodium diet, as well as both oral and entrotepenic steroid injections. He’s continued to have debilitating episodes of vertigo. These are classic rotary vertigo symptoms lasting two to three hours, and so he does still have usable hearing in this left ear, which is fluctuating. And today we're going to be doing a transmastoid endolymphatic shunt procedure.

Can I have the injection please? The 1:100,000. That’s 1:200. There are various philosophies about the shunt surgery. There are some surgeons who prefer not to do shunt surgery at all, as they do not feel that it is that beneficial. Where some surgeons prefer to just decompress the endolymphatic sac and the surrounding dura. And then the other option is to actually place a stent or shunt into the lumen of the sac, which is what we're going to be doing today. I prefer to use a t-shaped stent, which is made of .005 inch silastic, and that's something we will fabricate here in the OR prior to placing it.

We use a standard postauricular incision for doing this surgery. And 15 blade. We’ll make a postauricular incision a little bit smaller than a standard postauricular incision. We don't need quite as wide exposure as we would need if we were trying to turn the ear forward to get into the ear canal. Okay. And we'll carry this incision all the way down to the muscle periosteal layer superiorly. Can I have a bipolar please? Okay, can I have a Bovie now? Actually a large self-retaining retractor first. And the Bovie. Oops sorry. Sorry - didn’t mean to make it so difficult.

So we are going to score the muscle periosteal layer in a 7 fashion just to create a muscle periosteal flap and expose the mastoid cortex. Lempert elevator please. And we’ll take this muscle periosteal flap just to the posterior edge of the external auditory canal.

So we have the entire mastoid exposed now. The Spine of Henle can be seen anteriorly here and the mastoid tip. We're going to begin with doing a cortical mastoidectomy, and we will - our primary goal is to identify the lateral semicircular canal, antrum, and the sigmoid sinus. The endolymphatic sac often is located in an area if you draw a line tangentially along the lateral semicircular canal where it meets the sigmoid sinus just below and anterior to that line, is typically the area of the endolymphatic sac. And that is known as Donaldson's line. May I have the suction please? And then two folded towels and two Allis clamps.


Number four - fluted burr, but - but it's a pie burr. You have a gimmick? Focus right in here - right this area right here. All the way back posteriorly - we got to find the sigmoid. Good. Alright - keep going. Go through all that - that’s all hair cells. That’s all kind septum below you. You can open up a little bit more down there. Get down to the antrum. One thing you want to try to avoid is doing this - you want to try to avoid doing - like you want to kind of get your suction set up somewhere and then never move it and it's on and off kind of like I'm doing that. Thin that posterior canal wall. All that bone to your left - all that Turner septum - all the way back - saucerize it. Nah, he’s going home. Keep going. We don’t need to get too far anterior cause we don’t want to - we don’t want to open the antrum too much cause you get a lot of bone dust going in there, and sometimes it'll fixate the articular vein. That’s probably mastoid - give me a second.

Direct a little more securely there - yeah, come to - shift to your left, so you're looking up high. Thin the Tegmen cause that’s a kind of high Tegmen, and we’re a little low. Just undercut it… That’s going to be the antrum right in there. Okay - hey how are you doing? So there’s lateral canal deep in there - maybe - maybe we don’t see it quite yet. Yeah, I don’t think we do yet. Take a little bit of that. Just take this anterior ledge. Yep. Come all the way out laterally - yep, that’s good. Now - wait, look and see first - it’s going to be right there.

Okay then come back and open all this up. So now, we need to - we need to find sigmoid, but we need to kind of come back in - and focus in that area there. I'm starting to open. Should I saucerize? No, I don’t think that matters too much because the area we want to be is ultimately going to be right now in there. Starting to feel a little sigmoid there - right under there. Can we have a Bovie for a second? Okay. Right in there. Just smooth out a little bit more back - kind of - back to kind of to here. He’s got kind of a - he’s going to have a - more of a flat sigmoid. Okay. Gently thin some more of the stuff in here. Use the side of your burr - turn your - rotate your hand up. All the way towards the tip a little bit - yep, nice. All the way towards the tip a little bit. Yep. Right in there. All the way out lateral now, moving on it. Okay, now delineate your sigmoid better. His sigmoid doesn’t - doesn’t ride up like a big dome. It’s - it’s more of a - sort of a flat sigmoid. And really we'd like to kind of decompress the top of - the anterior half of it. We don't have to decompress the whole thing but…

So yeah, try to get some of the bone out of the sinodural angle. You know, where the sinus and the Tegmen approach each other. Okay, gimmick. Scott, now you want to get - all this bone in between? No, you want to get all this stuff out of here. There’s a lot of stuff. Very gently in there. I think there’s still bone there. Yep. Take that done there? No, I want to see lateral canal better. Yeah, I agree.

