Lecture: Superior Oblique Muscle Palsy

Objectives of this presentation are:

  • To describe the typical findings of 4th Cranial Nerve palsy or paresis.
  • To learn how to use the “Three Step Test” to diagnose cyclovertical muscle palsies.
  • Participants will understand why the third step confirms the diagnosis.

Lecture location: on-board the Orbis Flying Eye Hospital in Binh Dinh, Vietnam.

Lecturer: Dr Rudolph Wagner, Rutgers – New Jersey Medical School, Newark, NJ USA


(To translate please select your language to the right of this page)

DR WAGNER: I think what we’ll do is we will do the pretest. Is this the pretest? Yeah. Okay. So you can read them. Oh, I’d better read them, because people are listening online. So ocular torticollis or head tilt related to the eye causes may occur in: A, Duane’s retraction syndrome, B, fourth cranial nerve palsy, C, congenital nystagmus, or D, all of the above. So who thinks the answer is A? Anybody? You can certainly get ocular tort — you can get face turns or head tilts in any of these conditions. Duane syndrome can make you horizontally turn your head toward the side, where the palsy is. 4th cranial nerve palsies make you tilt your head to one side. And congenital nystagmus — same thing. You can have an abnormal face position with a null point, a neutral point. In Duane’s retraction syndrome, the upshoot or overelevation of the adducted eye is secondary to inferior oblique muscle overaction. Is that true? Or is that false? What do you think? True or false? Not really. The upshoot is more related to — some people think it’s related to the sliding of the lateral rectus muscle when the eye — when you attempt to adduct it. It gets very tight. And it slips down on the globe and the eye goes up. But I think that’s maybe true. Because if you have a person with a Duane syndrome, and you start them — if I have it in my left eye, and you have me look up and toward the right, I’ll get the upshoot. If you have me look a little bit down, sometimes you get a downshoot. So I think it’s related to the direction of gaze that you’re in, and I think it’s related to the slipping of the lateral muscles, up or down, depending on which way you start. And how about this one? The findings of a right hypertropia, in other words, the right eye is too high, right hypertropia, worse when you look to the left — so the right hypertropia gets worse when you look over to that left side, and on head tilt to the right side — where you tilt your head to the right shoulder, typical of which problem? Right inferior oblique muscle palsy? A right superior rectus, a right superior oblique, or a right inferior rectus muscle palsy? So I’ll show you how we figure that out. Okay? So okay. I’m gonna describe the typical findings of 4th cranial nerve palsy or paresis, if it’s totally weakened. We’ll learn how to use the three-step test to diagnose the cyclo-vertical muscle palsies, and then you’ll understand why the third step confirms the diagnosis of the condition. So superior oblique muscle palsy, also called the 4th or trochlear nerve palsy — it can be congenital, or it can occur following trauma. Head trauma. When it’s congenital, there are usually family photos showing the head tilt, and they have large vertical fusional amplitudes, we call it. There’s often inferior oblique muscle overaction, and it may be bilateral. So here’s a real typical one. This is a girl who has a head tilt to the right. She wants to look straight ahead, read, or whatever she’s looking at in the distance, tilts her head to the right. Why does she tilt her head to the right? Because if you force her to put her head — straight-ahead position — look at her left eye. So she has a big left hypertropia in primary position. And when she tilts her head to the right, it gets better. The eyes look lined up. If she tilts her head to the left, it’s gonna even be worse. So this is a typical example of a left superior oblique muscle palsy. So whatever eye has the superior oblique palsy, they’re gonna prefer to tilt their head to the opposite side. So let’s talk about the three-step test. Dr. Parks, he called it the three-step test. The other name for the test — the third step is called the Bielschowsky head tilt test. And we’ll describe it. So step one: Which eye has the hypertropia? Which eye is higher in straight ahead gaze? That’s step one. And step two: Is the hypertropia greater when you look to the left or to the right? And the third step: Is the hypertropia greater on head tilt toward the right or toward the left? So you have to answer those three questions in order to make the diagnosis. So let’s look at some examples here. Okay? So this is a girl who has — oh, she likes to tilt her head a little bit to the right. And she has a left hypertropia. But we’ll see that in a minute. So she tilts her head to the right slightly. So the left eye is a little bit higher than the right. So when she looks to the right, the left hypertropia is greater than when she looks to the left. So she definitely has some overaction of the inferior oblique muscle. And when she tilts her head to the right, the eyes are level. Good alignment. When she tilts her head to the left, the left hypertropia is greater. So a left hypertropia. Worse in right gaze. And on head tilt to the left is a left superior oblique palsy. So here’s how you remember