DIP Episode 543 - Facial Muscle Weakness and The USMLEs (+ worksheet)

Welcome to episode 543 of the Divine Intervention Podcast. In this podcast, I'm going to call this the Fischommossu-Wikness Podcast. Fischommossu-Wikness Podcast. This is going to be a pretty short podcast, but it's actually pretty high yield for a step one, step two and step three, and obviously, complex level one, two and three. So what if they give you a question about the 35-year-old male? And it tells you that, man, since he woke up this morning, he has been having trouble closing his right eye and whenever he tries to see, notice that, notice is that when he smiles, his face looks weird, that he has never had his face look like that before. What should you be thinking about? I really hope you're seeing this guy probably has bells, Paul's, guy probably has bells, Paul's. But I hope that I've kind of given you the vignette. Let's go into some little things here and there that are very important for the exams. This should be one of my shorter podcasts. The thing is on your exams, when you see Fischommossu-Wikness, you should think of two things. You should think of either bells, Paul's, or you should think of some kind of stroke. Bell's Paul's, you have some kind of stroke. And the stroke that will usually cause it, it depends, it depends. In fact, let me maybe give a more refined cause of Fischommossu-Wikness. You can get Fischommossu-Wikness because you have upper motor neuron problems or you can get Fischommossu-Wikness because you have lower motor neuron problems.

And the classic thing many people learn as they study for the exams is that, if you have an upper motor neuron cause of Fischommossu-Wikness, it's going to be the contralateral lower face that is weak and that's it and that's accurate. But if you have a lower motor neuron, Fischommossu-Wikness, you're going to get that from, you're going to get a Ypsilateral, upper, lower Fischo-Wikness. You can get Ypsilateral, upper, lower Fischo-Wikness. So, that's going to tease, and that's right as well. That's going to tease apart like, why is that the case? I think to understand that it is really helpful, it's really helpful to understand how your Fischommossu-Wikness works. Basically, your Mossu-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, your Fischo-Wikness, there's a two-neuron system that ultimately gets to those muscles. But remember, obviously, we have two crinonerv 7s. We have one on the right side, on the right side in the brinstem, in the lateral ponds, on the left side in the lateral ponds.

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They're going to do what? Calm down to the brainstem. They're going to calm down into the brainstem. And here's the thing, these upper moron neurons when they come down into the brainstem, some of them deal with the upper face and some of them deal with the lower face. Some of them deal with the upper face, so like your eyes and your forehead, some of them deal with the lower face, pretty much everything below your eyes and your forehead. Now, the thing is, these upper moron neurons, neuron number one, the ones that do the upper face, things are a little different with them compared to the ones that deal with the lower face. So let's start with the simple one first. Let's start with the lower face. Basically, neuron number one, the lower the upper moron neuron from the monocortex. When it comes down into the brainstem, the upper moron neuron dealing with the lower face, it gets to the brainstem and then it's going to cross to the other side. It's going to cross to the other side and hit the Fischo-Nerve. It's going to cross to the other side and hit the Fischo-Nerve. So, see for example, the fibers from the left primary monocortex, they'll calm down. So those dealing with the lower face, the upper moron neuron will calm down. It will cross from the left, it'll calm down, cross to the right side and then hit the right Fischo-Nerve. Okay. But the upper moron neurons that deal with the upper face, they do things a little bit different.

Again, they're still going to study in the primary monocortex, they're going to calm down. And then those fibers, the upper moron neurons for the upper face, they do something a little weird, splitting two sets. One set is going to cross to the Contralateral, cranial nerve 7 to the Contralateral Fischo-Nerve. But one set, the other half, I'm just going to stay on the same side and go to the cranial 7 on that side. Okay. Literally, stay on the same side and go to the cranial 7 on that side. Okay. So those upper face fibers, they actually hit both cranial 7s. Half of them hit the cranial 7s on the same side as the upper moron neuron. The other half hit the cranial 7 on the opposite side as the upper moron neuron. So if you think about it, it seems to occur with the other side, seems to occur with the other side. So basically, cranial 7, the upper moron neurons for the upper face, they hit both cranial 7s. But the upper moron neurons for the lower face, they hit only the Contralateral, cranial 7, if you understand this thing, you're going to be set for a lot of the integrations I'm going to make. Right? Because why would this be important? Well, this is going to be important because if you have like a stroke in the primary motor cortex, if you have an MCA stroke, it's only your Contralateral Lower Face that will be messed up. It's only your Contralateral Lower Face that will have weakness. Why?

