The Sistrunk Procedure: A Step by Step Guide to Thyroglossal Duct Cyst Surgery

[Dr. Gopi Shah]
Chris, tell us about your surgical approach.

[Dr. Christopher Liu]
Do you want the history of it or just what I do now?

[Dr. Gopi Shah]
Yes, the history. I want to know the evolution.

[Dr. Christopher Liu]
The evolution, oh my God. Every institution, I think, does their thyroglossal sistrunks a little differently, and how I was taught in residency and actually in fellowship, you find the cyst, you dissect the cyst out, you follow up, you find the hyoid. Maybe this is just me being a resident and not fully understanding what's being done, but my impression of the time when I was learning the operation was once you found the hyoid, you go above it and then you start bovie-ing muscle down. Most of the time, the senior resident was like, "Yes, man, that's the base of tongue," so get that down.

Then you find your hyoid and we use these really janky looking mayo scissors, the curved mayos to cut the hyoid bone. Half the time, those mayo scissors are dull, so then you're just struggling and it's a big struggle. As you take everything down, you release the hyoid and then allegedly there's a tract that you tie off, which was a little unclear to me at the time. Then you're done. You do that and that's the sistrunk. That's how I was taught or at least how I learned it. I don't know if that was actually what the intention of my attendings were in terms of how I was supposed to learn it, but that was what I understood needed to be done.

That's what I started off doing when I first started practice. I was in the suprahyoid area, I did what we normally did. Then when we got behind the hyoid bone where "the foramen cecum" is supposed to be, oftentimes people talk about-- I think there's a general fear of creating a pharyngotomy. People have a tendency to just say, "Okay, the tract is probably here, so take a little bit of it, but just tie it off." That's how it was taught originally or at least how I learned it, but over the years, there was a period of time where I had a lot of recurrences afterwards and I started doing some research and I came across this paper by Jeff Koempel at USC.

I've never met him, but Jeff Koempel, I'm going to give you a shoutout because you're my hero. One of these days I'm going to find you and introduce myself because that's how I do my surgeries now. It's called the Koempel method. Oh, and the other thing was, Dr. Mitchell, he's told us before in the past, he's like, "Sometimes with these recurrences, you just have to do almost a central neck dissection." You ignore the location of the cyst and you have to just take the stuff around it. Basically, the Koempel method, I think the biggest contribution of that paper was really on how you deal with the suprahyoid and foramen cecum area because everyone does it a little differently.

Some of the people tend to limit how much they take because they worry that they might do a pharyngotomy. When you get into that foramen cecum area, the muscles aren't super organized. The intrinsic base of tongue muscles are not very organized in the same way that skeletal muscle like the suprahyoid muscles are very organized in their vertical orientation, so you're just figuring it out. You're making it up as you go. Actually, I do tell families that although there's certain steps to the surgery, we do, in certain areas, have to make it up as we go because you just don't know what you're going to encounter in that area.

[Dr. Ashley Agan]
Yes, the anatomy isn't quite as beautiful and precise.

[Dr. Christopher Liu]
Yes, there's not fascial planes that you dissect out in the base of tongue. When I do the surgery, if it's a cyst that's never been infected, you just make an incision over the cyst and you go down. Then if it's an infected cyst or one that has ulceration or skin involvement, I make that fusiform incision around it to make sure I get around it superficially before I dive down deeper. The one thing that I don't do is if I know it's a thyroglossal duct cyst, I don't look for the cyst. I take a small rim, maybe a few millimeters of soft tissue around the cyst, and I basically just dive down after lifting a short inferior subplatysmal flap.

I'll basically dive down onto the strap muscles pretty much almost immediately. I try to stay maybe two to three millimeters, a couple of millimeters inferior to the area of concern. I find the midline raphe and I go straight down the midline raphe until I see airway. Once I see airway, I expose it a little more. We unzip it vertically a little bit, just to make sure that that's the airway. Then I take the medial, I would say about five millimeter of strap on each side. To me, people do ask, I've had residents ask, "Well, why aren't you preserving the strap muscle?"

I don't for two reasons. One is that you're going to be cutting the hyoid bone anyways, so you're disarticulating that strap muscle medially anyways, regardless of what you're going to do today, so why does it matter if you disarticulate it up next to the hyoid bone versus maybe a centimeter or two inferior to it? Two, I know that if I cut through the strap muscle there, I'm giving myself a little bit of space around the cyst to make sure I catch anything that I may have missed, potentially a small cystic or a protrusion that I may have missed. It just gives me a bigger margin of safety in terms of making sure I get around the whole thing.

