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Step I B1, b6, b12
Started by jammed
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Often by the additional symptoms.
Is the person also prone to autoimmune diseases? Have megaloblastic anemia? Have Crohns/recent ileal resection? ---> B12
Are they an alcoholic? Do they have high output heart failure? --->B1
etc.
I'm sure there's more to the finer details of the specific neuro symptoms between each deficiency, but definitely look for big picture things like those above first.
I can't imagine a USMLE question throwing a vitamin deficiency question at you without giving some additional hx/sx along with the neuropathy. For instance, you might have sensory/motor abnormalities in an alcoholic with additional symptoms of psychosis in B1; whereas in B12 you'll have a decreased vibratory sensation and paresthesias in a patient with a history of gastric surgery and chronic fatigue and perhaps they may even tell you they have megaloblastic anemia.
But to answer your question... the way I've always seen it is that B1 is more of a central defect with the brain itself.. so you'll see ataxia, eye movement disorders like abnormal EOMs and nystagmus, etc. In B12, the problem is a demyelination, so it's more of a peripheral and sensory disorder, affecting the posterior and lateral columns of the spinal cord... so you'll get decreased vibratory sensation and paresthesias. As for B6, it's pretty rare. I don't know the specific neuro sx for B6 deficiency. However, the most common cause of B6 deficiency, it's worth knowing, is isoniazid treatment for TB... so that might point you in the right direction...
B6 def causes a peripheral polyneuropathy, I think, along with sideroblastic anemia. Pellegra too ('cause it's necessary for the conversion of tryptophan to niacin).
OP, I think every thing you need is right here in this thread. They're not gonna ask you something like, "dude comes in with "numbness". Has a history of compulsive masturbation that was successfully treated with CBT. Which of the following reactions is deficient?"
OP, I think every thing you need is right here in this thread. They're not gonna ask you something like, "dude comes in with "numbness". Has a history of compulsive masturbation that was successfully treated with CBT. Which of the following reactions is deficient?"
good point about the b6 and pellagra, sideroblastic anemia... I think with the tb drugs the B6 def leads to mitochondrial damage ( don't remember the exact mech) which leads to the peripherial neuropathy.
