Endolymphatic Sac Decompression

CHAPTER 1

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 intratympanic 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.

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, whereas 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. Mm hmm. Oh, sorry - I 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.

Okay. 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, and 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.

CHAPTER 2

Number 4 - fluted burr, but it's a pie burr. Do you have a Gimmick? Focus like right in here. Right in this area, right here. All the way back posteriorly - we got to find the sigmoid. Good. All right - keep going. Go through all that - that’s all air cells. And that must all - Koerner's septum below you. Now you can open up a little bit more down there. Mm hmm. Okay, let's get down to 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 just on and off kind of doing like that. Mm hmm. And thin that posterior canal wall. All that bone to your left - all that Koerner's septum - all the way back - saucerize it. Mm hmm. Mm hmm. Good. No, he’s going home. Just keep going. So we don’t need to get too far anterior because we don’t want to open the antrum too much because you get a lot of bone dust going in there, and sometimes it'll fixate the ossicular chain. Yep. Mm hmm. That’s probably mast- give me a second. Mm hmm. Direct a little more superiorly there. Yeah, come - shift to your left, so you're looking up high. Okay, and thin the tegmen because actually she's got kind of a high tegmen, and we’re a little low. So don't... Just undercut it, then we'll have to take the space up here too. Mm hmm, that’s going to be the antrum, right in there. Mm hmm. Mm hmm. Okay - hey how are you doing? Good. Okay, so there’s lateral canal, right deep in there. Maybe - maybe we don’t see it quite yet. Yeah, I don’t think we do yet. Just take a little bit of that. Just kind of take this anterior ledge? Yep. Okay. Come all the way out laterally. Yep, that’s good. Mm hmm, now - wait, look and see first - it’s going to be right there. Okay. I'm just going to come back and open all this up. Yep, so now, we need to - we need to find sigmoid, but we need to kind of come back in - just focus in that area there. Okay - should I saucerize this? No, I don’t think that matters too much because the area we want to be is ultimately going to be right down in there. Okay, I'm starting to feel a little sigmoid there. Right under it. Just find the sigmoid. Can we have a Bovie for a second? Okay. Just smooth out a little bit more back - kind of - go back to here. You know, because he’s got kind of a - he’s going to have a - more of a flat sigmoid. Mm hmm, okay. And try to gently thin some more of this stuff in here. Use the side of your burr - turn your - rotate your hand up. Yep. Mm hmm. All the way towards the - yep, just in there. Mm hmm, all the way out lateral now, moving on it. Mm hmm, yep. Mm hmm. Yep, just now delineate your sigmoid better. Mm hmm. His sigmoid doesn’t ride up like a big dome. It’s more of a, sort of a flat sigmoid. Mm hmm. And really we'd like to kind of decompress the top half - 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? So Scott, now you want to get... All this bone in between? Well no, you want to, kind of get this stuff out of here. Okay. Those are all air cells still. Now very gently come in there. Mm hmm. Let me... Yep. Take that down there? No, I want to see lateral canal better. Yeah, I agree. So open up a little bit more of this bone right here. Okay. Thin the posterior canal wall a little bit more. Take out - did you see how thick it is? Put more up top here, focus it - yeah, right in there. Mm hmm. Yep. Mm hmm. Mm hmm. All right - hold on a second. There's that. Let's go ahead and get... Get a little suction in there now. It still looks like trabecular to bone, maybe lateral canal just under that... Right there. Right there is lateral canal. So you can come through some of this stuff here and smooth down some of that. Okay. Mm hmm. Mm hmm. I'm starting to see it a little better underneath this little trabecula there. Mm hmm. Now just cut through this and... Mm hmm. Yep. So there’s lateral canal, so - 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 just kind of thin all this down real quick. And then all I’m wondering is - is that still part of the lateral - or just part of posterior canal? Right there. Yeah, so see - let me have a Gimmick? Water off. Let's go to a 7 suction irrigator. So the 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 at about that level, just start kind of thinning that. We’ll look for facial nerve. Okay. All right, yep. Yep, all the way down - use the whole length. Mm hmm. Keep going. Mm hmm. Yep, right in that level right there. You don’t let white char build up. Mm hmm. Keep going. I'm starting to see it there. I'm starting to see it there, I think - right underneath me. Unless it’s just mucosal... Well yeah, could be. Just paint a little lightly - very lightly over that area. Yeah, I think you might be right. Can’t tell yet though. I'm just trying to kind of thin the bone around it a little bit. Mm hmm. 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 air cell and there’s the nerve. Yeah, I think that's it, and then there’s chorda right above it. Yeah. I think you’re right. Okay. 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. 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 need to remove bone from. Yep, get that bleeder. Mm hmm. That’s not fossa, is it? No. Okay, come up - bring it up laterally more. You’re just below it. A little bit more. Don’t put water on - keep the water off. Water off. Yeah, hold on, I don’t - yeah, I don’t - don’t do that. Get a little bone wax there or something. Okay. I can finish opening this up here though. Yeah, just open that a little bit more inferior to where you are. Water on. Yeah, right there I am. Just sort of inferior and medial to that. Here is the dura? Yeah.

