Surgery: Strabismus Surgery for 3rd Nerve Palsy: Disinsertion of Lateral Rectus, Transposition of Superior Oblique & Resection of the Medial Rectus Muscle

This 50-year-old man presented with acute 3rd nerve palsy involving the pupil and a ptosis. He was radiographically diagnosed with Schwannoma of the 3rd cranial nerve. The deviation was stable for over a year and he had diplopia when he lifted the ptotic eyelid. It was decided that he has to undergo a combination of strabismus and lid surgery and this video demonstrates the strabismus part of the surgery. The 3rd nerve is paretic, so the eye was turned out because of the still functioning lateral rectus muscle and the eye was turned down because of the still functioning superior oblique muscle.

During the forced duction test in the clinic, the eye was found to have positive forced duction test because the lateral rectus muscle had become tight and contracted. In order to relieve the restriction of the tight lateral rectus muscle, the muscle was disinserted and fixed to the periosteum. The superior oblique muscle was transposed from its superio-temporal retro-equatorial behind the equator location and was reimplanted adjacent to the insertion of the medial rectus muscle. The superior oblique muscle was transformed from an abduction muscle to an adducting muscle. In order to increase the passive strength, a large resection of the medial rectus was done.

Surgery Location: on-board the Orbis Flying Eye Hospital in Addis Ababa, Ethiopia
Surgeon: Dr. Douglas Fredrick, Mount Sinai School of Medicine, USA

Transcript

DR FREDRICK: So this is a 50-year-old man who presented a few years ago with gradual onset of a 3rd nerve palsy on the right eye. He had an evaluation which included neuroimaging, and neuroimaging revealed a lesion on the peripheral 3rd nerve, which turned out to be classified as a schwannoma. Now, this was not biopsied. This was a clinical diagnosis based on the MRI findings. I’m gonna do forced duction testing here. So you can see that I get the eye right to this position, and I can’t move it any further inward. So it’s very tight, the lateral rectus. The inferior rectus is not tight. The superior rectus is a bit tight. And then the medial rectus is very loose. Which is consistent with the findings. With a 3rd nerve palsy, you’re going to have weakness of all the muscles innervated by the 3rd nerve, which include the inferior rectus, the superior rectus, the medial rectus, the inferior oblique. So the only muscles that have innervation are the lateral rectus. Since the lateral rectus is unopposed for many years, it becomes very tight. The surgical principles to align the eye involve weakening the restriction and trying to generate some force to pull the eye inward. He presented with his eyelid — it was ptotic, and his eye was out to the side. When you lift the eyelid up, he had double vision, because of the exotropia. We warned him that after the operation, even if the eyes are perfectly straight, his ptosis will still be present. He might need to have ptosis surgery. We also warned him that even with surgery, there will be just a small area where he can fuse. So he understands that this is a long process, and he understands the goals of the surgery. So our goals of the surgery are to weaken the tight lateral rectus muscle and to bring the eye inwards by strengthening the medial rectus muscle and transposing the superior rectus muscle. So let’s first talk about weakening the lateral rectus muscle. You can cut the muscle and let it fly back, you can cut the