| Identifier |
Why_aberrant_regeneration_is_unlikely_to_occur_after_ischemia_Lee |
| Title |
Why Aberrant Regeneration is Unlikely to Occur After Ischemia |
| Creator |
Andrew G. Lee, MD; Hannah Wang |
| Affiliation |
(AGL) Chairman, Department of Ophthalmology, The Methodist Hospital, Houston, Texas; Professor of Ophthalmology, Weill Cornell Medicine, New York City, New York; (HW) Baylor College of Medicine, Houston, Texas |
| Subject |
Aberrant Regeneration; Ischemia |
| Description |
Dr. Lee lectures medical students on aberrant regeneration. |
| Transcript |
"So today someone asked me about aberrant regeneration and why this finding for third nerve palsy means it's not ischemic. So there are some findings that have likelihood ratios that are positive. The likelihood ratio positive means that piece of information pushes us towards a diagnosis, and there are some pieces of information that are likelihood ratio negative, which means it makes it less likely to be the diagnosis. And so this finding that aberrant regeneration is present means it's much more likely to be a compressive lesion, and you're not allowed to have it in ischemia, and that is a LR (likelihood ratio) negative for that information. But the question today is why: what is the mechanism for this? So as you know in the nerve -- so this is the third nerve -- all nerves and all tissues basically have to have blood supply, and so the vessels are like little penetrating vessels. Those little penetrating vessels are vaso to the nerve. You could have that same thing for the blood vessel too, a vasa vasorum. And you notice that in the third nerve the little penetrating vessels go to the substance of the nerve, and so if you have small vessel disease you'll get a localized infarct, but it'll be in the middle of the nerve as opposed to a compressive lesion which is on the outside, and so it doesn't matter whether this is a tumor or for third nerve, the thing we're worried about of course is posterior communicating artery aneurysm. That compressive lesion is going to press on the outside of the nerve, and the outside of the nerve is where the pupil fiber is, so knowing this anatomy right here helps us in two ways. One is why is an ischemic palsy likely to spare the pupil. The reason is the pupil fiber is on the outside, but the small vessel ischemia that's causing an ischemic third is on the inside of the nerve, and so it spares the pupil so ischemic palsies tend to spare the pupil. But the other way that it helps us is in order to get aberrant regeneration, you have to disrupt the train track, so the train has to be pushed off of its track, and that's why compressive lesions cause pupil involvement, but also it disrupts the track. In a vasa nervorum small vessel ischemia, the train track the third nerve is never disrupted, and therefore when the regeneration occurs it's just normal regeneration. So when an ischemic third recovers, it just goes right back to where it was supposed to go. The nerve fibers just stay on the same train track versus compressive lesions like aneurysms which push the track. When you regrow, you might regrow to the wrong place, and that is called aberrant regeneration, and we just don't see it in ischemia, but you need to know a little bit about vasa nervorum to answer these kinds of questions." |
| Date |
2022-03 |
| Language |
eng |
| Format |
video/mp4 |
| Type |
Image/MovingImage |
| Collection |
Neuro-Ophthalmology Virtual Education Library: Andrew G. Lee Collection: https://novel.utah.edu/Lee/ |
| Publisher |
North American Neuro-Ophthalmology Society |
| Holding Institution |
Spencer S. Eccles Health Sciences Library, University of Utah, 10 N 1900 E SLC, UT 84112-5890 |
| Rights Management |
Copyright 2019. For further information regarding the rights to this collection, please visit: https://NOVEL.utah.edu/about/copyright |
| ARK |
ark:/87278/s60gggeb |
| Setname |
ehsl_novel_lee |
| ID |
1751101 |
| Reference URL |
https://collections.lib.utah.edu/ark:/87278/s60gggeb |