So open up a little bit more of this bone right here. Thin the posterior canal wall a little bit more. See how thick it is? But more up top here - like closer to - yeah, right in there. Hold on a second. Get that. Suction in there now. Looks like trabecular bone - maybe lateral canal is just under - right there, right there’s later canal. So you can come through some of this stuff here and - and smooth down some of that. You can start to see it a little better with just a little trabecular over there.

So there’s lateral canal, and then here’s - if you look through - maybe it’s still lateral. I thought maybe that’s posterior down there. So one thing we can do to kind of speed things up, is kind of thin all this down real quick. And we’re going to be - there’s one down there. And I’m wondering is that - is that still part of the lateral or is it part of posterior canal? Right there.

Yes so see - can I have a gimmick? Water off please. Let’s go to a 7 suction irrigator. So lateral canal is kind of coming like this, and then that’s posterior canal, running like that. And so what I want you to do is just take your diamond - let's go to a - do you have a 4 diamond? And about that level, just kinda start thinning that. We’ll look for facial nerve. Alright, all the way down - use the whole length. Right in that level right there. Don’t let white char build up. Keep going.

Starting to see it there. Starting to see it there I think - pink right underneath me. Unless it’s just mucosal. Could be. Paint a little lightly - very lightly over that area. I think you might be right. Can’t tell yet though. Try to thin the bone around it a little bit. If that’s it, it’s going to be swinging up laterally. So this is one of those temporal bones where the air cells are right on the nerve. Sometimes you pop through an hair cell and there’s the nerve. I think that’s it, and there’s chorda right above it. Yeah. I think you’re right. Maybe? That’s what it looks like at least.

So now decompress the sigmoid - the top of the sigmoid and kind of the front part of it. Yeah, that's okay. Don't worry about it. The area you really want to be focusing is more superior on the sigmoid. So right where that lateral canal and the sigmoid meet - just below there is where we’re going to remove bone from. Get that bleeder. That’s not fossa, is it? No. Come up - bring up laterally more - you’re - you’re just below it. A little more. Don’t put water on - keep the water off - water off. Hold on - I don’t - yeah, don’t - don’t do that. Get a little bone wax there or something. Finish opening this up here though? Just open that a little bit more inferior to where you are. Yeah, there I am. Just sort of inferior and medial to that. Get rid of the dura.


Yeah, yeah, yeah. Maybe sac right there too. See how that’s real vascular. That’s a nice - real nice look at the posterior canal. Yeah. So here is lateral semicircular canal and then posterior semicircular canal, and I think maybe - what is that - a little water. I can’t tell if that… Seems a little bit strange though. I’m not 100%. We don’t really need to get too much. That’s dura there. Blood vessel on the dura. I’m going to go ahead and decompress this sigmoid a little bit more. And we’ll actually bipolar those little vessels on there. Some people say just decompressing is also good. He’s got a weird, really flat sigmoid sinus. Not a predictor of anything that we know of. There’s a retrofacial air cell in here. Very vascular. Not so sure that is facial.

Now, we want to come back this way. Decompress just a little bit more. Very vascular. Okay, now water off please. Can I get a bipolar? Now can I - do we have a J dissector like we did on that last case? What’s that? Wonderful. Can I have that please?

I like getting this bone really thin, and then rather than drilling it away, just kind of separating the dura cause I'd like to - if possible - I’d like to keep this dural surface really clean, and not get it abraded too much. Cause once he gets all of ratty and kind of abraded, it gets difficult to tell where the sac is. And so we’ll kind of just flick this bone off, and then push the dura away from the bone, and that way the sac - oh look at all these blood vessels. Let’s have the bipolar. Well, people have talked about the vasculature - like these - bipolar. These blood vessels between the sigmoid and the sac and the dura, and maybe - and maybe has something to do with it, but I don't - I don't, who knows. So I usually do bipolar them all.

