NBME 16 Answers ↦
itsalwayslupus
I was able to deduce the right answer, but what is the specific reason against "demyelination of the corticospinal pathways"? just out of curiousity
+1
2020-04-25T21:18:02Z
lsp1992
I believe it's because damage to the corticospinal tract would be considered UMN damage, while degeneration of motorneurons is LMN damage. LMN damage causes decreased reflexes. UMN disease would cause hyperreflexia....I think. That's how I reasoned through it at least
+11
2020-04-26T19:56:27Z
nbmeanswersownersucks
I also think you can rule out peripheral neuropathy because typically that includes both motor and sensory
+2
2020-05-16T20:55:00Z
saqeer
yes but is not Achilles an S1 reflex (sacral cord) ? how does the degeneration in lumbar cord affects it ? i rule it out first thing because of this :S
+
2020-06-21T19:38:47Z
meryen13
i think she just had a dics herniation. there can be problem with temperature and sensation in some case but those are usually very severe herniations. not sure tho... but it can on your differentials.
+
2020-06-22T16:01:49Z
djeffs1
I assumed that "motoneurons of the lumbar chord" means upper and not peripheral
+
2020-07-03T01:56:02Z
submitted by aoa05(22), 2020-04-23T22:07:17Z
Weakness with decreased muscle bulk implies problems that include the lower motor neuron system. Decreased DTRs implies a disrupted reflex loop but the absence of sensory loss implies that it is on the motor side of the reflex loop. Of the available choices, B is the best fit. "A" is arguably true because a strictly motor polyneuropathy (such as in lead poisoning) could account for the findings, but a 3-month course could hardly be called "acute."