muscle and suture it further back on the eye. In our case what has been found with 3rd nerve palsies is the lateral rectus muscle tends to recontract. So even if you do a maximal recession, even if you put the muscle back 12, 13, 14 millimeters, it still will adhere to the eye and pull the eye outward. So we’re going to do a procedure where we’re going to isolate the lateral rectus muscle, and then sew it to the periosteum on the lateral orbital wall, so that it reattaches to the orbit, not to the eyeball. So that way there’s no way it will have any contractile effect to pull the eye outward. So a schwannoma is any nerve sheath tumor. It’s actually best seen with an MRI. MRI is much better than CT scan. And the MRI, now that we have — they’re called sequences, or types of images that can look specifically at cranial nerves. So what a schwannoma looks like is: Once you find the 3rd nerve, you’ll see an enhancing lesion along the path of the nerve. So it just looks like a diffuse thickening of the nerve. Now, these are benign in the sense that they don’t spread. They grow slowly. The surgical excision would be much more dangerous than simple observation. Because what happens is: Once you correct the strabismus, then the patient can practice what the world will look like after the ptosis surgery by taping the eyelid open. And they can go about their daily activities with the eyelid lifted with a piece of tape, and they can make sure that the diplopia that still is going to be present isn’t bothersome. If it’s bothersome, then it’s not worth it for them to go ahead and proceed with the eyelid repair. So you can see how tight the muscle is. You can see that our assistant is pulling the muscle, and the eye isn’t rotating out anymore. So some trick we use when we’re doing tight muscles is we’ll use two hooked muscle hooks. So I’m gonna put a second hook in behind this one. And we’re gonna take our retractor out. And I’m going to put my suture through the tendon in an area that’s very safe. You see, this allows me to elevate the muscle away from the sclera. So I don’t worry about accidentally perforating the sclera when I put my suture in. So we’re gonna use a 5-0 polyester suture. Again, with a spatulated needle. Because we want this to stick to the periosteum permanently. Theoretically, we could always go back and find this muscle again. We know where it’s going to be located on the periosteum, and we know that we’ll be able to identify the polyester suture, which will last many, many years. Now, I’ve never had to go back. General you don’t want to ever have to go back and find this muscle. Because you want to weaken it maximally. If I were to just cut the muscle right here and not reattach it, it would still reattach itself to the surface of the eye. And that’s the whole point of this procedure, is to get it to reattach not to the eye but to the bone. So again, you can see I’m not too worried about being right at the insertion. I’m going to affix it the same way as I did before. Again, putting a three point fixation. This is not — 3rd nerve palsies are not common. They’re rare. Schwannomas are even rarer. I’ve probably only seen maybe 15 in my entire 25-year career. At a tertiary center. So a schwannoma is a tumor, benign tumor, of the peripheral and central nerves. The nerve sheath. So what other conditions do ophthalmologists need to know about, that involve growth of nerve sheath tumors and tumors even on the optic nerve itself? It’s a hereditary condition. What if I said they had an F-shaped deformity of the eyelid?

