NBME 22 Herpes encephalitis (NBME Answers)

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Retired NBME 22 Answers

nbme22/Block 3/Question#50 (reveal difficulty score)
A 56-year-old woman is brought to the ...
Herpes encephalitis 🔍 / 📺 / 🌳 / 📖
tags: infectious_disease

+19 upvote downvote
submitted by ∗drzed(332)

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I'm a simple man, I see encephalitis and temporal lobe involvment, I click herpes.

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asharm10 hahaha true that, overthinking is the reason for getting so many questions wrong +

chaosawaits So the protein level is high based solely on the invading lymphocytes? That and the borderline low glucose had me thinking bacterial. +

l0ud_minority But why does it have a preference for the temporal lobe I wonder???? +

sunnyside @chaosawaits I think of LP labs this way: Bacteria eat CSF glucose (low CSF glucose) and poop it out as proteins (high CSF protein). Viruses don't eat CSF glucose (normal CSF glucose) and are composed of proteins (high CSF protein). Tho I did get this question wrong because the CSF glucose was annoyingly borderline... should've just gone with the buzzword +

+6 upvote downvote
submitted by ∗imnotarobotbut(184)

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Although there are no specific herpes indicators, a CSF panel with mostly leukocytes indicates a viral infection (as well as the normal glucose). So you can rule out TB, neurosarcoidosis and bacterial. Brudzinski/kernig sign are related to meningitis, but even if you don't know what those are, the question says that there is an abnormality in the TEMPORAL lobe (meningitis = meninges). Encephalitis would be the best answer, especially because Herpes Encephalitis affects the temporal lobe.

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taediggity Also look for Kluver-Bucy like symptoms in the stem +1

mambaforstep why? +

b1ackcoffee I agree with everything but normal glucose. Glucose here is NOT normal. to quote wiki "The glucose level in CSF is proportional to the blood glucose level and corresponds to 60-70% of the concentration in blood. Therefore, normal CSF glucose levels lie between 2.5 and 4.4 mmol/L (45–80 mg/dL)." +

baja_blast NBME reference table gives normal CSF glucose to be 40-70 mg/dL. As far as I'm concerned, for the purposes of the exam the reference table is probably a better source than wiki. +5

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