 Welcome back to our MedSmarter question of the week where we're taking a smarter approach to preparing future physicians. Before we get started, if you'll take just a quick minute and click that like button and also subscribe and turn the bell on so that you'll be notified when we post new videos. Let's get right into that question. As always, we start with the last sentence and then go back and read the rest of it yet. If this patient's vitamin deficiency is not corrected, what neurological symptoms is she most likely to experience? A 75-year-old woman with asthma presents to her primary care physician for an annual checkup. The physician performs a physical exam and orders routine blood work, which reveals a macrocytic anemia. Subsequent laboratory tests show an elevated serum methyl-malanoic acid level. A peripheral blood smear is shown in the image. If this woman's vitamin deficiency is not corrected, what neurological symptom is she most likely to experience? Alright, so let's take a quick look at this image here. I see red blood cells and I see neutrophils. The red blood cells, they appear to be maybe a little bit less biconcave than normal in some of these instances here, but the main thing that I'm looking at here is these neutrophils. Those neutrophils have one, two, three, four, five, six, seven, eight, nine, at least nine segments here on the neutrophil. So this is a hypersegmented neutrophil. Anytime they have six or more lobes in the nucleus, then that is a hypersegmented neutrophil. So what that tells me is we're talking about some sort of a pathology that has to do with a megaloblastic anemia. We also see the patient has a macrocytic. So we know macrocytic and megaloblastic anemias can go together here. She has an elevated MMA or methylmalinoic acid level. So we're asking about the vitamin deficiency if it's not corrected. The most common vitamin deficiencies that are associated with a elevated MMA level alongside of hypersegmented neutrophils is going to be either B12 or folic acid. However, folic acid doesn't give us the methylmalinoic acid levels elevations. So that means I'm going to rule out any type of an issue with folic acid and this is probably a vitamin B12 issue. So we've gotten to that point. Let's take a look at our answer choices. Take a minute, look at them, come up with your answer. Write it in the comment box below and we'll get right back. Alright, so we're looking for a B12 deficiency and what neurological symptoms could develop if we have B12 deficiency that gets worse. Well, first and foremost, one that stuck out to me when I read these answer choices was B. Deficiency in this vitamin does not cause neurological symptoms. We know that to be false because a deficiency in B12 does cause neurological symptoms. So therefore B is not an answer choice for me. Let's look at A, confusion and confabulation. This confusion and confabulation doesn't really fit well with B12. B12 is going to be more along the lines of nerve issues and not brain issues. So this seems to be more of like a B1 deficiency and Vernike Korsakov. So confusion and confabulation does not match B12 deficiency in my book. Disarthria and Diplopia, unable to articulate and double vision. This is going to be more probably a stroke-ish. I don't see these often in vitamin deficiencies so I'm not looking for these to be one of our possible answer choices here. Parasthegias and Ataxia. So that's going to be more along the lines of nerve issues. We said B12 has nerve issues. So I'm going to leave this one in. And then syncope and lethargy. Not often associated with B12. A lot of times people think that when they get the B12 that they'll feel better. But that doesn't mean that if you're low on B12 you're going to pass out. So we're going to take E out. That leaves us with only answer choice D as a possible answer. And D is the correct answer. So like we said here, this is a vitamin B12 deficiency. So we have those hypersegmented neutrophils. Remember we said it has six or more lobes. So hypersegmented neutrophils coming in alongside of a macrosidic anemia gives us a megaloblastic macrosidic anemia. What's going on in this specific case here is B12 is a cofactor for folate for the methyl group donation and DNA synthesis. Without B12 and folate present alongside of a megaloblastic anemia you get those hypersegmented neutrophils. And then all of our blood cell lines are affected because of the DNA synthesis defect. So with B12 deficiency you get the MMA in the elevation, the methyl malanoic acid elevation, and impaired myelin synthesis. So the myelin is what covers that. There's the myelin sheath on the nerve. And that helps with conduction. And it mostly affects the posterior and lateral columns causing peristegias and proprioception issues. So B12 alongside of a megaloblastic anemia always in the assembly are going to consider that to be the vitamin deficiency not folate. And we've got peristegias and ataxia. If you found this material helpful for your studying please like and consider subscribing to the channel. Also share this video so that more people can benefit from it like you have.