Paul,

I did a search of b-12 and nerve regneration in pubmed.  There
have been a number of studies done on rats and mice but I could
only find four that tried it in humans.  The only one that had an
abstract talked about experimental injections of methylcobalamin.

I'm not a scientist and am very much an amateur when it comes to
molecular biology.  So take what I say with big helpings of salt.

I speculate that this drug would not have much effect when taken
orally.  There are two reasons for that.  One is that very high
doses might be needed (one study of rats showed no benefit from
low doses) and such high doses might only be achieved by
injecting it into the area of interest.  The other is that
putting high doses in the body as a whole might have deleterious
effects on areas other than the ones we want to regenerate.

In any case, this sort of treatment is very, very experimental.
I don't know if anyone yet has any knowledge of what kinds of
nerves might benefit from the drug, or what the dose should be,
or what kind of damage might be regenerated, or what amount of
regeneration might occur, or how much, if any, function is likely
to be recovered.

But, as I say, I'm a rank amateur in all of this.

   Alan