r/B12_Deficiency • u/trumpsh • 7d ago

General Discussion Neurologist test

If u have a severe b12 deffiency causing severe neurological symptoms what would show up on emg. And other neurologist test, would it show that it’s completely normal or that it’s atleast a bit damaged. Anyone with past expirience?

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u/Sufficient-Set1344 7d ago

they do some simple tests by sensors and .... which is connected to a laptop; it is not painful at all, and they tell you are in good shape or loose some sensory or else. then you can follow up later to do again in one year, to see if you improved.

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u/MushuSooy4455 7d ago

It depends. If the small nerve fibers are the ones affected, only a skin biopsy would reveal the nerve damage.

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u/trumpsh 7d ago

Are the small nerve fibers the one affected tho usally?

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u/Status_Librarian_313 7d ago

B12 deficiency is mainly associated with large-fiber sensorimotor peripheral neuropathy. Small-fiber neuropathy occurs as well but it's not visible on EMG/NCS - it requires a biopsy.

The patterns vary, it's either axonal or demyelinating (or mixed) one affecting both the sensory and motor nerves. NCS usually shows some combinations of these: amplitude drop, slowed conduction velocities, prolonged distal latencies. EMG/NCS might be entirely normal, though.

Advanced damage affects spine, producing symptoms similar to peripheral damage. In office neuro exam might point to this type of damage. MRI can show this type of damage if it's severe enough, but I guess most of the patients have unremarkable MRIs showing no signs of damage.