that. It’s left-right-left. Left-right-left, left superior oblique palsy. So therefore right-left-right is right superior oblique palsy. If you remember nothing else, remember that. Here’s another example. Same thing. She has a little right head tilt. Left hypertropia in primary position. And so — but let’s figure out how you really do this. Let’s go through the steps. How you figure it out. It’s easy to memorize it. I would rather you know how to figure it out. So step one: We have a left hypertropia. Now, if the left eye is hypertropic or higher, remember I told you the other day — if I make you fixate with that — I’m sorry. The left eye is hypertropic or higher, if I cover your right eye and make you use the left eye, we can then have a right hypotropic. Okay? So all you know when a person has a left hypertropia, okay, you know that you could have a weakness of the muscles that depress or lower the left eye — right? Which would be the left inferior rectus or the right… The muscles that… No, sorry. The muscles that depress or lower the left eye, which would be the left superior oblique or the left inferior rectus, right? Or you could also have — even though we call it a left hypertropia, you could have a right hypotropia. That means you could have a paresis of the right — of the elevators of the right eye. The right superior rectus or the right inferior oblique. That’s important to understand that, right away. So all we know is it’s one of these four muscles. That’s all we know at the first step. Right. So what we want to know is: Which — the next step is gonna be: Where is the hypertropia worse? In right gaze or in left gaze? So we know now that it could be one of these four muscles, and we know that the left superior oblique really is more in action in right gaze, and the right superior rectus is acting in right gaze. In other words, of those four muscles, only in right gaze are these muscles used. Whereas in left gaze, the left inferior rectus is prominent, and the right inferior oblique is used. So let me show you what I mean. So if I have… So I have a left hypertropia. My left eye is too high. Right? You know it’s one of these four muscles. When I look to the right, the muscles that are gonna be pulled — when I look to the right and look up a little bit — the elevator in right gaze is gonna be the right inferior oblique. Okay? It’s got nothing to do with — excuse me. The elevator of the right eye is the right superior rectus. Okay? And the elevator of the right eye is the right superior rectus in right gaze. That’s what it does. Okay? The elevator of the left eye in right gaze is what? The left inferior oblique. So you don’t even use that — you’re not using one of those muscles. The only muscle it could be in right gaze would be right superior rectus. However, if it’s a right hypotropia, that means that it could be a left… Excuse me. Right hypertropia, you could have a palsy of the right superior rectus, which elevates this right eye. But let me show you the next step. It’s easier to see it than talk about it. Of the muscles I showed you, the two muscles that work in right gaze are the left superior oblique, which would lower the eye, and if that was weak, or paretic, the left eye would go up. Or if I had a right hypotropia, the right eye was lower, and this eye was higher, I could have a weakness of the right superior rectus muscle. Does that make sense? Okay. So of the four muscles involved here, the only two that we had originally that could still be involved, because the… Let’s see. Because the left hypertropia was worse in right gaze, would be the left superior oblique or the right superior rectus. These are no longer in play here. Because they don’t work in that field of action. That’s clear. That’s really important. If you understand that, then we’re not gonna have any trouble. So now we have just these two muscles left. It’s one of these two that caused it. Now comes the third step. Okay? And the third step is: Which eye — when you tilt your head to the right or left, when is that left eye higher? And it turns out that it goes higher in her when you tilt her head — actually, this was flipped. This is not really — that’s correct. That is correct. This one should have been — the slide was reversed. Forget about this. But it’s worse when she tilts her head to the left. So it’s a left hypertropia. Worse on head tilt. Worse on right gaze and on head tilt to the left. So… So that means that, because it’s worse when she tilts her head to the left, that means that it’s left superior oblique palsy. Now, why is that? Okay? That’s what we’ve got to figure out. So we know the answer. Left hypertropia, worse in right gaze, on a left head tilt, is a left superior oblique palsy. But why — what’s important to understand is: Why is there a difference in the head tilt, and how do you figure it out? So here we go. So what you have to know is that the intorters are the superior oblique and the superior rectus, and the extorters are the inferior oblique and the inferior rectus. If I tilt my head to the left shoulder, in order to get — now my eyes are — the 12:00 position of my eyes is gonna be in this position. In order to get them straight, for me not to see tilted, my left eye has to intort toward the midline, and my right eye has to extort away from the midline. Is that clear? Is that