HY USMLE Q #1575 – Neuro

Hinzugefügt: 2026-05-21

[00:00:00]How's it going, guys? We have a difficult question for neuro.

[00:00:03]28-year-old woman, 1 week history of normal movement sensation. She also reports decreased visual acuity in her right eye.

[00:00:10]Now, a neurologic exam.

[00:00:13]Reduced motor function left leg, loss of pain and temperature right leg, reduced vibration proprioception of left leg.

[00:00:19]I made this very simple. We're not talking about spinal levels and all the nitpicky little details, okay?

[00:00:25]If you look at this, you say, "Oh, that's not hard, Mike.

[00:00:28]Isn't this just Brown-Séquard syndrome, right?

[00:00:32]When you have hemisection of the spinal cord, you get ipsilateral loss of your corticospinal tract, contralateral, which is ipsilateral loss of motor function {slash} paralysis, depends on the severity.

[00:00:45]Loss of pain and temperature contralateral, that's spinothalamic tract.

[00:00:49]And then ipsilateral vibration proprioception, that's dorsal column.

[00:00:54]So, it sounds like a Brown-Séquard syndrome here.

[00:00:57]It is a Brown-Séquard syndrome.

[00:00:59]And then, um, ophthalmology ophthalmic exam.

[00:01:03]Ophthalmologic examination.

[00:01:07]All right?

[00:01:09]20 over 200 visual acuity in the right eye. Left eye is normal.

[00:01:15]So, talk about this in a moment. CSF analysis shows IgG oligoclonal bands.

[00:01:20]Now, some of you say that's hyper buzzy and easy.

[00:01:24]Which of the following is the explanation of the patient's findings?

[00:01:27]Try to say anybody is against aquaporin 4 stochastic wrong. That's Devic syndrome, D E V I C syndrome, aka neuromyelitis optica, shows up on a 2CK neuro form.

[00:01:42]Essentially, I'll make this real clean and simple.

[00:01:44]If you get a vignette on your USMLE where you're reading it and it sounds like multiple sclerosis, everything about it sounds like multiple sclerosis, but they go out of their way to tell you that CSF IgG oligoclonal bands are negative.

[00:02:03]That's going to be neuromyelitis optica and you have antibodies against aquaporin 4. You think it's weird? Take it up with the NBME exam. Don't take it up with me. Wrong [ __ ] answer.

[00:02:16]Choice B, recent trauma, wrong [ __ ] answer because what you're going to learn in this clip is that Brown-Sequard syndrome is not going to be someone who was stabbed perfectly through half of their spinal cord. You could say car accident, whatever. It's very rarely due to trauma, actually, for USMLE purposes. It's going to be autoimmune disease as per my observation across NBME exam. So, I'll we'll continue through the clip. Wrong [ __ ] answer.

[00:02:48]Choice C, T-cell attack against myelin basic protein, correct answer. It's multiple sclerosis. Now, I've seen this as an answer choice in NBME as a mechanism for MS. Well, you can also have an answer which is T-cell attack against oligodendrocytes. Yes, that is also an answer. So, USMLE, they can have different mechanisms here. So, you're going to have a T-cell attack against oligodendrocytes {slash} myelin basic protein. You have a woman 20s to 30s.

[00:03:17]You have white matter plaques in CSF. In CSF, the [ __ ] am I saying? In the CNS.

[00:03:24]And they like giving you optic neuritis. It can be miscellaneous findings with the eye. Decreased visual acuity in one of the eyes. They can tell you there's color blindness all of a sudden. They could say central scotoma, which is a blind spot. So, miscellaneous findings in the eye for optic neuritis.

[00:03:42]Of course, you can get MLF syndrome, medial longitudinal fasciculus syndrome, internuclear ophthalmoplegia, which is your inability to adduct one of the eyes when you look laterally with contralateral eye.

[00:03:59]That's more of a lengthy seminar. I don't want to get into it, okay? So, MLF syndrome and optic neuritis are the two eye findings you get with MS. And you can get Brown-Séquard syndrome.

[00:04:09]They like urge incontinence and you have a simile for MS. All right, so let's just continue through. T-cell attack against Schwann cells wrong [ __ ] answer. So, obviously this is going to be your Guillain-Barré.

[00:04:24]Now, I'd say only about one out of five questions, truthfully, they'll tell you that dude went to a barbecue and got bloody diarrhea. So, Campylobacter jejuni as a preceding cause. They don't really make it obvious. They'll just say 24-year-old dude has loss of motor function in the legs distally and proximally and has lost some motor function distally in the arms only.

[00:04:51]And you'd say, "Well, he's had ascending paralysis in the legs. It has not yet ascended in the arms. Holy shit." So, they can be a little bit slick with how they present it. Okay, but T-cell attack against Schwann cells there might be also a a secondary antibody mechanism, but Schwann cells in the PNS, peripheral nervous system. Point is, wrong [ __ ] answer.

[00:05:16]Viral infection, wrong [ __ ] answer.

[00:05:17]Now, this is a little bit slick because viral infections can absolutely cause autoimmune-induced Brown-Séquard syndrome, 100%.

[00:05:26]So, viral infections can cause a lot of weird things. You can get acute cerebellar ataxia. That shows up. Viral infection causing Brown-Séquard, viral infection causing ITP.

[00:05:38]De Quervain subacute granulomatous thyroiditis.

[00:05:41]Viral infections can cause toxic/transient synovitis, which is hip pain in a kid.

[00:05:46]So, you say, "Well, why couldn't this be viral infection?" It's because we give you the optha ophthalmologic exam as well.

[00:05:54]All right? In a woman 20s to 30s, and we have the CSF IGG oligoclonal bands. This is buzzy for multiple sclerosis.

[00:06:02]So, if we gave you the same exact vignette and then told you IGG oligoclonal bands are negative, the answer could have been neuromyelitis optica. Choice A. But, we gave you the IGG oligoclonal bands positive, so we're looking at multiple sclerosis.

[00:06:16]And viral infection?

[00:06:20]Wrong [ __ ] answer.