I'm telling ya one thing...........I don't know how they tell the difference between MANY of those neurological disease, they all overlap so drastically.
Sometimes, it just boils down to "gut feeling" by the doctors, I hate to say. Some things they can rule out by "tests", but many more they can't because there aren't any tests or adequate "markers" or diagnostic methodologies that exist - yet - to make those determinations for certain. That's why you'll see so many people being diagnosed with different conditions each time they see a different doctor.
It is all mainly "subjective". No two doctors have ever yet agreed about what I may or may not have. And I've been hospitalized and tested since I was only a few months old. And I'm 49 now.
They still can't agree. Technically, I can claim I have just about any neurological disease you want to come up with, and it can't be confirmed! So, as I became accustomed to many years ago, I simply have a "CNS disease". Like my PCP said recently, we probably will never know for sure. I have suggested and my doctor has agreed that it would be good for me to do, is to donate my body to science upon my death. The only way to know sometimes for certain is via autopsy (or brain biopsy, which again right now, they can't do while you're alive).
In any event, a lot of the treatments for one neurological disease cross over and are helpful for others, also, so keep that in mind.
EDIT: That's why you'll see things that make the news as headlines if/when there IS a way to differentiate between diseases; the most recent example being the article the NMSS posted on their website regarding how they can now differentiate NMO from MS: http://www.thisisms.com/modules.php?nam ... opic&t=855
I'm not certain how productive it would be to try to continue down the road of whether or not your wife has been mis-diagnosed or not. But that's just my opinion. I'm just not certain it will get you anywhere. The more doctors you see, the more different diagnoses and opinions you may get. And then what?
SECOND EDIT: Well, darn, billf! Transverse myelitis encompasses quite a few diseases within it: Transverse Myelitis is a rare neurological disorder that is part of a spectrum of neuroimmunologic diseases of the central nervous system. Other disorders in this spectrum include, Acute Disseminated Encephalomyelitis (ADEM), Optic Neuritis, and Neuromyelitis Optica (Devic's disease).
Have you see this website yet? http://www.myelitis.org/tm.htm
It appears there isn't much difference, except that tranverse myelitis tends to be more of a one-time occurrence of problems, but if it happens again, they then will just say it has transitioned into one of those other diseases you see listed in that last link (MS being one of them). See what I mean? One overlaps the other!
So........bottom line..........can they "reliably" differentiate one from another? No, not really.