understandable? Okay. So when she tilts her head to the left, if the left superior oblique is weak or paretic, then the other intorter, to move that eye to the midline, intort it, bring that 12:00 position to the midline and intort it — is the left superior rectus. That’s the other intorter in the eye. Okay? So because the left superior oblique is paretic, when she tilts her head to the left, the left superior rectus muscle fires, and that also elevates the eye in left gaze. And that makes the left hypertropia worse on head tilt to the left. Right. So the last step — we know it’s gotta be either the left superior rectus or the — excuse me. Has to be the right superior rectus, left hypertropia — we already established that. So what happens, when you tilt your head to the left, as I told you, the right — the left eye has to intort to the midline. And the right eye has to extort away from the midline. To maintain your single vision. Okay? But the right superior rectus has no need to fire, because — no need to become activated, because it’s an intorter, and you need to extort the eye. Right? So there’s no reason — so in that last step, when you tilt your head to the left, the only muscle that’s gonna act is the other intorter, the left superior rectus. So maybe this will show it a little bit better. So in step 3, the left hypertropia is greater on head tilt to the left, and her left superior oblique is paretic. So the left superior rectus fires to intort the left eye, and that causes the left hypertropia, as the superior rectus fires. Whereas the other muscle in question was the right superior rectus, but this eye has to extort, go out away from the midline, so there’s no need to fire the right superior rectus. So you know the answer is gonna have to be left superior oblique. Does it make sense? Do you understand? But, you know, but almost always, these cases that we see with head tilts, if it’s an eye muscle problem, it’s almost always the superior oblique. You know, that’s the most common of them. But it’s just… It’s nice if you can reason your way through it. Understand why it’s that muscle. So there’s a lot of… One of the things you can do, if you want to think about it, if you want to memorize the thing, you can go… Left-right-left, left hyper worse in right, left in right gaze, left head tilt, left superior oblique, so therefore, right-left-right is right superior oblique. And the last step of this was the differential between the left superior oblique and right superior rectus. So if it’s right — if it’s left-right-right, then you know it’s gonna be right superior rectus. If it’s right-left-left, it’s gonna be left superior rectus. So it’s confusing, but you have to think about it. And you can use it. But clinically, in practice, most of the time it’s superior oblique palsy. It’s very rare to get — I’ve seen in my life, I think, three inferior oblique palsies, which turned out — and they look like Brown syndrome. They look like you can’t elevate in the adducted position, in inferior oblique palsy. But, you know, most of the time you’ll see them that way. So once we’ve figured out that we have a superior oblique palsy and a hypertropia because of it, the most common surgical procedure is to weaken the inferior oblique muscle, because usually — especially if they’re longstanding — the hypertropia is — you get secondary overaction of the inferior oblique, which is the antagonist. You know the word antagonist? The opposite effect of the superior oblique. The inferior oblique has the opposite effect. It elevates the eye in the adducted position. So if the superior oblique is not working, the eye goes up, and it looks like you overelevate, when you look to the side. The opposite side. So that’s most of what we do. And if the hypertropia is — if the vertical deviation is worse in downgaze and you have a superior oblique palsy, then usually you have to — on downgaze with the opposite side, you usually have to strengthen the superior oblique tendon. So your options are to weaken the inferior oblique, tuck or strengthen the superior oblique, recess the opposite inferior rectus, or even recess the same superior rectus on the same side. So the simple way to look at it — there’s something called the Knapp classification, which tells you, depending on where the vertical is higher, where you do it. But to simplify it, if I have a right superior oblique palsy, and it’s worse when I look up and to the left, then you would weaken the right inferior oblique. If it’s worse when I look down and to the left, you would strengthen the right superior oblique. But you can also — if it’s worse when you look to the opposite side in the right eye, in downgaze, you can also elevate or raise up the left eye to meet — because the right eye doesn’t go down as well. You can raise the left — you can do that by recessing the inferior rectus on the opposite eye. So here’s a right — child with a little head tilt to the left. Right hypertropia. Right hypertropia worse in left gaze. Okay? Hypertropia worse on head tilt to the right, versus the left. See it’s level here? And here it’s higher? So he’s got a right superior oblique palsy. And his was congenital. And he had a 14-millimeter recession of the right inferior oblique. This is after surgery. So surgery works when you get the right diagnosis. If you do it. So this is back to