Alright now, the - the J dissector again. It’s - it was a scheduling mixup. Yeah, you're absolutely right. It's going to really hurt me tomorrow. I have clinic all day tomorrow - busy clinic too. So then, we kind of flick some of that off, but we can also drill all that away. Yeah, maybe. That’s part of the sac right there. Okay drill - or drill.

I mean I’m looking at posterior canal here. I’ll take this right up beside the posterior canal, which is right there. These are the retrofacial air cells that we see. Water off for a second. He’s got a lot of… Alright, let’s see - control pedal. Water on. Water.

You have to be cognizant - coming in inferiorly there, right? Yeah, yeah the facial nerve? The facial is up here. So there’s the level of the lateral canal. Facial is running kind of in this direction. So if we - if we kind of come up here, we can - we can kind of follow it. And you see how it’s running now. You don’t always have to find the facial nerve. I think it’s a good idea to find the facial nerve cause when you know where the nerve is, you know how far underneath it you can go. And a lot of times the sac is located pretty - kind of far anterior down in this area here. I think we're seeing the edge of the sac right there. So we're going to just get a little bit more of this bone, and then we - we’re really pretty close to being - getting the exposure that we want.

Now that J dissector again. Please. Water off. So we’ll kind of push this down. Separate that - and that’s the sac right there. At least he’s got a pretty good sac though. You can actually see how these fibers are kind of radiating coming back that way. Okay, drill. I'm going to take this right up to the edge of the posterior canal. Water on.

So we’re just getting a little bit more anterior exposure here. Water off. J dissector. But you can see the area of the sac pretty well. See how it's real white right in there? And sigmoid is continuing to traverse down in this direction. So we can see, this is the top of the sac right here, and it kind of comes down at - like this. And if we draw a line along the lateral canal where it meets the sigmoid, usually that's about the area that is - which is the top of the sac. But you see - see how at it tenses up right there? Do you see that Scott? That’s - so this is all the sac here. We're just - get a little bit more bone, and then we're really done. He's got a good - this is a good one so. Can I have a bulb irrigator? There’s the sac right there. Completely decompressed.


Now we're going to fasten our stent. I’m going to take that silastic and on - if I can have it on a Teflon block. And I'm going to need a marking pen. And there’s no real scientific means to this. Can I have a bulb - I mean a green towel - fresh green towel? Silastic block and the marking pen. So usually - man that's bright - I will mark it out a little bit first - just a general. Okay, now an 11 blade. I hope so. Do you have an 11 blade? So I’ll make a little line like this. And then actually, this will be like that. Making a capital T? Yup. Have you seen that before? And it was a - it was a really crummy one - it was super small and tucked in. It was the one you ended up doing the lapendectomy on. Oh yeah. So, you can sometimes tell. Like, I don’t - like, he’s got a really good sac, so I think he will do well, but you are correct in that some people just, you know, it's just very nebulous. And those usually, you're kind of like, umm may not do as well.

Okay, so here is our T stent. We can kind of trim off a little bit more of this, and there's no magic ratio or size or anything. It's just we’re creating a little stent just to go in there. Let me have now some irrigation. And a damp sponge - oh jeez. Damp sponge. Just try to get some of the ink off of it. Now, Ariel can I have a pair of smooth alligators and a gimmick?

So now we have to come get this situated how we're going to put it in. So we take it - gimmick - and what we want to do is we want to fold these little T arms over on themself like so - one there and then one like that. And then we grab it so that when we put it in, those little arms will kind of spring open - will you hold that like this? And then I need a - let me have that irrigation one more time.

5910 sickle knife and then I'm going to need a - that thing is all bent. I'm going to need - a... Okay let's have the sickle knife, footplate hook. So now we are going to make just a little small incision right here. The lumen of the sac has kind of this glisteny appearance to it. Now the - the foot plate hooks. A smaller one. The micro footplate. Is there one smaller than that? Are you sure? There should be one smaller than that Ariel. This one was in the large spot, but it looks little. That kind of glisteny tissue.

Now the - the shunt. And it's weird - you can't probably see it well on there, but the inside of the site has almost this weird glistening kind of - like a weird glistening like surface to it. It’s all the sac. Right there. See how I kind of tense it all up? Let's have that footplate hook again. That’s exactly what you want it to do, and that's it.