MRI "raises a concern for previous demyelinating disease"

[gtg287y]

Basically, they found "small foci of periventricular white matter signal changes adjacent to the fourth ventricle" that seem like an atypical demelinating process, as well as a well defined old 6mm lesions at the base of the posteria fossa. BUT, since both the signal changes and the lesion are not supratentorial (they are in my cerebellum), it is "somewhat atypical of multiple sclerosis".

They go onto list a few types of tumors, tuberous sclerosis and ADEM as possible alternative explanations, but when I looked them up they don't seem to match my symptoms at all.

I have so many questions, if anyone knows the answers.

* What is the difference between a "signal change" and a lesion?
* Does anyone with MS on here have cerebellum lesions?
* If a "signal change" isn't a lesion, then they only found one lesion, and I need multiple for a diagnosis, right? If I had others, would they be in my spine?
* What if I only have the one lesion, what disease is that?
* From what I understand, the cerebrum controls muscles and balance. Since my symptoms focus on feeling dizzy, being unbalanced, walking clumsy and (sometimes extreme) weakness, that sounds like that lesion is my problem, right?