DIP Episode 457 - Horner’s Syndrome (a USMLE perspective)

All right, welcome. My name is Divine. This is episode 457 of the Divine Intervention Podcast. There's gonna be a short podcast. It was gonna be focusing on something that's pretty, pretty high-yield to know. So, I'm gonna be talking about Horners Syndrome. I'm gonna be talking about it from a USMD perspective. Many of us have heard of Horners Syndrome and many of us know Telsus, Mayo Cicin and Hydrosis. And that's it. That's true. For the most part, people that have Horners, they're gonna have Telsus, they're gonna have Mayo Cicin, they're gonna have and Hydrosis. The only thing is there's a little more in terms of complexity that you need to keep in mind with Horners Syndrome that many resources don't cover or they just gloss over. So first, let's talk about the Telsus Mayo Cicin and Hydrosis and why you have those problems. Telsus means you have a Drupi eyelid. Well, the reason that people that have Horners Syndrome have a Drupi eyelid is because the superior tarsal muscles are sympathetically innervated, superior tarsal muscles. So, if those muscles don't work, then you will not be able to elevate your eyelid. So you're gonna have your eyelid being droopy. That's Telsus. Now, we know that your that your dilators of your pupils, your popular dilators, they are innervated by the sympathetic system as well. So if those don't work, then your pupils will not be dilated, they'll be constricted.

And then finally, you're also gonna have an Hydrosis, the absence of sweating because again, your sweat glands for the most part are also controlled by your sympathetic nervous system. So this is basically a result of sympathetic failure to the eye. Now, the thing is they can make you look allies on an exam exactly where a person's Horners Syndrome is based on the symptoms that you get. Because the thing is that Horners Syndrome pathway, many people just think, oh, it starts in the lungs. No, it doesn't. Or it starts in the spinal cord. No, it doesn't. It's actually a three-neuron system. To be honest with you, many pathways in the body, you know, it's very common to hear two-neuron system, two-neuron system, and that's fine for most exams. But if you truly want to understand certain things, you need to understand the many of these pathways we see in the body, actually three-neuron systems, believe it or not. So let's maybe describe the three-neuron system of this Horners Syndrome pathway. The first neuron literally starts in the hypothalamus. It starts in the hypothalamus and it comes down in disanes through the brainstem. It goes through the lateral brainstem. It goes through the lateral brainstem and then it goes through the cervical spinal cord. It goes through the cervical spinal cord, like the C-eats to T-2 levels. This is one of those reasons why if a person has a lateral brainstem stroke.

I've said there's so many times on this podcast, you'll notice that those people have some antecedents of Horners Syndrome. And then that's the second... So after that hypothalamic fiber synapses on the spinal cord, the second order neuron then goes from the spinal cord, right? It goes from the spinal cord and it travels in the cervical sympathetic chain. It goes through the brachial plexus. It goes over the top of the lungs, right? So over the apex of the lungs. And then it synapses at the superior cervical ganglia. It synapses at the superior cervical ganglia. This particular neuron releases acetylcholine. So many times when you hear of a pre-ganglionic sympathetic neuron, this second neuron in this pathway is the pre-ganglionic sympathetic neuron. Is the one that releases acetylcholine that's going to ultimately act on nicotinic acetylcholine receptors on the post-ganglionic neuron. But that post-ganglionic neuron is the third neuron, is the third neuron in this pathway, right? So from the superior cervical ganglia, so that those fibers coming from the superior cervical ganglia, they are post-ganglionic sympathetic fibers. So they're going to release things like norepinephrine, okay? So even if it's a post-ganglionic neuron, it's actually the third true neuron in this pathway.

So these fibers, the key places to know that they pass through is that they travel around the internal corroded artery and they travel through the carbonous sinus, they travel through the carbonous sinus. That's very, very important to give it mind. They travel through the carbonous sinus. And then after that's the nerve-eating things that then cause, like again, like the superior trussomal souls, like the pubillary diameters and things like that. So the thing is, so how do you know? Because you can have a lesion of any of these three neurons. The first neuron coming from the hypothalamus going to the CH2-2 level, the second neuron going from CH2 to CH2, and going to the superior cervical ganglia. And then the third neuron going from the superior cervical ganglia that travels around the internal corroded artery and the carbonous sinus and then gets to the eye. So how do you know what you're dealing with? Well, you know what you're dealing with by the additional symptoms you have. It is not, is very rare for Buddha just have a corner syndrome and it's just toses, meiosis and anidrosis that they have and that's it. So the other symptoms will tell you what you're dealing with, right? So say for example, you see a person also having pain and temporary, they have a corner syndrome, but they have pain and temperature loss on one side of the face and pain and temperature loss on the opposite side of the body. Then that tells you that that problem has to be with the first neuron.

