I'm assuming that this neuro isn't an MS specialist, because the "..need 3 episodes for a final dx" comment doesn't fit in with the Mcdonald Criteria which is recognised world wide for an MS dx. Truth is, only 1 'clinical' episode is needed, if there is also enough evidence on MRI to meet time and space eg person has clinical episode of optic neuritis (ON) + MRI evidence of 2+ T2 brain lesions 'and or' at least 1 new lesion that lights up 'and or' 1+ spinal lesion.
http://www.medhelp.org/health_pages/Multiple-Sclerosis/Diagnosing-MS---The-McDonald-Criteria-Revised-2005-CHART/show/506?cid=36
The McDonald Ctiteria is a 'guide' to aid dx, its been revised numerous times because MS is difficult to dx. The guide when it first came out actually made it harder to get dx, it was interpreted to the letter and MS doesn't play out that way. There was also a reliant on MRI evidence and lesion counting, the revision tried to minimise this but unfortunately it still happens despite their attempts to fix it.
Do you actually know what your MRI report says, and maybe more important would be if you have had any other MRI's since the first 5 years ago and if there were chances etc?
I'm really sorry your in this possition! :o(
It does seem odd, for any neuro to put someone on a DMD for 5 years but still keep them in the 'possible MS' catagory. I really think it maybe time for a second opinion, so you know for sure if you do have MS or not. Getting MS confirmed by a neurologist that specialises in MS, sort of seems like it should be a prioriety after all this time. I dont know how long your neuro is going to keep you hanging, but still treating you for a disease he/she isn't willing to call, i think you've been hanging for too long already!
Hugs...............JJ