>> I think the answer was neurofibromatosis?

DR FREDRICK: Very good. Excellent.

>> Also known as von Recklinghausen’s disease.

DR FREDRICK: So we’re familiar with neurofibromatosis type I.

>> Right.

DR FREDRICK: So I’ve attached the muscle to the non-absorbable permanent suture. Now I’m gonna separate it from the sclera like we normally do with the Westcott scissors. So we’re familiar with neurofibromatosis type I. But there’s a neurofibromatosis type II. That ophthalmologists also need to be aware of. Now, usually the ear, nose, and throat colleagues know about neurofibromatosis type II, because it causes acquired deafness, due to…

>> Acoustic neuromas.

DR FREDRICK: Acoustic neuromas. That’s right. Hearing loss. But it’s important that all these patients who have acoustic neuromas be seen by an ophthalmologist, because they can have two different ophthalmic manifestations. What are those ophthalmic manifestations? If you have a child with what looks like an epiretinal membrane or a chorioretinal hamartoma, you want to think about NF2. Because they can have involvement in other nerve tissues as well.

>> And as a pediatric ophthalmologist, do you find that those PSC cataracts occur early in life, in the second or third decade? Or are they more later in life?

DR FREDRICK: These cataracts present later in life. And they’re sectoral cataracts. So they’re pie-shaped cataracts. They’re not PSC cataracts. They’re not nuclear cataracts. They’re cortical cataracts. And what we’re gonna do is: I’m gonna show you — palpate the lateral orbital rim. It’s right here. So I’m at probably about 5 millimeters from the opening of the lateral rim, right against the lateral orbital bone. Now, there’s nothing important here. So there’s no important structures that we need to worry about damaging. So this is a safe area to operate in. I’m just gonna go in bluntly and bluntly dissect the tissue. Right against the orbital bone. Just like the oculoplastic surgeon would do. And what I can see — but there’s some glistening white tissue of the periosteum. So I’m going deep. Right against the firm tissue of the periosteum. Okay. So we have one bite in. So now we’re going to do one other bite, going the other direction in the periosteum. So you see that’s a more acute bend to my needle. That way I’ll be able to go in to the periosteum and out. Good. So now you see the insertion of the muscle is up against the bone, the lateral rim. See, it’s pulled away from the globe itself. I have a little loop in my suture. That’s why it’s not lying flat. But that’s okay, because the main knot is up against the bone. So I’m gonna cut that. And what we can do to demonstrate that we’ve released the restriction — now I can get the eye over much better. And you can see the lateral rectus muscle is nowhere to be seen, because it’s up against the side of the wall. You want to create a space, and that’s why, when I’m gonna close this, I’m actually going to close the Tenon’s between the muscle and the globe. I’m gonna use the non-absorbable to close the Tenon’s between the muscle. So you see that’s the Tenon’s between the muscle and the globe. And by reattaching the Tenon’s to itself, there’s no fat coming forward. So you see I’m very careful not to penetrate the posterior Tenon’s, because I don’t want fat to come forward. Because that can lead to fat adherence and cause restriction of itself. So we close the Tenon’s. So now I’m just gonna close conjunctiva like normal. So now we’ll have the 6-0 plain gut. Now, again, because this eye has been turned out for so long, if I were to put the conjunctiva back, it’s very restricted. So it’s gonna pull the eye over. So I’m gonna recess the conjunctiva. I’m just gonna cover the area that we were working on. So again, not to get a pyogenic granuloma. Small details. Taking a few extra minutes to be meticulous in your closure makes a big difference in the outcome, both from a functional standpoint and, equally important, aesthetic standpoint. Because again, in other words, we cannot reanimate the eye. We cannot make this eye move the way it did before his 3rd nerve palsy. But hopefully we can get the eye straight enough so that he does have an area of single binocular vision. So we’re done laterally, so now we’re gonna switch places, and we’re gonna look medially. The medial rectus muscle is not working well, but it still has passive restrictive force, so we’re gonna do a large resection of the medial rectus muscle to pull the eye in. The other muscle that is working well is the superior oblique, because the superior oblique is innervated by what cranial nerve?

>> 4th.

DR FREDRICK: Good. So the 4th cranial nerve is still working. We assessed that preoperatively in the clinic. Normally, the 4th cranial nerve innervates the superior oblique, which makes the eye go down and in. Now, this is an eye that would not adduct. So we could not get the eyeball in the field of action of the superior oblique. So there’s no way to check the depressing force of the superior oblique muscle. Preoperatively, how do we check the function of the superior oblique muscle if we cannot get the eye into adduction? In other words, what other action of the superior oblique can we look for, to see whether or not the superior oblique is functional? So we’re looking for intorsion. So when we ask the patient to look down, even though the eye doesn’t go down, what we saw preoperatively is the eye — it would twist. What would happen is that, as we were looking at the eye, we would say: Look down. The eye wouldn’t go down, but the eye would do this. That tells us that the superior oblique was working. That means I can go to the superior oblique to try and recruit its function and change it from an abductor — right? And we’re gonna turn it into an adductor. What do we have to do to the insertion of the superior oblique to change it from an abductor to an adductor? We’ve got to put it in a different position. Where does it insert? Where does the superior oblique insert normally?

>> So behind the equator?