Once I divide those strap muscles medially, the one move I think that is really helpful in identifying the hyoid bone is actually you put your finger onto the thyroid cartilage. You should be able to feel that notch when you slide up. When you put your finger on the airway and you turn your finger up and you slide along deep to the strap muscle superiorly, you'll feel the hyoid bone. Because the strap muscles themselves are attached to the hyoid bone, so they'll lead you to the hyoid bone. The hyoid bone is actually the only structure that you can slide your finger underneath.

That's what I do to find the hyoid bone, is I basically use the strap muscles to lead me to the hyoid bone and then I find the thyroid cartilage just to make sure, you always want to make sure that the thyroid notch is there. Then the other thing that clues me in is that I can lift that hyoid bone up with my finger, because you're not going to be able to do that within any of the other structures like cricoid or thyroid. You're not going to be able to do that at all.

Then this goes back to, Gopi, I know you mentioned, what's the difference between older kids and younger kids, so when you think about how the hyoid bone is oriented in older kids, so let's say in a male, when you're younger, like you mentioned, your hyoid bone basically is telescoped on top of the thyroid cartilage. That move where you slide along the airway with your finger up, you're always going to be deep to that hyoid bone, you're going to feel it. In older kids, this just dawned on me a couple of months ago, in older kids, in men, you have an Adam's apple and that Adam's apple is your thyroid notch.

The reason that thyroid notch is so prominent is because your hyoid slides superiorly as you get older and then it falls back a little bit. It becomes-- I don't know what the phrase is, but it's not telescoped anymore. Actually, older kids are a little more challenging because their hyoid is going to be a little deeper and it's going to be above the thyroid notch. It's going to feel deeper when you're trying to look for it. Rather than, where you try to bovie on top of the muscle to get down to it, and a lot of times that muscle is really thick, I actually find that sliding technique from inferior is a very easy way for me to find the hyoid bone, even in older kids when you don't have the benefit of a telescoped airway.

[Dr. Gopi Shah]
When it is a younger kid, and let's say that the hyoid is maybe very low or even if it's not quite telescoped, it makes sense that it's going to be a little bit more prominent, more interior. It's not as superior and deep as in an older kid, but just by the proximity, is it easier to get into the thyrohyoid membrane if the hyoid and the thyroid cartilage are that close together, even if you can pull it up, or not really because you can pull it up and stay on it?

[Dr. Christopher Liu]
Yes, so I can pull it up. Basically, once I find the hyoid bone, I can feel the hyoid bone, I actually turn my attention superiorly, and then I finish raising the subplatysmal flap superiorly, I bovie through the fat, and then you bovie through the skeletal muscle like the platysma. Then eventually you'll run into the vertical muscle fibers of the suprahyoid straps. Then at that point what I do, once we get better exposure superiorly, we turn our attention back inferiorly again.

Once you can feel that hyoid bone-- I think it's a little hard for me to describe how I do it verbally, but basically where we cut the straps, five millimeters laterally, that lateral extent, the most lateral part of our cut, I basically have the resident or myself, we just follow that vertically up. Because the strap is going to lead you to the hyoid bone, what you're going to feel is you're going to cut through muscle and also you're going to bump into something firm, and that's going to be your hyoid bone.

Once I bump into my hyoid bone, and this is a little bit by feel, but basically I use the bovie to bovie over the top of it, over the anterior part of the hyoid bone until I can reach the superior portion of the hyoid bone, and I'll create a little tunnel or a little pocket for me. Then I take a Jake dissector or a mosquito and I put the Jake dissector through that pocket superiorly, and then I dip behind the hyoid bone and I pull it up laterally, and I open the dissector.

Then at that point, I tell the resident or the assistant, "Take your bovie." If it's a young kid, you'll be able to bovie through it. "Take your bovie," and just how we normally do our soft tissue dissection, "Just bovie between my tines and you're going to get through."

[Dr. Ashley Agan]
Yes, you're presenting the bone with the dissectors to your assistant.

[Dr. Christopher Liu]
Yes, you're basically presenting the bone to the assistant. If the bovie doesn't work because the bone is too ossified, I actually don't use heavy mayos anymore. I actually use the orthopedic bone cutters. You can get these small bone cutters. I think they're used for fingers or something. I don't know exactly what they're called, but we just refer to them as the ortho bone cutters. Sorry.

[Dr. Gopi Shah]
Good thing our audience is an ENT audience. They might be for some fingers.

