Question Title: b-12

Vitamin B12 deficiency affects the sensory nerves and spinal tracts affecting vibration and position sense and affects motor tracts in the nervous sysem as well. As multiple sclerosis paients can have these tracts affected as well, B12 deficiency can mimic problems seen in multiple sclerosis, but some clues can point you one way or another. Multiple Sclerosis often has the pattern of relapse then remit with multiple episodes. B12 defieciency progressively worsens (note - some pt's with MS describe this too). Multiple sclerosis can have other systems affected - for example, visual, coordination, tremor - and often years apart from the current problem. These are not features of B12 deificiency. In most cases history and exam can tell these two apart but sometimes one can mimic the other. If so, part of the workup could include a B12 level (and if suspicion is high, one can check Homocystine and Methylmalonic Acid levels, metabolites which are more sensitive for B12 deficiency) - these tests should give an answer if any question of B12 deficiency exists.