Well, because the lower face, the upper moron neuron fibers for the lower face, they only go to the Contralateral, cranial 7. That's it. But your upper face will not be affected. Even if one upper moron neuron has been messed up, why? Because the upper moron neurons for the upper face on each side, half of the fibers go to the cranial 7 on their same side, and half of the fibers go to cranial 7 on the other side. So it's almost like every cranial 7 has bilateral innervation, bilateral innervation. All right? Bilateral innervation from those upper moron neuron, upper face fibers. So if you have a stroke of one upper moron neuron, the other moron neuron, the other upper moron neuron on the other side, is going to pick up the slack. It's going to help. So you're going to be in good shape. All right? So that's the way you know you're doing with an MC stroke. Because remember, MC does the upper extremities and the face. When you have an MC stroke, you're going to have Contralateral lower facial weakness. But your upper face is going to be completely fine. Your upper face is going to be absolutely fine. Because again, it gets bilateral innervation from both cerebral hemispheres. Okay. But what if you have an actual cranial 7 issue? What if you have an actual cranial 7 issue? Again, remember, all those fibers, the upper moron neurons, both for upper face, lower face, everything is going to converge at the cranial 7.

If you mess up the cranial 7 itself, see for example, for whatever reason, you mess up the lateral ponds, for example. And you get Belspaw's, remember, Belspaw's is a cranial 7 nuclear c-shoe. Then the upper and the lower face are going to be both affected. Okay? They're going to be both affected. They're going to be both affected. Because at the end of the day, it almost doesn't matter where, because think about it as like all the upper moron neurons, regardless from one side, the other side, they're all going to converge on that cranial 7 nuclear. So it's almost like you're damaging the central hub, which is the cranial 7 nucleus in the lateral ponds. So in that case, the upper face and the lower face on the same side is going to be paralyzed. So those who are going to have trouble closing their eyes, they're going to have trouble wrinkling their forehead and things like that. Yeah, many times on the USM is they love to focus on things like a week smile, or they'll tell you that, oh, this person cannot close their eyes very well, or they'll tell you that the person cannot wrinkle their forehead very well. If you see a person that cannot close their eyes, cannot wrinkle their foreheads, that person is easy. That tells you that weight. It's cranial 7 itself that is messed up. That's a peripheral, like, phisomosu weakness, peripheral cause of the phisomosu weakness, because cranial 7 is part of the peripheral nervous system, is derived from neurocrest.

But if you see a person that, oh, wow, they have lower phisomosu weakness, but they can close their eyes just fine, they can wrinkle their forehead just fine. Then that's a central cause of phisomosu weakness, because it's a primary motor cortex problem. It's an MC stroke. When your primary motor cortex is obviously derived from the neural tube, it's obviously derived from the neural tube. Let's make a few more integrations here. I already said that while divine, we can differentiate the MC stroke versus like Bell's pulse, MC stroke. Contralateral lower phis is going to be affected, but is that all? How do you know for sure, beating your chest that way? This is an MC stroke. You're going to see all the problems, right? You're going to see the upper extremities on the contralateral side as well, being paralyzed. Because remember, your MC supplies your upper extremities and your face. Depending on how bad the MC stroke is, especially if it's like an left MC stroke, you may see some kind of a phisia. You can see a broken phisia or a wrenic phisia. You may see some visual field deficits. Because remember, your optic tracts, your optic radicians, they cross the going the cortex around MC territory. So when you see all those things, that's going to tell you that all weight this person has an MC stroke, an MC stroke. But, Bell's palsy or cranial seven issue, it can be caused by many things. People can get Bell's palsy from an Aica stroke.

They can get Bell's palsy from an infection. Remember, an infection is actually the most common cause of Bell's palsy. It's the most common cause. You know, many things we think is from like reactivation of HSV1. That's pretty high yield to move for your exams, right? So you can get Bell's palsy from many things. You can get it from a lateral brain's pointin's stroke. That's an Aica stroke. You can get it from an infection of some sort. You can get it from an acoustic neuroma. Acoustic neuroma. So that's like a cranial each tumor. That's compressing cranial seven. You can get it from many different reasons, right? You can even get it from Lyme disease, especially with bilateral Bell's palsy and your exams, you should think of Lyme disease. So the question then is this, like, man, divine, how can I differentiate an Aica stroke as the cause of a person's Bell's palsy from? Like an infection as the cause of a person's Bell's palsy. Actually, it's pretty straightforward. So the thing is when you have an Aica stroke, you're not just going to have Bell's palsy, right? Your lateral ponds has been messed up. So you're going to see like peanut temperature losses on the opposite side of the body. Because remember, your spinal phalamic tract for the opposite side of the body runs in the lateral brain step. So see, for example, you have like an Aica stroke on the left. You're going to see loss of peanut temperature sensation on the right side of the body.

