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."
itsalwayslupusI was able to deduce the right answer, but what is the specific reason against "demyelination of the corticospinal pathways"? just out of curiousity+1
lsp1992I 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+20
nbmeanswersownersucksI also think you can rule out peripheral neuropathy because typically that includes both motor and sensory+4
saqeeryes 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+
meryen13i 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. +
djeffs1I assumed that "motoneurons of the lumbar chord" means upper and not peripheral+
dawgtor@saqeer , i had the exact same question.
Can someone please help me out with this?+
ali_hassanwell pateller reflex is also diminished and it's an L3/L4 reflex so I wouldn't have ruled it out that quickly. I agree with @meryen13 it was probably a disc herniation that affected L and S of the spinal cord+
chaosawaitsHow would "loss of afferent Ia axons innervating muscle spindles" present? That's the other I was torn between.+2
an1@ sexymexican888 seems like it, but ALS is LMNL + UMNL. this patient only has LMNL. UMNL is a neuron issue before decoration, whereas LMNL will be affecting regions after the decussate (as in when they've reached the spinal cord)+
submitted by โaoa05(34)
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."