Can multiple sclerosis lesions 'hide?'

Here is My Question:
I read there can be "invisible" lesions. The article I read said this ""Can you reliably see a lesion for every symptom? Is there a symptom or can you find an abnormality on the physical exam for every lesion that is seen? The answer is an unqualified "NO". It said too many doctors try to draw conclusions about this. 

My doctor said (whom I really do like), made the comment to me that according to my MRI (I had 3 years ago) and how I have been doing, I should never have a problem walking. My problems have always been "cognitive" so quite frankly I hadn't worried about my walking, however, it did bother me that he said this, as I felt he didn't know "ME". We have talked since then and I think he gets my concern, so he is having me get another MRI since I haven't had one in so long. My question, I guess, is do you agree with this article? Could I have lesions that are "hiding" or just not seen? 

Answer:
A standard MRI scan provides important information about the structure of your brain. But even though MRIs are highly sensitive to changes that occur in the nervous system, an MRI scan, like any other test has certain limitations:

1. It is almost impossible to visualize demyelination in the cortex of the brain with a standard MRI. This is the part of the brain where most of the important neurons are located. We also know from other studies that damage to the cortex of people with MS is very strongly associated with both physical problems and cognitive problems

2. The white spots visualized on a standard MRI represent only a small fracture of the tissue involved. More sophisticated techniques are required to visualize these so called normal appearing areas of the brain

3. An MRI tells us nothing about the functional connectivity of the brain. For instance, you could have two white spots that are the same size with one causing severe problems because of the disruption of wide spread functional connections in the brain, whereas the other white spot has no significant effect on any functional connections. Like real estate, location is everything in the brain

Hope this helps.

Revere (Rip) Kinkel MD
Director of the Multiple Sclerosis Program
Professor of Clinical Neurosciences
University of California San Diego