medullary lesions

I just posted the previous quesion  last Thursday..I have progressive MS. Perhaps it would help to state that in my last MRI,  I  had two lesions in the medulla, that were determened to be 1.9 cm and 2.3 cm, large according to my neurologist. (I don't know how the judge what that means!) I am also experiencing dull neck pain and some problim swollowing.. As I said in the last post, I know that the data does not indicate a direct correclation with symptoms and the existence of lesions. But could the pain possibly due to the lesions in the medulla? Does the size  of my two lesions even matter, as the medulla is so small, that any size lesion could possibly have an inpact?

My problem: I have no idea what a lesion looks like, and how it could cause pain or obstruction of function. I have read the definition an MS lesion, but understanding the concept of lesion volumne, and how lesionst interact with nerves is beyond my current understanding. Could you possibly help educate me? Thanks so much.