In addition to the Bell's palsy on the left side, on the left side. Remember, cranial 7-dose in cross, right? So like wherever it is messed up that you're going to see the facial muscle weakness on that side. Remember, this is peripheral, right? This is peripheral, not central. So that's something to keep in mind. So you're going to see like peanut temperature loss on the opposite side of the body, on the same side of the face, because the fibers that control peanut temperature for the same side of the face. We actually see them running the lateral brains them as well. But if you have like an infectious cause of Bell's palsy like Lyme disease or HSV1 reactivation, you're not going to see many of those other things. You're not going to see many of those other things like the present having the peanut temperature losses and things like that. You're not going to see any of those things. Now, one thing I'm going to say is an acoustic neuroma, remember we'll find it in NF2. An acoustic neuroma causing Bell's palsy many times, you're going to see more of like a gradual progression, right? More of a gradual progression. And typically those people will probably have like some degree of hearing loss as well. Because an acoustic neuroma is a tumor derived from cranial eat from your vestibular cochlear nerve. Because I know some people may say, divine, how do I differentiate these things? That's literally what I'm discussing right now.

I'm giving you like the ins and outs of differentiating one thing from the other. So I think I should go ahead and stop here. Maybe the last thing I'll say is that if you want to treat Bell's palsy and you know, it's not from like a stroke, not from an AI-castroque, then you should probably give the pressing steroids or steroids for a while. Tell them that, hey, guys, just chill within a few days, weeks or months, usually by six months or thereabouts. The pressing's face is going to return back to normal. Alright, so thank you for joining me today. If you like the way I teach, you may be interested in my 101 tutoring. I offer a lot of 101 tutoring for all the USM Ds, all the complex exams. I also, in addition to all these things, I also offer classes for the USM Ds, Step 1 or the Widow Step 3. I actually have a bunch of classes starting next week Tuesday for Step 1 or the Widow Step 3. You can check my website. I made a separate podcast where I talk about those like the test-taking class, biostat class, social sciences and QIN ethics class, last minute review for Step 2, Step 3, and then the 20-hour Step 2, Step 3 class. Also, the 25-hour Step 1 class. Just check those out. I have this podcast on Apple, Google and Spotify. They have a You Tube channel, Divine Intervention, USM Ds, podcasts and videos that you can check out.

Then I also have another website called Divine Intervention Lifelessens.com, where every week I post about a podcast or two, we're from a biblical perspective, I address a live lesson, Divine Intervention Lifelessens.com. This is actually an Apple podcast associated with that called the Divine Intervention Life Lessons Podcast. If you're interested in any of my classes or my tutoring, I'll encourage you to just reach out to me and I can give you some more information. Everything is over Zoom. Again, I'm not a person that gives lectures. I'm a person that teaches you how to prepare for the exam. Teachers are your clinical presentations, teachers are your integrations, explains pathophysiology. If you like that style of learning, then you're going to be interested in my classes. I'll see you in a episode 544. Have a wonderful rest of your day. God bless you and bye for now. Thank you.

UMN lesions cause contralateral lower face weakness only; LMN lesions cause ipsilateral upper and lower face weakness.

Because the upper face receives bilateral innervation from both cerebral hemispheres, providing redundancy.

Damage to the CN VII nucleus in the pons (e.g., AICA stroke or Bell's Palsy).

Infection, often thought to be related to HSV-1 reactivation.

An AICA stroke (affecting the CN VII nucleus).

Acoustic neuromas typically present with gradual progression and associated hearing/balance deficits.

Contralateral lower face weakness only (spared upper face).

Ipsilateral upper and lower face weakness.

The primary motor cortex fibers for the upper face.

Acoustic neuroma (Vestibular Schwannoma).

Ipsilateral involvement of both upper and lower face (LMN signs).

Lyme disease.

Contralateral lower face weakness only (spared upper face).

Ipsilateral upper and lower face weakness.

The primary motor cortex fibers for the upper face.

Acoustic neuroma (Vestibular Schwannoma).

Ipsilateral involvement of both upper and lower face (LMN signs).

Lyme disease.