[Dr. Christopher Liu]
Those bone nippers actually look like the same bone nippers that I use for my aquarium. That's actually why I thought about using them because I know I've seen them in the ortho sets before, but they're amazing because they don't ever get dull.

[Dr. Ashley Agan]
Yes, why struggle, right?

[Dr. Christopher Liu]
Yes, so use a bone cutter to cut bone. Then I use that and usually what I want, because the bone cutters are so much more precise too, rather than having the resident or the assistant take one big bite through the hyoid bone with the bone cutters, I actually tell them to take a little bite and then we'll bovie the marrow to control the bleeding and then just take another little bite and bovie the marrow. Because the bone cutter is just so sharp and precise, you can get away with that. Then that's how we cut through the hyoid bone. Once you make your cuts, then you do the superior part of the suprahyoid part.

This is actually where the Koempel method was really helpful or how he, when he wrote his paper, did a really good job of showing what he did. Basically you look superior to the hyoid bone, but in the midline raphe. There's a midline raphe in the suprahyoid straps, and you dissect down in the raphe until you see this fascial layer. It's that fascial layer that transitions into the intrinsic base of tongue muscle. That's that fascial layer that people always see when they're bovie-ing away that skeletal muscle. Once you see that fascial layer, that is the deep extent of that part of the dissection.

Anything superficial to that, all that skeletal muscle superficial to that is fair game. Once you make that identification, you can make a very precise, controlled move to present all that superficial or all that strap muscle that's superficial and just divide it all usually in one go. It's literally just a couple of moves to get that superior part down pretty quickly. Then once that is done, you've released all your skeletal muscle from the attached skeletal muscle to the hyoid bone, the hyoid bone's been cut. The last part that's attached to the patient is right behind the hyoid bone. That will lead you into the foramen cecum.

What I do now, because I actually have been burned before tying it off once, it was very traumatic. Basically what happened to me was early on in my career, I had a patient who did have a very obvious tract and I tied it off. What ended up happening was that tract became a cyst because now this mucus had nowhere to go. He developed airway obstruction actually, because it became a big base of tongue cyst that was obstructing his airway. After that traumatic event, now anytime I see a tract, I chase these to as far as they'll go.

Basically what I'll do at that point is that attachment, that final attachment to the hyoid bone, I'll take a bovie and start to core out that area. I'll do it very slowly to see if there are any cystic elements or if there's a tract in that area. I haven't looked at my data recently, but I'd say at least a third of patients will have something there. If not a millimeter cyst, I've seen full-on one centimeter cyst back there. I've seen tracts leading all the way to the base of tongue, so I always core out that area to make sure that there's nothing there. If I don't see anything obvious, I might not go all the way to the back of the tongue. I usually won't.

If I do see something, I will follow it and I don't ever tie it off. If it means that we are going to get into the pharynx, that's fine. I do warn families that sometimes that will happen. Once that is done, then the specimen is out. If you do create a pharyngotomy, usually it's a small hole, you just repair it primarily and do your leak test. If there's no leak, you're pretty much good. How you manage that afterwards, I don't think there's a set way to do it. Originally, I used to keep these kids NPO for a few days, like how we do our cancer patients, but at the end of the day, these kids are healthy, they're not smokers, they're not drinkers. They heal really well. I've not really had any patients fistulize because of that.

[Dr. Ashley Agan]
How do you close your pharyngotomy?

[Dr. Christopher Liu]
I just simple close, your 304 or Vicryl, depending on the size of the kid. Then you can over-sew the muscle too. The muscle, the intrinsic base of tongue muscle, you can sew that together too to give it some belt and suspenders. Then we do a leak test afterwards. If I'm not super confident in the repair, I'll put a round drain. That is actually the only time I put drains in kids for a thyroglossal, but I do not routinely place drains in patients after the surgery. I don't routinely give antibiotics either. Then we close them up and then we get out.

[Dr. Ashley Agan]
As you're describing everything, I also think back to residency where you think of the cyst as this round cyst that you're removing. Really, it's more like this glob with projections and maybe other cysts like grapes. I think that pitfall of thinking of it as just this defined thing, like a dermoid, as opposed to this more amorphous structure that requires you to take that extra cuff of tissue, that's one of the key parts of preventing your recurrence would you say?

