b12 deficiency is a major differential dx when trying to assess if someone has ms. i had b12 deficiency on my record when i was diagnosed but the docs paid no attention. computer glitch was partially to blame on that one :S
did your wife have a spinal mri too, and was it clear? 'classic' b12 deficiency syndrome involves cervical and thoracic spinal lesions. i had these at dx, but my docs told me that my additional brain lesions and oligoclonal banding etc in CSF were more in line with ms, so they ignored the deficiency back story. not cool. with what i know now, i could have argued back - but hindsight blah blah blah
iima, is your wife vegetarian or vegan? if so i would tend more to suspect insufficient dietary sources. that was my trouble. if not vegetarian/vegan, then b12 absorption could be the problem.
anyway, if your wife is b12 deficient according to the bloodwork, and has no spinal lesions, that sounds atypical. at very least, there should be some more tests done specific to assessing b12 status, such as CBC and PCA. CBC can tell you if hematological measures related to B12 are correct, and PCA tells you if an auto-immune problem is causing intrinsic factor trouble in the stomach, with associated absorption issues.
supplementing is doable regardless of the results of the PCA test and any associated absorption problems, by using biologically active forms of b12 tablets or strips that dissolve under the tongue 'sublingual', and are absorbed straight into the bloodstream.
research has shown a whole list of nutrients that are low in ms patients. i was all 'yes doctor, of course doctor, save my life, doctor' about the ms drugs at first, but before they could even send the nurse out for an appointment i had read enough to have second thoughts. my personal decision was to figure out what optimal nutrition was, get myself there, and then decide about meds later. i am still drug free, but the work i did with nutrition and testing was really effective in my case.
here is my favourite web page about vitamin b12 deficiency. i used to rely heavily on wikipedia until i learned what all the medical terms meant
but it's awesome. http://neuromuscular.wustl.edu/nother/vitamin.htm#B12
by the way this line under the Causes heading: 'Antibody vs parietal cells' is the PCA test i was talking about.
welcome to the site, and if there's a silver lining to what you're going through, it's the learning curve - knowledge is power! i'll check back for any more details you care to throw in
ps. 157 pg/mL is 115 in my units (pmol/L) and yep that's pretty bad. my worst level ever was 'undetectable'. i like to be at least 500 pmol/L - based on some research i read a few years ago - which is... 677 pg/mL. i'm not often that high but it's such a non-concern for me lately, that i have not measured in a while.