the easy way to remember this. RLR equals right superior oblique, and therefore LRL equals left superior oblique palsy. RLL equals left superior rectus, and LLR equals — you’re gonna take a picture of it. That’s the best idea. And LLR equals right superior rectus. And then RRR equals LIO. LLL equals RIO. And then finally, RRL equals RIR, and LLR equals LIR. So, you know, it’s just something. The problem is — in Vietnamese, they’re not the same first letters. Right? They’re different. So how are we gonna do that? So somebody along the line must have figured out some kind of way to remember this in Vietnamese. I don’t know it. But we’re gonna try to figure it out. But like I said, this is more important for, like, a test or an exam, than it is for a patient, because most of the patients have superior oblique palsy, when you have that kind of thing. Now, this is what I was talking about earlier, about pseudo-inferior oblique overaction. Patients with Duane’s retraction syndrome often have upshoots, which can look like inferior oblique or downshoots that look like superior oblique overaction. But it’s not real. And we usually treat these by lateral rectus muscle recession, weakening, or Y splitting it. Because there’s some kind of a leash effect, we call it, where it slides, and this could take care of it. So this is an example of a Duane’s retraction syndrome, type 3, which means there’s a limitation of both abduction and adduction. So here he can’t abduct the left eye. Okay? And here he is in right gaze. And notice that he’s got narrowing of the lid fissure. Okay? And the left fissure widens on attempted abduction. Right? And here you can see, when he tries to look up and to the right, there’s overelevation, which looks like inferior oblique overaction, but really is related to this upshoot. I don’t have a picture of it here, but in many of these, if you start them looking down to the opposite side, you get a downshoot of that left eye. So just some examples quickly of some other vertical deviations. Thyroid ophthalmopathy, you can have inferior rectus — mostly involving the inferior rectus and the medial rectus. You get a hypotropia and esotropia with thyroid, most of the time. On orbital fractures of the floor of the orbit, you can get an entrapped muscle and you can get a hypotropia, or even hyper, if there’s damage to the nerve. And I was talking about this earlier. When they used to do retrobulbar anesthesia, they used to get a lot of inferior rectus fibrosis. Give you hypotropia. And it was very interesting. Because first you would get a hypertropia. Because of the damage to the inferior rectus. And then over the next few weeks, it would come down, down, down, down, down, and you would get a hypotropia, because it got fibrosed in height. And here’s a left orbital floor fracture, where there’s entrapment of the inferior rectus, and he can’t look up. And there’s something really interesting about this. A lot of kids, children, when they have floor fractures, they don’t necessarily have a lot of external signs. Like, they might not have an ecchymosis, black and blue. And they call it a white fracture. Right. White out fracture. And what happens is it just blows out, but it doesn’t show — it doesn’t take that much trauma to do it. And last time I had a patient like this, they called me to the hospital to go see, and he had double vision, and they thought he had a brain tumor, because he had new onset of double vision. They did an MRI, but they never looked at his orbit. They just looked at the brain. The brain was all normal. And when I went to examine him, I said… Boy. It looks like this could be entrapped. An entrapment. So we got a CAT scan and we saw it. We saw the fracture. But the kid kept saying — he goes — I told everybody. I was doing, like, tumbling over, and I hit my knee on my face, and no one believed me, he said. I told them that’s what happened. But they said I had a brain tumor. So, you know, but it’s important. Because you don’t necessarily get signs of external trauma in some of these cases. So here he is, after surgery, to free up the inferior rectus muscle. It came out well. So I think that’s gonna be it. I have a little bit — these are the objectives we talked about. I think we covered these very well. And we have the post-test. Which… Right? So this… Significant overaction of the inferior oblique… So yeah, definitely significant overaction, right, is more likely to occur in acute 4th cranial nerve palsy. No, that’s false. Right? So what is the answer here? What do you think? Which one is more likely? Congenital. Yeah. Congenital types. This is false, right? Yeah. The congenital type gives you the overaction. How about this one? The upshoot or overelevation of the adducted eye is secondary to inferior oblique muscle overaction. That’s true or false? False. Very good. And so a right hypertropia — worse in left gaze. So that’s right, left, and a right head tilt — right-left-right is which one? C. Right superior oblique muscle palsy. Right? Good. Okay. Very good. Thank you. And I think everybody should have a good weekend. Okay?

June 2, 2017

Last Updated: October 31, 2022

2 thoughts on “Lecture: Superior Oblique Muscle Palsy”

  1. There is a mistake on the PPT shown when the time is 19:44.The second line conclusion should be “RLL = LSR and LRR = RSR”.


Leave a Comment