[Dr. Christopher Liu]
Yes, I think it's coming to the realization that the cyst that you see is probably not the only part of the thyroglossal duct lesion. There's oftentimes additional ducts behind the cyst, additional cysts. Excise all that out, then the patient is at risk for recurrence because it's incomplete, but I do tell families, it's not a super exact science. Every thyroglossal duct is different and you do your best to try to get out every single element that you see, but there's going to be times where maybe the child has a microscopic duct that was not filled with mucus at the time and you just don't see it.

I'm not going to routinely do a pharyngotomy on everyone. I'm not going to routinely take excess tissue if I don't have to. We'd certainly do our best to get everything out. I do assure families that if I do see any pockets of mucus or cystic lesions, they're going to come out and I won't leave them behind. That's all I can tell the families when I do this. I keep them overnight. I think there are a lot of practices that do send patients home. Maybe it's just me, but every time I look at how much I remove, I always feel a little uncomfortable sending them home. It just makes me feel a little better at least.

To be quite honest with you, in the last 100-some-plus patients that we've done, we've only had 1 patient have a post-op day 1 complication, which was a hematoma that needed urgent surgical drainage. In terms of the usual stuff like PO and pain control, it tends to be very well-tolerated. Oh, going back to the surgery, I forgot to mention, the one thing in kids that I think I really beat on the residents on this because it's very easy to get lost is that soft tissue in children is very pliable. It's very easy, when you're pulling something or retracting something, to pull something that you weren't expecting closer to you than you want.

There have been a lot of occasions where people have gotten really close to cranial nerve 12 when they're doing the suprahyoid part of the dissection, because you're pulling down on that hyoid bone and that muscle. It's very easy to retract that hypoglossal nerve where it curves up into the tongue. It's very easy to pull that down with everything. Kids are really small, so it's very easy to get into it. It's just something that you have to keep in mind.

[Dr. Ashley Agan]
Thinking about just complications, we've talked about pharyngotomy may be a complication if you don't recognize that you made one, right? We've all seen patients where there was an accidental pharyngotomy that went unnoticed. You talked about the hypoglossal nerve that's in the neighborhood and that can be damaged. You mentioned hematoma, seroma. What other complications do we need to be talking to our patients about?

[Dr. Christopher Liu]
What I tell families is that the most common complication of the surgery is recurrence or swelling, seroma recurrence after the surgery. I think the numbers are all over the place in terms of how frequently recurrence happens. I think the average is 5% to 10%. I do tell parents, "Look, the reason I think this happens is not because the cyst conchal came back," it's probably because I or whoever did the surgery didn't see a small pocket somewhere and that pocket is starting to produce mucus and now you've got swelling because of it.

I do warn families the most common complication is going to be recurrence. It happens up to 10% of cases. What you oftentimes will see is swelling within the first one to two weeks after the surgery. How I manage those, it really depends on the child. If the child is not really bothered by it, meaning that they just have swelling, I'll leave it for now. I'll observe it, because oftentimes it will actually resolve. It will reabsorb. If it's bothering the child or it looks like it's getting infected, I will tap it in clinic. I will drain it with a needle. I don't actually really numb these patients up.

I just go through the incision site because that area is going to be insensate, so they're not going to feel anything. Usually what I draw out actually, almost always I get this mucoid material, it just looks like mucus. I tell families, "Look, it looks like mucus. He may have something there that's producing that mucus I didn't see the first time, but we'll give it some time, see if it'll go away on its own. If it goes away and it never reappears, then we don't need to think about a reoperation." I'd say the vast majority do go away on their own.

I do counsel them that after it goes away though, it doesn't mean that it's going to go away for good, so if it reappears again, please call me back so we can figure it out, but until it shows up again, there's no reason to look for trouble.

[Dr. Gopi Shah]
For that initial post-op, meaning it's post-op week one and there's some swelling or maybe there's some drainage through the incision site, is that what's going to tip you off as a mucoid return or mucoid drainage? Because I would imagine that seroma or wound infection could also be in your differential, or is it 90% of the time recurrence and a handful of times is it seroma or wound infection?

[Dr. Christopher Liu]
I'd say 95% of the time it's a mucoid seroma. Then of those, maybe a few will have an infection on top of it. I wish when I tap it, it's just thin liquid because then that'll make me feel a lot better, but 95% of the time it's not.

[Dr. Gopi Shah]
When they settle, do you put those kids on antibiotics or you've tapped it or, "Hey, it's a little swollen. I don't think we need to tap anything. Let's just watch you," is there any benefit in a course of Augmentin or something at that time?