It has to be a problem in that first neuron that is coming from the hypothalamus, descending all the way through the lateral brain stem before it goes to the cervical spinal cord from CH2 to CH2. Because again, those fibers, like I say, they go through the lateral brain stem and the lateral brain stem has fibers that control pain and temperature to the face and that's also where your spinal phyt systemic tract travels as is going through the brain stem. And many times you'll also see some cranio nerve deficits, especially like lateral brain stem cranio nerve deficits. Like for example, you may see the person having like, antecedents of Wallenberg syndrome, right? Like a dysphysia or swallowing problem, right? From a cranio-9 cranio-10 issue. But if the problem is in the spinal, if the problem is in the second neuron, because remember that second neuron, it goes through the spinal cord, right? And then it also goes around the brachial plexus and it goes around the apex of the lungs. So in that case, usually for the second neuron, you'll either see like signs and symptoms of a myelopathy, or some myelopathy, that's a spinal cord problem. So you'll notice that you have things like a sensory level, right? You notice that well below this level, they've lost all sensation. That's a very classic sign of a spinal cord issue.

Well, you may notice that people that have the second neuron problem, they're gonna have brachial plexus problems, they'll have brachial plexus problems because it's not like you just selectively damage that fiber and not torch some parts of your brachial plexus. So if you see a lot of hand symptoms, think of a second neuron problem. Very common cause of a second neuron problem is like a panko swimmer, a superior swacos swimmer. That's usually going to be scream a cell lung cancer, green at the apex of the lungs, and there's impingent on those fibers. Now, how do you know that you're dealing with the third neuron? The way you know that you're dealing with the third neuron is that typically, typically, typically, you're gonna notice that as well, gonna have a lot of extra ocular muscle deficits. Why? Because those fibers travel around the internal corroded artery and the also travel within the carbonous sinus, within the carbonous sinus. So if for example, you have like a cardinous artery dissection, or you have a carbonous sinus thrombosis, all those things can absolutely positively affect those third fibers. Right? So that's how you know. So if you see it all because remember, a lot of your acrocolomus ocular nerve travel through the carbonous sinus. So if you have problems with many of your acrocolomusules, right? And you notice that you have corner syndrome symptoms. That's a third neuron lesion. That's a third neuron lesion. That's a third neuron lesion.

So I'm gonna go ahead and stop here. This is really the thing that honestly matters. You know, there are some testing you can do to look at the super sensitivity. Those are fun to actually understand. But again, not very necessary for the USML. So we're gonna go ahead and skip that. So thank you for joining me today. I hope you find this podcast to be helpful. And I really hope it really helps you your understanding. Again, I offer review courses for step one for step two and step three of a bio stats class, a testing and strategies class, social sciences quality improvement and ethics class. And then I have these podcasts on the major apps. Apple, Google, Spotify, AvA You Tube channel, Divine Intervention, podcast and videos to You Tube channel like that's where I post the videos that I make. And then I also have a website called Divine Intervention Life Lessons.com. I post from a biblical perspective podcast that you know, address a life lesson. We have about 180 of those podcasts right now. You know, I put two every week, one on Friday, usually one on Sunday. So thank you for listening to me today. I will see you in a episode 458. God bless you and bye for now. Thank you.

Ptosis, Miosis, and Anhidrosis.

The superior cervical ganglion.

The second-order neuron (spinal cord/cervical sympathetic chain).

Pancoast tumor or superior sulcus cancer.

Damage to the lateral brainstem descending tracts (Hypothalamus $\rightarrow$ Brainstem).

The internal carotid artery and the cavernous sinus.

Hypothalamus $\rightarrow$ Brainstem/Spinal Cord (Neuron 1); Spinal Cord $\rightarrow$ Superior Cervical Ganglion (Neuron 2); Superior Cervical Ganglion $\rightarrow$ Eye (Neuron 3).

Extraocular muscle deficits, due to fibers passing through the cavernous sinus.

Pancoast tumor (Superior sulcus tumor).

The first-order neuron descending through the lateral brainstem.

Internal carotid artery and cavernous sinus (e.g., dissection or thrombosis).

Hypothalamus $\rightarrow$ Brainstem/Spinal Cord (Neuron 1); Spinal Cord $\rightarrow$ Superior Cervical Ganglion (Neuron 2); Superior Cervical Ganglion $\rightarrow$ Eye (Neuron 3).

Extraocular muscle deficits, due to fibers passing through the cavernous sinus.

Pancoast tumor (Superior sulcus tumor).

The first-order neuron descending through the lateral brainstem.

Internal carotid artery and cavernous sinus (e.g., dissection or thrombosis).