DR FREDRICK: Good. Behind the equator on the temporal. So what we have to do is move it in front of the equator. And move it to the nasal side. So what I’m doing is I’m preparing my medial rectus for resection, but I’m not gonna resect it until after I’ve worked on my superior oblique. Because, again, I don’t want to do a resection until I’m done manipulating the eye. And you see — it’s interesting. Even though this muscle is paretic, it isn’t skinny. It isn’t thin. It isn’t atrophic. That tells us that this weakness hasn’t been here for many, many, many years. If this was a congenital 3rd nerve palsy, this would be a thin little atrophic band. And it’s not. Okay. So now the muscle is ready for the vicryl, but we’re not gonna do the vicryl yet. We’re going to look for our superior oblique. We’re also taking care not to damage the superior rectus muscle. Because again, we’ve already operated on two rectus muscles. We’re operating here. We’re operating here. That’s one, two, three ciliary vessels. If I accidentally damage the superior rectus muscle, then I could lead to anterior segment ischemia, which I don’t want to do. So what I’m gonna do is I’m gonna use this muscle hook to grasp the superior rectus muscle. Now, I can tell that I have muscle because I can’t pull the hook down any farther. If I was in front of the insertion, this hook, which is right here, would slide down forward. So I know I have at least superior rectus muscle. What I also have to be careful is: I have to make sure that I don’t also have superior oblique tendon. I want to find the tendon, but I need to make sure that I’m separating the superior rectus muscle from the superior oblique tendon. So I’m gonna have the assistant hold the hook here. I’m gonna take the Barbie retractor, and we’re going to look here. And we’ll see if we can get a little hemostasis. So this is coming from the edge of my medial rectus muscle. So I’m just gonna put that there to sop up the blood a little bit. If it doesn’t stop, I could do a little bit of cautery just to get better visualization of the superior oblique tendon. We know the superior oblique tendon is coming from the trochlea. Sorry. The trochlea, which is here. We’ll come down from the trochlea, which is right in the superior nasal orbit. And we’ll come down in a band to go underneath the superior rectus muscle. So again, what I first want to do is I want to isolate and see that I have the superior rectus muscle. We’re right at the edge of the superior rectus. So we can see that here at the edge. We can see the insertion. So we know we have the superior rectus muscle. So now we have to look and find the superior oblique tendon. And we know it’s gonna be at the edge. So if you know where your anatomy is, you sometimes get lucky. And find this. So, you see, I’ve done no cutting. I’ve done zero cutting. Because I don’t want to inadvertently cut the superior rectus, nor do I want to inadvertently cut superior oblique. And so I’m looking for, again, a white fibrous band. Because the superior oblique tendon is going to be in its tendon sheath. So we see the shiny white. And now I’m not 100% certain yet that this is the tendon, but it seems to be going in the right direction. So, in other words, it’s going from here to there. So what I can do is I can follow the fibers and see where it goes. We can also do a little experiment. See what happens when I take our traction suture off. And I pull on this muscle. The eye looks like it’s rotating inward. You see that? See, as I lift up on this, the eye is already — this was at 12:00. Pulling on this tendon has caused the eye to rotate inward. So I feel confident that this is the superior oblique tendon. So I’ll have the assistant separate those two. I’m just gonna do a little bit of fine dissection to see if I can see the tendon more clearly. Now, some people would just cut this muscle. Because right now, in its current position, if it’s functioning, does it make the eye go up or down? We know — we talked about abduction as being one of the actions. We talked about incyclotorsion. But also remember it’s primarily — it’s a depressor. So with a 3rd nerve palsy, usually the eye is down and out. So if I cut it, at least I will fix the hypotropia. But I want to recruit this muscle. So what I’m gonna do now is: Now that you see how I separated the tendon sheath, so now I have a glistening white superior oblique tendon. So I’m gonna isolate that a little bit better. So I’m gonna take one of my Stevens out here. Again, I always leave two hooks around the muscle at all times. And then I’m going to take my little one and Dr. Masch is gonna take yours out and put it back in. Right in the middle. So now I have the superior oblique tendon. Now, this would be the tendon you’d work on if you were doing that right expander. This would be the tendon you’d cut if you were doing a Brown syndrome. I took care to make certain that at all times I knew where my superior rectus muscle was. Because the worst thing I could do would be: Think that this is the superior oblique and in fact be cutting the superior rectus muscle. Because again, here’s my superior rectus. And here’s my superior oblique. So I’m convinced I’m in the right spot. So now what I’m gonna do is I’m gonna take a vicryl, a double armed vicryl, and I’m going to attach it the same way. Get a full thickness bite in the middle. As I pull this through, I want to make sure not to get sheath inadvertently caught up in my dissection. With a 3rd nerve palsy, the ptosis affects the levator muscle. Levator. So you get a lot of droopiness of the upper lid. Why do you get ptosis with a Horner syndrome?

>> It’s due to sympathetic innervation of Muller’s muscles.

