| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (BL) Class of 2022, Baylor College of Medicine, Houston, Texas |
| Description |
Summary: Brown Syndrome • Constellation of oculomotor findings o Will have defect in ad-duction of the elevated eye o Unilateral • Etiology o Congenital forms o Acquired forms > Inflammatory > Mass compression > Muscle paresis • Pathophysiology o Can be due to issue with superior oblique, trochlea, or less commonly due to an inferior oblique paresis (in this case called pseudo-Brown syndrome) > Differentiate by forced duction test, where determine if able to forcibly pull eye upward-when able to pull up, is pseudo-Brown because no restriction on elevation but have paresis of inferior oblique • Imaging o Can determine possible etiology through CT or MRI of orbit, and determine if mass or reason for restriction • Treatment o Treat by etiology o Like with other causes of strabismus, correct with prism, strabismus surgery. |
| Transcript |
So, we're going to be talking about Brown syndrome-Brown Syndrome is a constellation of oculomotor findings that suggest there is an etiology, but it by itself is not a diagnosis. So, when we have a patient who has an ocular misalignment, but it's only present in ad-duction--the elevation of the ad-ducted eyes is impaired for some number, might be four or three, something like that. You may have a downshoot in the ipsilateral antagonist. There are two forms, the acquired form and the congenital form. With the congenital form, there are many theories about what's wrong with the superior oblique and its tendon and there are different congenital types, but we're just going to stick to the acquired form today. The congenital form normally is easy to detect, is often asymptomatic in primary position and they basically have an ad-duction elevation deficit and ab-duction the eye can still go up. So, the main differential diagnosis is: is there something blocking the ad-duction in the eye or is there paralysis of the inferior oblique muscle. So, you have an inferior oblique paresis or you have something that's involving the superior oblique or the trochlea that is causing it. So, for the acquired Brown cases, the patients can't look up when they ad-duct, and if we do a forced duction where we pull on the eye with forceps to see if it will go up, that will differentiate whether it's an inferior oblique muscle paresis. It'd be like a pseudo-Brown's, for example Myasthenia Gravis, producing an inferior oblique muscle paresis, and so if you do the forced duction it will just go up because there's no restriction, it's just the paresis of the inferior oblique. This is very rare, so you should try not to make this diagnosis. Or, is there something wrong with the superior oblique muscle, trochlea, or something in that space? So, the most common cause is trauma right here-that trauma can be surgical, or it can be orbital fracture. So, the fracture is here or there's some sort of trauma here and causes scarring, and now that I can't go up in a ad-duction. It can also be from inflammation of the superior oblique muscle, myositis or its tendon trochleatis. The most common association is Rheumatoid arthritis, however the other collagen vascular diseases can produce it and a lot of the cases are just idiopathic. The congenital of course is idiopathic too. So, when you're dealing with a Brown syndrome, it has a very characteristic look-it can not elevate in ad-duction, it's usually unilateral and ipsilateral only problem. It can be congenital, you're born with something wrong with that trochlea and superior oblique muscle. It can be acquired, either from inflammatory disease, trauma, or mass right in the location of the superior oblique muscle and trochlea. Or, it can be a mimic paresis-forced duction can differentiate that. If you have inferior oblique paresis, you should really be thinking about myasthenia gravis, skewed deviation, and other unusual causes. If we image this you might see the cause here, CT in the orbit or MRI of the orbit. We're going to look right here for any mechanical causes. As with all causes of strabismus, we can do nothing or we can do prism, or you can have strabismus surgery. |
