UWorld Form 1 Block 2 Question 1....

[Lord_Vader]

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How does alcoholism predispose to B12 deficiency? I thought B12 deficiency takes years to develop due to massive liver stores. In FA it doesn't mention alcholism as one of the risk factors.

 

[dfib slim]

Maybe he was an alcoholic for years, I forgot how that question was worded. Did he have the neurological findings seen with a B12 deficiency?

 

[Lord_Vader]

Maybe he was an alcoholic for years, I forgot how that question was worded. Did he have the neurological findings seen with a B12 deficiency?

Well the main neurological finding was a shock-like sensation that radiated to the feet on neck flexion. Two days later he felt better but he still had numbness and loss of vibratory sensation on the feet and ankles. It did say he was a long time alcoholic but they didn't give any hematological info and I was under the impression that B12 deficiency is something you see with vegans or pernicious anemia. I assumed that folic acid or thiamine deficiency was more common for alcoholics. Plus one major thing that threw me off is that the question specifically stated that muscle function was intact and that he had no weakness. Shouldn't B12 deficiency cause muscle weakness too? It was for that reason I thought he was having a pure sensory stroke and picked that as the answer. Maybe it was just a badly worded question but apparently 76% did get it right.

 

[dfib slim]

Well the main neurological finding was a shock-like sensation that radiated to the feet on neck flexion. Two days later he felt better but he still had numbness and loss of vibratory sensation on the feet and ankles. It did say he was a long time alcoholic but they didn't give any hematological info and I was under the impression that B12 deficiency is something you see with vegans or pernicious anemia. I assumed that folic acid or thiamine deficiency was more common for alcoholics. Plus one major thing that threw me off is that the question specifically stated that muscle function was intact and that he had no weakness. Shouldn't B12 deficiency cause muscle weakness too? It was for that reason I thought he was having a pure sensory stroke and picked that as the answer. Maybe it was just a badly worded question but apparently 76% did get it right.

The shock-like sensation on neck flexion that they described is called Lhermitte's sign and is caused by damage to the posterior columns. You can have muscle weakness as well but it isn't a requirement. I would think a pure sensory stroke would cause problems on one half of the body, not bilateral lower extremities. Also remember if you give someone folic acid who is deficient in B12 their neuro symptoms will get worse.

 

[Lord_Vader]

The shock-like sensation on neck flexion that they described is called Lhermitte's sign and is caused by damage to the posterior columns. You can have muscle weakness as well but it isn't a requirement. I would think a pure sensory stroke would cause problems on one half of the body, not bilateral lower extremities. Also remember if you give someone folic acid who is deficient in B12 their neuro symptoms will get worse.

Ahh that makes more sense. Thanks.

 

[pd1112]

Chronic alcoholism -> among other manifestations, liver disease (fatty -> hepatitis -> cirrhosis) + chronic pancreatitis.
1. Any degree of alcoholic liver disease (or any liver disease) would decrease the stores of B12.
2. Chronic pancreatitis -> pancreatic insufficiency -> malabsorption -> depleted fat-soluble vitamins & B12.
All of that is in FA but the dots are not explicitly connected.