DR FREDRICK: Beautiful. Good. Since it affects the Muller’s muscle, that’s in the superior. Why do you get inverse ptosis? In addition to getting droopiness of the upper lid, you get droopiness of the lower lid. The lower lid doesn’t sag down. The lower lid sags up. So it’s an inverse ptosis. But we still call it lower lid ptosis, which is classic for Horner syndrome versus ptosis secondary to a 3rd nerve palsy. Again, there are sympathetic fibers from the lower lid as well. It’s not called Muller’s muscle, but it does have sympathetic innervation. So what I’ve done is I’ve disinserted that superior oblique tendon, and again, just to make sure I’m confident, there’s my superior rectus muscle. So I know for 100% sure I did not accidentally cut the superior rectus muscle. And here I have the superior oblique muscle ready to use later. But now I’m gonna go back to my medial rectus muscle, and we’ll do our resection. When we see a child, a newborn, with ptosis, and a pupil that is small — not big — we’re worried about congenital Horner’s. What are three reasons that children have congenital Horner’s? Birth trauma. Good. Yes. Birth trauma. Definitely. So if you have a shoulder dystocia, big head, difficult trauma, you definitely can get damage to the region of the neck which can lead to the Horner’s. So is there a cause for most congenital Horner’s? Or is it just idiopathic? In other words, benign. We don’t know the reason. We’re gonna do a big resection. So I want to get at least 10 millimeters. So I’m gonna show you where 10 millimeters is. That’s 10 millimeters. So I’m gonna go as far back as I can behind that, safely. To put my suture on. Okay. So congenital absence of the ganglia. Yes. I’ve seen that a couple times. That’s quite rare. But you can have that. So yes. Congenital neuroblastoma. Now, in addition to having Horner’s, they will also have another ocular finding that strongly suggests the presence of congenital neuroblastoma. What would that ocular feature be? Raccoon’s eyes. Good. So that is definitely an ocular sign. So yes. Opsoclonus. A clonic movement is a sudden movement. In neurology, a clonus means a sudden rapid repeated movement. Opsoclonus is not nystagmus, because it’s not rhythmic. In other words, it’s not in a pattern. It’s not predictable. It’s chaotic. So we did — got about 11 millimeters back. Now, when you do a big resection like this, I’m not pulling up on my muscle yet. So I’m going to reimplant this muscle, just like we normally do. You can see I’m getting a lot of oozing from the muscle. When you operate very posterior on the muscle, you’ll always get bleeding, because again, it’s harder to isolate your ciliary arteries and cauterize them there. Again, I show myself the tip. I see the tip there. Once I see the tip, I can safely pass it into sclera there. The assistant is gonna pull the insertion towards him, as I pull the muscle towards me. I’m pulling tangentially. Good. And you pull back. Perfect. Beautiful. Regrab. Bring it forward. Bring it forward. Bring it forward. Good. Now you can let it go. And we’ll see that the muscle is tucked in nice. So now we’ve got the eye pulled in by the medial rectus. We have the lateral disinserted. But we still have our superior oblique. We’re gonna reimplant this. We’re gonna transpose this superior oblique tendon, and we’re gonna put it right next to the insertion of the medial rectus. So now it’s coming directly from the trochlea to the medial rectus. So its action is going to be to pull the eye in. So it will give us adducting effect. And since it’s no longer spread out temporally, it won’t have any cyclotorsion effect. We’re turning this into a pure adductor. It will also be a little bit of an elevator. Because it’s located above the medial rectus muscle. So it will help pull the eye up a little bit. Which is what we want to do. Because, remember, it was hypotropic in the first place. You can see that when we attached the vicryl suture, we did resect some of the tendon. I mean, there’s a lot of tendon that’s underneath the superior rectus that’s cut. Remember? That we didn’t isolate? So this muscle has also been tightened. Because, again, I want as much possible inward force. In other words, when we see him postoperatively, I want this eye to be esotropic. Because what happens is: The eye will tend to want to drift back out again. Even though the lateral rectus is not tight. Because what’s the position of rest of the eye? The position of rest of the eye is in abduction. Right? I’m right at the insertion of the medial rectus muscle.

>> Keep visualization of the metallic needle at about 30% to 40% depth.