[Dr. Christopher Liu]
For me, it's based on clinical exam. If it's tender, red, then I'll put them on antibiotics, but if it's just a bump and the kid's acting normally, I don't put them on antibiotics. I don't recommend draining those because the other thing that tends to happen when you drain these is that they can recollect.

I always warn families like, "We're going to drain it now because it's going to make him feel better, but it may recollect and it may recollect in a few days. If it's bothering him when it recollects, please bring him back and we'll just keep tapping it until it goes away where it stops bothering him." Some kids will need two or three attempts to get it to go away, but I try to manage these outside the operating room if I can.

[Dr. Ashley Agan]
Yes, because going back is just not as elegant once you've already been there, right?

[Dr. Christopher Liu]
Yes, and like I said, the incision site should be insensate. The kid may freak out, but in reality, they're probably not actually feeling the needle because you're going through an area where you've already been. In terms of other complications, we've talked about the hypoglossal nerves. Going back to the pharyngotomy too, I actually don't see the pharyngotomy as a complication unless, like you said, it's unrecognized. I see it as part of the operation when it's necessary to remove it.

Parents always ask about voicing, swallowing, breathing, and it really should have no impact on any of those three things. I would say, overall a very well-tolerated surgery. The most frustrating thing are the seromas and the recurrences that you sometimes will see.

[Dr. Gopi Shah]
Then how do you follow your patients? Let's say no issues post-op, maybe done a post-op visit, talked about the path. Do you survey them and do you have a way in which you follow them?

[Dr. Christopher Liu]
If they don't have a seroma at the three to four-week mark and they look great, I discharge them from clinic. If they've had a seroma, then it does concern me that they may have some thyroglossal duct cyst part or whatever that still remains in their neck that could cause a problem. I'll see them back in maybe six months just to check in but those visits tend to be really short and quick because most of the time the kids are doing really well.

Then at that point, I just counsel them like, "Look, there may be something there, if it's not bothering them, don't worry about it. If it shows up, call us. We're going to have to go look for it, but until that causes a problem for them, don't stress. Just treat them like a normal child." Then we just discharge them from clinic at that point.

[Dr. Gopi Shah]
For the child that maybe it's been a year and you see them back in clinic and now there is maybe some swelling there, what do you do next? How do you manage that? I know that's a loaded-- that could be a part-two podcast, but what's your management in terms of is that when you get your MRI or do you start with an ultrasound at that point? Then if you do have to go to the OR and your suspicion is high for recurrence, what are the nuances there?

[Dr. Christopher Liu]
Yes, so in those kids, I'll start with an MRI. If there's clearly something there, I'll just get an MRI and just see. I prefer MRI for these because MRI is really good at soft tissue differentiation and identifying fluid. You can see fluid really well. It'll be really bright on T2. That's why I prefer because these are fluid-filled cysts, fluid-filled tracts, so it'll show up real nicely on MRI. One of the reasons I do prefer the MRI for these is because if there is something in the base of tongue and I see it on the MRI, it lets me know that perhaps we just needed to do more of the foramen cecum and I can just go look for it, but that's a patient of mine.

If it's one of my own patients, that's how I would approach it because I know I've done the sistrunk and gone through the hyoid bone already. If it's coming from somebody from the community or a referral or a patient who had a sistrunk years ago by someone else, I still get the MRI because it helps me know what's been done in the neck already. Also, it helps me identify if there's any disease in the base of tongue area. Unfortunately, on the MRI, it's really hard to see the hyoid bone, but I think it's just really helpful. I think it's good practice, especially if you're going back for revision surgery, to have some sort of cross-sectional imaging to help you plan.

Surgically, though, I would almost say that the surgery is a little easier when you're talking about a recurrence because at that point, you're not really looking for the hyoid bone anymore. The ideal situation is the patient actually does have something that you can feel. Then you basically follow it, core it out. You do want to leave a little bit of soft tissue around it because we've talked about this before, these little projections that you worry about, you just want to make sure you get all of it. Then you just follow it down to the foramen cecum.

If there's cysts or ducts there, you just keep going until you get it all out. I actually just recently did a kid who had a base of tongue recurrence, literally in the vallecula. We had to chase it all the way down. He was quite challenging because we saw it on the MRI, but he had no external defect. There was nothing for me to follow. He had come back with an infection a year later. Then the MRI showed that he had a one centimeter cystic mass, basically in the vallecula. I told the parents we could do it, but there's a chance I couldn't find it. It was challenging trying to find it, because you're just going through scar tissue and then suddenly there's a sac there, and you're looking for a needle in a haystack.