Not all MRI's pick up lesions. A 1.5Tesla machine isnt as powerful as a 3.0Tesla.

If you have neurological signs that can be detected on a physical examination, you probably have an MS lesion somewhere. If your neuro is good at what they do, they can usually tell you where your lesion is based on where/what your symptoms are. Some neuros however, really want to be able to confirm it with an MRI.

My neuro told me that I probably have a lesion somewhere on or near my thalamus, told me that my symptoms (right side numbness, from nearly head to toe) was a symptom of a lesion on the left side of my brain around the thalamus. My neuro is probably in his mid-80s, so he's been doing what he's doing for quite awhile. (I think he's got a diploma in his office that's dated 1948) If you have a younger neuro, he/she might have been taught to back up their "theories" with "data" (MRI scans and blood tests and LPs)

My neuro diagnosed me based mostly on symptoms. I had a couple of MRI's that showed lesions in my spine (T-12 and C-4). I'd had an MRI earlier that year that showed a few white dots in my brain, but they said that was due to my history of migraines. (the dots were in areas that werent "typical" for MS)

Have you had an MRI of your spine yet? Lesions can be found anywhere that there's brain matter. (brain, spine and optic nerve)