DR FREDRICK: You can see how it’s grey. You can see it glinting there. You see also I’m putting this close together. I’m not trying to spread this out. Because this is a tendon, and I don’t want the tendon to be pulled apart. I want it to be right next to each other, pulling the eye in that direction. So here is the medial rectus. Here. Here is the superior oblique tendon, right on top of it. I’m going to do a forced duction here. No problem getting the eye in. And if I do a traction test here, I can’t move the eye any more than that. So the eye is nice and tight and fixed. Now, the other thing you need to be cognizant of is when we close the wound. Since this eye has been turned out this way, in abduction, for a long period of time, the conjunctiva gets all stretched out. So that if I were to just sew it back without removing some of the conjunctiva, the patient would be very unhappy, because it will be bumpy and look ugly. So I’ll do a little bit of a conjunctival resection as well. Remember also we talked about: You have the plica semilunaris, which is here, and you have the caruncle, which is here. In a sense, what I’m gonna do is I’m going to recess this a bit, so that the plica — this swelling will go away. This will flatten out. But the plica will be back here in its proper location. The other thing is: If I put this back like this, he would come in a week later, complaining that a lot of pain and irritation and photophobia — a dellen, exactly. A dellen can evolve into an ulcer. A dellen is just an area of epithelial loss and corneal thinning, due to lack of normal hydration of the cornea. That’s why we use ointment rather than drops. It’s always important, when you’re examining somebody with ptosis, to check the pupil. Especially before you dilate the patient. Once you dilate the patient, you’ve lost that ability. Also, when we dilate patients’ eyes, we often use tropicamide, and we often use phenylephrine. And phenylephrine will affect the lid position. It will correct some of the ptosis. Now, one thing I do want to mention is that there’s a newer technique that has been described recently, where the lateral rectus muscle is split along its length as far back as you can go. And the superior half of the muscle is brought underneath the superior rectus muscle, and sewn to the insertion of the medial rectus muscle. And the inferior portion of the muscle is passed under the inferior rectus, and sewn to the medial rectus muscle. So you transform the abducting muscle into a passively restricting adducting muscle. The reason I did not choose to do that is that there have been several significant complications, including optic nerve edema, including choroidal effusion, that have been described with that procedure. So in weighing the risks versus benefit, I chose to do a surgery which has relatively low risk. It has a good chance of increasing the alignment of the eye. We’ve reapproximated the conjunctiva. And now we’re gonna look and see if we have to do any additional adjustments. So you can see that nasally, there’s no heaped-up conjunctiva. Temporally, there’s recession of the conjunctiva. Superiorly, where we were working on our superior rectus, I have a little bit of bulging Tenon’s. I’m just gonna snip that Tenon’s. So I use the conjunctival hangback technique when the conjunctiva is restricted. So we did hang back this conjunctiva somewhat, but I don’t leave it hanging back too much, because — a couple things. If you hang it back too much, it’ll expose your insertion of the rectus muscle, which I think can put you at increased risk for infection, increased risk for scleritis, because you have an exposed operative muscle. So I don’t use it too much. And the last thing we’re gonna do — so I’m satisfied with the appearance of the eye. You can see the eye looks great. It’s nice and straight. If it stays this way for the rest of his life, I would be very happy. He would be very happy. We’re gonna inject some local anesthesia. Because this was a big operation. He’s gonna have some discomfort. We use a mixture of 4% lidocaine and 0.75% bupivacaine. The lidocaine is good, because it works fast and it lasts for a short period of time. The bupivacaine is good because it lasts longer. And this mixture is a nice combination. It’s the same combination which I’m sure many of you use when you do peribulbar anesthesia for your cataract surgery. So you can see I’m injecting it in the peribulbar space. I use a blunt cannula, so I’m not risking damaging the muscle, because it is possible to inject bupivacaine into the muscle inadvertently, which will cause restriction and muscle damage. That’s not possible when you use a blunt cannula. The follow-up for him will be: He’ll be seen in one week’s time. Once he’s healed up, then he’ll try a trial of taping therapy, where he’ll just use a piece of paper tape during the day, and see if he can find an area of single binocular vision. And then if all goes well, he can have a sling performed. Because he doesn’t have any intrinsic levator function. So he’ll need a sling, either using silicone or autologous fascia lata. Whatever is available here.

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October 31, 2018

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