CHAPTER 3

Good. Oh, yeah. Yeah, yeah, yeah. I think maybe it's sac right there too. See how that’s real vascular? That’s a nice - a real nice look at the posterior canal. Yeah. So here is lateral semicircular canal and then posterior semicircular canal. And I think you may be - let's see, where is that? A little more water. I can't tell if that... I think I'm right about that... Yeah, I think you might be. And there's chorda coming off of it... It seems a little bit strange though. I don't know, I’m not 100%. We don’t really need to get too much... And that’s dura there, and that's just a blood vessel in the dura. And so I’m going to go ahead and decompress this sigmoid a little bit more. And we’ll actually bipolar those little vessels on that. Some people say just decompressing is also good. Yeah, he’s got a weird, really flat, sigmoid sinus. Not that that is a predictor of anything. That we know of. There’s a retrofacial air cell in here. Mm hmm. Very vascular. I'm not so sure that is facial. Now, we want to come back this way. Let's decompress just a little bit more. It's very vascular. Okay, now water off, please. Can I get a bipolar? Uh, huh. Now can I - do we have a J dissector like we had on that last case? It's right on your tray. What’s that? It's on your tray. 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 because I'd like to - if possible, you want to keep this dural surface really clean, and not get it abraded too much because once it 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 won't - look at all these blood vessels. Yeah, they're huge. Let’s have the bipolar. Well, people have talked about the vasculature, like - bipolar - these blood vessels between the sigmoid, and the sac, and the dura, and maybe, you know, maybe have something to do with it, but I don't - I don't, who knows. Mm hmm. Come on. So I usually do bipolar them all. All right now, the - the J dissector again. So then we can kind of flick some of that off, but we can also drill all that away. Mm hmm. Well, maybe. Yeah, that’s part of the sac right there. Okay, drill. Or drill. I mean I’m looking at posterior canal - here. We’ll take this right up beside the posterior canal, which is right there. Yeah, that's probably the sac. These are the retrofacial air cells that we see. Water off for a second. He’s got a lot of… Mm hmm. All right. Let’s see the control pedal. Water on. Water? You have to be cognizant of the facial nerve coming in inferiorly there, right? Yeah, the facial nerve? Yeah. The facial is up here. So there’s the level of the lateral canal. The 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 because 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’re really pretty close to being - getting the exposure that we want. Mm hmm. Now that J dissector again. Please? Water off. So we’ll kind of push this down. Uh huh. 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. So 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, which is the top of the sac. But you see - see how at it tents up right there? Do you see that Scott? Mm hmm. That’s - so this is all the sac here. We'll just get a little bit more bone, and then we're really done. He's got a good - this is a good one, so…

CHAPTER 4

Can I have a bulb irrigator? There’s the sac right there. Completely decompressed. Now we're going to fashion 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 cut like that. And then... Are you making a capital T? Yep. All it is is a T. Have you seen that before? I had one really, really, really long, and 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 - it may not do as well. Okay, so here is our T stent. And 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. Okay, a damp sponge. Go ahead and just try to get some of the ink off of it. Okay, now, Ariel - can I have a pair of smooth alligators and a Gimmick? So now we have to kind of 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.

Then I need that 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 footplate hook. Oh, a smaller one. Is there one smaller than that? No. Huh? No, that's the smallest one. Are you sure? There should be one smaller than that, Ariel. That kind of glisteny tissue. Now the shunt. And it's weird, you can't probably see it well on there, but the inside of the sac - it has almost this weird, glisteny kind of - like a weird, glistening-like surface to it. And it’s all the sac. Right there. And see how it kind of tents it all up? Mm hmm. Let's have that footplate hook again. That’s exactly... What you want it to do, and that's it.

CHAPTER 5

[No Dialogue.]