MS is an autoIMMUNE disorder, not an autonomic disorder. Here is a web page that describes what an autonomic disorder is:
These do not show up on MRI's. Generally a diagnosis of MS won't be made if there isn't evidence on an MRI either of the brain or spine (or both), combined with clinical signs, sometimes a positive spinal tap, and other evidence of MS.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....